Heat-pump water heater: Air volume, etc.
Lots of good information here about Heat Pump Hot Water Heaters, thanks! My situation is unique, so I thought I’d get some feedback before I pull the trigger and purchase 2 Stiebel Eltron 80-gallon units to install in place of 4 40-gal resistance hot water heaters servicing 4 2-BR units in a multifamily building.
I am thinking of installing these units in a small mechanical room (5’x8.5’x8′ tall) that also houses two ~80 gallon pressure tanks for the well. It will soon also have a water treatment system with salt canisters and green sand to deal with arsenic. I would replace the existing door with a locking security screen door to connect the air space with the staircase (8’x4’7.5′ tall), landing (6.5’x8’x8′ tall), and hallway (4’x12’x8′ tall) immediately outside the room. Then there is a fire door that I would install a specially designed louvre system into to connect with the front entry area (5.5’x5.5’x7.5′ tall). By my calculations, this would give me almost exactly 1600 cuft of air volume. I thought I would also add another louvre system to the fire door at the top of the steps to connect with an upstairs hallway, landing, an additional staircase and an additional hallway on the third floor. I didn’t measure this space, but it is at least 1000 cuft more, perhaps 2000cuft including the third floor.
I will be installing mini-split heat pumps in each of the units (total 6, including 2 1BR units on the third floor; LED lighting; and eventually solar panels once I have the load reduced considerably. Paying for all of this by including utilities in the rent going forward.
The mechanical room shares a wall on both sides with a bedroom in each of the ground floor (1/2 basement) units. There are resistance base board heaters in all the hallways.
1. Would you install these units in this space to be shared by two separate units? Anything you would do differently?
2. Do I need to be concerned about noise in the bedrooms?
3. I would plan to set the temperature very high (149 degrees is what rep said on the phone), put in mixing valves, and install low flow shower heads. Anything else I can do to make sure tenants have enough hot water at peak times?
Any other thoughts or considerations are welcome. Thanks in advance!