Heat Pump Water Heater Placement
Hey All,
New construction build in CZ 6. The basement is half finished basement (conditioned and airsealed) and half drive under garage (unheated and airsealed).
Currently, we have a 4′ x 5′ mechanical room that is to house an air handler, heat pump water heater (Rheem Proterra or similar) and Broan ERV. In the attached image you’ll see the room outlined in red.
Many would likely say this room is a bit small to fit these items in, especially with the HPWH. The plan would be to use louvered doors to make sure there’s enough air flowing in and out of the room for the water heater per requirements.
If this sounds like a good plan, we will keep it — as it’s of course the simplest with the shortest plumbing supply runs (all bathrooms are pretty much right above this mechanical room across a couple floors). However, the more I’m learning about heat pump water heaters, the more it seems like they like / need a lot of space.
Another thought I’ve had recently is to place the HPWH in the unconditioned garage on the other side of this basement level wall. There’s plenty of room in the garage. It could even be enclosed in an insulated room of it’s own (air sealed from garage fumes) if necessary. Obviously this is more work and makes the mechanical room a bit disjointed, but might be necessary?
Appreciate any thoughts on these two options. Also, for those who have HPWH in a similar size mechanical room — to hear of any issues with the size.
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Replies
Short runs from the tank will give you almost instant hot water. This is something you will appreciate everyday. If you can't keep delivery times under 10s with moving the tank, I'd strongly suggest keeping it where it is.
In CZ6, you've going to want to keep the heat pump water heater somewhere inside the conditioned envelope of the house. So, you then have two options. Duct a monolithic heater so that it can get sufficient airflow in that room, or go with a split system like the Sanco and move the heat pump unit to another location (still within the conditioned envelope) where it can get enough airflow.
The Sanco is 2-3x more expensive than the Rheem. That's a large premium even though it is quieter than any monolithic heater I've seen (37db), and 10-20% more efficient.
As for the mechanical room size, it will be tight. Make sure you work with your installers to optimize the layout so that the equipment can be serviced. Often times, serviceability is an after thought. So you get everything crammed in there with no easy way to repair or replace individual systems.
Sanco looks nice but that pricing doesn't work unfortunately. Good point on the short runs. I think it makes the most sense to keep it where it is.
Louvered doors is all you need. If you have an open return from the air handler nearby you should have plenty of airflow.
Do you have combustion appliances? Having just a return will depressurize the room ever so slightly, which could be a problem if you're burning fuel.
Thanks -- There won't be any combustion appliances in the home.
Seems to me a laundry room is not a showplace I see no reason to hide the water heater in a closet.
Walta
That is an option we considered. Open the back wall of the mechanical room and connect it to the laundry.
I recommend installing generously-sized louvred grilles both high and low on the wall, to encourage air exchange. I have had clients unhappy with how cold utility rooms can get with a HPWH and they can be loud in adjacent spaces, but I've also put them under stairs a couple of times now and they seem to work fine if they have the vents.