The ones I have are shown here: http://www.bestnest.com/bestnest/RTProduct.asp?SKU=CIC-00891&src=froogle&kw=CIC-00891
They are about $10/ea on sale (at Lowes). You have to be careful when you remove the plastic end cap from the thermocouple (discard this part).

Hmm, looking at the chart and thinking about what my system is doing, it seems that maybe actual temperature is not as important as delta, depending on the system/volume. I'm not sure my delta, but it's about 5 F I think. The system is taking 67 F air and raising it to 87 F, keeping the house around 71. I mean, taking 5 and making it into a 20 degree rise is pretty good! I'm just concerned that I'm at 32 or below....I can pull a 5 degree delta out of 32 F **AIR**. The whole point of geo (broadly speaking) is that the ground is warmer than the air most of the time in winter.
The RWT is lower than 32, and condensing like crazy on the pipes. The EWT is about 32 (the thermo scale stops at 30 F). It's been pretty cold here in PA (We had the winter storm, and last night the temp went down to 17 F). House has no aux heat (manually off, still) and a night setback currently from 71 to 67. This morning, though, the house wouldn't get up to 71. It was stuck at 67 with the system running. Granted, the return duct issue still exists...but the DATs was only 83 F.

My installer is checking the Rehau...since we're sort-of pioneering the Raupex piping here. I'm just surprised, still, at such low temps.

Again let me re-iteratethat the low ewt may not be an issue at all. Fix your duct issues and enjoy thesystem. Typically geo likes a constant temp with no setback. It takes way longer than fossil fuels to overcome the set back. You need to know what the design temp was for your system from whomever made the initial calcs to see if you are on target or not. It is not uncommon for loop systems to be designed with very wide bands of fluctuation accross the loops to save on exchanger costs. Since no end ofsummer data is available it is hard to tell. I have had engineered systems be as high as the low nineties at the end of initial summer start up with no winter load. That sent them into winter with very high ewt from which to extract heat. You may be able to start the cooling season with 32 or lower and get back on track by next winter with high ewt from summer.

I'd go get a number of rolls of duct tape, and temporarily fix this, ASAP.

Heat moves through the earth exceptionally slowly.  It may take weeks or months for heat to move through the earth to replace the heat you're taking out now - some obviously unnecessarily.

If your EWT is already down to 32°F, you need to be as maximally efficient as possible with heat removal from the earth to have enough left at the end of the heating season without EWTs dropping so excessively low that you lose signficant performance from your GSHP unit.

Best regards,

Bill

 

If your LWT is 5 degrees below EWT which you think is 32F then the condensation would be frost(Frozen).

Later in the heating season I have frost on my LWT and EWT P/T ports which would indicate both are below 32F

I think the thermometer that you are using is giving you incorrect measurements, might find that the meat thermometer that you used was more accurate.

I have considerable condensation on both my LWT and EWT ports. My EWT is 38 and LWT is 35F.

Regards

John

Today, the LWT *did* have frost on it....more like ice. The loops are fairly well insulated because the PEX is really thick. Just condensation, but the manifold is brass and had a little ice. The RWT is definitely warmer....no condensation at all, but the analog thermo reads 32. Clearly, something is wrong with the thermo, methinks. Will try to get a good thermometer tonight and get some proper readings.

If your unit or manifold is equiped with pt ports, a digital meat thermometer works great for about $8.00 at wally world.

I don't think it does. It's the following:
http://na.rehau.com/construction/renewable.energy/geothermal.ground.loop.heat.exchange/pro-balance.manifold.shtml
I've tried just taping the end of a meat thermo to the manifold with electrical tape, but it's hard to get the very tip to make good contact with the brass. No PT port that I can find.

Here's an example.  Look for something that appears like what's in the lower left corner of the image below.

Best regards,

Bill

Is this your system? Are those desuperheater lines above wrapped in insulation? Mine aren't...should they be? They always feel warm and they are in the basement with the system (unconditioned basement). I'll check for that little blue-topped valve thing, but it doesn't look familiar. Thanks!

Yes.

Yes, my DSH lines are wrapped in armorflex.  Wish my water loop lines were too.  Don't know if they should be.  Do know that Armorflex is expensive.

My unit's up in an attic.  Temperature ranges in the attic from just below freezing to 135 degreed F, across the year (Dallas climate).

I'm hard pressed to believe you don't have P/T ports some where.  It's pretty tough otherwise to measure loop temps and pressures.

Here's a picture of a pressure measuring instrument, that slips into a P/T port, that enables a pressure measurement.

Best regards,

Bill

Yep, it has them. They were well-insulated. Found them, tho'. My meat thermometer has a really wide shaft, so much that it only just fits through the brass opening. I'm afraid to force it through. I'll try to find one with a thinner measuring probe, tho, and get some better results. Thanks!

Stuart, you want some kind of temp measuring instrument that has a narrow diameter probe, like what's shown in the picture above.

Best regards,

Bill

Go to wally world, get digital meat thermometer, wet it, insert into pt port.

a0128958,
RE: loop lines not insuilated- they may sweat and drip. Armorflex is cheap, insulation and drywall isn't. :)
Adam.

Adam, thanks, I agree.  It's on my 'to do' list.

Fortunately, so far, I haven't had any sweating due to attic temperature usually being greater that water temp.

Best regards,

Bill

seems to me i have the same problem, today i found ice and frost on my lwt line and but ewt is normal, I dont know what the temp since i never measure it. I do know that even when the system is running on stage 2, it takes a long time to raise at least 1 or 2 degree like half hour long. I have fiber glass duct and I do want to redo the whole duct, I think that is the problem. am I suppose to insulate the return air duct? is it normal to have frost on the lwt line? I did changed the speed setting on the cfm and heating speed to speed 3, and today the unit ran and it the hwg line doesnt seems to have any hot water generating??