# Heat pump water heater ducting question?



## EbS-P (Dec 17, 2019)

Hi am having an 80 gallon heat pump water heater installed in the basement.  It will be in a mechanical space that is 15’x2’.   One long and one short wall are crawl space walls while the other long wall is  half bathroom wall and half back of closet.    The Bedroom room then is about 15x15 (minus the bathroom).   I run one dehumidifier in the basement year round and a second in the summer. 

the contractors were concerned that the bedroom may be as many as 10dF colder if I exhaust to the bedroom.   My thoughts were.

1- vent to the bedroom anyway it is easy. 
2-vent to crawl space. It’s pretty easy. But I would need a makeup air as I don’t want to affect downstairs fireplace which may get a wood burning insert. 

3-vent to crawl space and tie into HVAC cold air return. Basement doe not have air return. Most complicated install.

4-other ideas?

thanks in advance for your responses.

evan.


----------



## mellow (Dec 17, 2019)

Which one are you getting that you can vent it?


----------



## EbS-P (Dec 17, 2019)

It’s a Bradford White. Most models I looked had an optional ducting kit. Manual states I can run a total of 100, of 6” duct.


----------



## MacinJosh (Dec 17, 2019)

I have an 80 gallon Rheem HP water heater. It’s in my basement as well. I love it in the summer time since it blows cold air, but not so much in the winter. I was thinking of doing the same thing you are and maybe duct it outside. Then my HVAC guy pointed out it would just create a vacuum in the house and cold air from the outside would come in through cracks, small openings, etc. so what was the point.

He kind of got me there. Are you looking to duct for the same reason?


----------



## peakbagger (Dec 17, 2019)

What about venting it under the refrigerator?.  I have seen some design guide for ERVs that advocate this for fresh air return.


----------



## EbS-P (Dec 17, 2019)

Yes external (crawl space)   venting seems like a net energy loss. The plan was to add a second wood burner so I didn’t really care where is was vented(think wood heated water) , but those plans have been shuffled down the priority list.

I don’t like the idea of seasonally switching where it’s routed too. I just won’t do it one year and that’s where it will stay forever.

I like the fridge idea but the kitchen is at the other end of the house with no way to run duct.


----------



## orlkc (Dec 17, 2019)

What else is in the mechanical space? Does it have a door to the rest of the basement that's closed all the time? 

Since you want to dehumidify the basement year round you want the water heater intake and exhaust to both be within the house.

I'm wondering if you could just duct the intake from the bedroom and exhaust into the mechanical room itself, or not bother with venting it at all.

We have a HPWH in a mechanical room in the basement. No ducting. I do tend to leave the mechanical room door to the rest of the basement at least partly open, but I'm not sure that's needed.


----------



## EbS-P (Dec 17, 2019)

Thanks for the feedback. It will be closed off by a door. Only other items back there are a lift pump and a steam generator unit and plumbing.  
I really have no idea how much air it will be moving. We are a family of 6 with 4 boys under the age on 9.
I’m afraid if I just vent into the mech space all the cold air will just find it’s way into the bedroom.


----------



## Brian26 (Dec 18, 2019)

My Geospring is in my fully insulated open 800 sqft basement. I have a temperature sensor monitoring the basement space temperature. It has very little effect on the space temperature. It usually runs for an hour and drops the temp a degree or 2 but the temp will recover quickly when it shuts off. These units are around 5000 btus which is not really that much cooling for such a large space .


----------



## maple1 (Dec 18, 2019)

What is above?


----------



## EbS-P (Dec 18, 2019)

maple1 said:


> What is above?


A Bathroom that are in the process of being built. It’s getting electric radiant floor as half of it over the crawl space and would never get warm If we heat with the wood stove.
It’s just not a big enough space to vent to as we will keep the door closed in the winter to keep the bathroom above 65.


----------



## MacinJosh (Dec 20, 2019)

EbS-P said:


> We are a family of 6 with 4 boys under the age on 9.



I have two boys under ten and I thought I was busy. God bless you sir. Haha


----------



## NoGoodAtScreenNames (Dec 23, 2019)

I have one in my basement near my boiler. Even with the heat pump tuning my basement is still 62F. I’d run it without the venting at all at first and see whether you even have a problem to begin with. 


Sent from my iPhone using Tapatalk


----------



## NoGoodAtScreenNames (Dec 23, 2019)

I thought about venting when I installed it a few months ago. Then I did some quick math. I’ll probably pay about $10 in electricity per month to run the thing. If venting made it 10% more efficient then that is saving $12 per year. The ducting would have cost $80. So almost a 7 year payback. Didn’t seem worth it to me. Now if it was making a living area cold without the venting then that would be something different. 


Sent from my iPhone using Tapatalk


----------



## Highbeam (Dec 24, 2019)

Not only worry about cold but the racket that dang thing makes. Try sleeping next to that!


----------



## begreen (Dec 27, 2019)

Highbeam said:


> Not only worry about cold but the racket that dang thing makes. Try sleeping next to that!


That bad, eh? What make/model do you have?


----------



## EbS-P (Dec 27, 2019)

I have an 8 year old that can sleep though anything but the crack of dawn on a weekend


----------



## Highbeam (Dec 27, 2019)

begreen said:


> That bad, eh? What make/model do you have?



oh no, I can’t have one. Way too loud. Read the specs for the decibel output. Some are worse than others. I have lived with a refrigerator on the other side of the bedroom wall, not desirable!


----------



## begreen (Dec 27, 2019)

I just looked up the Rheem and it lists the sound level at 49db, which is pretty low. Like the sound of rainfall or a quiet dishwasher. I could live with that.


----------



## MacinJosh (Dec 29, 2019)

I have the Rheem and it is whisper quiet. I can barely hear it running and have to stand right next to it.

I love it! Can’t recommend it enough.


----------



## sloeffle (Dec 29, 2019)

Highbeam said:


> Not only worry about cold but the racket that dang thing makes. Try sleeping next to that!


Ours is right below our bedroom. Our older one was a lot louder than our current model and the wife and I had no problems falling asleep when it was running.


----------



## Highbeam (Dec 29, 2019)

sloeffle said:


> Ours is right below our bedroom. Our older one was a lot louder than our current model and the wife and I had no problems falling asleep when it was running.



Do you think that below you on a different floor is the same thing as a closet in the same room or on the other side of an interior wall? Hopefully the newest models are quieter, quieter is better.


----------



## sloeffle (Dec 29, 2019)

Highbeam said:


> Do you think that below you on a different floor is the same thing as a closet in the same room or on the other side of an interior wall? Hopefully the newest models are quieter, quieter is better.


Yep. I'd say it would be quieter in our closet because the interior walls in our house are insulated. The floors between the basement and first floor are not. I agree 100% that quieter is better. As I get older, I enjoy piece and quiet more and more.


----------



## brenndatomu (Dec 29, 2019)

MacinJosh said:


> I have the Rheem and it is whisper quiet. I can barely hear it running and have to stand right next to it.
> 
> I love it! Can’t recommend it enough.


I agree, I just installed a Richmond (same as Rheem) HPWH and you certainly would not hear it on the other side of a wall. I'd say it's quieter than the blower is on our Drolet 1400i insert stove! (on high)


----------



## MacinJosh (Dec 29, 2019)

brenndatomu said:


> I agree, I just installed a Richmond (same as Rheem) HPWH and you certainly would not hear it on the other side of a wall. I'd say it's quieter than the blower is on our Drolet 1400i insert stove! (on high)



Yep, there’s no way in hell anyone could hear this thing running on the other side of a wall....insulated or not.

Can we post videos here? Happy to take one with it running.


----------



## begreen (Dec 29, 2019)

Highbeam said:


> Do you think that below you on a different floor is the same thing as a closet in the same room or on the other side of an interior wall? Hopefully the newest models are quieter, quieter is better.


Put some micore or roxul in the closet wall as a sound barrier if you are light sleepers. At 49db we are talking pretty low noise.


----------



## brenndatomu (Dec 29, 2019)

begreen said:


> Put some micore or roxul in the closet wall as a sound barrier if you are light sleepers. At 49db we are talking pretty low noise.


Yeah I think I have heard ceiling fans that make more noise than that!
We run a small desk fan in the bedroom to drown out various minor noises...I used to need it dead quiet, but have gotten used to the fan, and its hard to sleep without it now.


----------



## EbS-P (Dec 29, 2019)

Looks like mine is 55db. A bit louder. It will be noticeable but probably no more than the exhaust fan down there now.


----------



## mellow (Dec 30, 2019)

Funny this came up, I had taken a video of mine over the weekend and sent it to my friend that has a Rheem hybrid to see if his was that loud and it looks like the AO Smith is considerably louder.   I am glad I put mine in the garage.


----------



## brenndatomu (Dec 30, 2019)

Mine says it is running on low all the time...guess I haven't heard high yet? Might be a big difference in noise?
Not sure how you would make it run on high since the dishwasher was run, and 3 baths/showers were taken all in about 2-3 hours...I would think that would do it if anything would...upper/lower tank temps were both way down. I am set to "heat pump only" mode though...not hybrid. Wanted to try it out that way first...so far so good.


----------



## MacinJosh (Dec 30, 2019)

brenndatomu said:


> Mine says it is running on low all the time...guess I haven't heard high yet? Might be a big difference in noise?
> Not sure how you would make it run on high since the dishwasher was run, and 3 baths/showers were taken all in about 2-3 hours...I would think that would do it if anything would...upper/lower tank temps were both way down. I am set to "heat pump only" mode though...not hybrid. Wanted to try it out that way first...so far so good.



I started that way too but in the winter months the heat pump just couldn’t keep up alone. There are four of us in the house and even with 80 gallons, one element would kick on to bring it up quicker. If you are okay waiting for long recovery periods after a quick high demand, you should be ok. I want “hot” water at all times, not luke warm after a big demand.

In the summer time, it never uses anything but the HP.


----------



## mellow (Dec 30, 2019)

I need to put a blanket on mine like my old HWH since it is in the garage, hopefully that will help, can't see it hurting it.  I keep it in Hybrid mode as well just in case, the element from what I have seen doesn't come on much unless it is under heavy use.


----------



## brenndatomu (Dec 30, 2019)

MacinJosh said:


> I started that way too but in the winter months the heat pump just couldn’t keep up alone. There are four of us in the house and even with 80 gallons, one element would kick on to bring it up quicker. If you are okay waiting for long recovery periods after a quick high demand, you should be ok. I want “hot” water at all times, not luke warm after a big demand.
> 
> In the summer time, it never uses anything but the HP.


Summer/winter won't matter much here...my wood furnace is about 15' away, so truth be told, it will probably have warmer ambient air temps to work with in the winter than in the summer.
So far the water temp been very adequate even in just HP mode. My wife is the only one in the house that likes "hot" showers, so as long as she doesn't go last of the 4 of us (and that never happens) probably never be an issue at all.


----------



## jetsam (Dec 30, 2019)

begreen said:


> Put some micore or roxul in the closet wall as a sound barrier if you are light sleepers. At 49db we are talking pretty low noise.



Homasote is an easy answer for a closet too. You can put it under drywall, or use it as drywall if you don't mind a slightly funky wall texture in the closet.

(side story: I laughed at one of their sales reps one time when he told me that stuff was waterproof. He looked at me, broke off a chunk of the stuff, threw it in a cup of water, and said, "Come back and look at it in a week."

He was right! )


----------



## EbS-P (Jan 3, 2022)

Well following up on this two years later…. Maybe only one since I installed the ducting. The room is no longer a bedroom it’s a library with an open door way connected to the rest of the basement.  Mechanical room is now closed off by louvered bifold doors.    

The reason is it it completely vented indoors.  With the ducting kit and 2 adjustable elbows  an some flex duct, the intake draws air from above the the bifold doors from the library through an extra filter  (and a bit from the suspended ceiling space). The exhaust elbow points down to the floor.    This arrangement keeps the air very stratified.  Hot moist air up too cold dry air down low.  

The HPWH can cook the basement significantly when we use lots of hot water.  Last winter it was not uncommon to have basement temps in the high 59s low 60s.  We didn’t spend much time down there and I was still trying to heat 100 % with wood from upstairs.      This winter has been warm and we are using the heat pump more and now we have the wood insert installed. 

I am a bit concerned about condensation on the outside rear of the unit.  It’s enough at times to run down the side but I never see a puddle at the bottom. This usually happens during the summer but it was warm and humid enough for it to occur yesterday.  I don’t see any way to avoid it.  Eventually if it runs enough it dries out. 

Thinking of the absolute best way to vent would be to exhaust to the the air return we only have one).  But running cold 40-50 degree air through the crawl space is asking for moisture issues I think.   Any colder climate than ours it’s going to increase heating load if venting/ installed in a finished space.    

It’s been a great investment and has cut  the amount of time we run a Dehumidifier in half. 

Evan


----------



## begreen (Jan 3, 2022)

I'm confused. I thought the HWHP would cool the space as it pulls warmth from the air to heat the water.


----------



## EbS-P (Jan 3, 2022)

begreen said:


> I'm confused. I thought the HWHP would cool the space as it pulls warmth from the air to heat the water.


It does. And if you are heating 80 gallons it takes a lot of heat out of the living space.  So during the winter it can make it quite a bit colder down there.


----------



## maple1 (Jan 3, 2022)

EbS-P said:


> It does. And if you are heating 80 gallons it takes a lot of heat out of the living space.  So during the winter it can make it quite a bit colder down there.


Maybe when you said cook the basement, you meant cool?


----------



## Max W (Jan 3, 2022)

Must mean cool.  Looks like the install worked out well overall.  We also appreciate the dehumidifying we get from our HWHP In the basement.  I’m far from a pro but I managed to install ours. I’m guessing your HP must have has condensate drain and the backside condensate is separate from that?


----------



## EbS-P (Jan 3, 2022)

Max W said:


> Must mean cool.  Looks like the install worked out well overall.  We also appreciate the dehumidifying we get from our HWHP In the basement.  I’m far from a pro but I managed to install ours. I’m guessing your HP must have has condensate drain and the backside condensate is separate from that?


Yet you are correct I meant cool. And yes separate from the drain.


----------



## Max W (Jan 3, 2022)

It looks like the plastic nipple is the condensate drain and if it is it should have a drain tube.  I was lucky to have a cellar gravity drain to run the clear plastic line pictured to.


----------



## EbS-P (Jan 3, 2022)

Max W said:


> It looks like the plastic nipple is the condensate drain and if it is it should have a drain tube.  I was lucky to have a cellar gravity drain to run the clear plastic line pictured to.
> 
> View attachment 289083


My understanding is both are draining the condensation.  The small one is there if the the big one gets plugged the water has somewhere intentional to go.


----------



## Max W (Jan 4, 2022)

EbS-P said:


> My understanding is both are draining the condensation.  The small one is there if the the big one gets plugged the water has somewhere intentional to go.


Clearly then that’s not the cause of the moisture.  I wonder that there is a cold area where the moisture condenses on the metal jacket and if a thin layer of foam insulation, like what’s used in a toilet tank, over that would prevent the condensation. It does sound like it’s evaporating.  I thought about ducting the air intake on ours from outside and leaving the exhaust as is in the summer for some gain but that didn’t seem worth the initial effort and the twice a year changing over. I guess that would add additional moisture for the system to drain off as well.  My unheated cellar drops as low as 45 or 50 at the coldest times. I pretty much keep it electric mode at 50 or below.


----------



## EbS-P (Jan 4, 2022)

Max W said:


> Clearly then that’s not the cause of the moisture.  I wonder that there is a cold area where the moisture condenses on the metal jacket and if a thin layer of foam insulation, like what’s used in a toilet tank, over that would prevent the condensation. It does sound like it’s evaporating.  I thought about ducting the air intake on ours from outside and leaving the exhaust as is in the summer for some gain but that didn’t seem worth the initial effort and the twice a year changing over. I guess that would add additional moisture for the system to drain off as well.  My unheated cellar drops as low as 45 or 50 at the coldest times. I pretty much keep it electric mode at 50 or below.


Intake from the outside negates any dehumidification during the summer for us.  I agree it’s not worth the hassle of swapping.  I would like to the how the efficiency changes with temp on these units.


----------



## jetsam (Jan 5, 2022)

The biggest part of efficiency is how ya use it.  Mine has a resistive-only mode, a heat pump only mode, and a mode where it can choose between the two based on demand.

(Fun fact: If you put it in heat pump only mode, the app constantly displays a large banner warning you that you need to put it in automatic mode for best efficiency.... )


----------



## EbS-P (Jan 5, 2022)

jetsam said:


> The biggest part of efficiency is how ya use it.  Mine has a resistive-only mode, a heat pump only mode, and a mode where it can choose between the two based on demand.
> 
> (Fun fact: If you put it in heat pump only mode, the app constantly displays a large banner warning you that you need to put it in automatic mode for best efficiency.... )


I run mine in heatpump only.  Is there an explanation why automatic mode would be more efficient? I can’t think of one.  I can see users complaining that they ran out of hot water sooner because they are no longer using the top element.  We ran with an old 40 gallon unit for so long that a cold shower was common and it was a rule that mom always got the first bath and the dishwasher always was set with the delay function.


----------



## mellow (Jan 5, 2022)

I run mine in hybrid mode and still saw enough of an electrical usage drop vs our old WH that I have just left it that way.  Mine is in an unheated insulated attached garage so I like to make sure it its warm with 4 people using it.

My WH used $1.15 in electric yesterday and it was 17 degrees out,  usually runs about half that.  I am even OK with $1/day for as much as we use hot water including the dish waster.


----------



## jetsam (Jan 5, 2022)

EbS-P said:


> I run mine in heatpump only.  Is there an explanation why automatic mode would be more efficient? I can’t think of one.


I puzzled  over that for a while.  I only came up with a couple ideas...

1) As intake air temperature decreases, there is a point where resistive is more efficient.  On the other hand, presumably that point is around freezing,  and hopefully that doesn't happen much in your house?  Maybe it pertains to bad installs where the unit is shut in a closet with insufficient airflow?

2) Every other part of the app is riddled with bugs; why would it be a surprise that this warning is attached to the wrong mode?


----------



## begreen (Jan 6, 2022)

EbS-P said:


> The HPWH can cook the basement significantly when we use lots of hot water. Last winter it was not uncommon to have basement temps in the high 59s low 60s


Sounds like there is a typo here. Did you mean cools, not cooks?


----------



## stoveliker (Jan 7, 2022)

Yes was noted before.


----------



## torpesco (Mar 31, 2022)

MacinJosh said:


> I have the Rheem and it is whisper quiet. I can barely hear it running and have to stand right next to it.


Wow... this makes me wonder if something is wrong with mine (Rheem installed in March 2021). I just used an app on my iPhone, so probably not as good as a proper meter, but above the unit it measures 75dB. Near the outlet, 67dB. 3ft away, 65dB. If I close the bifold door in front, then at 3ft away it's 52dB. The app says "quiet home" for 52dB... but it certainly doesn't feel quiet to me. Maybe it's partly the frequencies that make it seem worse. When the compressor is off, the room is more like 30dB.

Mine sounds more like mellow's AO Smith, I think. If not worse.

Edit: A google search led me to a couple posts of people commenting on the current generation being loud. One person described it sounding like "an industrial ice maker at a cheap motel." Seems about right.


----------



## torpesco (Mar 31, 2022)

EbS-P said:


> Well following up on this two years later…. Maybe only one since I installed the ducting. The room is no longer a bedroom it’s a library with an open door way connected to the rest of the basement.  Mechanical room is now closed off by louvered bifold doors.
> 
> The reason is it it completely vented indoors.  With the ducting kit and 2 adjustable elbows  an some flex duct, the intake draws air from above the the bifold doors from the library through an extra filter  (and a bit from the suspended ceiling space). The exhaust elbow points down to the floor.    This arrangement keeps the air very stratified.  Hot moist air up too cold dry air down low.



I've been considering ducting for my HPWH because it's in a somewhat inappropriate space... so I wonder what you & others here might think of this wacko idea.

It's in a tiny little utility closet in the centre of my main floor that barely fits it and the air handler for the ducted heat pump we replaced our furnace with. I was left feeling like the sales guy wasn't interested in selling us the right system for our application. (Proper air volume, proximity of noise to living area.)

To deal with the tiny room getting very cold and probably operating inefficiently, I removed a piece of sheet metal that was screwed over a hole that duct cleaners punched in the air return for the heat pump (top right in the photo). Its fan runs at a low speed continuously, so the cool air from the water heater mixes into the air in the whole house. Seems ok. The house is comfortable. What I don't like is that the gap under the utility closet doors now functions as an air return.

I was wondering how crazy it'd be to connect the HPWH to that air return duct on both intake and outlet.

Now that I'm actually writing that out, I can think of a some possible negatives:

If I just connect both ends to the air return duct, it'll create a loop (say if the air heat pump is off)
If I split that loop, then air will be continuously moving through the HPWH and its filter will become a pre-filter for the air heat pump. The pipe diameter would be smaller, too, so it couldn't be a full split.
There may not even be enough clearance by the outlet -- there's just 4.5" between it and the air handler.
Now I partly wonder if I should add an intake vent above the doors like Evan, with the cool air just making its way out under the doors... but what I don't like about that is the thought of dumping cool air onto any area of our concrete floor in cooler months. The semi-adjacent kitchen is bad enough already. I also don't like the idea of the visuals of a vent like that in our family room. :-\


----------



## EbS-P (Mar 31, 2022)

torpesco said:


> I've been considering ducting for my HPWH because it's in a somewhat inappropriate space... so I wonder what you & others here might think of this wacko idea.
> 
> It's in a tiny little utility closet in the centre of my main floor that barely fits it and the air handler for the ducted heat pump we replaced our furnace with. I was left feeling like the sales guy wasn't interested in selling us the right system for our application. (Proper air volume, proximity of noise to living area.)
> 
> ...


You I think you need the ducting kit.  The air return is now unfiltered with that hole.  At least tape a washable window ac filter  over it.  Could you do what I did and put an 8” air intake above the closet door? Doesn’t have to be ducted if you duct the exhaust to the air return.  Ie is there a header for that door?   I have a washable filter on mine.  If I were you I would.  

Do you even have room to add the ducting kit for the HPWH, or will you have to make your own?   

It’s a tough space but you have the air return. I say use it for the exhaust. If you do duct it you will need need to clean the filter much more often.  I have a filter on my intake above the closet doors and the mesh screen that the units uses.  If you did add a vent over the doors you could work to better sound seal and insulate the doors.  Then make/buy a duct silencer for that it might not even need to be attached to the unit.  Just An air return for the room.  

My thoughts were these.  Take the warmest air up by the ceiling in and dump it out on the floor would give me the best efficiency.  

For you I don’t know if the intake even needs ducted if the exhaust is.   

If you are running the hvac fan 100% of the time that seems unnecessary.  Does your thermostat have a circulate setting where it might cycle?   Mine does.  

The most uncomfortable the library room gets is in the winter when the incoming water temp drops and the HPWH runs more.  I like the cold room in the summer.  It would be unbearable in the winter when we are running the wood stove and the heatpump is off. Think like 57-60 degrees.  

Man that space is tight.  Good luck.


----------



## torpesco (Apr 1, 2022)

torpesco said:


> Wow... this makes me wonder if something is wrong with mine (Rheem installed in March 2021).
> ...
> Edit: A google search led me to a couple posts of people commenting on the current generation being loud. One person described it sounding like "an industrial ice maker at a cheap motel." Seems about right.


Read the rest of the comments on a Green Building Advisor thread on it  and it sounds like units built in Feb 2022 or later are quieter. I'll have to look into a warranty replacement.


----------



## torpesco (Apr 1, 2022)

EbS-P said:


> You I think you need the ducting kit.  The air return is now unfiltered with that hole.  At least tape a washable window ac filter  over it.  Could you do what I did and put an 8” air intake above the closet door? Doesn’t have to be ducted if you duct the exhaust to the air return.  Ie is there a header for that door?   I have a washable filter on mine.  If I were you I would.


The filter is right at the top of the unit, where the return connects to it. (It's technically installed upside down -- our ducts exit at the bottom, under the slab foundation.)



EbS-P said:


> Do you even have room to add the ducting kit for the HPWH, or will you have to make your own?


I'm not very optimistic about the kit fitting. It'd be nice to get more dimensions than Rheem has on their website.



EbS-P said:


> It’s a tough space but you have the air return. I say use it for the exhaust. If you do duct it you will need need to clean the filter much more often.  I have a filter on my intake above the closet doors and the mesh screen that the units uses.  If you did add a vent over the doors you could work to better sound seal and insulate the doors.  Then make/buy a duct silencer for that it might not even need to be attached to the unit.  Just An air return for the room.


That sounds pretty reasonable. Yeah, I'd probably add a 2nd filter for the intake if I ducted the exhaust.



EbS-P said:


> My thoughts were these.  Take the warmest air up by the ceiling in and dump it out on the floor would give me the best efficiency.
> 
> For you I don’t know if the intake even needs ducted if the exhaust is.


Probably not, yeah. The main reason I can think of would be for noise, but if I'm lucky and get a newer, quieter replacement, maybe that will be less of a concern.



EbS-P said:


> If you are running the hvac fan 100% of the time that seems unnecessary.  Does your thermostat have a circulate setting where it might cycle?   Mine does.


It's the way the system is designed. There is no 'off' option other than to turn the system off completely. Variable speed fan and variable speed compressor. I guess the theory is that running the fan on the lowest speed continuously keeps the temperature a bit more uniform and comfortable? Seems to work well.

Actually, one neat thing is when I use our fireplace (zero clearance, wood), the house warms up higher than the thermostat is set, the compressor doesn't kick in, and the temperature stays pretty even - (though warmer in the room with the fireplace, of course).



EbS-P said:


> The most uncomfortable the library room gets is in the winter when the incoming water temp drops and the HPWH runs more.  I like the cold room in the summer.  It would be unbearable in the winter when we are running the wood stove and the heatpump is off. Think like 57-60 degrees.
> 
> Man that space is tight.  Good luck.


Hah. Thanks. Seems like I may end up trying to make my own duct fitting for the exhaust.


----------



## schweigert85 (May 20, 2022)

Heres my novel experience with my heat pump water heater so far touching all the topics covered in this thread - 

I just got an AO smith 80 hybrid couple weeks ago and installed it in a small 4x10x8 utility closet - with the intention of ducting the exhaust to the larger "laundry room" its connected to - as I live in a year round warm climate, and and to take advantage of the cool exhaust air - as well as getting that cold air out of the closet to improve the tank and warm water pipes efficiency.   I'm also running the condensate line through the wall and raining into a wash basin that my washing machine also drains into. 

I installed it on a tile floor, on a pizza pie layout of bricks so its off the ground - did not use a drain pain. 

I used the water heater  for a week with the door to the closet door off just to make sure everything works before i drill holes into it for the vent kit, and also running the exhaust vents through the drywall to the laundry room.

NOISE - 
Its not quite when you're next to it with the heat pump going... sounds exactly like the youtube video posted (I read its a fan rattle) - I've called AO smith for replacement fan and motor (which is the reason I went with AO smith as they have the best customer service) and they're sending the parts our immediately. with the door open, it echoes around the house about 30 feet away or so. 

With the door closed, you cant really hear it at ALL - so drywall on stud (no insulation) seems to be enough to muffle the noise. 

When its in a small room, they say you can run a louvered door, or duct kit.  I think obviously the best is to use a duct kit - that way the noise stays in the room, and you get the cool air away from your warm stuff - i just wish they specified how MUCH of a louvered door they need. 


DUCTING
My current configuration - is I installed two different 8" registers/vents in the drywall from the closet its in to the larger room - with the intention of one being for intake, and one for exhaust - however as I thought about it you dont really need to run duct for the intake, as it will be sucking in air through that vent anyway.   I connected the exhaust and ducting to the other vent, and its pumping cold air out into the other room. 

*Heres the problem with venting the cold air away into another room *-  now you have a "warm" air space, and a heat pump pushing "cold" air through the ducting out of it.  That means MAJOR condensation - all around the exhaust of the water heater, and on the ducting leading out - just like a a cold glass of water on a hot day - and all this condensation is on the exterior of the unit now.  It... might be harmless... but it doesn't seem right.  


I might try to swap my venting to the exterior room so that instead - its pulling the air directly from the exterior room, and instead the exhaust can escape from the other "unducted" vent  - not as ideal, as then that closet would be cooled down instead, but probably preferable to all the condensation


----------



## EbS-P (May 20, 2022)

schweigert85 said:


> Heres my novel experience with my heat pump water heater so far touching all the topics covered in this thread -
> 
> I just got an AO smith 80 hybrid couple weeks ago and installed it in a small 4x10x8 utility closet - with the intention of ducting the exhaust to the larger "laundry room" its connected to - as I live in a year round warm climate, and and to take advantage of the cool exhaust air - as well as getting that cold air out of the closet to improve the tank and warm water pipes efficiency.   I'm also running the condensate line through the wall and raining into a wash basin that my washing machine also drains into.
> 
> ...


I get the condensation on the unit and my exhaust short duct elbow too.  It has never dropped off though.  It will probably condense on the unit no matter what you do.  

I have considered insulating with bubble wrap or the foil faced bubble wrap.  Cut everything to fit.  Spray on some adhesive.   Stick it all up.  Haven’t done it yet. 

Just my thoughts.


----------



## schweigert85 (May 20, 2022)

Yeah Im going to dry insulating the duct a little better with some duct wrap, and also maybe around the exhaust connection on the water heater itself


----------

