Geothermal locking out intermittently for over a year - help!

Hi all -

I have a Trane Water Source Heat Pump WSHPC-IN-5, 72-9006-03. It's a 4 ton. Our geo heats house and hot water. Our home is just over 3,000 sq ft. We live on the wet coast of BC - meaning we don't usually have the extreme cold that the prairies and most of the US faces during the winter. Our days are usually between 35 & 40 degrees F - and our nights usually get down to about 32 - altho we have been down in the high twenties as of late, due to the winter we've all been dealing with (an unusual one). So, for the Canadians reading the list - I do refer to temps in F because I lived in the US for so long - it's just how I understand temps

So - we built our home just over a year ago. We've been living in it for just over a year. We'd investigated geo for a while - and had talked to 2 different local companies. Both companies said that our pond would be sufficient to carry geothermal (as we'd excavated it to quite a depth - probably at least 20' deep - and it's hundreds of feet long by wide - and has a natural stream running into it that keeps the water moving). The company's quotes were very close - but quite frankly it was the one owner's poor attitude that caused him to lose the job.

So they showed up with the loops - and started installing the duct work. Turns out, after 3 days of work - another guy comes in and says it was all run wrong - and rips it all out and starts again (this may be important further down in our saga).

When we moved in - we didn't realize that there was an issue with our geothermal - as we'd never had a heat pump before much less splurged on a $30,000 geothermal system to be more environmentally friendly. However, we'd lived in a 20 year old home, prior to this home, that was same square footage, and had baseboard heating. So, when I got my first few bills on the geothermal system (in a brand new, energy efficient home) and saw that my bills were more than the old house - I blew a gasket!

I contacted the company. Turns out - our system kept locking out - and going to back up heat. So - I threw the back up coil breaker to try and monitor when this happens. It was intermittent. Usually liked to kick out on weekends and holidays. They couldn't figure out the problem. So - they subcontract the repairs to a company that lives just 10 min from me (the installing company is 45 min away). He comes out and takes all the measurements/flows/etc. He can't figure out the problem either - and puts tattletale switches on - TT24's to be exact. Now we're into summer - so of course it's not going to lock out because it's not being run. Fast Forward to September. Now, on the chilly nights - it's locking out occassionally - but doesn't trip the tattletale switches. He thinks it might be the loop.

Back and forth we go - because the company thinks it's something else - back and forth back and forth them sending guys out to take measurements - and sometimes doing something - but most times just taking measurements and leaving - and meanwhile me having to deal with 'throwing the breaker' everytime the heat pump locks out because that's the only way to reset the damn thing. The company tells me that maybe it's a power issue - so I have the power company come out and check my lines (obviously these lines, transformers are all new because we're a new build). They check the lines and the transformer and my panel in the house - and no problems.

Finally - the geo company decides to pull the coils - and find that the one wasn't run correctly - so they fix that. Eureka! We think we've found the problem - but alas we obviously haven't - or I wouldn't be spending an hour typing this out.

So - I ask an independent company to come out and see what they have to say. The guy that comes out is 3rd generation journeyman sheet metal worker and heat pump installer/repairer, etc. These are his comments (in blue are my geo company's comments/replies and he did reference his sheetmetal circle with calculating the ductwork/heatpump we have).

A 4 ton heat pump needs 1600 cfm minimum. Correct – however this is a variable speed unit and runs as low as 800 CFM, Mike measured the airflow and it appears to be fine, we can review that again. Filters must also be clean and not restrictive.

The current duct work in our home is only good for 1200 cfm. The duct work installation is very restrictive, so he is unsure that it even meets 1200 cfm. same as above

The return air is only doing around 700 cfm. The cfm varies with fan speed between 800 and as high as 1600 There is no fresh air coming into the heat pump from an outside source, which should be coming through an insulated pipe. – I agree on that, there should be a fresh air coming in 4 inch to the plenum, that should have been included

Some of the loop equipment looks used (we're referring to a Grundfos circulator)- and more than a year old. There is nothing used in our equipment

There is a lot of condensation – some condensation is normal on geo piping, it is moisture in the house collecting on a colder surface, excess condensation in the crawlspace is probably from moisture wickng up thru concrete and is not that uncommon in crawlspaces, a mechanical dehumidifier may be required to remove that excess moisture – the heat pump cannot remove moisture in heating mode. Excess humidity can also be due to cooking, showers, dishwashers, laundry, occupancy, pets, etc. Any moisture that is emitted in a house has to be removed by exhaust fans. Not sure if you have a humidistat that runs the main exhaust fan continuous or intermittent.

Mold is becoming an issue as it's growing on the stand and the insulated foam around the pipes from the constant moisture.

I mentioned to him the condensation issues we'd had in the spring and fall - and he said this would be explained by the lack of duct work. He also pointed out how poorly the duct work was done - that if it had been done correctly - it would not have needed to be caulked. As it is - the caulking that is there isn't even sealing the joining seams where it has been placed to join. We caulk or seal all ductwork if any has opened up at the plenums, I will get the guys to reseal it.
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On his comments this is my response re: bathroom fans/humidistat

FYI - to share with you - our 3 bathroom fans are 190cfms which are overkill for the house - and we don't shower - so all that moisture is not in the air. We pour 1 tub every 3/4 days - and we all share that tub. I've never had these condensation issues in other houses...so can't figure out why the spring/fall condensation is because of us not having the humidistat on all the time. We've run the humidistate. I lived in many homes that I never even used the humidistat - and didn't have condensation issues (didn't know until our house on Meadowview what a humidistat was and only then just asked what it was because having that brown box at almost eyelevel on the wall was an eyesore!)


I get that some condensation is normal on the geothermal - but the overabundance of moisture has been pointed out on several different occassions by different people sent up here...and now that I see mold - this is a serious issue. It needs to be addressed.
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Regarding his comments re: the filters - they are cleaned a minimum of once a month - sometimes more than that - as my husband is frequently going down to clean them - as we are a new build and there tends to be a bit more dust the first year, we're told.

To be fair - the guy who was subcontracted to try and find the problem (who lives 5 min from me) did say this regarding the duct work
I actually teach for TECA which trains contractors on heat loss and duct design and I did not measure exactly what sizes ran everywhere but it would not be as undersized as much the guy is saying. The unit never ran hot when I was checking it and if the duct was that much too small it would run really hot.
But I would have to go over it to see how bad it is. The other thing you have is a variable speed blower which will always push whatever the CFM it is set to no matter what the duct sizing is. I still believe it is a loop or unit problem.

So - this is what I know of the system:

• Trane Water Source Heat Pump WSHPC-IN-5, 72-9006-03. It's a 4 ton.[/*:m:m5mca91j]
• We have 4 loops in the pond of 300' each. The first 2 coils are 3/4" pipe and are run parrallel. The 2nd 2 coils are 1" and they are connected in parrallel with the first 2 coils.[/*:m:m5mca91j]
• The pipes going from the pond to the house are 3' apart and buried probably 12' below the ground (because we raised and levelled our driveway)[/*:m:m5mca91j]
• There is NO fresh air going into the heat pump from outside.[/*:m:m5mca91j]

Now - they did change the coils to run in series - but the pressure was too low (altho in 1 week the system only kicked out once - which is bad enough - but since they changed it over to run parrallel - it's kicking out at least once a day - if not twice).

So - please - I'm trying to get these guys to think outside the box or brainstorm or whatever...so really could use your professional opinions about this.

Tammy

 

Re: Geothermal locking out intermittently for over a year - help

It's now been 3 years - and it's still locking out.

Tammy

 

Re: Geothermal locking out intermittently for over a year - help

Note - I just saw the other thread and hadn't reviewed, so it is likely I'm overlapping on my suggestions.

Some further questions (no answers yet).

Does your system have any way to indicate what it is locking out on? Most heat pumps indicate the issue that locked them out through some blinking lights or such. I'm not familiar with Trane, though, I'm sure the spec's are online.

I'm wondering about a few things, but it is based on flow issues (water flow). Your loop construction sounds a little "unorthodox". As it is described, most of your flow would be through the 1" pipes; thus, leading to a short loop problem. All loops should be constructed of equal diameter pipe to equalize pressure drops. Headers are constructed of different diameter pipes to deal with the varying flows along their length. 300'/ton is tight as well.

What is the % of antifreeze in the loop? How are the loops placed? Are they spread out or still in coiled bundles?

 

Re: Geothermal locking out intermittently for over a year - help

Hi urthbuoy

Loops have now been replaced - so we 1800' of loop all same size - just can't remember the size right now.

I don't know the % of antifreeze :-(

It's a Trane - but supposedly it doesn't come with a board that indicates the problems - as they've had to put on tattle tale switches to try and figure out the problem.

Just got an email from the company - it's been 3 years they've been trying to 'fix' this system - now they're blaming it on our pond (not big enough - altho it's 14' deep) - and saying the hydro coming to it is too low - altho I have an expert letter from the power company proving the power is more than adequate to service the unit - according to the faceplate and specs of the unit.

Tammy

 

Re: Geothermal locking out intermittently for over a year - help

None of this should be guesswork. There should be a record of temperatures, pressure drops (flows), voltages, amps, and so forth to help with diagnosis.

You'll find folks like to focus on their area of expertise. The sheet metal guy goes after the air, the refrigeration tech the refrigerant pressure/temps, and so forth. Geo is a system, and if we have the readings, we can sort this out for you.

My gut instinct is suggesting a flow issue leading to cold EWT - as it is about 90% of the troubleshooting we seem to get involved with and the one area the conventional HVAC guys don't know how to deal with. Whether this is due to a short loop, inadequate antifreeze, low pumping, air lock, or a combination.

If you can get us some entering and leaving water temperatures (source side) and the pressure drops (to determine flows), then we can start focusing the potential issues.

P.S. I'm familiar with designs throughout BC, so should be able to get you through this issue.

 

Re: Geothermal locking out intermittently for over a year - help

I agree with Urthbuoy's gut on this one. Unit may well be tripping out on low EWT

 

see updated thread

Hi guys - sorry - but I somehow managed to make 2 threads for this issue. So - for anyone who has found this and is trying to troubleshoot their own system, or research for their own system and you are having the same issues we've had - this is the link for the updated thread.

It looks like we fixed the system finally. The problem was that the loops weren't slinkied out across the pond - and I've put up pictures on the new thread to show the difference between incorrectly installed pond loops - and correctly installed pond loops.

http://forum.geoexchange.org/geothe...ions/458-trane-heat-pump-locking-out-for.html