I am so unhappy with my huge geothermal investment and looking for some help or hope that I can make it work. In 2007, we installed two WaterFurnace Envision series units, each one 4 tons. Our home is 2200 square feet and divided into two zones. The problem, I think, is that the contractor who did the work only gave us 765 feet of vertical loop. What makes the situation most frustrating, however, is that this contractor was recommended to us by WaterFurnace. That's the #1 reason why we chose him.

He has since gone out of business and is nowhere to be found. To drill another bore hole costs much more than we can afford. So we're stuck. Unless anyone has any suggestions that might help. I've started thinking about abandoning one unit and just running one off of our loop.

My biggest questions are these, and thank you in advance for any help:

1. How bad is our short-loop situation? Is there any chance that the loop is fairly close to the right size?
2. Is there any chance that WaterFurnace would ever help us out, given that they recommended our contractor? We've been trying so hard to make it work for almost four years now.

We are going to need more info to try and help.
Diameter of the loop installed?
Number of loops in the bore?
Type of bore, rock or other?
What is your ewt and lwt now?
Have yoU talked to the original driller/loop installer about typical loops in your area?
Eric

Need much more information before making suggestions,
however at first glance, it appears there might be hope
for a not-too-expensive fix.

Suggest you try to supply the info suggested in the sticky
"Problem with your heat pump?" post near the top of
the forum. In the meantime, my wild "rule-of-thumb" guesses:

Bad news: 765' is on the low side for 8 tons total capacity.

Good news: 8 tons is FAR more capacity than would typically
be needed for a 2200 sq.ft. residence. So, there's a fair chance
that your loop is big enough for your heating load.

My 55+ year old home in southeastern PA is about 2000 sq.ft.
and gets along extremely well with a single 3-ton Envision and
one vertical bore 450' deep.

I think that we have 1 1/4 inch PVC pipe, with all the right kind of grouting done around it (I checked the specs early on to make sure that all was OK and it seems to be). The entering and exiting water temp has always been on the low side -- between 28 and 33 degrees in the coldest months of winter (we're in N.J. -- it gets very cold). I did contact the people who did the original drilling and the best they could do was offer to come put in another bore hole. But that's the solution we can't afford, unfortunately. 

Thank you for your help!

Wow -- there might be some good news in here. So you think it might be possible to have a short loop that is still functional because it is enough to cover the heat load? Are there two ways of looking at the loop size -- the length in comparision to the tonnage of the hvac unit and the length in comparison to the heat load? Very helpful. Thank you!

Entering water should be warmer in the incoming pipe called "source in" or "EWT" (entering water temperature). If EWT is not much lower than 30 degrees during the peak of the winter, and LWT ("source out", or "leaving water temperature") is not much lower than 25 F your loop is doing fine and correctly sized. You might have 2 over sized heatpump on a correctly sized loop. The heatpumps might not turn on much because they are too large, at the end of the day the amount of heat they take out of the ground is the same as 2 smaller ones running longer. Depending on the insulation of the house and the diameter of the pipe, 765 ft of vertical pipe in our neck of the wood would support 5-6 tons of heat load, usually more than enough for your size house.

Thanks for trying to help. I've looked up the info from the driller and here's what we have:
Main is 1 1/2 PE (polyethylene)
There are 3 vertical bores, each one 1 1/4 PE
It is approx. 115 feet from our pump to the loops.

The driller isn't sure about other loops in the area. But someone else did mention to me a similarly "short" loop not too far away. Is this a trend?

One other thing: we have 8 tons of system, but that is way more than we need for our heat load. Is it possible the loop is enough given that we aren't really using all 8 tons?

You say you're unhappy with the system and can't make it work,
but you haven't said what the symptoms are. Not enough heat?
Uneven heat? Too expensive? System shut downs/lock-outs?

More information required.

So why are you unhappy with your geosystem? Loop size and temperatures seem to be more than adequate.

It seems to cost a lot to run the system.  Our most recent electric bill probably contained about $600.00 worth of heating costs. We have a meter that allows for off-peak/on-peak metering, and we try to use that option well. We keep the house at an even 65 degrees and have sealed up windows, doors, cracks. Nonetheless, it's not as though we have an extremely tight or efficient house. But $600 is so much to pay for geo heat, I think it's probably a sign that the system isn't running as efficiently as it could.

It does sound like your system is over sized – WAY over sized and your ground loop WAY undersized for 8-tons! You should be able to comfortably get by with 1 4-ton HP and you probably would have PLENTY of ground loop (765ft) for 4-tons.

Was a Manual J load calculation done on your home?

Do you have anything in writing where WaterFurnace suggested this installer (whether they’re still in business or not), even an e-mail?

There is the possibility, as ‘Looby’ alluded to, that your system could be reconfigured by abandoning 1- 4-ton HP, redoing your duct work, maybe adding zoning, and using all the ground loop on the remaining 4-ton HP.

You may be able to recover most, if not all your costs by selling the surplus HP.

I don’t think you need more borehole.

Keep us posted & good luck!


SR

Posted By Princeton N.J. on 05 Feb 2011 07:56 PM

One other thing: we have 8 tons of system, but that is way more than we need for our heat load. Is it possible the loop is enough given that we aren't really using all 8 tons?

Yes

Do you think 95 feet of loop per ton is enough? That's my main question. What we aren't happy with is that it seems to cost a lot of money to heat the house. Our last electric bill was sky-high, and we aren't going much above 65 degrees ever inside. I thought that maybe we'd run more efficiently if we had the right size loop.

Yes, there was a manual J load calc done -- and I think the system was sized accordingly. Everything seems to be OK, except the ton-to-loop ratio, which is probably where the installer just cut a corner.  I will ask about the reconfiguration next week. And unfortunately, I have nothing in writing from WaterFurnace. It was a phone call that sent the (in retrospect) pretty terrible recommendation my way. I thought that the company would never want to have its name associated with a bad job. Live and learn.

And no, nothing in writing from WaterFurnace. It was a phone call that led to the recommendation. Live and learn.

I'll post more news when I find out a little big about the reconfiguration.

Thank you so much for your help!!

No, I don't think your installer did cut corners, he might spend more money on bigger equipment than he should have, using smaller units. Loop size seems OK, but I would check into the kind of circulation pumps you have for both units. They can be energy hogs. Let us know what kind of pumps you are running, and how many.

There is the possibility, as ‘Looby’ alluded to, that your system could be reconfigured by abandoning 1- 4-ton HP, redoing your duct work, maybe adding zoning, and using all the ground loop on the remaining 4-ton HP.

You may be able to recover most, if not all your costs by selling the surplus HP.

What they said.

Posted By Princeton N.J. on 05 Feb 2011 08:15 PM
Do you think 95 feet of loop per ton is enough? That's my main question.

That question is mainly unanswerable without more information.
For example:

- do you have 765 feet of bore? ...or is that the total length of pipe?

- $600/mo isn't very useful; electricity prices vary 3x-4x with location.
-- How many kWh/month?
-- How did you heat before geo?
-- How much fuel did that require?

- Do the heat pumps have electric aux/backup heat strips?
-- Are you sure they're not running excessively?

- What make/model thermostats do you have?
-- Are they set up correctly?

- How many circ pumps? What model? gpm?
- EAT, LAT, EWT, LWT?

- etc., etc., etc.

765 feet of bore. There's probably another 115 feet of loop connecting the bore holes to the pump. Does that count?

We estimate that $600 for heating because our total elec. bill was close to $900, but $200 seems to be about our base each month. Months when we use no heating or cooling, our elec bill is always between $170 and $250. We are really careful not to use/waste electricity - but it's expensive anyway.

Back-up heat isn't running excessively. The thermostat is by WaterFurnace and was intalled with the system. The pump is a Bell & Gosset Series 1535 Close Coupled Centrifugal Pump. Is that a good pump?

Not sure about the latest EWT and LWT. I'll try to find out.

We only have one pump: A Bell & Gossett Series 1535 Close Coupled Centrifugal Pump. Does that sound right? Thanks.