Simple underfloor heating

[iep]

I'm installing underfloor heating in a house extension where the original building is heated purely by rads.

I gather that the usual install would be to add a thermostatically controlled manifold and pump where the water in the underfloor pipe work is circulated by the dedicated pump and the temp is maintained by measuring the return temp of the underfloor pipe(s) and 'topping up' with hot water from the boiler flow as required.

Fair doos, makes sense.

However, I was chatting to my uncle recently and he told me that he had installed underfloor heating in a bathroom using a simpler method.

All he did was run 10mm coper pipe across the floor using 12mm plywood as a former and then tiled directly over this. He then hooked this pipework up to the normal flow and return of the central heating boiler (same circuit as all the other rads in the house) with a standard radiator balancing valve and TRV to regulate the temp. Apparently it has been working for over a year now and the room is kept at a perfect temp.

Perhaps this only works because he only has one room using this approach so balancing is possible?

Either way, I'm trying to work out what the pitfalls of this approach might be and if it might work for a larger room (ie the kitchen in the extension).

Cheers,

iep

 

[Dan Robinson]

How well that would work depends on the capacity of the heating pump to cope with the extra length of pipe.

You should also have a temperature regulator to stop the water temp in the circuit going above 45 or so degrees.

 

[mysteryman]

It may or may not be OK for DIY, depending on how it survives over several years. It is not a professional job for a paying customer.

 

[iep]

Thanks Dan. The more I think about this, the more problems I foresee. You're quite right about the temp regulator of course. If the HW cylinder is calling for heat for example, the flow temp of the boiler will be about 80degrees and so the floor in the kitchen would (at least near the flow end of the pipe) be dangerous to walk on.

This problem is minimised in a smaller room because you can restrict the flow to a minimum and run the first section of the pipe in an area without foot traffic.

Balancing would also be tough since the flow rate though the underfloor heating will be critical to its successful operation in a larger room.

Long and short of it, I'll need to install the proper system.

My only worry about the conventional system is that, in the instance where only the underfloor heating requires heat (it would be on a separate zone), it would likely require very little heat from the boiler which would then cycle constantly (I guess). Can this be a problem when hooking up underfloor heating to a heat only boiler?

Cheers

iep

 

[Corgigrouch]

That's called a Monkey floor......Oo....Oo...Oo...Oo...With every step