I would suggest contacting other contractors that can install in-floor hydronic heating.

IMPO

SR

I'm no underfloor heating expert, but I have done some work in thermal transfer. Wood is not a good conductor of heat / heatsink. PEX embedded in a cement floor - the cement will act like a heatsink and hold the heat. You could then install a prefinished wood floor over that (I know - not what you wanted).

Also, how would replace the blocks? Can't nail them down.

The floor is 1.4 inches thick. That is an OUTSTANDING thickness for a wood floor. The traditional heat system you use with wood is hydronic. So I'm not sure what your installer is talking about.

Yes, you will loose some heat because of the THICKNESS of the wood. That is a given. But so long as you have a PRIMARY source of heat (the in-floor radiant heat being used to WARM the floor at your feet ONLY) this shouldn't be a big deal. The PRIMARY heat source (electric baseboard or water baseboards with boiler or forced air) will do all the work heating the space.

I would NOT recommend using the in-floor radiant heat to create the heat for the ENTIRE SPACE. The amount of energy consumption would be as HIGH AS YOUR CEILINGS! Churches, as elegant as they are, are HORRIBLE places to heat. In fact, the traditional way to heat a church = church goers! Yep. PEOPLE used to heat the church. Plain ol' body heat.

So...you are welcome to use in-floor radiant heat to WARM the wood floors - so long as you are WELL AWARE that you will need a primary source of heat. And plenty of FANS to knock the heat DOWN out of the rafters.

Sophie, I think that you are too harsh in calling this a vanity project. The poor OP is just trying to learn if this is practical.

I know nothing about how parquet floors are put down and their tolerance for adapting to heat and different levels of moisture. Kudos to the OP for looking to save it.

Not every little country church has high ceilings. At 1000 sq, I don't think that this is going to qualify as exactly an example of a "high steeple church" as my wife calls some." (She is in the business.) First thing you need to do is get clear on how much heat you can make a parquet floor take. Then you will know how much heat the floor can emit at that temperature. That is a simple calculation for a hydronic heat engineer. Lastly, does that number match your heat losss calculations?

Thickness of the wood does not bother me that much. If there is enough insulation underneath the heat source, it is not going to change your heating costs. If the R=value of the parquet is 1.4, underneath is R-30 and the overall R-value of the building walls and ceiling is R-30, where is the heat going to go?

What kind of heat to use? That depends on what fuel sources are available. If you have natural gas, you need to have a boiler. Any boiler can make 80 F water, you just need a thermostatic mixing valve. If your structure is amenable to radiant floor at that temp, you will have uber combustion efficiency.

Radiant floor combined with some other heat delivery mehanism is going to be uber expensive. Who can afford to install two heating systems? I guess it might be 1.5 since a single boiler could supply both floor and other types of emitters (think cast iron radiators.)

Finally, if you can't have radiant and parquet floor there may be more than one way to punt. One way, of course is another kind of hydronic or forced air heat. If your heart is more set on radiant than parquet floors, you could put the parquet to another use. How does a parquet wall or two appeal to you? You could do parquet wainscoating, or parquet trim around windows and doors. How about a parquet ceiling? I've never seen parquet kitchen cabinets, but why not?

OK, my calculations cold well be wrong, but I think this is correct. Assume 70 degree heat difference between inside (70 F) and outside (0 F) max, for ceiling and walls. Assume R-30 composite for walls and ceiling and 2x the surface area as the floor. Assume 30 degree difference between the ground and inside and R-10. If the R value of the parquet is 1.4 the temperature of the underside of the wood would have to be 14 (F) degrees higher than room temp to match the heat flux out of the structure. Can the parquet take 84 degrees F on the underside?

What was the originally heating system? Any reason why you are not considering something other than radiant floor heating?

thanks to everyone for the comments and feedback.. its amazing that some of you have taken so much time to help us find a solution!!

some more info..we live in the uk... our church is not a listed building, but it is classed as a local heritage asset, and we do want to retain as many original features as possible, and re-using the original parquet flooring is part of that.

two thirds of the internal space will have a mezanine floor, with 3 bedrooms and a viewing gallery looking over the remaining third which will remain open from the floor to the vaulted ceiling.

We will then have a second floor with a gallery/workshop and some loft storage space.

the bedrooms will have their own heating system, we have no natural gas in the village so we will have to consider other options.

we are planning on using an air source heat pump to heat the underfloor heating system if possible( we dont have enough land to use a ground source heat pump)

we will be installing a log burning stove into the open plan living area..

the church has been heated with electric heaters only in recent years... many years ago there was a coal fired heating device using locally mined coal, but that was removed many years ago

would it help if i uploaded the plans ?.. we are going to submit them for planning approval in the next 3 to 4 weeks as we have to apply for change of use as well..

and to confirm, this is not a vanity project.. we used all our life savings to buy the church at auction, and we now have to figure out how to pay for the work required to turn it into our dream home.. all ideas gratefully received!, but we will definitely be working to a tight budget..

If you are on a tight budget, you might want to skip the in-floor radiant heat. It is one of the most expensive "retrofit" projects you can purchase for an existing wood floor.

A poster above mentioned the need for the adhesive to withstand 84 F (or higher). Traditionally interior adhesives (the new ones...the one's that are SAFE to be used indoors) have MAXIMUM heat tolerances of roughly 85F. At 85F or higher, the adhesives reliquify and then let go. And that leads to complete floor failure.

If you had a STONE floor which you wanted to save, I would say "Go for it! Have fun!". But you don't. The thickness of the wood floors is going to be too great to allow the air to be heated effectively/efficiently.

You are going to have to deal with the vault of the ceiling. The mezzanine is going to be treated the same as "open trusses" because it is open to the space below (unless of course you wish to glass in the mezzanine area to create a fully encapsulated upper level).

I personally would look into the efficiency of air flow using fans and heat pumps to keep the heat DOWN out of the ceiling. I would POUR as much money into INSULATING the ceiling and walls as I can possibly afford. These old stone buildings have just about ZERO insulating factor (R value).

I would also look at radiator heating (either electric or water) for the entire home. Heating the upper level won't be a problem. It is already "up" in the rafters where all the heat will gather.

Having a professional come in and give you all the options (heat pumps, circulating fans, baseboard heat, etc) to effectively and efficiently heat the space will be your BIGGEST asset moving forward. It is WELL WORTH the "quote fee".

And remember: the money you save on the LABOUR for the wood flooring installation will go towards the new system.

As for your photos, there is a section of parquet that has been taken out. Is there a reason for that?

About the boiler - most boilers have a minimum operating temp of 130 - 140.

I would use radiators. You can get some nice, 'clean' looking radiators nowadays. Maybe the wood burning stove could supplement the hydronic heat to the radiators, if it had boiler tubes.

Wood burning boiler

Wood burning furnance

Look at doing recirculating chases with fans that take air from the peak and send it down to the floor. Reverse in summer. In addition to whatever HVAC system you decide to use. It is the only way to combat natural convection.

Geoffrey_b, I do not understand your numbers. For an old fashioned non condensing boiler, that is too low and may result in boiler damage. On the other hand, 130ish F is the maximum return temperature you would want a condensing boiler to operate near. That means that they can fire up to 150 for the typical supply-return differential. At that temperature they are only just beginning to condense flue gas water vapor so you just as well should get a lower efficiency, less expensive, simpler non condensing boiler.

You need to go much lower to get anywhere near full efficiency. This is highly dependent on boiler design, but 85 F return water will get you between 95 and 99% efficiency so you need 105 F supply for that and condensing boilers will do that and, some, even much lower.