Radiant Floor Heat With an Outdoor Wood Boiler

We’ll be happy to assist you any way we can with your radiant heat furnace project!

radiant floor heat

A very common question we get from our customer is this:  Can you use a wood stove with radiant heat?

The answer to that question is a resounding yes!

Radiant heat off your furnace is the best type of heat and keeps your floors toasty warm! radiant floor heat is about 20% more efficient and you can keep the water temperature much lower; saving you even more wood or coal!

The water that runs through your floor for radiant floor heat is never any warmer than 140°. Hotter temperatures will crack the floor if you have concrete and may warp your wood if it is any hotter.

One nice thing about radiant floor heat, is that it keeps the lower 10 feet of your room the warmest. This eliminates heat going up to the ceiling and out the roof where it is ultimately lost. This is one of the reasons for the great savings with radiant floor heat. this is fabulous for rooms that have tall ceilings, such as in great rooms.

It is also very nice not having air blowing around. This means that air is not blowing around either and it ends up feeling warmer.

Hydronic heat, means heat distributed via water.

Radiant heat is heat transferred through space from a surface without being carried by air or other fluids. It feels like warmth from the sun. For instance, you are out for a walk on a cool day, then you are drenched with sudden warmth from the sun! That’s what radiant heat feels like.


 How Hydronic Radiant Floors Work

Here is how hydronic radiant floors work. Water is circulated through special tubing, called PEX Tubingthat runs under the floor. The warm piping radiates heat through your floor, making it toasty warm.

Radiant floor heat is more efficient because it heats you directly. The room’s humidity is also more ideal. It gradually releases radiant energy to the cool objects in the room. The warmth is greater at floor level and decreases as it reaches the ceiling. This is both more comfortable (Your head feels cooler and your feet are warmer) This type of heating is not new! It goes back to the Roman Times, and is still a very popular way to heat in Europe.

Think about installing radiant floor heat in your new or existing home. The benefits of this superior heating system include, even warmth, higher efficiency, quieter, cleaner, cozier and healthier heating!

If you have an existing home, you may be able to put radiators in their; either the old-style cast-iron radiators, baseboard Hydronic heaters ( they look just like electric baseboard heaters except they carry water and are extremely more efficient), newer style radiators that looked much better but then again if you have an older house then the old-style cast-iron radiators may look very good – and are usually very cheap if they are but used!

 A new construction we usually recommend that you put Pex pipe in your flooring. This can either be on the sub-floor or underneath the sub-floor, with the finished material on top – be it ceramic for porcelain tile, carpet or Hardwood.

PEX Tubing

The most common pipes used today are leak resistant, non-toxic, high-temperature, flexible piping called cross-linked polyethylene or PEX as it is known in the industry. Popular due to the fact that it can handle both aggressive concrete additives and also water conditions while not becoming brittle over time, PEX tubing has been used in Europe since the 1970s and in the US since the 1980s. PEX tubing has proven to be much more reliable.

This is what is called a double run. This gives you more heat between the joists and better heat distribution than a single run of pipe.

The metal plates are nailed to the sub-floor and hold the Pex pipe in place.

The metal plates transfer the heat across the floor so that you don’t have hot and cold strips. However, this way you have to heat up the sub-floor first before the heat can be transferred to the flooring.

A better way – in new construction – is just the piping on top of the sub-floor. This way you are heating the finished flooring instead of all the wood in the sub-floor.

This is accomplished by putting floaters on the floor, as spacers for the Pex pipe.

An even better way is to use a pre-made product that has grooves cut it to accommodate the Pex pipe and it already has the aluminum on it (and in the groves) to spread the heat over the floor. The best product that I have found is called Warmboard.  Warmboard is a structural radiant panel that is 1-1/8 thick, made of Douglas Fir 7 ply plywood, and is sold in full-faced tongue and groove 4 x 8 sheets.

radiant floor heat warmboard

This is what constitutes your sub-floor. Once you put it down over your floor joists or truss, your floor is done! this saves a lot of extra work. Simply put the Pex pipe in the grooves and put your flooring over it. You will end up with a VERY solid floor.

It is not the cheapest on the market but it certainly is the best!

SLAB Radiant Floor Heat can be a DIY project.

You start with a bed of gravel and then put insulation down. This is a must so that you are heating the ground. Is usually required under most building codes, as well.

I prefer a product called TheBarrier. It is better then the hard foam panels – pink or blue – because it is extremely flexible and will not crack or break up when you walk on it. Remember, you have to walk on it to put the wire down and tie the Pex pipe to it and then the workers will be pouring concrete and walking all over it.

 TheBarrier insulation is a flexible type that comes in a roll and it has its adhesive strips to attach it to the piece next to it. This is designed so that it forms both a vapor barrier and a radon barrier in one simple step. If you use the big sheets of Styrofoam, you would then have to go back and put plastic over it the form the barrier needed.

Most people put 6″ x 6″ wire down, that comes in a roll. You will then use wire ties to loosely attached the Pex pipe to the wire. This stops the Pex pipe from floating to the surface and ruining your nice new floor.

Some people use rebar instead of the wire which you’ll give you an even stronger floor. Sometimes the rebar is supported so that it isn’t sitting on the bottom.Pex pipe concrete floor installation

This is an upstairs floor – not a basement slab. That is why the concrete is so thin, because it is extremely heavy. A typical basement slab is 4 inches thick.

As you can see, to layout radiant heat to an outdoor wood stove is not as daunting of a task as you would imagine.

Hydronic radiant heating with a wood stove is definitely a viable option to heat your space!

If you have any other questions about radiant heating with wood boiler, you can reach us by calling Randy @ (608) 519-4664.

Wood Heating Solutions LLC

(608) 519-4664