geothermal radiant combination for residential use

radiant_4

We have had many problems with our new heating and cooling system since it was built 3 years ago. Installer used staple up under floors with NO transfer plates for the hydronic radiant system with two heat pumps (a four ton and a five ton) supplied by 9 geothermal slinkies in the ground; the slinkies are in one big hole - 100 x 38 feet and about 6 feet deep, each line laying right next to the other; no space in between; five lines about a foot deeper than the other four. We live in the northeast and our heating has been far from adequate; likewise with the air conditioning. The five ton heat pump has always been noisy and finally died recently(for the third time but this time for good; the compressor looked like it had been in there for 20 years - rusty and we had had two previous leaks). While all this was happening we found out that geothermal and radiant are not good for residential; unless you have all tile or put the radiant runs in concrete (however our contractor assured us that his system would work - even with our carpet) Question is: do we replace the five ton heat pump that died and try again? We have gone to a new contractor who hooked up a connection to the UNICO AC system to be supplemental heat; which worked well until the five ton pump died. They are suggesting that the ground loops are not getting enough heat out of the ground (because of their placement - each coil right next to the next one and not deep enough) and that is what made the pump work very hard and eventually quit. If we do nothing to improve the loop field, won't we be in the same fix again in three years if we repair the five ton heat pump? This has become a very costly undertaking to repair a system that was "supposed" to work. And we hate to abandon the environmental friendly geothermal system since it is already there and go to a propane boiler. Any suggestions?

GMcD

Slinky coils

What you've described is NOT an environmentally friendly geothermal system, and from your description the geothermal field is not designed or installed properly at all. Slinky coil fields must be installed such that the centerline of the loops are at least 6 feet under the surface and each slinky coil 'run' is separated by at least 8-10 feet in order for adequate heat exchange to occur. Short of digging up and reinstalling the field, there is not much you can do. Whoever designed and installed this thing ought to be taken to task: did they do proper heating and cooling calculations? Thermal energy balance of the field vs heating/cooling loads? Soil conductivity tests? There is quite a bit of engineering required to install a properly functioning geothermal heat pump system and it's unfortunate that a lot of Contractors are selling these systems without the proper background and engineering. Trying to use staple up radiant which requires higher heating water temperatures versus radiant slab systems is not a good match with the low heating water temperatures that heat pumps like to run with. Geothermal with radiant concrete slabs are a good match provided the whole house and heating/cooling system is designed properly on a "whole building basis".

You might be able to salvage some of the system if you can get a specialist geothermal person involved to see what the heating and cooling capacity of your existing field is, and then mix and match whatever heat pump capacity you can salvage with some conventional system components (small condensing boiler set, keep the Unico A/C system...)

Craig Bergman_2

Ground Loops

We do a lot of Geothermal/Radiant jobs. However, I would never try a staple up system with Geo. We will only do Geo with an overpour because 120 deg water is really the max temp we can achieve with out giving up system
performance. We have a water to water unit that can provide 130 deg. water temps but the COP starts taking a nose dive. 120 deg. max water temp (lower whenever possible) is what we design for. At those temps we can still achieve a 3.0, and better, COP. Even with transfer plates, 120 deg. water is not going to work with a staple up. At least from what I've seen with systems we have designed. Others here on the wall may have more experiance on this one...

Your contractor can also set your system up so the Unico handles the heating load until the outside temps get below 32 deg. This will prevent the radiant from over shooting it's setpoint.

As far as the loop field goes...You first need to get a contractor that can determine what is going on with the loops. They will need to check flow rates through the system, water in and water out temps so they can do the math and see how many BTU's the system is giving up to, or bringing in from the earth. You also need to find someone who REALLY knows loops. They might be able to dig above the loops and put in a watering system. If you can keep the loops damp they will work better. (Just One idea??)
I would also get the manufactures rep involved. They can be a great help!!

Good luck...
Craig

Nron_9

geothermal

You may want to supplement the heating system with a gas boiler to give that extra boost on the coldest days of the year, adding heat transfer plates to the system would help too, but not much, your water temp from geothermal is just to low, usually at this point the only economic viability for the home owner is to add the supplemental heat, I hope the contractor will come back and help you out , the compressors are usually warrantied by the manufactures for more than 5 years call and ask .

radiant_4

Thank you, thank you, thank you. Someone with a reply to our question about geothermal. Can't find much help on this subject. And as far as our original contractor, he insists he put the slinkies in correctly, has hundreds that work, and the flooring in our home is what is causing the problem. For the record, some of our flooring does have higher R values (something we found out after trying to discover why our system wasn't working properly) but the contractor knew what we were putting in. And the manufacturer of the heat pumps, Econar, will not replace the dead 5 ton; nor come and visit the site. They had our new contractors replace the control board and compressor and it ran for one day before it died for good. Now they told the contractors to send the 5 back to them so they can examine it. And we have been without it for over a month. Unfortunately the 5 ton was also the pump doing the AC so if we are to keep the AC we have to replace the 5 ton. Between a rock and a hard place. But thanks for all your advice. Will pass on to new contractor.

Nron_9

warrenty

Econar gives 5 years on the refigeration Components

hr

What is the building load?

have a heatloss calc and design done on your home. Only then will you know if the radiant will, or ever can, meet the load. Actuually with a completed home and know floor coverings you should be able to get a real accurate load and design.

If you are close, adding transfer plates may get you over the hump with the temperatures that the HP is capable of providing. The design will give you the info you need.

As to the HP install itself, sounds like another set of eyes may be a good idea. Any pictures taken of the loop installation? This would help the next contractor evaluate.

hot rod

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radiant_4

radiant_4

geothermal slinky field

I have attached a photo (hopefully) of our loop field. We took almost daily pictures during the building of our house and now they come in handy. Just for your enjoyment. How not to put in geothermal.

radiant_4

geothermal slinky field

I have attached a photo (hopefully) of our loop field. We took almost daily pictures during the building of our house and now they come in handy. Just for your enjoyment. How not to put in geothermal.

Troy_3

Transfer plates

I agree with Hotrod. without knowing all the facts you don't know for sure but transfer plates can double the output. We have fixed many jobs just by adding transfer plates. Make sure you use extruded plates. We always use Thermofin plates. Run the numbers and lower the "r" values in floor covering and you might do it.

GMcD

Yep, a 50% efficient field

Those individual runs of slinky should have been at least 6-8 feet apart. Another alternative at the time would have been to create slit trenches in the base of that large scale hole and insert the loops so they were vertical, and at least you would have got some separation between them without having to increase the overall scope of the main hole.

Andy_6

I would have the first contractor supply you with the list of the hundreds of satisfied customers and their phone numbers. You most likely need to add more loops to your loop feild. Personally I would not go back to the same manufacturer or contractor that would not warranty the first unit. Take your business to a competent contractor and you will see the rewards in your energy savings. Just for the record the water furnace heat pumps are not as loud. You may have a dealer in your area. www.waterfurnace.com

Weezbo

Hmmm...

sir may i ask what your coldest days are in F degrees? what are the indoor temps like ? is there any zone that "Heats up"and works properly? is the floor space insulated under the staple up floors? during the summer does it "Work"...is there a temerature at which (outside temps) it starts to lose against the cold,or,does it just never seem to come up to temp? there are things that are hard to know not being there.....as a guess there is some time that it seemed to work then you went to supplimental heat sources then it would work again then its summer and everything works ok on the cooling side? ....

radiant_4

There is 3 inches of foil faced insulation under the tubing with an air space; tubing at 4" spacing on second floor because of the carpeting, 8" on first floor; no plates; one or two rooms of one particular zone will heat adequately most of the year - all the rest (6 house zones plus finished concrete floor basement and garage ((garage is turned off most of the time and the basement is fine at 60 degrees))find it hard to come to temp (70 in living spaces, 65 in entry way). Especially when the outside temperature is below 45. Now we understand that our flooring materials, in some zones, are higher R value than we expected - a Wilsonart tile and heart pine that required foam pads. But the rear hall and entry way struggle to get to 50 some days - our winters can be cold (0-10 for a week at a time((near Buffalo, NY). And as the winter wears on, the system has to work even harder as the heat is depleted from the ground with our loop field. Also the AC never worked adequately. Finally last year the contractor at least got the first floor to cool but the upstairs still struggles. It would be cooler outside by middle of the night so we would open windows (76 degrees inside). We had a heat loss detail study done by a second contractor who calculated that the radiant system is 27% undersized with 115 degree supply of the geothermal. In an attempt to help the situation they incorporated the UNICO AC system into the heating system to provide forced air back up heat. Worked well until the 5 ton heat pump died a week later. And now in our investigation we have also come to the assumption that the loop field is placed improperly - slinkies laid side by side in one big hole six feet deep; thus reducing the actual heat draw field. And that is as much as we know right now. Econar is still working on letting us know why the heat pump died - bad to begin with or system design failure.

Troy_3

Buffalo?

call me man. We are installing an Econar system in a new house in Hamburg NY. We put the tubes in 1-1/2" gypsum concrete. Maybe I can Help. I have been designing and installing radiant since the mid 80s I hate to see a sick system installed. It not only fouls your life, you will foul my future prospects. Let's get this fixed! 716-649-5723 cell 716-818-4072

hr

Now that's an offer you can't refuse!

As a fellow contractor I visited Troy at his shop in NY several summers ago. (I'm a former WNY resident, born in Buffalo, lived in the farm country area of Orchard Park

I'll bet Troy can help you get into the radiant comfort zone. Good luck, keep us posted.

hot rod

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Weezbo

Sir Your Prayers were answered..

There was an offer from someone near your neck of the hollar,there are things he can look at, see and make determinations. there is some math to do as it were so dont expect the answer to roll right down off the guys frontal lobes and out his mouth. i passed out the other morning attempting to back engineer the thing from the information i had ask about. my work loads kinda tedious at this time.
Your needs are met .contact the Troy guy.he knows howta doit:)