# Central Air Q's for the HVAC Peeps--UPDATED W/Quotes



## thinkxingu (Dec 4, 2011)

Hello All,
     Planning to have central air installed this spring.  We have a split-level home, 1500 sq. ft up, 1000 down.  Since the basement is half underground, and usually maxes out at 75 on the hottest days, can I get by with just installing vents upstairs (via the attic)?  We have all new windows, doors, siding, etc., so I'm thinking a 2.5 ton with vents in the ceilings of every upstairs room will do--and the cool air will drop to the basement.  The 2.5 ton is a bit bigger, but since it will be in the attic, I think it makes sense.

Thoughts?

S


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## dave11 (Dec 4, 2011)

Do you already have ducts in place? If not, you might look into a ductless mini-split system. Less hassle to install, and less wasted energy to air/cooling losses from the ducts themselves.

If you are going with ducts, you need to base the size of the unit on the heat calculation done for the structure. No way to just guess and get it right. Most companies tend to install units much bigger than you need, which costs more out of pocket, and leads to frequent cycling, which wastes energy for the life of the unit.


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## thinkxingu (Dec 4, 2011)

Dave,
     We do not have any ducts, since we have electric heat, but the attic is wide o  pen to run ducts to all the top floor rooms.  The issue I was thinking with the mini split is that it would be on only one end of the house (our wood stove is on one end and, though it does a good job of heating the back rooms, there is a few degrees difference).  To put it on both would not work, since we don't have a shared wall on one end (the hall goes right into a bedroom).
     As for the calculation, I did one using a calculator I found and it said between 2 and 2.5. Since the handler would be in a hot attic, I figured the higher of the two.  Can I assume the HVAC people should be able to do that/that it would be part of a good service's routine?

S


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## schlot (Dec 4, 2011)

My two cents:
Both living areas need to be ducted and returned - balance and humidity would be an issue
Don't put your handler in the attic - maintenance would be a nightmare
Upsizing generally is a poor idea - typically will result in more spikes in temperature and more humidity (both related to less run time of the unit)


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## thinkxingu (Dec 4, 2011)

From what I've seen, what I'm thinking of doing is fairly common- where else would one put the handler?  As for both zones being ducted, that would be much more difficult and costly and result in my losing a lot of closet space.  One person recommended just putting a return in the basement.

S


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## woodgeek (Dec 4, 2011)

I retrofitted a central air (and heat pump) into a 1960 house.  I agree with above that you need to run some air to the lower story for dehumidification and ventiliation, period.  In my case, I ran two 6" round insulated ducts along one side wall of a bedroom closet.  I walled them in, losing about 8" of 'rod length' in that closet.  No bigs.  We cool and heat the downstairs through those.  You also likely have a plumbing stack you can drop at least on good sized line down, if it ends in the right place.

As for the attic thing, modern ducting code is R-8 insulation on rigid or flex ducting.  My guy went with a rigid metal fabbed duct for the 'trunks' with a heavier insulation, with R-8 flex branches.  No problem with it except the guy undersized and did not insulate or airseal the central return--but we got that fixed.  And my roofers tromping through my attic stomped on everything, breaking flex and rigid seams and caving in the rigid ducts in a couple places...got that fixed too.  Watch ANY non-HVAC workmen in your attic.

Make sure the air handler is located in an accessible location, you have a hatch big enough to get it in an out, and have them hang it from the roof, rather than sit it on the 'floor' (for noise).  Also, remember that all systems will eventually leak condensate, no matter what they tell you about interlocks and safety systems.  Mine waas mounted over a load bearing wall, so the water ended up 15' from the source, ugh.  Install a water alarm yourself.


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## flyingcow (Dec 4, 2011)

Used to install HVAC(not design). All good posts. Properly designed and balanced system is critical. I agree with the returns in the lower levels. Stay away from flex duct as much as possible, no more than 12 inches long. (Horrendous air flow restrictions) Very good point on hanging from roof, or have it on properly sized isolators. Pay attention if you hire installers.  I have  followed crews and "fix" the hack jobs. I have seen "fittings" made of cardboard that was duct taped together and painted silver. Don't forget, you can hide an amazing amount of screw ups when the ductwork is insulated. If they show up with duct tape anywheres on the job, be aware. Some guys use it to seal joints(connections). Horrible idea. Only use approved sealant. kind of went off on a rant, sorry. does a mini split sound better?


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## thinkxingu (Dec 4, 2011)

Am I right about needing multiple mini-splits?  How far away can they be and still be effective, and will the air move around corners?  I get the hanging idea, and there's a pull-down that should fit the handler through.

About the downstairs, would it be sufficient to have just one central return and no vents?

S


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## gzecc (Dec 4, 2011)

I also installed ac in my house. I would only recommend rigid trunk line followed by insulated R8 flex (< 5') to each register. I would also run at least one return and one supply to the lower level. They should be positioned far from each other. When installing in closets, use interior walls and install rectangular 3x10 ducts that fit inside the stud cavity. You really only need two walls to line up to get a register in the lower ceiling. This won't take up any living space. You will however need to do some sheet rock repair.


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## thinkxingu (Dec 4, 2011)

One contractor said I could run a return to the basement through a closet almost dead center of the house, but getting supplies would be harder. What about the mini split- can that be on one end of the house? It's 40 feet or so end to end.

S


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## schlot (Dec 4, 2011)

Good info. Are you doing this work yourself? Remember RA (return air) duct work should be about 20% larger than SA (supply air). Also SA ducts to the exterior wall and RA on interior walls (if using more than one)

I agree on keeping flex to minimum. Code allows more than I'd recommend because of the turbulence (noise and additional flow restriction problems)

You can use soffits and wall extensions as areas to place the duct work or as pipe chases.


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## thinkxingu (Dec 4, 2011)

schlot, I was thinking about it, but from what I've heard from contractors is that the labor portion isn't all that much--specifically, that the work I wouldn't want to do (working in the attic) would only add a few hundred dollars.

I've attached a diagram of the top and bottom floors of my home--maybe it will help with suggestions.  The return I've mentioned I could put in would be over the stairs (going from inside a closet to the basement).

From what I've found, a mini-split is only really good for up to 30', which is definitely not enough.  The question becomes, then, how much I try to get to the basement--remember, the hottest it ever really gets down there is high 70's, but it does get humid.

S


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## dave11 (Dec 5, 2011)

Ductless mini-splits are not as common yet as the traditional ductwork and central system, but they are gaining popularity. Bit not many people have much experience with them. Never heard the limit to 30 feet of run. Where does that come from?

A friend here just retro'd his 1910 brick 4 floor home (3 living areas plus basement) with ductless splits. He has no complaints. There's one air handler on the top floor, two on each of the middle floors, and none in the basement. 

AS for your basement, I can't imagine it would need to be actively cooled in your climate. Plenty of cool dry air will pour down from the upper floors. As for moisture, a devoted dehumidifier with drain would be much preferable IMO to keep it dry, as opposed to running the central system for that purpose, or putting in a separate air handler there, if you go ductless. Is moisture a big problem? If so, you might look into reducing the entrance of moisture into the basement, rather than trying to remove it later.


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## thinkxingu (Dec 5, 2011)

Dave,
     I read about the distance issue, and thought it made sense since (if I'm not mistaken), there's only one source of air in the mini split system?  I do have a dehumidifier in the basement, but it would be nice not to have to run it for sound and cost purposes. In the winter, it's off.

S


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## maverick06 (Dec 5, 2011)

CONSIDER A HEAT PUMP

yes, I did mean to put that in caps. We had our AC replaced a few years ago. of all the companies that came to quote us only one mentioned "oh yeah, well for an extra $500 (i think) we can make it a heat pump" that was is... nothing else. 

smartest $500 I ever spent!  The thing is wonderful on the shoulder season. I buy my wood and if it is over 45F I let the heat pump run. The existing oil heat in the house is left there as a backup (if there is a large demand or if it goes below 20F, thermostat does all that). 

Even if you use the wood stove mostly, I suspect that $500 will have a very fast return on investment! Especially when you sell your house. 

Rick


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## woodgeek (Dec 5, 2011)

^^^^^ Yeah, what mav said!


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## thinkxingu (Dec 5, 2011)

Does the heat pump thing only count for the mini split?  I'm still trying to figure out if the mini split is an option.

S


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## maverick06 (Dec 5, 2011)

my heat pump/ac is a 3 (or 3.5 ton i forget) ton outside, primary (not split) system. I would suspect that you can make any AC a heat pump depending on the manufacturer. not sure, the manufactures info should be able to identify.


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## mrfjsf (Dec 6, 2011)

Definitely go heat pump, weather traditional split system or ductless split, go heat pump. If you go heat pump, you will need to add return ducts at floor level, otherwise, you will shortcycle the airflow. 

They make ductless splits that can have more than one indoor coil run off of one condensing unit (outdoor unit). IMHO, ductless splits are great if you have an open floor plan. If you dont, and you only use 1 or 2 indoor coils, you will be uncomfortable. 

I like the idea of having the air handler in the attic and running drops into each room. I see air handlers in attics and behind knee walls all the time and they work fine. Biggest thing is INSULATE and AIRSEAL the ductwork. Minimize the amount of flex to no more than a five ft run off main trunk. Im assuming you are having a professional install this? Make sure he at least does the above few things. If he says he wants to flex duct your whole attic, politely ask him to leave. 

2.5 Tons will be fine for your space. Your sq footage is closer to 2 ton than it is 2.5, but honestly, I like to oversize just a pinch. It gives you flexibility to add a run or two to an addition and not overwork your equipment. And your not too badly oversized to the point you will be shortcycling. If you do wind up shortcycling, you can add in a delay on make timer to keep it from straining the compressor. Certain mfg's will even give an option for adding a "anti short-cyling" or "compressor protection" kit.

You dont really need to "condition" your basement, unless it is finished. If it is unfinished, just run a dehumidfier and be done. With your slight oversize, you will always have the option of running a few drops down from the attic in a stud cavity if you ever feel the need for a/c down there.

Hope this helps.


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## thinkxingu (Dec 7, 2011)

mrfjsf--that was perfect.  One piece of clarification: the basement is finished, and I've run a dehumidifier down there these last few summers.  It usually needs to be emptied every other day.  I think it will be easy to run a return, but maybe not a supply.  Will a return help with the humidity, or should I really try to get a supply or two down there.  If the latter, which rooms would I choose to put it in or do I just do the rooms I'd be able to get to through closets, etc.?

Thanks again!

S


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## mrfjsf (Dec 7, 2011)

thinkxingu said:
			
		

> mrfjsf--that was perfect.  One piece of clarification: the basement is finished, and I've run a dehumidifier down there these last few summers.  It usually needs to be emptied every other day.  I think it will be easy to run a return, but maybe not a supply.  Will a return help with the humidity, or should I really try to get a supply or two down there.  If the latter, which rooms would I choose to put it in or do I just do the rooms I'd be able to get to through closets, etc.?
> 
> Thanks again!
> 
> S



Sorry, I just found your home layout sketch on pg 1 and realized your basement is finished. Doh! 

My suggestion for the basement is; if you are happy with the comfort level in there in the winter and summer AS-IS, then leave it alone. If you only put a return in the basement, you will not actually be exchanging air in the basement for the benefit of comfort. Remember, in order to have an air exchange and maintain comfort in a given space, you must be able to pull out the same amount of air you put in. That one lonely return in the basement will draw air down your steps and straight to the return. If you want to try and take just the "staleness" out of the air, then I suggest making a supply drop at one end of the basement and a return drop at the opposite end. I suggest the supply in the downstairs living room and the return in the downstairs kitchen. It's not going to do much for the areas that are divided by walls, but it will at least allow for some airflow down there.

Once again, if you are happy with it as is, just leave it be.

As far as drawing humidity out of the basement, 1 supply and 1 return is bare minimum to accomplish any kind of dehumidification. Another thing to keep in mind (I know this is a lot), the more humidity you subject your hvac system to, the more system capacity you are using. So, if you plan to FULLY condition your basement, you will likely need to upsize to a 3 ton system. 1 or 2 supplies and a return wont hurt you at 2.5 ton, but full ductwork downstairs will. You can help offset this by running your dehumidifier on a low setting.

Hope this answers your question.


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## sir james (Dec 7, 2011)

flyingcow said:
			
		

> Used to install HVAC(not design). All good posts. Properly designed and balanced system is critical. I agree with the returns in the lower levels. Stay away from flex duct as much as possible, no more than 12 inches long. (Horrendous air flow restrictions) Very good point on hanging from roof, or have it on properly sized isolators. Pay attention if you hire installers.  I have  followed crews and "fix" the hack jobs. I have seen "fittings" made of cardboard that was duct taped together and painted silver. Don't forget, you can hide an amazing amount of screw ups when the ductwork is insulated. If they show up with duct tape anywheres on the job, be aware. Some guys use it to seal joints(connections). Horrible idea. Only use approved sealant. kind of went off on a rant, sorry. does a mini split sound better?



12" of flex?Might as well not use any,you`ll have no problems if the flex runs are kept to a minimum,around 6' or so.
Air handler in the attic is fine,just make sure it`s left accessible.


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## gzecc (Dec 7, 2011)

Think, 
With regards to a return in the basement, realize the possibility of creating a negitive pressure situation. Do you have carbon producing appliances in the basement?
If you do, account for any negitive pressure that may be created by a return only, in the space. You don't want to wake up dead!
Try to equilize the pressure with a supply and return of the same size or smaller.


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## thinkxingu (Dec 7, 2011)

OK, to summarize:

1. Air handler should be suspended in attic
2. Solid ducts for the trunk, flexible for 5' or less to each of the rooms
3. All ductwork insulated at R8 or better
4. If doing anything in basement, at least BOTH a return and supply--far enough from each other
5. 2-2.5 ton is about right--to be calculated exactly by HVAC tech
6. Make sure installers don't screw things up in the attic/check for leaks, etc.

One last thing: does shape/size/placement of vents make a whole lot of difference?  I've read vents are usually placed over windows, but one installer said it wouldn't really matter (I'm not sure if it's because he was looking for symmetry with my in-ceiling speakers or because it would have been an easier install, or because he's right).

S

PS My in-ceiling speakers (in every room) are round--should I get round vents?


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## mrfjsf (Dec 7, 2011)

thinkxingu said:
			
		

> OK, to summarize:
> 
> 1. Air handler should be suspended in attic  Yes, or on anti-vibe blocks
> 
> ...



Post up what the install guys come back to you with on a quote and scope of work. When they come to install the system, pm me and ill give you my phone number if you have any questions or if something looks fishy while they are doing the install. Im tired of seeing people get ripped off or BS'ed when in comes to hvac installs and service work because they know that the avg homeowner does know jack about the workings of an hvac system. Dont want to see that happen to a fellow member.

Cheers!


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## flyingcow (Dec 7, 2011)

mrfs- is spot on. Not that you didn't know that already.

Proper sealing of ductwork is often half assed. Sloppy work often is the norm. Leaks will loose A/C or heat and will effect the flow in the rooms. You want all of your return air coming from the rooms, not attic. Be easier(less $$$'s) to cool return air from the rooms than a seriously hot attic. 

I don't even like any flex runs over 2ft. The last 2 ft to the register. What sometimes happens is the hard duct won't fit easily, but the flex will be jammed in tight spots. Squished, used to make 180 degree turns, etc. 5ft is OK as long as its straight and stretched out a bit. If possible i would put an elbow on top of register to make the turn and connect straight flex in between. And check the straps used to tie the flex on, lightly pull on flex to see if it comes off.

I agree with the ductwork insulated on the outside. Sometimes we would insulate(inside) the first length of duct off of the unit, as stated above this was for noise. It works well.

BTW- all these points made are alot of times easier said than done. Most generally its a PITA to retrofit a house after it's completely built.

If possible with hold the last 25% until you have a punch list done, and the system runs for a few days to see if it performs as designed.

Good Luck!


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## thinkxingu (Dec 7, 2011)

Guys, thanks for the info--truly.  I called three local mom & pops today, all in my town (I'd like to keep the money in town, if possible).  All three sounded like they wanted the job, and it was good talking to them with some information on what I want.  Two of the three said they do what I'm asking fairly often, and lately they've been doing them with heat pumps.  Those two also said they've had good luck with just cooling the upstairs and letting the cool air drop.

Only one mentioned brands, and he was all about Trane.  So, brand info?  I've seen Goodman, York, Trane, and Westinghouse in the area.

S


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## mrfjsf (Dec 8, 2011)

-Trane(American Standard)makes a good piece of equipment. Can be frustrating to work on because they are very different from any other brand. The saying at work goes "It may be hard to stop a Trane, but when it does, its even harder to get it going again". In my experience, parts for Trane can be a little higher than competitors. Would I install Trane equipment at my house, maybe. It would come down to a "how much can I get for my money with Trane vs Competitor A?"

-York in my experience is a good brand. They build a nice quality product and have a some pretty nice units out right now. They are affiliated with Johnson Controls. Johnson controls is top notch. I would own York equipment no doubt.

-Goodman is junk IMO. At least the ones ive worked on have been. They are cheaply built (very thin guage metal, pisspoor design, etc). A fellow tech told me Goodman is starting to clean up their act nowadays and building better equipment. Im not sure, I still wouldnt own goodman products. Im sure someone will chime in and sing praises over their goodman furnace, or tell you their neighbor has had their goodman since 85 and it runs just like new. Good for them, maybe they got one of the good ones, i dunno. I still say they're junk.

-Westinghouse is made by Nordyne. I don't have a whole lot of personal experience with either. Ive not heard anything great about them. Heard they are cheaply made. I would probably steer clear. JMHO

From all the choices above. I would probably go with York. But thats just me. Do some research, compare bells and whistles, compare SEER ratings, etc.

I definately respect you trying to keep the business local and give it to the mom and pops. Props to you for that.


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## flyingcow (Dec 8, 2011)

FWIW- In the old days when i did this, Johnson controls were good to deal with. But all I did was install equipment. The Johnson guys would make it easier.


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## thinkxingu (Dec 8, 2011)

OK, the first of three companies came out today.  Here's what they said:
1. They don't hang the air handler, they put it on a pad made of foam/plywood/rubber dampers.  He thinks it's more secure, quiet, and it sits in a pan.
2. Solid trunk the length of the attic, but he uses some flexible to control noise.
3. R8 insulation for all ductwork.
4. One supply in each bedroom, one in bathroom, one in kitchen, one on border of dining/kitchen, one in dining, at least two in living room (one near the stairwell).
5. Three returns at least: one in each bedroom (so doors can be closed?) one in living room/hallway.
6. Square vents, as round tend to be noisier, and placed as closely as possible to "wash" the window (never heard that before).
6. Feels that conditioning upstairs is more than enough as cold air will drop down large stairwell.  Suggests I start with that and then look at returns/supplies in basement if necessary.
7. Thinks heatpump would be great addition, but will price out both.
8. He uses Trane and Carrier--used to use York, but said they weren't as easy to deal with or something.  Agreed with Goodman's past being questionable.

Love feedback on anything this guy said (above)--like the company story: parents began company in late 60's, all family owned/operated, town residents.

S


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## mrfjsf (Dec 9, 2011)

thinkxingu said:
			
		

> OK, the first of three companies came out today.  Here's what they said:
> 1. They don't hang the air handler, they put it on a pad made of foam/plywood/rubber dampers.  He thinks it's more secure, quiet, and it sits in a pan.
> 2. Solid trunk the length of the attic, but he uses some flexible to control noise.
> 3. R8 insulation for all ductwork.
> ...



1. That will be fine, sounds normal. Pan under is good in case condensate pan decides to leak for no reason. 
2. I would want him to be more specific on the amount of feet of flex he plans on using to make the runs off the main trunk. 
3. Good
4. Sounds ok to me
5. Just make sure the total return is larger than the total supply (i.e will flow more cfm than the supplies. I think it is supposed to be at least 10% larger, not sure on that number tho.
6. Never heard of the rounds being noisier. I agree with the washing of the window. Kind of like The air curtains you see in supermarket doorways for a matter of speaking.
2nd # 6. I agree with that. Just make sure that the system will be large enough to handle a few supplies and returns in the basement if you decide to ever add them. 
7. Cool. Expect a good price jump for heat pump.
8. We use Carrier almost strictly. Unless we can get a better price on something else comparable or customer requests other brand. Carrier is definately top notch. You never mentioned it as an option so I never suggested. Sorry.

Sounds like a reputable company!

EDIT: Forgot to add that Carrier's new Greenspeed line in heat pumps has something to be said for itself. I heard it has been performing quite well in low ambient conditions.


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## thinkxingu (Dec 9, 2011)

Great, thanks--he was a nice guy and spent a lot of time with me.  I'll be sure to ask him about the length of the flex and total return vs. supply.
As for round vs. rectangle, he was just saying that in his experience rounds need to be larger to be quieter (without whistle?).
I liked that he was concerned about look/performance as opposed to ease of access/simplicity.  Also, he gave me some suggestions on how to mount my dehumidifier in the basement to drain into the washing machine drain, if we ended up still needing it.

S


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## thinkxingu (Jan 11, 2012)

OK, quotes are starting to come in.  First one (not sure if this is heat pump or not, and my electrician friend will be doing electrical):

We hereby submit specifications and estimates to:
ï‚§ Furnish and Install (1) One 2.5 Ton York Air Handler (horizontal in attic)
o Installed With Emergency Drain Pan And Float Switch
ï‚§ Furnish and Install (1) One 13 SEER 2.5 TON York Model YCJD030 Condenser (with pad, leveled)
ï‚§ Furnish and Install All Required Ductwork Per NATE (North American Technician Excellence) Standards
ï‚§ Ductwork will supply air as follows â€“ One Zone â€“ one supply for each bedroom and each bathroom upstairs. One central return and filter grill for the upstairs.
ï‚§ Furnish and Install all necessary low voltage wiring, condenser piping, venting, and drains
ï‚§ Furnish and Install Slim Duct for covering lineset piping on condenser side of house
ï‚§ Customer Will Be Responsible For All High Voltage Electric Work From Panel To Equipment
ï‚§ ONE YEAR WARRANTY ON PARTS AND LABOR
ï‚· Optional Upgrade:
o To Affinity Series A/C Condenser +$350.00
We propose hereby to furnish material and labor â€“ complete in accordance with the above specifications for the sum of: $6,340.00 Six thousand three hundred forty dollars with payments to be made as follows â€“ (50%) $3,170.00 deposit at signing of this contract for equipment and materials and the remaining amount of (50%) of $3,170.00 due at startup of second system.

Thoughts?

S


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## mrfjsf (Jan 12, 2012)

I see no mention of warranty on compressor, nor did I see any mention of duct insulation...did I miss something? 2 Very big deals. As far as the insulation goes, They can say "Install per NATE standards blah blah blah" all they want, but if the customer (you) does not know what NATE standards are, then they can/will likely just slap it together and out the door they go.

Otherwise I like everything else with the exception of the central return. This is a "no no" in my book, at least around here with summer temps. I have a feeling that the rooms furthest away from the return will not be as comfortable as you expet them to be. A/C systems were just simply not designed to work this way. The ONLY time I would EVER recommend a central return is if structural design simply did not allow for it. In your case I dont think it is an issue and I strongly recommend against it. JMHO


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## thinkxingu (Jan 12, 2012)

I asked this guy about adding returns to the bedrooms (one installer said he would add them, so I could shut the doors--not sure I understand this) and he said one central return would be fine.  I think he said R12 is what he does for insulation.  I did think his pricing was a bit high.

S


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## woodgeek (Jan 12, 2012)

who is going to do the high voltage wiring....that will cost too and they will have to coordinate.


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## thinkxingu (Jan 12, 2012)

My buddy's an electrician, and since this guy didn't want to quote me the electrical portion--because I have a slightly more difficult request--he left it out.

S


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## woodgeek (Jan 12, 2012)

thinkxingu said:
			
		

> I asked this guy about adding returns to the bedrooms (one installer said he would add them, so I could shut the doors--not sure I understand this) and he said one central return would be fine.  I think he said R12 is what he does for insulation.  I did think his pricing was a bit high.
> 
> S



R12 is the current standard for rigid ducting in unconditioned space IIRC.  I threw unfaced R-30 over my R-12 wrapped ducts after they left.

Many retrofits go for central return, usually on a upper central hallway.  The door comment is that the doorway/hallway provides the return flow, if the door is tight, there will be a slight pressurization, enough to close the door by itself when it is just ajar.  In principle, the supply to the room could drop when the door is closed...with a temp change.  In my case this hasn't been a problem at all, the 1/2" gap at the bottom of the door provides sufficient return. The rest of my house is pretty open plan.

If you go with one big return, be careful about sizing.  My guy put in too small a grill (24x24") for the airflow, and it made a huge 'air noise' that I could hear all over the house.  I made him upsize it to 24x30 (the biggest available filter size) and it is still audible in the hallway, but not objectionable.

Hard to judge your quote price since it comes down to the amount of ducting fabbed and installed.  A cheap guy will put in a ton of flex (bad) with leaky joints.  A real pro might do a perfect rigid system, masticc'ed on all the joints and meticulously wrapped to R-12.  If the second guy charged you 2x as much, I personally would go for it.

BTW, you want the ducts masticed.  Period. Watch them during the install. Once they get wrapped, you can't see how shoddy a sealing job they did.  That is my only regret...I ended up unwrapping my ductwork in several places, sealing the joints myself and rewrapping.


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## woodgeek (Jan 12, 2012)

Make sure to get a heatpump and a decent tstat--I like my visionpro.  The simplest/cheapest case, you wouldn't install any electric strip heating in the handler (the wiring costs can be significant), so defrost cycles would be unpleasant...so you would lock out the HP below 35-40Â°F, and the stat would call your boiler below that.  At those temps, the HP would provide very cheap heat (COP~3.5-4). Sized for A/C, it probably won't keep up much below that anyway.


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## thinkxingu (Jan 12, 2012)

Ok, so that price did not include a heat pump, so I think it's a high estimate.  Said he'd include it if we started next week, but not digging the price or one return.

S


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## woodgeek (Jan 13, 2012)

thinkxingu said:
			
		

> Ok, so that price did not include a heat pump, so I think it's a high estimate.  Said he'd include it if we started next week, but not digging the price or one return.
> 
> S



As much as I love HP's I wanted to temper/explain my earlier statements given your cold climate.  South of the mason-dixon line, heat loads and A/C loads are similar, the minimum temps are pretty moderate and I don't understand why ANYONE would get an A/C versus a HP, given that the sizing in heat and cool are similar and the equipment is so similar.  In my climate (Philly burbs, tracks NYC metro temps), conventional HPs (i.e. looks like and installed like a central A/C) are not as popular, but it works for me since I tinker with it.  I had to oversize--a 4 ton PURON unit carries my (now) very tight 2200 sq ft to ~21Â°F, and I might spend only ~250 hrs/yr at temps below that.  In A/C, I would need a 2.5 ton unit, so I am oversized, and that can limit RH control in the summer.  BUT, I get >95% of my winter BTUs from the pump.

Anyhoo...I think you should price out a HP unit sized for your A/C needs, and not get any electric backup, with an external temp monitor on the tstat that locks it out below 35-40Â°F and calls your current heating system.  Without the backup and wiring, it might be less than $1k more, and would cover your shoulder season heating much more cheaply than something like oil or propane.  The ROI would require you to estimate the fraction of your total HDD that comes in above your lockout temp--not easy to calculate, you could probably guess from a monthly climate table if you were mathematically inclined.


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## woodgeek (Jan 13, 2012)

Oh yeah...about the hanging...I have a pan under my unit too.  It just hangs a couple inches over the pan, on some unistrut cross-bars held to the roof joists with threaded rod and couplers.


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## thinkxingu (Jan 13, 2012)

Hey,
     I'm thinking that I would do the size I need for AC, 2.5 ton, and just use the HP when temps are above 40. Anything below, I would usually have the stove going (my electric baseboards with the new t-stats aren't too bad).

S


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## thinkxingu (Jan 17, 2012)

Here's the second of three--this guy seems wayyyy off, and I'm not sure why!  The other three estimates from this guy only go up!  Thoughts?

Air Design Services, Inc. is proposing to provide the necessary labor, material
and equipment for the installation of the following:
$11,540.00
I. Install one Carrier 2.5 ton air conditioning system with the following:
* One Carrier 13 seer "Comfort" model 24ABB330 air conditioner
* One Carrier single speed model FB4CNF air handler
* Externally insulated duct work system (supply duct and return duct)
* Registers, grilles and diffusers
* Installation complete

S


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## saladdin (Jan 17, 2012)

maverick06 said:
			
		

> CONSIDER A HEAT PUMP
> 
> yes, I did mean to put that in caps. We had our AC replaced a few years ago. of all the companies that came to quote us only one mentioned "oh yeah, well for an extra $500 (i think) we can make it a heat pump" that was is... nothing else.
> 
> ...



The 45F is key to remember. I don't know the exact number, but around 45, heat pumps lose effiecency and the "electric strips" kick on which can really raise your electric bill.

Do research.


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## saladdin (Jan 17, 2012)

woodgeek said:
			
		

> Make sure to get a heatpump and a decent tstat--I like my visionpro.  The simplest/cheapest case, you wouldn't install any electric strip heating in the handler (the wiring costs can be significant), so defrost cycles would be unpleasant...so you would lock out the HP below 35-40Â°F, and the stat would call your boiler below that.  At those temps, the HP would provide very cheap heat (COP~3.5-4). Sized for A/C, it probably won't keep up much below that anyway.



Heat pumps require a "special" t'stat. Make sure the 'stat says works with heat pumps.


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## saladdin (Jan 17, 2012)

thinkxingu said:
			
		

> Here's the second of three--this guy seems wayyyy off, and I'm not sure why!  The other three estimates from this guy only go up!  Thoughts?
> 
> Air Design Services, Inc. is proposing to provide the necessary labor, material
> and equipment for the installation of the following:
> ...



Not sure, but isn't SEER 13 the lowest rating?


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## thinkxingu (Jan 17, 2012)

It is the lowest rating, but for two months' use it would be a long time to recoup the difference in money, yes?

S


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## saladdin (Jan 17, 2012)

thinkxingu said:
			
		

> It is the lowest rating, but for two months' use it would be a long time to recoup the difference in money, yes?
> 
> S



You are right. I always forget not everyone has the summers that we do.


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## Highbeam (Jan 17, 2012)

saladdin said:
			
		

> The 45F is key to remember. I don't know the exact number, but around 45, heat pumps lose effiecency and the "electric strips" kick on which can really raise your electric bill.
> 
> Do research.



Indeed, do research. Modern heat pumps with 410a can make very good heat down to zero degrees F. These things are becoming as useful as fossil fuel burners.


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## saladdin (Jan 17, 2012)

Highbeam said:
			
		

> saladdin said:
> 
> 
> 
> ...



Mine is not one of them. 1.5 year old and anything under 45ish and it struggles to keep the house at 70 and runs nonstop. House is tight and insulated to the hilt.


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## woodgeek (Jan 20, 2012)

saladdin said:
			
		

> Highbeam said:
> 
> 
> 
> ...



Dude, sounds messed up.  There are a lot of mistakes and design errors that the installer can make--have somebody competent fix it and put it to work.


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## Highbeam (Jan 20, 2012)

Exactly, your heat pump is either undersized or broken. 45 degrees was easily warm enough in the 80s.


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## thinkxingu (Jan 22, 2012)

Feedback on these numbers?  All include a single return and no electric (my friend will be doing).  I think we're now leaning away from heat pump, which looks to be more like $1000 more when you add cost of HP, wiring, returns, etc.

Trane Heat Pump 13 SEER XR13 and TAM7 variable speed air handler $7213.00
Trane Heat Pump 13 SEER XR 13 and 4TEC3F24B or Equivalent TAM4 multi speed Air Handler $6820.00
Trane AC XB14 14 SEER and TAM7 variable speed A.H. $7263.00
            Same Condenser as above but with TAM4 A.H. $6980.00
Trane AC XB 13 SEER condenser and TAM4 A.H $6735.00
Trane AC XB300 13 SEER Condenser and TAM4 A.H. $6575.00 (Compared with YORK AC YCJD 13 SEER Condenser and AHR24 multispeed A.H. $6475.00)


S


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## woodgeek (Jan 22, 2012)

I assume all the quotes are the same tonnage....

I went for the variable speed blower, and am glad I did.  The system cycles on ans off a lot, and the variable speed blower allows a slow ramp up and ramp down on each cycle that makes the unit operating noise less noticeable.  I'm a kinda light sleeper, and I always wonder when I wake up in the early AM if it is because of me hearing the unit cycle on and off?  While we're on the subject, don't put the compressor outside a bedroom window.

SEER 13 is the lowest  commonly installed, but I would guess your AC needs in NH are pretty light, so it would be hard to make the $$ back in reduced operating costs--did you ask for the price difference with a higher SEER unit?

As for the heat pump, it really comes down to how you currently heat during the shoulder season....if you are burning scrounged wood exclusively, and enjoy that shoulder season effort, then don't get a HP.  If you're running oil backup in the shoulder seasons, and switch to wood or wood supplement in the real cold, OR if you buy your wood, that I think the HP has a decent ROI.  The HP above 40Â°F will be cheaper per BTU than any source other than NG or scrounged wood, and the latter only depending on the value of your time.


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## woodgeek (Jan 22, 2012)

So, they want to add more returns with the HP system than for the AC system?  Weird.  The cfm and return size should be a function of the tonnage only, and I thought you are talking the same size.
Are the AC systems for a 'high velocity'/small duct system?  I don't know about those, but I was leery of the air noise.

When I researched it I got all this info that you can't heat with ceiling registers (in an attic retrofit), etc.  My registers are all just where they would be for an AC unit (ceiling) and no problem.  At the mild temps where the HP would run, I can't see it beng a problem at all.

On the return.....I already discussed this, but talk to them about it.  The SOP is 1 sq ft of return per ton, and my guy did that initially....and it was way too loud.  Also I wanted to use a near-HEPA filter at the return, as we all have allergies, and the 1 sqft/ton rule makes it hard to run anything but a 'see through' filter (that exists to keep large lint from clogging the system, not to actually filter the air).  I upsized 25% from the SOP, a LOT quieter, and can run a near-HEPA 1" filter no problem (changing it according to a 30-day run timer in the tstat).  I use one box of 6 filter per year ($100), you would use half to a third as many.


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## thinkxingu (Jan 22, 2012)

woodgeek,
     I've been having a side conversation with another member and it was mentioned that unless I put a return lower that I would just be sucking up warm air--given that the place the central return would be going is the warmest part of the home--weird, but definitely noticeable--it seems to make sense that it would be cycling the same warm air.
     As for what we heat with: all electric baseboard, with the wood stove on weekends/vacations.  BUT, given the insulation and thermostats, it's not nearly as expensive as you might think: we pay just over $200/mth for an all electric house.

Thoughts?

S


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## woodgeek (Jan 22, 2012)

All I can say is that I have a multistory house with a return at the top of a central staircase, and all my registers are also in my ceilings, and I don't have a problem, and I run down to 15F, not 40.  There is a little stratification (warmer near the ceiling than the floor), but not really noticeable to me. Of course, I did run some duct to my finished basement, don't know about all the heat on one level.

Is the $200/mo a january figure? a six mo average, or a 12 mo average? 

All I can say is that if ~25% of your heating degree days are >40Â°F, and the COP = 3 for the heat pump, then you will save 67% of 20%, or about 16% on the heating portion of your electric bill, relative to running the baseboards.  If you have a sense of how much you are paying for elec heat, then you can compute your payback.

Why did you rule out mini-split again?


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## thinkxingu (Jan 22, 2012)

woodgeek,
     I ruled out mini-split because I've only got one end with a flat wall.  The other side of the house is a bedroom, which obviously wouldn't work with the door shut.
     $200/month is our yearly budget.  Our regular electric (during the summer) is about $100, so we pay approximately $150/mth to heat.  Of course, that's higher during cold months and lower during shoulder.  I think I'm just worried that, with a split level and all the heat coming to this one area where the return will be, that most of the warmth will be recycled.

S


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## thinkxingu (Jan 26, 2012)

OK, spoke to the second to last installer and we worked out a deal that would be less expensive.  So, we're comparing the following two contractors--the major difference is one would use Trane and one would use York.  The top estimate lists three intakes, whereas the second would only do one--but he said there'd be three different filters, and I'm not sure if that's right or not.  Still not sure on heat pump, but it's about $300 more in my case.  Thoughts?

$5850 ($300 more for variable handler--see end):
INSTALL 2.5 TON 13 SEER 410A AIR CONDITIONING SYSTEM COMPLETE
INCLUDES:YORK 2.5 TON CONSENSER,COMPOSITE PAD,LINESET TO BE
COVERED BY SLIMDUCT GUTTER SYSTEM,DRAIN,WET SWITCH,SECONDARY
PAN,AIR HANDLING UNIT HUNG FROM RAFTERS,YORK CONVENTIONAL MULTISPEED
2.5 TON AIR HANDLER, SUPPLY DUCT TRUNK WORK,THREE RETURNS WITH FILTER
RACKS,SUPPLY DIFFUSSERS(MV PVC TYPE),HONEYWELL PRO300 DIGITAL T STAT.ALL
LINE VOLTAGE WIRING BY OTHERS.ONE YEAR LABOR WARRANTY, FIVE YEARS MAJOR PARTS.
CHANGE AIR HANDLER TO YORK VARIABLE SPEED AIR HANDLER.THIS UNIT ONLY
AVAILABLE WITH THREE TON COIL AND TXV .A/H WOULD REQUIRE RETROFIT TO 2.5 TONS.


$5975 (I think $600 more for variable handler, 2.5 ton would be $200 more)
Trane 2-ton AC XB 13 SEER condenser and TAM4 A.H


S


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## woodgeek (Jan 26, 2012)

Don't know the York/Trane hardware...I would still get the variable speed handler.

The filters are right at the return grate...three returns, three filters.  You were thinking it was at the handler?

$300 for the HP version seems a no brainer....if it only covered 15% of your seasonal load, you would make it back in what, a year or two?  If you didn't like it for some reason (noise/comfort), IMO unlikely, you are out only $300.

Are they going to mastic all the ducts in the attic prior to wrapping??


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## thinkxingu (Jan 26, 2012)

Ok: one guy will use liquid mastic, the other mastic tape.  As for the return, the guy with three said it would be simple enough just to run three flex runs together (I think) whereas the other said more than one return would require a second trunk with the filter at the handler.  As for the hp, I'm not sure what other costs there are other than the condenser.

S


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## woodgeek (Jan 26, 2012)

thinkxingu said:
			
		

> Ok: one guy will use liquid mastic, the other mastic tape.  As for the return, the guy with three said it would be simple enough just to run three flex runs together (I think) whereas the other said more than one return would require a second trunk with the filter at the handler.  As for the hp, I'm not sure what other costs there are other than the condenser.
> 
> S



In the setup we are discussing, there is no difference to the ducting, so the only difference is the compressor, a tstat that can operate it (with a couple extra wires in the low voltage wiring) and some (cheap) valving in the airhandler.  You seem convinced that a HP won't work for you...above 40Â°F it adds very little complexity and similar ducting/sizing from an AC will be fine.  Instead of coolth from the registers in the summer, you will get warmth spring and fall, at a 70% discount per BTU versus your baseboards.

Think of it this way--you are sinking a chunk of $$ into all this AC hardware that will not run so many hours per year in your climate.  For the cost of a couple valves, a nicer tstat and hooking up a couple wires, maybe a 5-10% markup you will be putting otherwise idle hardware to work for you to save you money.


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## thinkxingu (Jan 27, 2012)

Alright, I think we're close, but one last question: variable speed vs. multi-speed handler.  Sounds like VS would be quieter, more efficient, and better at dehumidifcation (important to us) but more expensive to repair.  Thoughts?

And a summary of where we're at:
Trane XB13 (no heat pump, since no returns at lower level)
Trane Handler (VS or MS, depending)

S


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## gtjp (Mar 28, 2012)

How does it work in our 80-deg winter days?

Definitely agree returns in all doored-rooms , not bath nor too close to kitchens..
and NOT LOW unless in the south of KY...even there design a 'ZONE return air chase with dual purpose damper... GREAT for church-style buildings to have damper-high/low returns.
if heating is significant...

double ceiling 16x30's are possible ret grilles now

Central return is fine WITH room returns, I believe.
Getting down to 11 btuhs / sq ft requires great return systems.
Thanks Paul Doty of Heat Controller, Century Heating, WeatherKing, FLA: 1981 seminar.


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## heat seeker (Mar 28, 2012)

I have a VS air handler, and like it. It's very unobtrusive unless the demand is high - at startup in a warm house, or really hot days. Then it really moves a lot of air, and you can hear the air coming out of the vents. The compressor is a two speed, so they work together. I believe that helps with the dehumidification, which can be significant here in New England in summer. I have no data on repair costs, but if they are higher than a single speed, I think it's worth it.


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