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Geothermal system without using radiant floor heating?

Posted by Ibewye (My Page) on
Sat, Sep 14, 13 at 23:59

Okay decided to to go with a geothermal system to and radiant floor to heat our new 2800 sq. ft home in upstate ny. We were surprised at the cost of the radiant floor hearing which was near 30k i(ncludes both labor and material) we've been considering just using forced air because the ductwork already has to be installed for the cooling portion.
My question is 2 parts:
1-I've read that the low operating temp needed for the radiant floors makes it the best choice to use alongside a geo system. Will using a forced air system still allow the geo system to efficiently heat my home during the freezing winter months?
2-The labor portion of the radiant floor heating costs seem to be the biggest factor in the estimates. If I were able to install the radiant floor pex tubing (and aluminum reflector plates myself in all the floors then hire a contractor to make all the connections and handle the manifold setup, etc... Then it seems like the best way to make the radiant hearing choice affordable. Would installing the pex myself (I work constriction and have installed snow melt systems that operate under the same requirements that the radiant system requires) reduce the overall price significantly or not enough to make it worth it. Thanks for all your help.

Follow-Up Postings:

RE: Geothermal system without using radiant floor heating?

Glad you’ve decided to go with geo - a great choice!

Yes, geothermal and radiant in-floor are a great match. No whole house active space conditioning system will be more efficient.

If you are capable, you could install your own in-floor radiant. I would suggest that you work with an accredited and experienced geothermal contractor that knows liquid-to-water and an accredited, experienced in-floor radiant contractor that knows geothermal.

You must know the design water temperatures you will be working with and space the in-floor radiant loops accordingly. You can use the same system for in-floor radiant cooling as well if it’s properly designed and controlled. If the house will be tight you will still need to bring in fresh air and control humidity via an ERV/HRV.

Any properly designed, installed and commissioned geothermal system will be able to heat your home through the entire winter. There should be a backup in case of compressor lock out and the geo system doesn’t have to be designed to handle the very coldest days. It may be designed to handle about 95% of the winter with the backup handling the rest. This type of configuration may save thousands of dollars on installation costs and provide a faster payback.

If you were going all forced air I would recommend the Waterfurnace Series 7. For forced air heating and cooling with in-floor radiant heating look at the Waterfurnace Synergy 3D. For all water, both hydronic heating and hydronic cooling look at the Waterfurnace 5 Series.

Choose your contractors well. There will be some overlap and they’ll have to work together - but you’re in charge!

You don’t have to be able to DO everything but you should at least UNDERSTAND everything.

Bone up on EVERYTHING; this is going to be a marathon!

Enjoy the pursuit.


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

RE: Geothermal system without using radiant floor heating?

Thanks for all the great info. I've started building and at this point still haven't finalized my choice on radiant floor or forced air. I have chosen the synergy 3d unit and have installed radiant pex tubing in basement floor. The big dilemma I'm having how is with these aluminum heat transfer plates, I've learned enough to feel comfortable installing the pex tubing in the floor joists and then having a pro come in to pipe manifolds and heat pumps, but the cost of the plates is outrageous and would cost almost $8-10k for 4' extruded aluminum plates. My fear is that if I skip the plates the efficiency of the heating system, I'm not knowledgable enough to know just how capable the geothermal system and Synergy 3d of heating if plates aren't installed. Are you suggesting that the synergy 3d is capable of supplying both hydronic and air simultaneously? Therefore if I found my radiant floor wasn't heating as well without the plates I could compensate by using the forced air system?

RE: Geothermal system without using radiant floor heating?

Is there a reason for installing radiant in between the floor joists under the floor in new construction as opposed to above the sub-floor? I’ve never been a fan of this method, seems rather inefficient to me.

Regarding the operation of triple function geothermal heat pumps, the method of operation is usually programmed to have either the full capacity hot water or the forced air heating as the priority mode of operation. Only after the priority mode has been satisfied will it switch to the secondary mode.

Can it operate in both modes, hydronic radiant heating and force hot air? The answer is yes. This is because the design should include a buffer tank for the storage of hot water for the radiant heating. This tank is separate from and not to be confused with the buffer tank for the desuperheater and the domestic hot water (DHW). One of the technical reasons for this full capacity hot water buffer tank (of a sufficient size) is to prevent short cycling of the heat pump when in the full capacity hot water production mode. The performance benefit is that the system can operate in priority forced air heating mode while drawing down the temperature in the radiant hot water buffer tank before it has to cycle again to increase the temperature in this buffer tank as there is a ‘range’ of operation before the hot water cycle has to re-commence in the HP - without causing short cycling. The net effect is to operate in both modes simultaneously.

Have you considered an all hydronic system incorporating geothermal for heating AND cooling - ductwork for fresh air exchange only? This is what’s being done in some cutting edge high-end homes. Everything old (hydronic distribution) is new again. Have a look at the link below and forget everything you thought you new about split fan coil units - who says they have to be ugly!

BTW: Just stating the obvious. Not for the faint of heart - deep pockets required!


Here is a link that might be useful: Hydronic Emitter Panels

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