Heat pump water heater ducting question?

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EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
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.
 

EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
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

Feeling the Heat
Mar 4, 2015
310
Crestwood, KY
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?
 
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peakbagger

Minister of Fire
Jul 11, 2008
7,199
Northern NH
What about venting it under the refrigerator?. I have seen some design guide for ERVs that advocate this for fresh air return.
 
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EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
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

Member
Nov 9, 2017
71
Eastern MA
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.
 
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EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
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

Minister of Fire
Sep 20, 2013
650
Branford, CT
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 .
 

EbS-P

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
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.
 

NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
447
Massachusetts
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
 
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NoGoodAtScreenNames

Feeling the Heat
Sep 16, 2015
447
Massachusetts
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
 
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begreen

Mooderator
Staff member
Nov 18, 2005
93,149
South Puget Sound, WA
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

Minister of Fire
Jan 19, 2019
2,405
SE North Carolina
I have an 8 year old that can sleep though anything but the crack of dawn on a weekend;)
 
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Highbeam

Minister of Fire
Dec 28, 2006
19,693
Mt. Rainier Foothills, WA
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

Mooderator
Staff member
Nov 18, 2005
93,149
South Puget Sound, WA
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.
 
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MacinJosh

Feeling the Heat
Mar 4, 2015
310
Crestwood, KY
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.

4bc91265e6462364fd659c3a04298dae.jpg
7064f1171a350c8946950b8aa7fe1dee.jpg
 
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Highbeam

Minister of Fire
Dec 28, 2006
19,693
Mt. Rainier Foothills, WA
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

Minister of Fire
Mar 1, 2012
969
Central Ohio
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. ;)
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,123
NE Ohio
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.

4bc91265e6462364fd659c3a04298dae.jpg
7064f1171a350c8946950b8aa7fe1dee.jpg
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

Feeling the Heat
Mar 4, 2015
310
Crestwood, KY
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.