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Hydronic floor heat - boiler or water heater?

I am having a hydronic radiant floor heat system installed. Our house is in cool climate, 3,100 sq ft (crawl space) and we are having to remove the 15 year old existing system due to tubing failure. I am unclear as to which heat source is best, most efficient. Should I use a boiler, a water heater or a boiler/water heater combo? I have read conflicting information that causes me concern - the efficiency of the boiler may be good but length of service is questionable. A water heater is good but not necessarily designed for floor heat. I would also like to incorporate a solar hot water collector. How does this come in to play?

Regards to all and thanks for your thoughts.

Re: Hydronic floor heat - boiler or water heater?

Why not Try a Combination unit such as the Smith boiler model GC160
You can look them up on line.
they a 5 to 1 ratio for heating and an on demand domestic use with about 93% efficiency
I've sold several of these with very positive results.
Call your local contractor you are comfortable with and ask his opinion.:)

Re: Hydronic floor heat - boiler or water heater?

Thanks Nate.

I did look it up and it seems that would do the trick. In your experience does the recirculating pump have a timer or does it circulate instant household hot water all the time? We have a Grundfos pump and can set the time to circulate (like a light timer). Also, I am not sure I understand the 5:1.

A Boiler

You want to choose a piece of equipment that is rated for the job. A boiler is rated as such a water heater is not. Some combi unit are also not rated as a heating appliance. In some areas you cannot install a piece of equipment as a primary heat source if it does not have the "H" stamp rating of a boiler.

Here are a few links to a couple of solar realted pieces that I use to assist in the design process. The files are too large to upload as attachements.



Re: Hydronic floor heat - boiler or water heater?

Thanks for that info. Is the "H" stamped on any unit that can be used as primary heat? Would the mfg have that information included in the specifications for that model? How do I determine, before I purchase, that it can be used for both applications?

Re: Hydronic floor heat - boiler or water heater?

All BOILERS have the rating. The tankless mfgs don't call them boilers, they call them combi units, heating boxes or use other terminology. They don't have the rating. Just pull the installation manual for the product you choose. All the ratings are in the installation manuals not necessarily on the literature.

You local building inspector will also let you know whether you can or cannot install a tankless combi water heater as a primary heating source in your community.

What is your domestic demand? How many showers at the same time and what is in those showers? Do you have a whirlpool or other fixure that needs high demand?

Re: Hydronic floor heat - boiler or water heater?

I currently have a boiler used for a hot water baseboard system. Do you how difficult this might be to convert the bathroom to an in floor heat system off the current pipes coming into the baseboard?

New Zone

You would have to add a zone to the boiler. This zone would need a mixing valve to reduce the water temp for the radiant and a separate circulator.

Here are a couple of nice pieces that provide loads of information.



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