copper pipe underfloor heating in concrete - not warming

[bowgieman]

Hello,

I hope someone can help me. I’m a newbie! Although I’ve been on here many times and found useful answers.

I have copper pipe under floor heating in my living room which covers approx 8 meter squared. This has been bare (no denso) in solid concrete and tiled over for more than 15 years and has worked perfectly until a few weeks ago. I took this as an opportunity to have my CH boiler upgraded as it was a very old inefficient boiler and had a new combination boiler fitted (Potterton Titanium 33E). The system was flushed, and I also had a magnetic sludge filter installed. So much crap came out! However the UFH is still not warming up.

The UFH is connected to a towel radiator via the flow and return. It is the last (or furthest radiator in the house from the boiler). Currently the towel radiator warms up very slightly but the warm water does not flow in the UFH (in the return).

I have tested by shutting off all other radiator valves throughout the house and just running the system on the UFH/ Towel radiator. This makes the towel radiator really hot but no change to the UFH!

So, my guess is that the UFH copper pipes has corroded somewhere and has undersized which is reducing the flow of the water?

Can anyone suggest or advise what else I could do to fix this please? I’m nearly at the point of ripping the whole thing out!

Many thanks for your help guys

 

[kbdiy]

Sounds like the underfloor circuit has been blocked by the crap flushed round the rest of the system. Can you get to both ends - flow and return - of this circuit, disconnect completely from the rest of the system and blast it through with mains pressure from a hosepipe perhaps?

It might need a bit of imaginative plumbing to achieve that but at least you will know if it is blocked or clear. Also has the system been properly balanced again after it was flushed through and the new boiler installed?

 

[bowgieman]

Thanks. I think i'll give it a shot at flushing the underfloor circuit separetly in the weekend - Although i did have the system flushed with the new boiler installation and again after two weeks because the UFH still wouldn't work.

If i do find that there is actually some blockage or corroded pipes in the circuit, what options do I have? Ultimately we want to have UFH again. Would it be a good idea to replace and install new copper pipes in denso or is there a better option. I have come across plastic piping for UFH. I'm not quite sure this would conduct enough heat transfer in concrete/tiles?

I will be replacing the floor tiles soon so dont mind to do this extra work if required.

Many thanks

 

[jcb208]

The big new builds we work on have plastic under floor heating throughout and were talking at 6-8000 square ft,always works and they don't seem to get any problems with it and some of there houses are now coming up to 20 years old..The way they install is 6t inches of celotex in 2 layers, then an eggbox type plastic system where all the pipes are clipped in to then 3- 4 inches of screed.So If you replaced yours you would need to dig out a good foot to do the job properly unless you went for the surface install option with wooden floors covering the pipes