Garn It!

[rvtgr8]

Jim and Joe,

You guys are the greatest. I do have a couple of questions.

1] is $100 a good price on the 0010?
2] If it is a good price should I buy the other for backup or the future greenhouse loop? 100' away on 1.5" pex
3] Would it harm the hot tub loop with the old fashioned radiator or should I go for a 007?
4] Where do you get your capes? We have no super heros here in Elbert.

 

[Jim K in PA]

Jim and Joe,

You guys are the greatest. I do have a couple of questions.

1] is $100 a good price on the 0010?

Pexsupply.com shows a "regular" 0010 going for around $200 each. I think the price is definately right on those CL pumps. I am just not convinced those are the right pumps for you. Perhaps Joe has some insight.

2] If it is a good price should I buy the other for backup or the future greenhouse loop? 100' away on 1.5" pex

Here is the TACO official spec page for that pump: (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/100-20.pdf) As long as you are not exceeding 9 feet of head, you should be fine. However, given you have 200' of pipe (supply and return) plus the radiant(?) tubing in the GH, plus fittings, you will likely be at or beyond the max 9' capacity of this pump for the GH. Here is a chart on head loss for PEX and Cu tubing: http://www.cozyheat.net/MTR/tubing/pdf/headloss.pdf Just the 1.5"piping (in copper) will give you about 4' head loss if you are pushing 100k Btuh (have you done a heat load calc for the GH? They consume a lot of heat)

3] Would it harm the hot tub loop with the old fashioned radiator or should I go for a 007?

Possibly, due to the high velocity. Erosion of fittings starts to occur at high flow rates, plus it makes more noise (you may not care).

4] Where do you get your capes? We have no super heros here in Elbert.

I like warm apples on my crepes. Sometimes IHOP has a special . . . ;-)

For future controllability, you may want to consider a 3 speed pump like the Grundfos or Wilo.

 

[BrownianHeatingTech]

Jim is right - the 0010 is for primary loops, not really for delivery of water to zones. It produces high flow, but very little head.

Joe

 

[rvtgr8]

Jim, do you have a model number on these two units? I go before the building inspector tomorrow to run some of my changes past him. He will be asking me how the Garn gets the word when it needs to join the party. Also, I took your advice on the smaller Grunfos for the hot tub and am looking to use the 0010 on the primary loop.

Ken - you and I are now in full understanding of each other, I think. I think you and I are skinning the cat in two slightly different ways, but getting to the same point. As far as the primary pump having to run continuously, that is not necessarily so. I solved that issue with a TACO Zone Valve Controller and a TACO Switching Relay Controller. Any zone on the house triggers the end switch on the ZVC, which then triggers the circ on the house loop. The SRC has an end switch that starts the primary pump whenever any secondary pump is energized. The units are not cheap, but not bad either (~$190 each).

I am also not convinced that bronze pumps are an absolute necessity in a GARN application. Although technically an “open” system because it is not pressurized, there is no appreciable O2 reuptake unless you are refilling due to a leak. Standard ferrous pumps are perfectly OK, IMO.

Ken, do you think that the correct placement for the Taco 0010 is on the primary loop, at about six or seven feet out from the Garn? Can I make it closer?

 

[slowzuki]

The pumps can be as close to the Garn as you like. Actually the closer the better! I can see it would be a bit cleaner to have them in the room though if need be.

RE the building inspector, its really just contact outputs that will turn each circ on or off. All the safety controllers that he should be worried about should be built into the Garn's combustion controls.

The hot tubs and green house will likely be some type of basic thermostat, the HX circ we haven't talked much about yet but can be done a few ways off the existing system. I'm assuming your thermostats are wired inside of walls and not really accessible. We can help you out with that, a few different approaches available. I'll try to get a chance to relook at the diagram today.

 

[Jim K in PA]

The pumps can be as close to the Garn as you like. Actually the closer the better! I can see it would be a bit cleaner to have them in the room though if need be.

As long as it is nice and low, close to the floor.

RE the building inspector, its really just contact outputs that will turn each circ on or off. All the safety controllers that he should be worried about should be built into the Garn's combustion controls.

The GARN is an unpressurized system, and has few "safety" controls. There is a low water cutoff that disables the draft fan, an on/off switch, and a mechanical timer that controls the run time of the draft fan. That's it.

The hot tubs and green house will likely be some type of basic thermostat, the HX circ we haven't talked much about yet but can be done a few ways off the existing system. I'm assuming your thermostats are wired inside of walls and not really accessible. We can help you out with that, a few different approaches available. I'll try to get a chance to relook at the diagram today.

He'll need another water:water HX for the hot tub. Something small and compatible with his treatment chemicals. He can probably use the temp controller from the hot tub that currently actuates the relay for the resistance heater, and use that signal to start the circ pump for the loop. If he wants to have the radiator on this loop to run independant of the hot tub, then a second controller and pump will be needed.

 

[slowzuki]

Really, the Garn doesn't have a high temp cut out for the fan? What stops you from boiling it over?

 

[Jim K in PA]

Really, the Garn doesn't have a high temp cut out for the fan? What stops you from boiling it over?

Correct. YOU are what prevents a boil over. I was also concerned about this before I started using my GARN. To actuallly get to a boil over, you REALLY have to try, or be VERY inattentive to it's condition. Here is a link to my thread about this very point: https://www.hearth.com/talk/threads/29420/

After living with it now for 6 weeks, and having my teenage sons running it for a couple of weeks when I could not, I have to say that boil over risk is very low.

 

[slowzuki]

I'd say our local inspector would make you wire a high temp cutoff aquastat into the fan controls. Just strikes me that if you were to boil it over it has the power to make a lot of steam. Do you plumb a vent through the roof?

 

[Jim K in PA]

I'd say our local inspector would make you wire a high temp cutoff aquastat into the fan controls. Just strikes me that if you were to boil it over it has the power to make a lot of steam. Do you plumb a vent through the roof?

The manway is "sealed" with a gravity set lid and gasket, and there is a vent pipe that goes from the upper manway down through the tank and out the front wall. That will let you see if there is steam emanating due to over-firing BEFORE there is a boil over. Given the substantial thermal mass of over 1800 gallons (or 1400 gallons in Robert's situation) there is a much more gradual buildup toward boil-over than with a unit that is only heating 10, or 50 or 100 gallons of water.

If you go through the other thread, you will see that there are consequences of shutting down the draft fan with a full burn going. The risks associated with a boil over are primarily water and (unpressurized) steam release. Messy, but no danger to life, limb or property.

 

[slowzuki]

I've not read of the risks, my Jetstream simply turns off the induced and forced draft fan when it overheats. You may get a bang from a back puff.

 

[rvtgr8]

I have a question about the HX size. I had an engineer friend do the heat loss calculations on the house including the garage not too long ago and he gave me a 43,000 btu figure. This was before my indoor storm windows and the garage was supposed to be a garage. He designs radiant systems and has a good reputation, so I don't think he is too far off. My question is that if I am going to run my greenhouse off the Garn side of the system, is a 90 plate or even an 80 plate overkill? I am not sure I am using some of the suggested sizing software correctly, but it looks like a 50 or a 60 are more than adequate. I plead ignorance. Any suggestions?

 

[Rick Stanley]

Hi Robert,

Take what I say with a grain of salt as I'm still trying to figure my own system out. The pro's in here will give you some solid answers as always. But it's my understanding

that the only reason I need a hx at all is to interface with my existing pressurized boiler and distribution system.

Any loads that don't exist yet, like a greenhouse, may not need a hx. Just pump Garn heated water directly through the new distribution system.

Just a thought.

Rick

 

[slowzuki]

How are you heating the green house? Rick is likely right.

 

[Jim K in PA]

I have a question about the HX size. I had an engineer friend do the heat loss calculations on the house including the garage not too long ago and he gave me a 43,000 btu figure. This was before my indoor storm windows and the garage was supposed to be a garage. He designs radiant systems and has a good reputation, so I don't think he is too far off.

That is an impressively low number for your area. What was the design max delta T? Had to be about 80 (70 inside, -10 outside) at least.

My question is that if I am going to run my greenhouse off the Garn side of the system, is a 90 plate or even an 80 plate overkill?

Are you saying that you will supply heat to the GH directly rather than through the HX? There is no reason why not.

I am not sure I am using some of the suggested sizing software correctly, but it looks like a 50 or a 60 are more than adequate. I plead ignorance. Any suggestions?

As I understand it, there are two primary factors in sizing the HX. One is the AVERAGE maximum load, the other is the maximum PEAK load. Secondary factors are efficiency of transfer as the load and supply temps get closer, and the amount of head loss through the HX.

The peak load issue is something I discovered after letting a radiant heat guy size my HX. He convinced me that a 20 plate HX was more than adequate for my calculated 70k Btuh house load. The HX does actually keep the zones warm at max load (we just went through below 0 temps), while the zones are running. However, PEAK load, when cold zones start up, and/or when there is a prolonged hot water demand (Showers) the oil burner kicks on to keep the temps up.

Consider that a shower is roughly equivalent to a heat load of over 112k Btuh (3 gal./min, delta T of 75). And when a zone kicks on after a period of inactivity, the return temp is near ambient, so you have a big Delta T on each zone to catch up with. If multiple zones hit the HX simultaneously that way, well, lets just say that the HX will be taxed.

I am upgrading my HX to a 50 plate for the peak load capacity, and to reduce the head loss through the HX. Without the hot tub and GH pulling heat through it, I think the 50 plate will be quite adequate.

 

[rvtgr8]

The Greenhouse will be built this year, and while I would like to run some heating tubes in some of my beds, the idea is not to heat the entire space. There are problems that I will deal with to even do the most modest of system. I do not have the luxury of having soil between here and the greenhouse, its situated on the lee side of a sandstone escarpment. Not impossible to get through, but if the cost of running a loop exceeds the cost of a smaller boiler dedicated to just the greenhouse...well that's a situation a couple of years down the road. Truth be told, besides the new hot tub and radiator, the 43,000 btu figure is pretty solid on that side of the HX. The HX does not have anything to do with any of the future plans for now.

Robert

 

[TCaldwell]

robert, i have a historical heat load that fluctuates from 55k to 65kbtu/hr weather dependant , consisting of 7 zones however as jim states momentary heatloads of 3 plus zones at the same time and it temporarily jumps to 300k+btu/hr, you want to try to cover these demands even with a low supply temp, maximizing your storage. most hx manufacturers will help you through proper sizing, based on heat load, supply temp range, flow rate and desired delta t.

 

[slowzuki]

The other way to deal with peak loads is to put something like an 80 gal tank into the hose loop but I'd much rather keep a large hx and reap the benefits of being able to drain the Garn down to low temps so you can go longer between firings.

 

[rvtgr8]

Thanks for the input guys. It gets a little easier to understand every day. On another note, the inspector wanted to know if there was any problem using a HX and then circulating the water through the Burnham boiler on the old loop. I explained that I it would not. The only difference between the way it is hooked up now and the way it would be hooked up after the Garn is hooked into the system is that it would be like the temps in the old loop stayed warm perpetually, never dropping low enough to fire the propane in the boiler unit. He wanted to know about the possibility of a mixing circulator at some point. I talked to him about that possibility based on the information I have received in this thread, and he liked that. I hope I was correct in my explanation. He really wanted a little more detail. Any suggestions?

Robert

 

[rvtgr8]

Slowzuki,

I see your point and will be going with the larger HX. Thanks for your valued opinion

 

[slowzuki]

Hi Robert, I don't know what kind of relationship you have with your inspector, I don't know why he wants so much info but its best to keep him happy.

My opinion is the current radiant setup without the mixing circulator may not be the best but it works well for you from all reports. I would be hard pressed to start messing with it although some type of mixing may eventually be needed for when the Garn is at its highest temperature. This could be avoided by a variable speed circulator on the Garn HX or a 3 way/4 way mixing or injection setup on the house side.

The problem a mixing device can solve is the water being too hot causing the temperature in the slab to swing too high overheating the occupants. If you don't have a problem it won't help you other than in some cases you may be able squeeze a bit more useful heat out of a storage tank.

By using a VS pump on the Garn side of the HX, you can just put a temp sensor at the discharge side of the house side of the HX so the Garn will only run the pump enough to maintain the temp. Once it falls below the target temp it will run the pump faster and faster until it is at 100% speed. Fancy variations of this include "outdoor reset control" which would change the house temp setting based on outdoor temp. This is really the exact same as injection mixing just through a HX.


EDIT and looking around they seem to be really expensive. I'll keep looking to see if there is a cheap one I missed. Kind of silly, VS drives are dirt cheap now.

 

[rvtgr8]

The inspector and I go way back. I built a straw bale hybrid (first in my county), put in a bio-peat filtration system on my septic (first in Colorado) and then ran for commissioner. Nice guy, but he looks at me as some sort of a dreamer/schemer. He is just curious, but I do have to stay on his good side. I have more weirdness planned here at the ranch. :cheese:

Would the Grundfos UPS 43-44FC that Jim K is using be a good VS circulator for the primary loop on the Garn with the 2" pipes. There is not a lot of head loss in my system yet. Who knows what the future hold? But for right now, I want to start narrowing in on some concrete solutions for pricing purposes.

Robert

 

[Jim K in PA]

Would the Grundfos UPS 43-44FC that Jim K is using be a good VS circulator for the primary loop on the Garn with the 2" pipes. There is not a lot of head loss in my system yet. Who knows what the future hold? But for right now, I want to start narrowing in on some concrete solutions for pricing purposes.

Robert

Th Grundfos is a 3-speed PSC pump, not a variable speed. You can control it with a differential setpoint VS controller like the TEKMAR 157, or 356, or . . . ?

I thought you already bought those TACO 0014s?

 

[rvtgr8]

Jim,

No, the guy still has them at the same price ($200 for two Taco 0010's) but I was not picking up the vibe that it was not the pump that would do the trick. Do you know of a good three speed that I can run on the primary loop and perhaps run on an outside reset?

Robert

 

[rvtgr8]

I now find myself mired in the "which pump" zone. Its a confusing place filled with red, green, pink and black devices. They come with charts and numbers and wires and mighty flanges. I am humbled. I know that I am a reasonably intelligent human being, able to do math without assistance from fingers and toes, but I lack any tangible experience in hydronics. I spent countless hours perusing data sheets on circulators this weekend. I read and reread any posts that have a Garn installation discussion. I have come to the conclusion that this process takes a great deal of "hunch" decision making. I am trying to decide between a three speed Taco 0010 or a comparable Grundfos UPS 43-44FC/BFC SUPERBRUTE. Hands down Grundfos has the Taco beat in terms of cool names. The red paint looks good. But the Taco has that cool green that goes with the ugly paint on my garn. Never mind that the literature has the two rated as a toss up.

Long story short! How do you guys make these decisions? Cost? Availability? Color scheme? Coin flip? Ground hog?

Help!

Robert