John, try that question in a new thread, please.

Not to hijack this thread, but what types of things would we experience with low flow?

We attached a pressure gauge to my P/T port on a Climatemaster 5-ton unit feeding a (3x300ft) loop (reverse return) and I barely see any pressure on Entering/Leaving side (The guy that flushed the system is coming back tomorrow to add water/increase the static pressure.  Our EWT/LWT seem to be OK at 64/73 after an hour of continuous running. but the readings were so low, I couldn't get a delta-p to calculate teh actual GPM.... which indicates to me that I might be way lower than the 5-ton unit needs running 2nd stage.

the odd thing I see is that after a few hours of running, the system doesnt seem to bring things below 71F inside with an outside temp of 81/82F, even with decent EWT/LWT. 

Would this performance be due to low loop flow?  As long as the EWT/LWT are in the desired range, would the unit be operating at its design EER? or am I looking more at a unit that is undersized?

The pump unit is dual Grundofs -99s.

If your EW AND LW temps are in range, which it sounds like they are, then you are getting all of the performance you can expect out of your heat pump.

You might be looking at an undersized unit. Get a probe thermometer and check the air temp coming off the top of your heat pump.

Good luck

A few hours ago, Air temp coming out of supply (above the unit) was around 50-53 and return temp was in 70s.
The thermostat was set at 71, outside temp in low 80s, and it seemed like the unit would not turn off running solid for at least an hour, but temp was maintained at 71..... as soon as I set it at 72F, the unit started cycling reasonably.... but by then the temps started falling too (outside/ambient).

So, regardless of flow, it sounds like it might be behaving within design. I asked for the latest copy of their geodesigner application report to double check what design temps they used. If they designed at 95out/75 inside for summer, I guess 83/84 outside would have long run times, right? ( I did ask them to go lower, but now not sure..... we are in SE Pa, north of Philadelphia).

My previous air-to-air unit was a York Stellar Plus 2000 (5-ton), and had no issue with cooling at this level..... it ran a few times an hour.....

Q: Is there / would there be that much of a difference between the York ASHP and the ClimateMaster GSHP at 5-ton capacity cooling?

I did order a set of tools for myself (digital thermometer, pressure gauge, etc) and we are going to increase water pressure in the loop tomorrow, but this thing got me wondering......

Your heat pump is performing as it is designed to do.

You raise a good point about design temps. If the system was designed for 75° inside when 95° outside, you probably won't get below 70° inside when it is 85° outside.

You do need at least 30 psi system pressure. This won't improve anything, but it will keep you loop pumps from cavitating.

You asked about first and second stage. This is controlled by the thermostat. Usually first stage will run for so many minutes (user defined) and then second stage comes on. I am not familiar with your stat, but the manual should tell you as long as it is a 3 stage heat 2 stage cool stat. If it is a 2 stage heat, then you need to exchange it.

Keep us posted.

Daniel, Did you ever sort out why your pressure measurements are non-existant?

Yes, we did.

Most of this stuff turns out to not be rocket science. The problem is trying to purchase tools when it is mainly only possible to get things via HVAC companies, as distributors don't tend to sell to homeowners.

My issue was simply that the loops needed to be pressurized to somewhere between 35-50psi..... All that took was a tool that can be pushed into the P/T and connects to a hose. Our driller came back to add pressure, and I tracked down a small company in Indiana that would sell me the "Pressure Ram" to do it myself in the future.

The pressure standing doesn't really matter to the flow, it apparently just eases the job of the pumps. After increasing pressure in the loop, it is possible to measure the pressure drop across Entering/Leaving P/T points. From that, with the EWT we are able to get the GPM rates for the loops/pumps, which are right on target for our three sets of loops.

My three systems installed are almost working properly now. Our single remaining issue is that the Climatemaster FP2 thermistors that connect to the air-handler seem to always be throwing a fault (there is no wasy place to put them on the Amana/goodman 3036 air handler. We disabled the UPS (unit perfmance sentinal) until the distributor tech guy can come take a look to check the thermistor location on the coil (where they suggested it be placed).

The biggest problem I faced was arrogance (in the online community and installers that were not up-to-speed). It was a very unfortunate experience. Everyone was so cocky, I just decided to learn it myself..... Sometimes installers that truly can be experts act like children and try to keep-the-secret, even when someone is paying over $85K for an install.... They don't realize that a Homeowner needs attention, questions answered, etc when this much money is going out........

I digress...... lesson learned:
    1. Online forums and "experts" can be quite arogant and unfriendly/unhelpful.... but there are exceptions (thanks geodean, robotec)......
    2. Loops are simpler than people say, but installers tend to go on the low side (those that I talked to). I demanded larger loops and am very happy I did it.
    3. Loop pressure (above) is not a show stopper..... specs recommned summer/winter pressure to look for, so just getting the right tool solves that issue. Things worked with low pressure, but now I'm to spec.
   

Final comment to the other threads about cost: Geothermal is EXPENSIVE in Pa. Vertical Loops including everything in the ground up to the house basement wall was $15.50/ft. Then there is the inside plumbing from basement wall to units (in my case 30-50 feet for each of three loop sets (time and materials). Climatemaster has limits on lineset to 65ft! (watch out for that in large homes.... you will need to bring the loops as far in as possible to reduce lineset length.  Antifreeze - propylene glycol.... up-there..... Finally the normal HVAC stuff cost almost as much as the loops installed! All told, for about 11tons of geothermal in three systems....... pushing $85K as we near the end...... Will I recover? probably not in a reasonable timeframe...... for us we might save $6.5K / yr in oil if lucky........ happy? yes. Quieter, stable..... as happy as we could have been? no.... thanks to all the friendly, cocky remarks we got when asking questions, what started out as a fantastic "science experiment" and major investment became anti-climactic as we kept getting put down as if we were idiots by the experts!......

Sorry, I forgot to add. The temperature issue was just not understanding what was happening in the house. We went a few weeks without any systems so ambient temps were a little weird. Walls, floors, air all had to stabilize. Also, it appears that it takes a few days for the thermostats (Honeywell TH8321s) to stabilize. Once we just waited out the process, we are staying perfectly on temp. There is anywhere from 15-25 degree drops in cooling across the coil, and now in heating we are having similar rises. The loops didn't have anything to do with that part.... Temps stabilized before we even got the loop pressures up....