Soundproofing around a Rheem HPWH?
I just discovered that the previously listed noise ratings for the Rheem hybrid heat pump water heaters (Prestige Proterra) were incorrect and have since been changed. All models were rated at 49 dba but upon calling Rheem to inquire about our very loud equipment, they informed me it is actually expected to be around 60 dba once installed in a home. Had I known this I would have ensured we seriously soundproofed the area. As far as I know, 60 dba is about 4 times louder than 49 dba in terms of noise perception, but actually 12.59 times higher in terms of sound intensity. That is a pretty big difference and I am sensitive to sound to begin with.
Heat pump water heaters seem great but I was not anticipating this noise… what can be done to soundproof the area given that we’ve already finished drywall/painting?
We have located the water heater in a basement pantry/storage room, tucked away from a rec space and gym. When it is running, it can be heard throughout the basement even with the doors shut. I find the high frequency sound especially bothersome but it’s just a very loud piece of equipment which differs from all other appliances which are really not noticeable from a distance (i.e. a fridge). Didn’t want to close it off from the pantry room itself because the whole point is that the unit will provide cooling for the room to store produce and dried goods, while utilizing the heat from some appliances (freezers).
See drawing below and pics showing the space pre-drywall. The mech room north of the water tank has plywood on the walls, unfortunately there is no insulation in the wall separating from the water tank but I suppose we could remove the plywood and try to add some. On the other side the tank is right against an unfinished bathroom, also no insulation on this wall but it’s just an open cavity right now so we could easily add something here to soundproof it if that would help. The big problem I see is that we have no insulation in the wall separating the pantry room (loud with the tank in it!) from the living space and it’s already drywalled/painted now.
Just curious how you would approach trying to block the noise from the water heater in the main area. We will keep the mechanical room door closed so it doesn’t matter if it’s loud in there. The pantry room door can also stay shut but there is a large gap below. The bathroom door will stay shut for now while unfinished, but it would be nice to someday be able to use that bathroom without an extremely loud mechanical noise.
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Ducting it will help, they make in line duct noise dampeners, I would do multiple in line. I would use insulated flex duct and make sure I did a couple of bends, with the dampeners soon after the bend. On the unit you can try mlv and rigid rockwool (or batts) over that. They do make ceiling acoustic dampeners that would help keep the noise isolated to the pantry. If you duct you could also isolate the unit, either with a full wall or even just plywood. You could also adhere a sound dampener to the plywood in the heater side.
Weather stripping and adding a threshold sweep to try and air seal the door will also help contain it
Duct sounds like a good idea. You can insulate the duct (interior preferably) and add a few bends and that should help. I'd also insulate all the walls and ceiling that you can with mineral wool before you close them off. They make the sound batt insulation that would work well for this application. You can do weather stripping around the entire door to hopefully help that area.
I agree with the ducting, I have the same water heater and ducting the exhaust made all of the difference. I just used the flexible insulated duct and worked like a charm. I didn't need to duct the intake, as once I ducted the exhaust noise was manageable.
Wow this is great news… thanks guys!
Unfortunately the walls/ceiling is already mostly closed so as I mentioned the only spot we can easily add insulation is in that bathroom/shower wall which is still open since the bathroom is unfinished.
This might be a stupid question but… where does the duct go? You can see the installation, where is the duct supposed to be directed?
I ducted mine to exterior, but you could also duct to a crawlspace or attic if you want. The other thing is that it actually puts out quite a lot of cold air, so beware of that for where you vent it.
The question is how much does the noise bother you in dollar terms?
For 100$ you can caulk the gaps in the drywall and weather strip the door.
For 1500$ you could also blow cellulose insulation into the walls and ceiling.
For 3500$ you could also cover the walls and ceiling with acoustic tiles.
According to the manual for the water heater is the room large enough for the unit with the door closed?
@schmoot - Well we want the cold air in this room, that was the point of putting it in there. So we don’t want to send the cold air elsewhere… unless we close off the little area where the tank is and vent into the main pantry room. It is shown on the drawing I attached.
@Walta - I suppose I’ll have to wait until we move in and see how bad it is! We’ve never lived in or even been inside of a house with loud equipment like this so it is very off-putting. It seems odd because our builder says clients have never mentioned the noise… but here on GBA or Reddit, it seems heat pump water heaters have a well known noise issue. Your blown cellulose idea is an interesting one! Sounds easier than opening the drywall to add the mineral wool safe n sound batt product we have virtually every where else aside from here where we really need it!
Venting it indoors is the correct approach, from an energy perspective.
I have a different brand but I was able to quiet it noticeably by putting about 6' of 8" insulated duct on the exhaust.
It amazes me how Rheem has f'ed up their HPWH's. I have a gen4 installed in 2019. It's as quiet as a church mouse and has been flawlessly dependent. It really does operate at 49db. Then the gen5 comes out and it's a jet engine taking off. And they have generally refused to admit their errors nor correct it.
The fact that you're perceiving a high pitched noise and not a low pitch or vibration is actually good news from a sound abatement standpoint. High frequencies are best absorbed by a baffle on top of your wall surface (not inside the wall). Hard surfaces will reflect the sound. Soft surfaces will dilute/obsorb the sound. If the soft surface is on top of a hard/dense wall you get the benefit of it obsorbing the sound waves twice: once as they pass through the soft material on the way to the wall and again after they've bounced off the wall and traveled back through the soft material.
Recording studios often put cloth or muslin over apholstery foam sheets or frames with fiberglass batts for an inexpensive clean look. These assemblies can be hung on walls or ceilings.
There's also non-toxic flame retardant treatment you can use for the muslin. You can find it at theatre supply houses. It's used for treating props and curtains for code compliance. It's a powder you mix with water.