Problem with Geothermal System - Looking for Input
Last Post 24 Jan 2017 09:25 PM by docjenser. 32 Replies.
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TanjaUser is Offline
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17 Mar 2016 11:14 AM
We are having trouble with a geothermal system, have some thoughts on how to fix it, and could use any suggestions/comments/criticisms that people have the time to make. Thanks in advance! Background: 1. We have a 7 ton Waterfurnace split system in the house. There is 3 tons upstairs and four tons downstairs. Model and serial numbers are: NDV049A111CTR, Serial No. 110400562, ND2038A11AC Ser. No. 110401016 2. A 4 ton system was installed underground (2x 300 foot wells in Maryland). HVAC contractor is bankrupt, well driller claims to know nothing. 3. We have an old house with approx. 4300 square feet, 1600 feet in partially above ground basement, 1700 in main floor, 1000 in second floor. There is good insulation in the attic and 600 foot addition, and good crack sealing, but it is an old house with nothing in the rest of the walls, and 50 old and leaky windows. 4. Before we had the geothermal system installed, the house was heated with a gas boiler and radiators. They are still in the house, and as far as we know functional. The gas boiler was installed in 2006, input 130,000, model 205ncc-TE12, ser. 64881444. 5. Our units operate fine on AC in the summer, we hold at 78, and the units stay in phase 1. AC bills in the $150 monthly range 6. In the winter the units work ok until the mid-20s at which point they freeze out and I have to reset. The winter bills are 200s in the mild months and 400 in the cold months (too high). Last year we were not able to maintain heat in the cold spell. Solutions? 1. Add 3 tons+ underground of wells ( clean fix but expensive, ruins my landscaping, and maybe too much for the house, leading to short cycling) 2. Connect the gas boiler to the heat pump to function as auxiliary, limit waterfurnaces to phase 1/5 ton system (cheaper, makes use of what we already have, but inefficient use of 7 ton system) 3. Add insulation and insulate Windows (would help but not sure if it would fix the problem) Any thoughts on this options, other options, and things we should be looking out for would be much appreciated. Tanja
Dana1User is Offline
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17 Mar 2016 11:48 AM
Line breaks would make it easier to read. Formatting of posts on this forum work better with some web browsers than others. (Firefox & Chrome seem to work fine...)
jonrUser is Offline
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17 Mar 2016 12:50 PM
If you have nat gas and the equipment, I'd use it during the coldest weather and slightly scale back the use of geothermal. Check your costs/efficiencies; nat gas is likely to be less expensive than geothermal as the geothermal loop temp hits ~30F. Far less expensive if electric aux heat is used.
ChrisJUser is Offline
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17 Mar 2016 02:50 PM
Why would the contractor install 7 tons of equipment and only 4 tons of ground loop??? Were you suppose to use the 4 ton for heat and the 3 ton for cooling?

Adding 3 tons of ground loops(underground wells) would not make it short cycle, but will likely stop the units from locking out(freeze out).

Seaching for the 3 ton with that model number doesn't work.

Did the well driller know 7 tons was going in?





Dana1User is Offline
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17 Mar 2016 03:24 PM
What's "worth it" depends on if your goal is to save on heating bills, keep up with the heat load, or boost comfort.

No matter what you're heating with, upgrading the building envelope's thermal performance will do more for comfort than adding 3 tons of ground loop, and will probably be sufficient for the system to work as-is. Whether that work "pays off" in terms of the net present value of the financial return over time may be questionable, but if the house has leaky single pane windows and no wall insulation the payoff in comfort will be there.

It all starts with air sealing first- if the obvious leaks are already caulked, consider doing a round of blower-door and infra-red imaging directed air sealing. There are often HUGE air leaks in 50 year old houses that are hard to see without ripping the house apart, but easy to find with a blower door test.

If the leaky 50 year old windows are beat up aluminum or steel sashed units replacement is really the best option. If they are wood-sashed windows that can be tightened up with a quality weather stripping and minor rebuilding, doing that work and adding low-E exterior storm windows can bring the performance way up, approaching that of a code-min vinyl replacement window, at a fraction of the cost of replacement windows. The better grades of Larsen's low-E storm window sold through box stores are decent & widely available, but there are others. Look for air tightness ratings. Even though the low-E glazing is more expensive than clear glass, the "pay back" is quicker with the more expensive low-E storm windows than clear glass, and MUCH quicker than replacement windows of comparable or better performance.

Air sealing and insulating the walls is essential, but without knowing the construction type it's hard to make specific recommendations. It's often easier and cheaper to do than you might think.

If there is no foundation insulation, that too is usually cost effective, if most of the below-grade portion is currently unfinished space.

The 130,000 BTU atmospheric drafted boiler would be more than 2x oversized for most 4300' 2x4 framed houses with storm windows and retrofit cellulose or fiberglass in the wall cavities, some air sealing and a bit of fluff in the attic. Four tons GSHP would handle it too. I suspect the oversized the pump to the ground loops based on peak hot water use or something. An atmospheric drafted boiler is itself a heat leak when it's not actively burning, but it's probably worth keeping it until you're sure the GSHP can keep up.

When the system didn't keep up, what were the average indoor & outdoor temperatures (or did you fire up the gas-burner)?

CHuntMDUser is Offline
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17 Mar 2016 05:54 PM
I'm in maryland also. Give Love's heating and cooling a call. Been happy with them since insinstall of 09. Ceh
TanjaUser is Offline
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18 Mar 2016 10:49 AM
Would you also do the insulation? Thanks tanja
newbostonconstUser is Offline
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18 Mar 2016 11:02 AM
There has been a big issue with TXV valves in those units...do some research.

http://hvac-talk.com/vbb/showthread.php?518382-txv-frosted-on-waterfurnace

If it has never worked then it is likely not the TXV put if it slowly got worse it can be.
"Never argue with an idiot. They will only bring you down to their level and beat you with experience." George Carlins
TanjaUser is Offline
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18 Mar 2016 11:05 AM
Thanks everyone for the thoughts. Here are responses: 1. We have had two energy audits and both have not recommended insulating the walls, not cost effective. I was surprised. Is the answer different if you have a geothermal system? Also my house is in a historic district (1920 bungalow) with wood single pane Windows (cannot change outside appearance) and stucco. I like the idea of insulation but blowing into then walls is expensive and the Window repairs aren't cheap either ($10,000 plus). I would need to know it worked. 2. Can anyone recommend a good insulating contractor in MD/DC suburbs? 3. Thanks for the recommendation on Loves, talked to them and liked him. 4. On the questions about the prior contractor and why the system doesn't work, driller claims to know nothing. Don't know what the HVAC guy was thinking, but he was discussing 4-5 tons originally. I think 4-5 tons may work fine for new construction/good insulation but not in a leaky old house.
TanjaUser is Offline
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18 Mar 2016 11:14 AM
More: System freezing out in mid 20s (outside), holding (barely) 68 inside. Fine in the summer but we hold at 68. Thanks for the txv issue I will look into. Another question:Is there a significant difference in my area (Maryland) between summer and winter loads that would suggest it is hard to optimally size a geothermal unit? That would suggest adding gas in the winter.
ChrisJUser is Offline
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18 Mar 2016 11:22 AM
Did the Audits give you a Manual J heat loss/gain number?

Larson also makes interior storm windows.

Without Entering Water Temp(EWT) and Leaving Water Temp(LWT) don't know if it is locking out because of water temp below antifreeze levels.

Some heat pumps have a setting for open loop, when raw well water is used for exchange, but for closed loop w/antifreeze that setting is changed to allow colder water to run through without locking out.

TanjaUser is Offline
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18 Mar 2016 11:34 AM
No manual j from the audits, but I ran some very rough numbers (not qualified to do manual j) and I have a huge number of large and very inefficient Windows relative to their standard assumptions.

Thanks for Larsen. The ewt was at 40, in the beginning of the winter when (I think) they added antifreeze. It is close to freezing now.
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18 Mar 2016 03:19 PM
Posted By Tanja on 18 Mar 2016 11:14 AM
More: System freezing out in mid 20s (outside), holding (barely) 68 inside. Fine in the summer but we hold at 68. Thanks for the txv issue I will look into. Another question:Is there a significant difference in my area (Maryland) between summer and winter loads that would suggest it is hard to optimally size a geothermal unit? That would suggest adding gas in the winter.


Rather than indicating burning more gas, it's an indication that you'll get there by tightening up the house. If it's almost keeping up at 25F that means you don't really have that much load reduction to do for it to keep up at +15F, which is your approximate 99% outside design temp:

https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf

The load at +15F is only about 20% more than what it is at +25F, and your house has low-hanging fruit on the building envelope front in spades!

Insulating empty stud bays with a highly air-retardent fiber insulation like cellulose or 1.8lb density fiberglass would probably do it, even if you didn't touch the windows. What is the material wall stackup, from the interior paint to the exterior paint?

Insulating an uninsulated foundation could almost be enough to get there on it's own too.

Blower door directed air sealing of all the leaks into the basement and out the upper floor can cut stack effect infiltration drives by an order of magnitude.
Dana1User is Offline
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18 Mar 2016 03:36 PM
FWIW: My house is a circa 1923 wood framed bungalow with wood clapboard siding. When I moved into it there were clear glass exterior storms over the original wood sash doublehungs, minimal attic insulation, no wall insulation, and no foundation insulation. The heat load at that time was ~48-50,000 BTU/hr @ +5F, as measured by fuel use against heating degree-day data.

With air sealing, retrofit wall insulation over 85-90% (the parts that could be done without messing up the interior or exterior), additional attic insulation (again, where it was easy, and still sub-code), and insulating the foundation, the current heat load is about 35,000 BTU/hr @ 5F, a 30% reduction. As interior rehabbing projects and re-roofing comes up I anticipated being able to bring it under 30,000 BTU/hr without swapping out clapboards to allow for exterior foam, or swapping windows, etc.

If anything, your house is in even crummier shape than mine (from a thermal efficiency point of view) from where I started, and it should be easier to pull that down even further.

What was included in the "...$10,000 plus..." quote for window repairs? That seems egregiously steep (unless it included a 2 week vacation in Thailand while they did the work). How many windows do you have? Are you at all interested in doing any of the window tightening yourself?
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21 Mar 2016 11:17 AM
The question of whether wall insulation is worth it is usually evaluated based on the cost of fuel or electricity to run a heating system. It may or may not be worth it from that perspective and is rarely a slam dunk. However, if you are are the edge of needed to buy expensive HVAC equipment or not, the savings in equipment alone can pay for the wall insulation, and the

But you may not even need wall insulation to get there. Air sealing and doing something with the windows may be enough, however, and might be cheaper. Depending on your historical constraints, some form of storm windows may be a good solution. Exterior low-e storms are often the best solution, but interior storms work well too, and can be surprisingly low-visual-impact.

Your climate is a good one for the heating and cooling loads to balance reasonably well for a GSHP loop. I would not worry about that. But you will be getting awesome air-conditioning performance from the system early this summer after you've thoroughly chilled the ground!
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21 Mar 2016 07:22 PM
Wall insulation almost always IS a slam dunk compared to the cost of drilling another well or otherwise hacking on the GSHP system or ($10K of window upgrade), even it may have a lousy net present value relative to the operating cost reductions of a GSHP.
docjenserUser is Offline
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29 Mar 2016 05:07 PM
Guys, I am shaking my head here.

What is the issue here? Geo heat pumps work independently of the outside temperature, if they run into capacity issues we have supplement heat kicking in.

If both units lock up when higher capacity is needed, there is likely an issue with the antifreeze levels. Who knows, the loop might support 7 tons of heat pump capacity, in case they are oversized and only pull 4 tons of heat out of the ground in the worst case scenario.

Especially when so far the vague information we have (loop is close to freezing, meaning 32F?) and the $200 - $400 bills (total electric bills?) might suggest a 4 ton overall load on the loop.

Everybody jumps in with unrelated advise, no one is asking the reason for the lockout?

So here we go: What is the reason for the lockout? (error code?)

A water temp of 32F for the loop at the end of the heating season is absolutely normal. The bills are normal, again suggesting a less than 7 ton load.

Are the heat pump running at full capacity? Is the heat extraction OK? Is the water flow OK? Do they steal water from each other when they are both running? How about antifreeze setting? Dip Switch setting for closed loop? Chris was the only one asking this question, which is most likely issue, given that both units go into lockdown ("freeze"?) and need resets. Followed by not enough antifreeze.

There is a reason the units go into lockdown, and it is not the 32 F loop temp, nor is it the missing insulation or the leaking windows. It seems that every time someone reports a problem, no matter what problem, people are jumping on it and give lectures about better insulation, how low-E are better windows, etc.

Lets work the present problem, this is not rocket science!

Tanja, we need more information. What is the current water temperature coming in when the units ran a bit? What is the flow they have when one is running, and when both are running? Both are dual stage units, are going into second stage? What size pipes are in the ground (diameter)?

It seems that you need a qualified installer in your basement checking out what is going on. Not to panic yet, who knows, this might be an easy fix, maybe more is needed.

Start here:

http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/76608/afv/topic/Default.aspx
www.buffalogeothermalheating.com
Dana1User is Offline
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29 Mar 2016 05:55 PM
Shake your head all you want- where have you been for the past 12 days? :-)

"It seems that you need a qualified installer in your basement checking out what is going on. "

True! Do they grow on trees yet?

The fact that someone local (the installer, maybe?) had recommended adding 3+ tons of well loop as the "solution" indicates they're probably not swarming in Tanja's neighborhood.

Any house with the described thermal envelope deficiencies is worth upgrading, independent of any issues with the mechanical systems.
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31 Mar 2016 11:48 AM
Posted By Dana1 on 29 Mar 2016 05:55 PM
Shake your head all you want- where have you been for the past 12 days? :-)

"It seems that you need a qualified installer in your basement checking out what is going on. "

True! Do they grow on trees yet?

The fact that someone local (the installer, maybe?) had recommended adding 3+ tons of well loop as the "solution" indicates they're probably not swarming in Tanja's neighborhood.

Any house with the described thermal envelope deficiencies is worth upgrading, independent of any issues with the mechanical systems.


Sure, It is worth upgrading, but it does not address the current issue at hand (lockout). Also, what people call a 4 ton loop might support 2 tons, or 6 tons of equipment. In addition, we don't know what the actual house load is. The fact that boreholes of 300 ft each are still at or around an EWT of 32F means that the load of the house is less than 4 tons. Thus an immediate jump to "lets upgrade the house envelope", when this was not the question being asked, is inappropriate. You are not helping people here if this is your standard answer to just about every problem posted here.
www.buffalogeothermalheating.com
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04 Apr 2016 01:46 PM
Thanks for the input, both heat pump and insulation discussions are helpful. Some answers to the heat pump questions: The water temperature in December when it was still pretty warm here (DC suburb) was 40, the contractor who installed the underground system said it was too low and that the system was mismatched. Contractors have more recently talked about it being freezing. I will try to get more specifics on heat and water entry and exit temps. When the system freezes out it is typically only the downstairs system. Both systems are 2 phase and the vast majority of the time they are on phase 1. If they both move to phase 2, the downstairs one is likely to freeze out soon. Last year, when it was very cold there was no water in the system at some point. This year (warmer) everyone seems to think it is OK. The pressure levels fluctuate a lot though, between single digits and 40+. At some point contractors thought this was a leek, but one contractor thought (this makes sense to me) that there was a lot of expansion and contraction going on in the pipes while they strained to deal with the 7 tons. The loop in the ground is 1 inch and he flow center is also limited to 5 tons.

I will try to get more info from the contractors on heat temps, etc. Can someone tell me a little about antifreeze setting and dip switch settings? What are the options and pros/cons? Is there a good web site for this? Would like to understand a little more about this before talking to contractors.

Also, is there some way to post a document with my message? I have an analysis from the original contractor if that helps.

Thanks for everyone's time. Tanja

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