Geothermal (GSHP) replacement

DavidRNovember 11, 2013

My almost 80-year-old mother's house was built in 1998 with a Waterfurnace GSHP. The blower motor seized a couple of weeks ago. The service tech who replaced it (over $800? Seriously?) said the compressor was cycling on and off because it was drawing too much current. There's also a leak at one of the hose connections to the circulation pump and the pump is pretty badly rusted (though it still seems to work OK).

He's suggesting a totally new system rather than a new compressor, says system efficiency is better now, she'll get a tax credit, and so on. So, OK, we let them do a bid, and we had a couple other installers bid too.

Two of the bids are very close in price, right around $11k - $11.5k.

One is for a 4-ton Climatemaster Tranquility TT30 with "auxiliary hot water heater" (DSH?), brass twin pump, and 15kw backup. According to Climatemaster's web site, this is a 30 EER, 4.8 COP unit.

This is from an installer over an hour away who didn't even come to the house! I have no idea how he knew how to size the system, unless maybe he somehow had the info on her system on file. I suppose it's possible these were the people who did the original installation, but that's a total WAG. But the distance away and their reluctance to actually visit makes me very leery about these guys.

No warranty is stated on the estimate.

The second bid is for a 4-ton Carrier 50YDV049. This is rated for 16.2 - 27 EER and a COP of 3.6 to 4.6. It includes DSH, new 15kw backup heat strips, new thermostat, and "new sump kit with dual pumps."

Their warranty is 10 years parts, 5 years labor.

The last bid is from a more or less local contractor, who mom didn't much like because she says "he kept trying to push all kinds of add-ons." I wasn't there when he visited, so I don't know what that's all about, but I assume he was just overly pushy.

That bid is a couple thou higher, $13.8k for a Geostar Aston (they spelled it "Ashton") 4-ton with DSH and aux heat (no power stated), new thermostat, et cetera. This is also a 30 EER, 4.8 COP unit. I don't know whether the extra 2k is justified or not for this.

Same warranty as above, 10yr/5yr.

I suppose the cheapest route is to put a new compressor in the old Waterfurnace, which IMO should have lasted longer than 15 years. However, as I said, the circ pumps are also rusted from the leaking hose connection above them (gotta start checking the stuff in her basement more often), so they might have to be replaced too.

1. Do you think it's worth the extra money for a brand new system, or would you say "fix the Waterfurnace and put in new pumps if you have to"?

Keep in mind that she's getting up there in years. The scrawled-estimate guys are offering 36 month no interest financing. However, with her retiree's low-AGI tax, it'll probably take her 4 years to use up the tax credit, and (I hate to say this), who knows whether she'll still be living there then.

2. Are these - Carrier, Climatemaster, and Geostar - all good brands and models? Does one have a spectacularly worse or better reliability record?

3. Is the Geostar Aston worth ~2k more than the other two?

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I’m with you, your Mom’s Waterfurnace should last at least another 15 year. I would repair the Waterfurnace; you’ve already replaced the blower motor. I’m skeptical of the short cycling due to excessive compressor current draw. The system just might need to be serviced by an honest tech that knows what he’s doing.

I can’t say for sure without seeing pictures, but I wouldn’t be surprised if the pump is rusting because the circulator volute is not properly covered in Armaflex to stop it from sweating. Same thing goes for the ‘leaking hose’ particularly if it’s at a coupling that’s not properly protected with Armaflex insulation.

Would you know if this is a ‘pressurized’ ground loop system? Did anyone do a complete evaluation of the system and record all measurements that were then given to you as a copy and bothered to explain them to you?

I bet your Mom has a terrific system. I would call Waterfurnace and tell them that you want it properly evaluated and spec’d out, that you’re willing to pay for any reasonable repairs. Ask them to recommend another installer in your area that will take the time to make and record all pertinent measurements - and give you a copy. You could then at least forward this to Waterfurnace for their own analysis of what may be wrong. Ask Waterfurnace for a copy of the ‘start up procedure & check list’ for your model so that a tech will be able to follow the procedure and fill in these measurements.

Do you have a copy of all the original ‘start-up’ measurements from when the system was commissioned for a comparison? This document is vital!

You must have the ground heat exchanger check out before deciding on anything. New GSHP with defective ground loops is not a good option. Most likely you need routine maintenance on the whole system. Worst likely case, you may need new compressor and flow center. By the way, I don’t like a dealer that calls a flow center a ‘sump kit’. Where was he trained?

Don’t give up!


Here is a link that might be useful: International Ground Source Heat Pump Association at Oklahoma State University

    Bookmark   November 11, 2013 at 8:03PM
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I'll try to get out there tomorrow to shoot some photos of the rusty pump and leaky coupling.

One of the problems is that we seem to have a shortage of really good GSHP techs around here. I put in a couple of hours on phone tag just to find someone who would look at the WF's crispy blower motor.

Almost all of them are regular heating dealers, not GSHP specialists. The only one I found that seems to be GSHP-only is the one I mentioned that's a couple hours away, and didn't even come out to the house. I'm not too thrilled about working any further with those guys.

The local-ish tech who worked on the blower motor put a set of gauges on the refrigerant lines and measured the compressor current with a clamp ammeter. All he told me was that the current was right at nameplate maximum.

I did see the compressor start, then shut off a minute pr two later while the air handler continued to run.

I don't know if the second tech who bid did a similar evaluation of the system, and AFAIK neither of them has done any testing of the ground loops.

I don't think the ground loops are pressurized in any way. I did see and feel glycol solution weeping from a PE (?) pipe between the WF's heat exchanger and the pump near the floor. It appears that this has been leaking for a long time.

I've cleaned the filters periodically, but Mom can't remember the last time she had routine maintenance done on the system. She says that someone came out to check it yearly "for a while," but she doesn't know when they stopped coming. Nor does she recall who it was, and I haven't been able to find any paperwork in her records. I also see no maintenance logs anywhere around the unit. However, *someone* has worked on it, because at some point someone removed the electrostatic air cleaner that it came with.

I can do another search, but I didn't find any startup documents either.

Back in '98, the builders of this house suggested a GSHP mainly because there are no gas lines out where mom lives. One other family member is pushing for junking the GSHP and putting in something more conventional - electric furnace, propane, fuel oil. Because of operating cost, I really don't think those are good options here in zone 5.

That said, it would be kinda ugly if the installers got a new unit in there, or at least a new compressor on the WF, and then said, "Oops, looks like your ground loops have to be replaced. How could we have known?"

If that happened I don't see us digging up the yard. Seems to me that in that case the better (than traditional fuels) answer would be a conventional air exchange heat pump. What do you think?

What should I have them do to make sure the ground loops are OK before we go any further?

Complicating the situation is the fact that the weather is turning colder and mom's afraid of being caught without heat. She wants to do something now, if not yesterday. It's not the best situation for a thoughtful approach.

Thanks for all the ideas here.

    Bookmark   November 11, 2013 at 11:06PM
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I’d say you’re in a tough situation. You have to verify that the refrigeration circuit is working properly and if not what’s defective. You also need someone to come on-site that has and knows what to do with a flush cart. The ground loops have to be pressure tested to see if the pressure holds to determine if there is any leakage. The ground heat exchanger and HP have to be flushed and purged at a minimum flow rate velocity of 2-feet per second to purge any dirt, debris or trapped air. The antifreeze concentration must be verified and adjusted if necessary, as you do not want any pipes or heat exchanger to burst due to freezing.

Did it run properly in air-conditioning mode? You can try it even now in A/C to see what happens. The problem might be related to a defective reversing valve or something else in the refrigeration circuit.

What do you know about the ground loops? Are there headers in the mechanical room? How many pipes penetrate the foundation? Are the ground loops vertical or horizontal; how many feet per ton?

Is there any instrumentation to measure ‘Entering Water Temperature ‘(EWT) and ‘Leaving Water Temperature’ (LWT) to and from the boreholes and flow rate? Are any flow valves closed that should be opened?

I like to see a flow meter installed, like the one linked to below, so that anyone can visually see the flow rate as well as bubbles, fine particles and color of the water in the ground loops. Just observing this type of flow meter over time might indicate many things to even the most non-technical person. Otherwise you’re just staring at a big box that makes noise.



Here is a link that might be useful: Blue-White Liquid Flow Meter

    Bookmark   November 12, 2013 at 12:49AM
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SR, many thanks for all your help here. It's greatly appreciated.

Any idea what kind of cost we'd be into to have all this done?

What does a pump typically cost, installed? A compressor?

The folks we've been talking to are telling us that by the time we change the compressor and pumps, we're getting close to the cost of a new system. And they point out that on a new system you get a warranty and a tax credit.

Of course, that's what they want to sell.

We may have a qualifications problem here. I checked the list of dealers within 50 miles from Waterfurnace's website, and compared it against the list of IGSHPA directory in your link. *ZERO* correspondence. Not a good sign.

I sure wish I could find a service tech around here I really trusted.

    Bookmark   November 12, 2013 at 10:38AM
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I had a compressor go on a 12 year old Florida Heat Pump geo system. Replacing the compressor gets into issues with contamination, needing line dryer, etc. I ended up replacing with a new Waterfurnace system (yes the federal tax credit helped).

As for loops holding pressure, I had problems with one of my loops holding pressure so we added a zero-pressure flow center system. No big leaks - the water level in the tank hasn't dropped a bit in 8 months. New system, new pump setup, etc was around $12K. I'm in Lexington KY with several good local installers.

To the original poster, sadly you need a better tech to diagnose the system. The compressor may be failing and drawing high current or it may be elsewhere.

    Bookmark   November 12, 2013 at 1:30PM
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Thanks to both of you for the thoughts. I called a few of the techs listed on the Waterfurnace website as dealers, even though they're not on the IGSHPA whitelist. We'll see what they say. At least that should give us more opinions, and maybe more options.

    Bookmark   November 13, 2013 at 2:40AM
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Any geothermal heat pump should last longer than12 to 15 years - that’s the point of geothermal. In addition to much lower operating costs, there should also be a much longer life cycle. These premature failures seem to point to poor installation from the get go.

Geothermal should last longer than air-source!

Re: jreagan

Your installer solved your loop problem without dealing with and repairing its source. His solution, which was a practical one, was to (probably) install a ‘QT Flow Center’ and change you ground loops from pressurized to non-pressurized. It’s a legitimate solution and almost guarantees that the installer will not be bothered with nuisance calls as long as you were instructed on its maintenance. I don’t know your situation but I may not have gone that route unless it was determined that the problem lay ‘somewhere’ out in the borefield, as this solution ‘fixes’ the problem without excavation and disturbing landscaping. If the problem were determined to be within the mechanical room then the preferred method would have been to correct all the original causes without unnecessary replacement of equipment that was not yet even half way through its life cycle. This solution is also less than optimal in that it requires the owner to monitor the fluid level in the flow center. Note that I say ‘fluid level’ not ‘water level’, as this may be a complex mixture of chemicals. If you live in a climate where freezing is not likely to occur then this may not be a big imposition. However, if you do live where the ‘Leaving Water Temperature’ (LWT) may be close to or below freezing, then the owner not only has to monitor fluid level but also antifreeze concentration level as well and be able to correct for the lack there of. Unmixed antifreeze can be very dangerous to store and handle, some having a flash point of just 54˚F, a flame may not even be visible - you won’t know you’re on fire - at first anyway! Bacterial, microbial and corrosion factors may also become issues over time as well. You may have to become somewhat of a ‘basement biochemist’!

Regarding compressor replacement in your case as well as the original poster's case, we certainly want to replace defective compressors where possible before the insulation on the motor windings really burns up and completely shorts out, contaminating the oil contained in the refrigerant, making the flushing of contaminants from the refrigeration circuit more challenging.

I’m glad its worked out for you. I know of cases where the owners have just abandoned the GSHP technology all together. I hate seeing good equipment scrapped, not a very ‘green’ solution.

Back to the OP:

You may have to replace the ‘pump’ whether you repair or replace the existing Waterfurnace, unless you go to an air-source HP. If the damage to the flow center is only surface rust caused by sweating because of poor or no insulation on the circulator volute, it may look bad but may not have to be replaced, just properly insulated. If there is a defect in the buried ground loop system, you may have to adopt the ‘Reagan solution’.

So then you’re basically looking at a possible replacement of the compressor, or maybe a lesser expensive part, possibly more if a heat exchanger is also defective. A properly constructed and insulated commercially built 2-motor flow center module with brass valves and fittings may cost about $1500.00 plus installation but what you have might be repairable at a reasonable cost. After all, when all is said and done it’s just a pair of pumps, just 2-circulators - that’s basically it! A compressor change out should be no more expensive than in most other refrigeration equipment.

I see that your 2-biggest problems are no one within your geographical area qualified to diagnose your problem(s) and the even larger elephant in the mechanical room, that exists everywhere, that no one is usually willing to talk about and tell you, is the reluctance of any technician or company to step in and ‘attempt’ to repair someone else’s ‘disaster’ - that they will then own!

No good deed goes unpunished!

I hope my posts are not too long-winded and down into the weeds…



This post was edited by fsq4cw on Wed, Nov 13, 13 at 10:56

    Bookmark   November 13, 2013 at 10:40AM
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I called a Waterfurnace dealer about 20 miles away yesterday and asked them to send out a tech for a full evaluation of our existing system.

When he arrived, I was a little skeptical at first - this guy looked to be maybe 25 years old. But he did seem to know what he was doing, even if he admitted he'd never worked on a unit this old before.

He measured some voltages, then connected his gauges and a clamp ammeter. And what do you know, at 14.6 amps, the compressor current was actually below the factory rated RLA of 17.1 amps. The refrigerant pressures were very close to factory recommendations. Temperature rise from intake plenum to exhaust plenum was 28+ deg F.

It turns out that we have an unpressurized loop with a reservoir. He did a visual check of the level and flow, though he didn't check the glycol concentration.

He put a second hose clamp on the leaky pump hose barb. He says the rust on the pumps looks ugly, but isn't affecting their operation at this point. He said we should keep an eye on it for condensation in the summer, and if it's a problem, he can install insulation on the pumps. (Or I can, probably.) I assume this is the Armaflex that SR mentioned.

"Your compressor's in pretty good shape for 15 years old," he said.

So why did the first tech get high current readings and a short-cycling compressor?

Today's tech asked, "Did he test it with this panel on or off?" (Pointing to the air handler cover.)

Well, now that you mention it, I'm pretty sure he had the front panel off the air handler when he was testing. There was thus no airflow through the coil. According to my tech today, that's why the compressor behaved abnormally.

Why would the first guy do that? That question will be left as an exercise for the reader.

Why didn't any of the other techs who came out recheck his work? That one I think I can answer: they saw a good chance to quote on a new system, and no particular reason to question another company's evaluation.

Bottom line: Mom is cozy again, at 1.7% of the cost of a new system, which is a LOT easier for a retiree to handle.

The only question remains, what about that glycol mix? I had no idea that was something we were supposed to check periodically.

Now I know how to check the level, but what about testing the concentration? Can I do that with an automotive antifreeze tester? If not, what tool to I need? If it's not the right concentration, where would I get the glycol to add?

Or should I just stick to cleaning the filters spring and fall, and pay these guys to come out once a year and run all these tests for me?

    Bookmark   November 14, 2013 at 3:22AM
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Glad to see that everything worked out and you were able to save your Mom’s system. This made my day!

This was pretty much what I expected, HP & ‘pumps’ good. I can’t imagine why any tech would try to run the system without blocking off the blower compartment. This could have been done either by a poor tech or someone that thought they could make a quick sale.

Most units are made today with 2-doors as opposed to 1-tall full-length door just for this very reason. This way you can have access to the compressor etc. while not interfering with the airflow to the blower & coil.

A ∆T of 28F is excellent. That means that not only the HP but the boreholes too are working very well.

Don’t be put off by the age of a techs, I’ve seen some very young ones that are quite brilliant.

You can ask the service person who did the work what type of antifreeze is being used and how you can check it yourself. You might be able to use an automotive antifreeze tester. The ground loop heat exchanger fluid also has to be monitored for proper levels of corrosion inhibitors that reduce oxidation of heat pump materials as well as stabilizers that may also be added to limit the formation of acids that can lead to corrosion.

It might be a good idea to have this system serviced once a year, preferably by the same tech, seeing as you had difficulty finding anyone reliable. This way should there be a break down between routine annual service calls you’re already a client and there’s someone on staff that knows your machine; you’re likely to get faster, more reliable service.


This post was edited by fsq4cw on Tue, Nov 19, 13 at 0:16

    Bookmark   November 16, 2013 at 12:45AM
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Buy that young man a nice Christmas present or suggest to mom that she provide some cookies when he comes for an annual checkup.

Judging from my limited automotive and less limited chemistry experience, you need to test more than the glycol concentration. You need to test the pH and that is probably more critical.

The types of glycols used for freezing protection (and simultaneously raising the boiling point) oxidize (break down) to acids. There are pH buffers in automotive coolants to counteract this. After the buffering capacity is used up, the pH starts to go down fast after a long period of stability, The freezing point is not going to change much unless you get something else mixed into your heat transfer fluid because a little degraded glycol is not going to make a dent in the overall concentration (measured by density or refractive index) but will affect the pH relatively quickly. Degradation is going to depend on a lot of factors including water quality, temp, oxygen admitted to the system, and what kind of metal is present.

Corrosion inhibitors are the pH buffers, and chemicals that chemically coat (passivize) the metal components in the system. Phosphates, silicates and borates are all used for that purpose in cars (Japanese, old-fashioned green coolant, an European, historically.) Less often seen in passenger car coolant are nitrites and molybdates. Now we have organic acids all around (OAT/HOAT).

    Bookmark   November 18, 2013 at 8:04PM
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ionized - I just read the above on pH and glyol concentration, sounds like that might be happening in our loops - concentration is 12% should be around 16% though I don't know what it was at installation or last service. Tech said 15 gal of glycol may do the job, but should some buffer solution be added as well (and perhaps less glycol as I assume pressure was OK since he didn't mention any problems when I asked him if this indicated a leak he said no just degradation)?

    Bookmark   March 18, 2015 at 9:14AM
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I am not an expert in these types of systems so I can't say what might be considered normal maintenance. My feeling is that your glycol concentration will not measurably change under normal operation. If you've gone from 16% to 12%, there must have been some fluid exchange in the system.

The corrosive degradation products will be a problem long before the glycol concentration is detectably lower by normal glycol monitoring methods. As the breakdown products accumulate and the pH buffer is depleted, the pH will not change much until you reach a critical point after which the pH will rise sharply.

I can't tell you how the chemicals in residential systems are typically maintained. I suspect that normally a canned mix of fluid is added containing glycol, pH buffer, passivating agents, anti-cavitation agents, colorants and maybe more. Then it is probably changed out in bulk when test strips and visual inspection indicates the need. I am certain that ingredients can be bought independently and the chemistry maintained that way, but at what scale? This is the way coolant in truck fleets is maintained, testing and sometimes adding some of the individual components. It would not be economic with individual passenger vehicles. I suspect it is not with 100-gallon ground-sourced heat pumps scattered across the landscape. I can't say for sure.

    Bookmark   March 18, 2015 at 12:21PM
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So even if pressure was OK, you suspect a leak? How else would you have fluid exchange in a closed system?

    Bookmark   March 18, 2015 at 8:39PM
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