Underfloor heating doesn't get warm

[AnonyDIYnot]

I had someone out last week and he said the temperature was too low for my set up so increased it. He also remarked that the space under the UFH is huge (which I knew) so if there are any gaps in the insulation I could be losing heat. The increase in temp had no effect that day because it was freezing cold but the weather changed the following day and now it's milder the warmer water temperature is definitely making a difference hence me thinking only way forward is to lift floor. It costs me an absolute fortune and of course increasing the temperature will make it even more expensive

 

[SpecialK]

Do you have temp sensors on the flow and return? Get some fish tank temp sensors and stick them on if not. Make sure the boiler is not going in to anti cycle mode as the UFH will not draw much heat away. You may need a buffer tank or radiator on the UFH loop if this is the case.

 

[AnonyDIYnot]

I am googling this right now. I need to work out what it means but I often find little heat coming out of the cupboard containing the manifold despite the boiler and heating being on. Thank you!

 

[Mr Chibs]

I've stopped programming my UFH (kitchen) and just leave it set to 18ºc, it comes on, as and when the thermo tells it too.
I find it's more comfortable in temperature this way. The bills are not big either.

I used the aquarium sensors as previously mentioned, you can get them cheap off eBay. They are handy to set the UFH up.

As for gaps in the insulation, I wouldn't expect that to make the sort of differences you are seeing. Do you know how much insulation is in your floor?

 

[AnonyDIYnot]

Thanks Mr Chibs. There is definitely something wrong. I set the overnight temperature to 15 and it's consistently about 11 or 12 when I get up at 5 or 6am. When it is really cold outside it won't get above 14 or 15 C all day. I think I need to lift the floor to see what's going on underneath,

 

[Mr Chibs]

Yes, sounds wrong doesn't it.

What is the floor? is this solid concrete & screed or an overlay on suspended floor?

You might want to post some photos of the system, might get some more ideas.