Can you read through this and tell me if anything pops out? It’s notes from a client of mine in Ohio. My house design work was done long ago, and he’s close to moving in, but he’s having all kinds of HVAC (geothermal) trouble. He has about 4000-4500 sf in the residence. He has three 150′ wells w/ a 3 ton ClimateMaster heat pump…we had an 800′ well and a 4 ton GSHP. Would that alone be enough to super-chill the water in the pipe, as he is seeing?

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Well, I have good news and bad news.

The good news is that yesterday my house became an electric generating utility, when its PV panels and wind turbine came online. No sun then, but the 3100 watt PV array generated around 500 watts anyway in the cloudy and snowy weather. The wind turbine was intermittently producing power as the wind alternately went above and below its 7 MPH cut in wind speed.

The bad news has to do with what can only be called my clown HVAC people. My geo thermal heatpump is freezing up the ground source loop, giving a 31 degree source water temperature, on a day when the air temp is around 34 and the ground temp at 150 feet should be around 50 degrees. Can’t get very much heat out of that. I’m running my buffer tank resistance element again to keep up, which allows the compressor to cycle on and off, allowing the geo loop to ‘recharge’ in order to be able to withdraw more heat later. Basically my three 150 foot vertical wells don’t have enough capacity to feed the 3 ton compressor. This could be due to three reasons that I’ve come up with. Just not enough pipe in the ground, the fact that they back filled the wells just by hand shoveling the drilled out rock dust back into the well, possibly leaving insulating air voids, or that they didn’t connect the three wells in parallel using reverse return connections, resulting in uneven flow in the three wells. My HVAC guys told me to give them my load study, even though that has nothing to do with this problem. I don’t think they understand how a heat pump works.

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I found out yesterday that geo wells are supposed to be grouted, and mine wasn’t. I don’t have the details on what geo well grouting is, but I’ve heard it involves bentonite, which is an expanding clay. I have a new set of HVAC guys hot on the trail. More $$$$$. Heavy sigh.

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I found out that the State of Ohio requires all wells to be grouted, so that surface water cannot contaminate the lower level ground waters. Thus our drillers are in violation by not grouting our wells. After asking around, I’ve found out that other geo thermal drillers have been following behind the guys that did ours, fixing their problems. These guys were hired as subs by my HVAC guys.

My HVAC guy also had the same guys drill his wells, 5 of them for his 5 ton installation. He is also having the same problems I am. He is arranging a meeting with me, him, and the Climate Master heat pump rep, so that he can understand what’s going on.

Ultimately, I’m going to need one or more wells to make up for the current poor performance. I can see a battle in my future.

If the incoming water temp is too low, the coefficient of performance of the heat pump starts to approach that of resistance heating. Yikes. I can feel the breeze from my electric meter spinning.

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We have a 3 ton Climate Master Genesis Series GSW036, water to water heat pump. We have three wells, each 150 feet deep, mostly into limestone and sandstone. Plastic U piping in each well, hopefully connected in a reverse return connection, although I don’t know this for certain. We are running a 25% ethanol, water solution in the geo loop.

Instead of proper grouting, they hand shoveled the drilled out rock dust back down the 6″ bore. I can’t imagine that filled the bore well, and there is probably plenty of air voids. I’m told when properly grouted, the contractor lowers a pipe to the bottom of the well and pressure pumps a grouting mix of bentonite or concrete until it comes out the top. Then his fill pipe is withdrawn. I’m told it’s difficult to grout a well after the fact, since they cannot get the grout piping thru the backfill to the bottom of the well.

I’ve been in contact with the Ohio E.P.A. on well contruction requirements and they are emailing me a detailed summary of the requirements.

When it was 35 deg F outside, I was getting 31.4 deg F source water and 26 deg F return water in the geo loop. I’m having difficulty maintaining 100 deg F in my 50 gallon buffer tank. My load is three Unico M1218 1-1.5 ton air handlers using the water based cooling coil as both heating and cooling. Flow from the heat pump to buffer tank is about 12 GPM with its own pump, and from the buffer tank to each air handler is about 4 GPM each, with each air handler having its own pump. The three air handlers have their own thermostat and come on randomly relative to each other. Thus I can have any where from 0, 1, 2, or 3 air handlers running. The heat pump runs independently of the air handlers, maintaining the buffer tank temperature. My Energy Star load study came up with a heating requirement of 36,300 BTU/Hr. My HVAC guy sent me a local study on the geo system that says that I should have an average (not sure the definition of average here) supply temperature of 46 deg F, with a minimum of 36 deg F.

At the low buffer tank temp, my three air handlers are on all the time, and so is the heatpump, freezing up the geo loop. I’m now running with the 4.5KW heating element in the buffer tank on, so that the heat pump cycles on and off, allowing the wells to ‘recharge’ somewhat. This brings my buffer tank up to 120 deg F, and the airhandlers don’t run all of the time. But as you say, Jim, I’m feeling the financial pain of resistance heating.

I have a meeting scheduled with the Climate Master rep with my HVAC guy next Tuesday.

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Unfortunately in my situation my heat pump source water temperature is not dominated by the average ground temperature. My heatpump is trying to extract heat from a limited capacity well set faster that the conductivity of the surrounding earth can restore it. This is resulting in localized cooling of the ground, down to 30 deg F or less, which is a much lower temperature than the average ground temperatures in our area. I suspect I have two problems, not enough total geo loop length, ie, not enough wells, or not deep enough wells, and the wells I have are not properly grouted, and posess air gaps around the tubing, limiting the heat transfer from the earth to the circulating water. Air pockets are great insulators. So, warmer outside temperatures should result in less heatpump run time, and therefore less localized cooling of the geo wells, allowing them to warm up to a higher average temperature. I’m sure the lag of the average ground temperature, as you mention, is also a complicating factor.

lI’m meeting with the president of the HVAC company I’m using and the Climate Master heat pump rep tomorrow morning. The HVAC company sent a guy out to my house today to check some system pressures, and to also clip a programming jumper wire that would change the geo water source low temperature cutoff for the heat pump down to 10 degrees F from the current 30 degree setting. How’s that for solving the problem? I quickly vetoed cutting that wire. Allowing the heatpump to operate in an even less efficient condition does not fix my system.

With average winter air temperatures what they are here in Cincinnati, I’d be better off using an air source heatpump. There is no advantage to using the more expensive geo thermal heatpump if my source water temp is going to be 10 degrees F. Heavy sigh! These guys just don’t get it. How can they be in this business with such a lack of understanding of how their product works?

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I had the meeting with the heat pump rep and the HVAC big cheese this morning. The HVAC company had made some pressure measurements on the system yesterday, and the rep analyzed them. He concluded that 1. The geo loop had a flow rate of 5 GPM, and the minimum spec for the heat pump is 3 GPM per ton, or 9 GPM for my 3 ton unit. 2. That the refrigerant pressures were way off, indicating that the refrigerant was low or contaminated with what he called non condensables. Because of all his, my heatpump was only generating 1 1/2 tons of heating instead of the spec’d 3 tons.

So, tomorrow the HVAC guys are going to empty my refrigerant, evacuate the lines, and refill it with new refrigerant to spec. Then a second pump will be added to the geo loop pump assembly, as it has a mounting provision for the second pump to increase the loop flow rate. The rep also admitted that the wells should have been grouted, and that not grouting is a violation of state law.

I’ll get the heat pump hardware working properly first, and then fight the well war. At least there is a smoking gun to work with.

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I was looking at Climate Masters website and it said vertical wells need to be from 150 to 250 feet deep per ton. I wonder if I’ll need to have them made deeper than the 150 feet they are now?

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The HVAC guys emptied the refrigerant and reloaded new stuff. It apparently works better now according to their measurements, but the geo loop still has frost on it inside the house. The wells suck. The now more efficient heat pump is placing a higher demand on the wells. Oh ya, the boneheads forgot to bring the second geo loop pump that’s needed to bring the system up to the manufacturer’s specs. Worthless.

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Looks like they’re at the absolute minimum at 150 feet for each my three wells, plus the fact that they didn’t grout them. Add to that not meeting the flow spec through the loop, but at least they’ve agreed to add the extra pump to fix that.

I need to try and get my existing wells grouted, if that’s even possible now. I’ll probably still need at least one more well, and more if I can’t grout my existing wells.

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Once they increase the geo loop flow to the manufacturer’s spec, the wells will be even further taxed. Hopefully then it will be obvious to my bonehead HVAC guys that the wells need to be fixed. I have a bad feeling that they won’t be able to pull the tubing out. But still, I guess it would be easier to just redrill through the tubing and ground rock dust and then re tube and grout. We’ll see how it goes.