Radiant Floor Heat 101


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Old 08-29-07, 08:55 PM
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Radiant Floor Heat 101

We are renovating an old farm house that has a kitchen build over a concrete slab. The house has hot water baseboard heaters and we are going to install a wood burning stove before the winter.

The kitchen is ~11x17 with only one 4 foot section of baseboard and the previous owner mentioned that the kitchen was always cold. Because of the layout of the kitchen, it would not be possible to add another baseboard.

We are considering installing radiant flooring. Because the rest of the house is already on hot water heat, i am leaning towards a hot water system as opposed to electric. From what i have learned, there are two main types of hot water systems, the "track systems" with a PEX line, and lines that are set in concrete.

Are there other systems that i should be aware of? Can anyone tell me some pro's and con's of these different systems? I would be happy to provide more details on my setup if needed.

Also, where does a DIYer buy these supplies? I cant find a store that can even get me pointed in the right direction.
 

Last edited by BGehl; 08-29-07 at 08:56 PM. Reason: typo
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Old 08-29-07, 09:44 PM
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I'd go with a convector maybe... use a t-stat controlled fan. Ideally you want to design a solution that uses the same water temps or you are gonna be spending a bunch just keeping a bunch of pumps running. Could you put vertical panel rads and TRVs in? They'd help keep the kitchen temps from overshooting when cooking or crowded and not require much complexity in the piping design. Unless the floor is full insulated underneath, you'll literall sink a lot of heat in it trying to go radiant, and you'll need a bunch of control logic and pumps to maintain the lower temps it will need once it hits temp. It wouldn't be very responsive to temp changes like the rest of the house.
 
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Old 08-29-07, 10:01 PM
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thanks for the response, but some of it is going a little over my head. I think i can picture a vertical panel radiator, but i don't know what a TRV is?

As far as i can tell from what i have opened, there is no insulation under the floor, and there are short, 4 inch floor joist, which does not leave much room for adding insulation.

I am also not sure what a convector is. Would this just allow the hot water to run through it and then have a thermostat controlled fan on it?

Sorry for the newbie questions. I really appreciate the help.
 
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Old 08-29-07, 10:19 PM
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TRV is a little mechanical (wax powered actually) valve that you set to a given temperature and then it self regulates and opens flow just to maintain it. No wires or pumps, just some spare flow is required.

A convector in that case was a small baseboard with a fan behind it. I'd prefer that as a plan B. More noise, mechanical risk etc, moderate electrical increase, but cheap with quick recovery.
 
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Old 08-30-07, 08:20 AM
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TRV stands for Temperature Regulating Valve. It is essentially a non-electric thermostat that will control the heated water going through the heat emitter.

In a kitchen, fan-forced toe space convectors make a lot of sense. You may need to use a relay to have the thermostat control both the fans and the circulator pump.

While I do like radiant floors using them in conjunction with baseboard convectors requires a bit more in the way of controls. Radiant works at much lower temperatures than any other heat emitters and that requires temperature regulating valves. For one room only radiant is usually not a good choice.

Your lack of insulation under the floor is another no-no. Radiant heat travels equally in all directions and if you have no insulation under the floor a huge amount of the heat will be wasted.
 
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Old 08-30-07, 10:00 AM
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well you all have me convinced that radiant is not the way to go in this case (now i have to break it to the wife).

The last question i have is the placement of the convector or vertical radiator. how critical is it for the unit to be under a window? I could rather easily put a unit in where the baseboard is currently. With a lot more work, i could get it over to where the window is. just not sure if it is worth all the trouble.
 
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Old 08-30-07, 10:30 AM
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My attitude would be that in the kitchen, you do what you can... ;-)
 
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Old 08-30-07, 11:53 AM
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Thats great, you guys just saved me a lot of work and money!
 
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Old 08-30-07, 01:53 PM
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Who is correct. Sometimes it is just not possible to do things in what would normally be the best or most efficient manner.

The reasoning for installing the heat emitters under the window(s) is that it is the window that has the greatest heat loss hence by placing the heat outlet at that point it becomes less noticeable to the room occupants.
 
 

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