Ruud/Rheem Heat Pump and Thermostat Wiring Question

[rtimgray]

For a recent addition to our house, I installed a Ruud/Rheem 3 ton heat pump - it had R-410A refrigerant and 10kW heat strips. I installed a Hunter programmable Auto Temp Heat Pump thermostat.

All summer, it seemed to work fine for air conditioning. This is my first programmable thermostat, and I think I liked it for summer. Now, I'm not sure about cooler weather, but that's the source of my question.

It seems that now that the heat needs to run, anytime that the unit runs, the heat strips are running. I basing this on how warm the air is from the register, as well as how fast my electric meter is spinning! I''m wondering if I have something mis-connected in terms of wiring.

This is how the unit is currently wired:

Function Label(Tstat) Wire@Unit

24VAC supply R Red

Compressor stage 1 Y Yellow

Auxiliary Heating W Black & White

Emergency Heating E (Jumpered to W @ thermostat)

Reversing Valve O/B Blue

Fan G Black & Green

24VAC Common C Brown

I don't know if any of this makes sense, or if I need to get some more information together. I just know it appears as though when the heat runs, the strips are running as well.

The other unit that services the old part of the house is a Ruud/Rheem split system heat pump (the new one is a package unit). It has an old, non-programmable, manual thermostat. When I turn it to "Heat", just the unit runs; if I want the heat strips to run, I have to turn it to "Emergency". With that unit, I can feel a big difference in air temperature when the heat strips are on and when they aren't.

I've also read that some programmable thermostats will use and "Auto Recovery" feature, and if the difference between the current temperature and the desired temperature is too great, then it will activate "emergency heat". I haven't investigated this portion yet either.

Some of this is coming up because it is just now getting cold enough for the unit to need to heat, so I haven't had a lot of chances to see what's going on with this. I was just hoping to solicit some advice in case anyone was familiar with this situation.

I appreciate any help anyone can provide.

Thanks in advance.

Good luck and take care.

 

[rtimgray]

Okay, the "chart" I tried to type in didn't work out at all. I will sketch something up and post a picture.

 

[LD1]

I cannot comment on the wiring, but first thing I would do is verify if the heat strips are actually working or not. Dont just base it on temp and your meter. Those can be misleading.

Second, most of those programmable T-stats, if you call for more than 2 degrees warmer than ambient (IE: Its 70 in your house and you set it to 73+) they automatically kick in the Aux strips cause it assumes you "want it warm and now". They also operate on time. Like 15 minutes. IF the HP cannot satisfy that in 15 minutes, it gives up and tries AUX.

Now I have never had one with electric B/U, always propane. And propane wont run at the same time as the HP, so it was easy to know what source you were using. But also in deciding on propane vs HP, there is a t-stat in the outdoor unit. It locks out the HP below a certain outdoor temp and anything below that runs on Aux. I dont think units with electric strips use this feature since the strips and HP can operate at the same time. But i still think they have that adjustment outdoors, and perhaps its set higher than your outside temps.

 

[rtimgray]

Thanks for the quick comment - I found in my thermostat manual where I can turn off the "Auto Recovery" feature, so I'll try that this afternoon too.

 

[rtimgray]

Hopefully, here's a sketch of the wiring for the thermostat to the unit.

I had the opportunity to talk to an HVAC technician yesterday (he works for a contractor that is doing work in the plant). He looked over my manuals and the diagram, and he said it was wired correctly. He said that the most likely explanation is that when the heat pump gets 2-4 degrees behind what the setpoint is, the thermostat will tell it to run the heat strips to make up the difference as quickly as possible. He has a unit with a Honeywell thermostat and said that is what his does.

I'm going to try running mine in manual mode where I can also "de-select" emergency mode and see it will run without running the heat strips.

Thanks for the help. Sorry for not having the information in a more easy-to-view form earlier.

Good luck and take care.

 

[mddorange]

I have a 4 ton Ruud/Rheem Heat Pump and LD1 is correct that if the temp is more than a set amount, it will kick in the heat strips. On my thermostat I can set that "kick in amount" to how much difference I want. You need to check that setting as it can be set too as little as 1 degree..