To hot for vinyl floor covering

[dogfonos]

A new ground floor extension was added to our existing home. As part of the build, three new radiators were installed. One of the new radiators was positioned just inside the old part of the building and the central heating pipework that feeds this radiator presents a problem.

All of the new central heating pipework (plastic) runs beneath the floor. In the new build, the pipes are placed beneath 100mm insulation covered by 100mm concrete screed - no problem with that - but the last 500 to 600mm of central heating pipework that feeds the new radiator positioned inside the existing building has been installed just below the surface of original solid concrete floor in a shallow channel. At a guess, I'd say this last couple of feet of pipework is only an inch below the floor surface. I've measured the concrete surface at 47C which is far too hot for me to have a vinyl floor laid.

Would really appreciate advice on my options on reducing the surface temperature to around 27 - 29C which I understand is the maximum acceptable temperature for sheet vinyl.

 

[Doggit]

I'm afraid you'll need to hack the concrete out, insulate the pipes, and then relay it. As the last bit of the pipework hasn't been insulated, then it's obvious that the rest of it hasn't so you're heating the lower slab, and that's a complete waste. I'd have a chat with the installers, and get them to redo that upper part of the floor.

 

[endecotp]

the pipes are placed beneath 100mm insulation covered by 100mm concrete screed - no problem with that

On the contrary, there is a problem with that if it's really what has been done - are you sure?
You are wasting a huge portion of your heating into the cold ground.

 

[dogfonos]

On the contrary, there is a problem with that if it's really what has been done - are you sure?
You are wasting a huge portion of your heating into the cold ground.

I agree there will be heat loss into the beam & block but I don't know about huge - that depends on how we use the three new radiators, e.g. one of the radiators hasn't been needed yet. However, this isn't an issue I intend to do anything about (the upheaval required to insulate the pipes would be unbearable). I'm afraid it is what it is.

 

[endecotp]

I don't know about huge

Probably about 40 Watts per metre of pipe (both flow and return).

Did you pay someone to do this? Was it under building regs?

 

[dogfonos]

Probably about 40 Watts per metre of pipe (both flow and return).

Did you pay someone to do this? Was it under building regs?

Yes, the plumber employed was/is a member of CIPHE. Yes, all work carried out under bldg. regs.

 

[John D v2.0]

It's against building regs to have uninsulated heating pipes in an unheated area.
Unfortunately not easy to fix afterwards.
If the pipes are actually embedded in the slab, the heat loss will be very high. Even in free air the heat loss is excessive, so in concrete it is basically the opposite of under floor heating.
You can measure the temperature of the boiler flow, and the radiator flow. They would be pretty similar soon after switching on. If not, the heat is going elsewhere. The installer may well have insulated only where it was in a unheated area -fingers crossed
I ran our heating pipes above the ground floor insulation pretty much everywhere, to avoid heat loss into the void.

To answer your original question, the floor temperature will always approach the water temperature over time, but you can dissipate the heat over a wider area with a metal plate covering a reasonable area around the pipe.

 

[dogfonos]

I ran our heating pipes above the ground floor insulation pretty much everywhere, to avoid heat loss into the void.

I guess your heating pipes were then covered with a substantial concrete screed? Has that given any problems so far?

If the pipes are actually embedded in the slab, the heat loss will be very high. Even in free air the heat loss is excessive, so in concrete it is basically the opposite of under floor heating.

Our central heating pipework was clipped directly to the topside of the beam & block flooring leaving a very small air gap (maybe 5mm?) between pipe and b&b floor. All this plastic pipework was run around the room perimeters to supply the three new radiators. From memory, the b&b floor was coated with bitumen-type damp proofing liquid before 100mm insulation was laid over the entire floor area (and thus the pipes too). A damp proof membrane was then laid over the insulated floor followed by 100mm concrete screed. I think it's likely that much of the pipe run would have been pressed down against the b&b floor due to the sheer weight of concrete above it but the pipes won't be embedded in concrete. To the sides of the pipes, I imagine just air gaps with the insulation pressing on the pipes from above. Not ideal but as I mentioned, I won't be doing anything about it - far too disruptive - we'll have to take the heat loss hit.

On a general note...

Having fairly extensive building work carried out last year whilst still living in the property was an interesting experience. It meant that I saw the work progressing every day. On several occasions, I questioned either the methods employed or the workmanship but was always mindful not to hack off the professionals who knew their job better than I did so I held back on many more occasions, such as when I spotted the non-insulated plastic central heating pipes.

Generally, I thought the builders did a good job (unsure about the plumbers though) and I was conscious that we had great difficulty getting reputable builders to quote for the job in the first place because, with so much residential building work going on in this area, builders could afford to be selective and our build had a couple of 'challenges' that most didn't want to deal with. Can't blame them, who wouldn't take the easier (or more profitable?) option?

 

[John D v2.0]

I guess your heating pipes were then covered with a substantial concrete screed? Has that given any problems so far?

No screed, we were insulating under the original timber suspended floor and upgrading the heating at the same time. Just celotex with grooves cut in then timber floor boards. No problem yet but we designed the system to condense in the boiler even in -1 temperature, so the system water temperature is relatively low. Less than 60c.

builders could afford to be selective and our

Sounds like you've been very pragmatic, better to focus on the whole job not on too many details. But some details are absolutely critical so sometimes it helps to have an architect on your side.
We basically decided to get the builders to do the main structure and plasterboard finish, but we took on the electrics, plumbing, and work in the existing areas. It isn't worth it financially, despite saving a fortune, but if you don't mind having DIY as a hobby you can get exactly what you want down to the last detail. Best of luck!

 

[endecotp]

Having fairly extensive building work carried out last year whilst still living in the property was an interesting experience. It meant that I saw the work progressing every day. On several occasions, I questioned either the methods employed or the workmanship but was always mindful not to hack off the professionals who knew their job better than I did so I held back on many more occasions, such as when I spotted the non-insulated plastic central heating pipes.

Generally, I thought the builders did a good job (unsure about the plumbers though) and I was conscious that we had great difficulty getting reputable builders to quote for the job in the first place because, with so much residential building work going on in this area, builders could afford to be selective and our build had a couple of 'challenges' that most didn't want to deal with. Can't blame them, who wouldn't take the easier (or more profitable?) option?

You have my sympathy. My typical reaction is "OK I'll just fecking well do it myself then". This is fine, until I'm told I'm not allowed to.