radiator pipes in concrete

[Stephen]

Hello,

My downstairs radiator pipes go into the concrete floor and run along three of the four walls in the room. This means that they must be running back and forth the length and width of the house. I am concerned that these unlagged pipes must be losing a lot of heat into the concrete floor.

Since we are decorating, I wondered about re-doing the plumbing at the same time. The only way I could see was to drop pipes from upstairs. However this would mean that each drop would require its own drain and I worried that lagged pipes would be too thick to chase into a wall.

I read some old posts (2006) that were still on the newsserver in which someone was recommended to bury his pipes in a concrete floor after lagging them. Is this the best approach?

Would lagged pipes loose more heat when surrounded by concrete compared to air? Is it best to keep them above the floor?

What other options are there? Hid the pipes behind the skirting board, or aren't I allowed to do that in case someone puts a nail through?

Thanks, Stephen.

[Unbeliever]

Presuming that the pipework is copper:

I would be more worried about leaks in the pipework due the chemical reaction between the concrete and copper - than heat loss!

You don't lag the 'dropped' pipework (ugly) or 'bury' it in the walls (you are just storing trouble)!

If you *MUST* bury copper pipes in concrete, then use the plastic coated pipe and ensure that any joints are also protected by taping them.

Always best to keep things above a concrete floor - as for heat loss, heat rises into the room.

Unless you are using microbore, then you will have many problems in hiding pipes behind the skirting - what about crossing door openings for starters. You will also have problems hiding microbore as well!

On any exposed pipe-drops, simply box them in - or buy pipework trunking (plastic)

Unbeliever.

[Broadback]

My pipes (I live in a bungalow) simply drop from the attic to the radiators. In some cases they are hidden behind the curtains, where not as we have emulsioned walls, no wallpaper) they are emulsioned as the walls, so are hardly noticeable. Though, if money is no problem, perhaps you could use the skirting board heating as seen on Dragon's Den.

[Bob Squirrell]

Or maybe one of the other skirting board heating systems now available in the UK? Enter "skirting board heating" into Google, you should get quite a choice ... Declared interest - I distribute one of them but I'm not going to say which one!

[meow2222]

Corrosion is only a problem when the concrete contains flyash.

Pipes losing heat: radiators are designed to lose heat from the pipe to the air, and pipe heat does much the same, so is not normally a problem.

NT

[The Natural Philosopher]

Total bollocks. All pip[es corode when there is a mixture of air and water, and any acid makes things worse. Fortunately screed sis fairly alkaline, so tats on there, but there is still a possibility of dampness due to absorbed moisture.

More bollocks. especially if the pipe is buried in uninsulated floor covered in carpeting, which provides the main thermal barrier to the cold ground.

All pipes buried in concrete should ideally be wrapped in some form of mechanical and chemical and thermal barrier. Typically split foam is good - before being buried in concrete. Otherwise thermal differential expansion may rip the pipes apart, and heat loss will be quite bad.

The corrosion aspect is probably the lesser problem, but its still not good to leave pipes in contact with anything whose chemical composition and humidity content is unknown and variable.

[meow2222]

but not to a problematic extent

concrete of course is alkaline

yes, which doesnt lead to corrosion in plain mixes without flyash. We've been thru all this before.

Really? I didnt know there was some fundamental difference between the rad giving off heat to the room and the tails doing the same :)

in this case the heat output from pipe to room will be very much smaller, and time delayed a little. To regard it as 'lost' heat is incorrect.

ideally yes, but IRL lots arent

true for very long runs, but not for your average house.

no

concrete is no mystery. There are millions of houses with copper pipes in contact with concrete on the exterior, where they get wet every week. Safety inspectors are entirely unconcerned.

NT

[John Stumbles]

So if you've got pipes already embedded in concrete how do you know whether it contains flyash or not?

There was a photo in CORGI's Gas Installer magazine this month showing a length of copper pipe which had been installed running along an external wall. One secrion of the pipe was in contact with mortar and had corroded right through.

[meow2222]

If you come up with a clever answer, let us know.

If this were genuinely a big problem from a safety point of view, why are the resulting incidents so rare?

I'm sure we all realise that financially interested parties love to tell people how dangerous old equipment is, and how we collectively need to spend a small fortune with their trade members to get it all put right. So as grown ups we can hardly take one picture as evidence that this is some big problem waiting to blow thousands of us up.

In fact, as far as corgi regd gas safety inspectors are concerned its a non issue. There's a clue.

If laying new, yes, wrap it, but I've seen no evidence that existing concreted pipes have any more injury rate than at the rarity level. OTOH there are other common caues of regular injury and death in houses that do deserve a little time and money spending on them.

NT