Under Floor heating control question

wildefalcon

Afternoon All,

I just want to double check my thinking on a little job I'm doing in the house. I'm taking out the radiator and fitting hot water underfloor heating, using aluminium spreader plates over insulation (old house, wooden floor, upstairs).

Now I know the proper way to control the heat is to use a mixer system, but it's a guest bedroom, in an old house, and the work to install the proper system would make the job too expensive. So what I was planning was to use an analogue wall stat controlling a honeywell 2 port valve, cutting the heat off when the temperature hits requirement.

Now, will this work?

I can't see why it wouldn't, may not be super accurate, but it would be close enough.

Thanks.

nmacc

So you're planning to use the wall thermostat to cut off the heat to the floor when the room temperature is adequate?

And the water in the system will be at 65-70C?

I really don't like the sound of that.

The thermal mixing valve is designed to keep the water entering the floor to around 35-45 C. I rather think hot water will warp all of your timber floors.

The system you are suggesting is quite costly compared to radiators (and can be tricky to get right). It would be silly to spoil it for the cost of a mixing valve. If you don't want to splash out on the combined manifold/valve/pump assembly, you could just use a regular TMV like this.

wildefalcon

Well, it just seemed overkill to get the manifold system and all for just one room. The TMV idea is a good one, that, and a 2 port valve on a thermostat, would allow me to control the temperature and keep the pipes at 40 c.

Thanks for that, now all I have to do is get the stuff.

Lovely.

W.

nmacc

If you haven't worked with the aluminium spreader plates before, remember the most important part of the job is to ensure there is zero clearance between the aluminium and the timber.

Any kind of air gap will dramatically reduce the heat transfer. It's vital that the insulation supports the plates very well and that they make good contact with the timber. Very important that no-one tramples around before the timber goes down.

wildefalcon

Thanks, I didn't know that!

I only thought of the idea because the pipes to the rad in the room at the moment can be felt through the floorboards. So I figured it might work, researched the tech, and am going to try it. I hate rads, ugly things blocking up the walls, always needing cleaning. UFH all the way, in my book.

Thanks again.

W.