Indiana New system questions

The tech visited in early November, here are the data from that visit:

Total volts 243
Total amps 9.7
Supply air temp 99
Return air temp 70
Water pressure in 42
Water out pressure 38
Water temp in was 46
Water temp out was 38

I see the pump in Stage 2 most of the time... are you saying that just because it says Stage 2 doesn't necessarily mean it's accessing Stage 2?

I poked around everywhere in the thermostat looking for the temperature thresholds, but no luck so far. I'd love to be able to make them higher.

I think at this point I'm looking at having the tech back out to test the things you mentioned.

The EWT is a big concern, I think. It's down from 46 to 30 in just over a month, and the coldest part of the winter is yet to come...

 

I also think the 30-deg EWT sounds like a problem.

I was just noting that 18000 BTU is consistent with stage 1 operation and a misconfigured thermostat could prevent stage 2 operation.

 

30deg EWT is the problem. Question is why is the water temp at 30 degrees so early.

You can download the Bryant specification manual for the GZ series www.shareddocs.com/hvac/docs/1009/Public/06/PDSGZ-02.pdf
For the 3 ton unit: at 30 deg water, 70 deg entering air, water flow between 6 and 9gpm, you are going to get a heating capacity of ~19kBTU/hr in stage 1 and 28kBTU/hr in stage 2. Corrected for loop antifreeze and these are ~1kBTU/hr little less (for pg or methanol; ~2kBTU/hr less for ethanol). so the data from early November looks like it was in stage 1 at the time. I would expect it to be in stage 1 at that point; you really wouldn't need stage 2 until Jan/Feb. Have a tech check the unit parameters but anecdotally, the unit seems to have been working properly in early Nov.

Back in the early posts, you indicated the house is 5500 sqft. Doing a thought experiment and using some rules of thumb (which may not be perfectly applicable but will be roughly correct), I would expect a total heating load somewhere between 100kBTU/hr to 150kBTU/hr. That means your 28kBTU/hr heat pump (stage 2 at 30 deg water) is barely good for 20 to 30% of your heating load. Granted this is at design temps and we haven't hit that yet. Is the gas furnace (natural gas or propane?) capable of making up the remaining 80 to 70%? It sounds like it isn't or conflicts with the heat pump operation due to the combined operation of the furnace and heat pump to the same "zone". If the GSHP is doing the heavy lifting here, then that would explain the higher than normal stage 2 operation and lowering of EWT so early in the season because of the combined system. If you shut off the GSHP, could the furnace heat the whole house to allow the ground loop to recover (since we aren't at design temps yet)? Based on the what has been provided, the gas furnace has to have more heating capacity than the GSHP.

 

New observation: what it looks like to me (maybe?) is that the system isn't letting the EWT get below 30.0 degrees. When it hits 30.0, the aux comes on (with the HP still running) until it recovers somewhat. Is that a thing that systems do?

 

Not likely. What you are seeing is likely due to water's heat of fusion. Once the water in the ground external to the loop pipes gets to 32F as a result of the water inside the pipes being <32F, the water external to the pipes begins to freeze. And the water inside the loop pipes doesn't freeze because of the anti-freeze installed. This freezing or fusion of the water external to the loops requires much more energy be extracted from the ground to drop the temperature below 32F.