Heat Pump Water Heater

[greenjp]

Digging this back up since I have a bit of a functional update. Actually, more of a piece of advice for anyone who has bought a Rheem Proterra.

Go ahead and spend the $20 and order a new set of 4 thermistors.

https://parts.rheem.com/en/product/RPD-AP18087

Oooh this is great and timely info. I installed one of these at the mother in law's a few years ago, works great but lately the compressor has been shutting off. Threw some low suction error or something (don't really the number literally just deleted it earlier today), shutting the whole thing down for a bit seems to reset everything, but it keeps recurring. I'm not local but should be able to repair over Christmas if this is in fact the issue.

jeff

 

[ctechbob]

Oooh this is great and timely info. I installed one of these at the mother in law's a few years ago, works great but lately the compressor has been shutting off. Threw some low suction error or something (don't really the number literally just deleted it earlier today), shutting the whole thing down for a bit seems to reset everything, but it keeps recurring. I'm not local but should be able to repair over Christmas if this is in fact the issue.

jeff

99% chance that is the case. By all accounts the actual compressor assembly is solid, it's just let down by the thermistors.

When mine went out I was shocked at how much power the elements use. I know that's what I used to use to heat my water, but when you use about 3kw on an average summer day, and all of a sudden you see the usage shoot up to 12+kw it is a little bit of a shock to the system and feels super wasteful.

 

[ctechbob]

I just realized I accidentally deleted the manual from my Google Drive.

 

[greenjp]

Ok so it happened again overnight per the app. Getting error A006 Suction Temperature Too Low, along with a hardware alarm that the filter is clogged. I had them wash the filter off so don’t believe that’s actually the problem. Consistent with the thermistor issue?

 

[ctechbob]

Ok so it happened again overnight per the app. Getting error A006 Suction Temperature Too Low, along with a hardware alarm that the filter is clogged. I had them wash the filter off so don’t believe that’s actually the problem. Consistent with the thermistor issue?

Most likely.

There is a key combination you can press to display the thermistor readings and cycle through them. One of them will be way out of whack.

A004/005/006 are all thermistor related.




This guy shows how to get into the thermistor check mode.

 

[ctechbob]

If you go into test mode you'll probably see that the 'ST' temp readout either isn't reading, or it is reading far too low. It should start to slightly climb up towards ambient when the compressor is running.

 

[ctechbob]

I debated adding to this post and starting another one. Apologies to those who get a little out of sorts by digging up an old post, but this will be valuable information for DIY people that own the Rheem Heat Pump Water Heaters.

As I posted above, the thermistors are a bit of a weak spot for these machines. It used to be that the Rheem thermistors were a few bucks a piece and you could replace all 4 of them for around $20.

Being a big company, they have discontinued the thermistors and now sell them as a 'kit' that includes new clamps that you don't need as you can easily reuse the old ones.

I'm not paying that, and you shouldn't either.

Digikey to the rescue.

Being that I've already replaced mine once, I saved the old thermistors, hacked off the connectors, solder, heat shrink, Bob's your uncle.

I did compare values of the new vs the 'old' ones. They match up perfectly. I had replaced all 4 of them the first time one went bad, so 3 of them were still good. That was what I compared the new Digikey ones to. Room temp, 160 deg, and 40 deg, all the readings were almost dead on, so I'm confident these will work when the time comes.

 

[ctechbob]

Just dropping in to confirm that the Digikey replacements work like a charm. I had the suction side thermistor flake out on me the last few days and I replaced it with the DIY one. Back up and working like a charm.

Dumb thing didn't alert me that it had gone wonky again. Just started using the elements all on its own. Only reason I noticed it is that the last week or so I've walked out into the garage when we'd been using hot water and knew the compressor should have been running and it wasn't. Didn't think much of it until I got around to looking at the ap tonight and noticed that my power usage had gone through the roof.

Like from 4kw a day to over 15kw. That would have added up...

 

[Donald]

‍

Just dropping in to confirm that the Digikey replacements work like a charm. I had the suction side thermistor flake out on me the last few days and I replaced it with the DIY one. Back up and working like a charm.

Dumb thing didn't alert me that it had gone wonky again. Just started using the elements all on its own. Only reason I noticed it is that the last week or so I've walked out into the garage when we'd been using hot water and knew the compressor should have been running and it wasn't. Didn't think much of it until I got around to looking at the ap tonight and noticed that my power usage had gone through the roof.

Like from 4kw a day to over 15kw. That would have added up...

Maybe there is kind of a fail safe mode to try and get you hot water even if the values it detects are wacky.

Or "keep the wife happy mode".

My wife would not really care whether the coil or compressor heated the water as long as she got hot water for her shower or bath.

 

[ctechbob]

‍
Maybe there is kind of a fail safe mode to try and get you hot water even if the values it detects are wacky.

Or "keep the wife happy mode".

My wife would not really care whether the coil or compressor heated the water as long as she got hot water for her shower or bath.

There is, that's exactly what it is doing. It just doesn't do a good job of warning you that something is amiss.

Other than that minor annoyance. Still highly recommend for the energy savings. Although I will admit, if you're not capable of DIY'ing the fix, then it will be super annoying to you.