Radiator pipework connections

[jaretti]

Hi,
We live in a 1960's bungalow that we move in recently.
We got recommended local builder, who is doing rooms completely - plastering, painting, skirting boards etc.
One of the jobs was to replace old radiators for new ones, which involved modifying pipework in the concrete floor (btw, old pipework was just burried in concrete without any shrouds/insulation, surely that's not right?)
He has now spend two days trying to solder pipework but he says he can't do it as old pipes are too damaged and there's still some water left inside pipework. He tried getting the water out of the pipes but it's still there, it's steaming and messing up with flux, and breaking floor to replace old pipework is not an option
Unfortunately he doesn't have a tool to do a press-fit, so instead he installed lots of compression fittings which would be shrouded in foam pipe insulation and then pour concrete to make floor good.
It's a vented system, and he swears that it will be fine and won't leak.
I've attached picture for one of the rads.
Has anyone here had something like that done? I know it's not ideal but what would you do in this situation?
Thanks,
Jay

 

[Deluks]

He should've used the bread trick!

Shutter round it for the concrete, fit some sort of access plate over it.

 

[Why Not Indeed]

(btw, old pipework was just burried in concrete without any shrouds/insulation, surely that's not right?)

I hope for your sake that the slab is insulated. Any sign of that anywhere?

 

[jaretti]

I hope for your sake that the slab is insulated. Any sign of that anywhere?

It has thermal Marley tiles on top of the floor, in majority of the floor area, if that is what you mean?

 

[jaretti]

He should've used the bread trick!

Shutter round it for the concrete, fit some sort of access plate over it.

That would be six access hatches in total as there are three radiators.
I just want to know how secure compression connections would be, it would be shrouded for natural movement and changes to pipe under different temperatures. I would run heating for a few days without covering it in concrete, to check for leaks etc. After few days, if all was OK, it would be covered in foam shroud and concreted

 

[Deluks]

Compression joints are as good as any other joint. It's the skill of the fitter and the environment it's in that will determine if it leaks.
You're more likely to get a leak from the existing pipe in the concrete. Especially if it's fairly old and not wrapped in anything.
Not replacing that might bite you in the backside a few years down the line.

Concrete over the foam might crack round the edges, leaving a bouncy spot that would put pressure on the fitting. (Although directly under a rad would be a low foot traffic area)
Consider shuttering around with box made of cement board, with a cement board cap, then screed that patch. It will be easier to locate and dig up if it comes to that.

 

[Why Not Indeed]

There's nothing wrong with heating a concrete slab with pipes buried in it, but if the slab isn't insulated from the ground and the walls then you're going to be losing a of that heat. Putting insulation on top of it only compounds the issue.

Look at this detail of how it would be done from scratch:

https://forum.buildhub.org.uk/uploads/monthly_2022_07/CBD1A745-0A41-4658-846C-0D3A4BF6F819.jpeg.bf580213c38c4efa4a98ecd0cec940e6.jpeg

Obviously retrofitting that is, er, something of an exercise.

If the slab isn't thermally broken from the surroundings then now is a good time to decide if you're going to do anything about it.

 

[oldbuffer]

1. Whoever did that is not a plumber. You never use PTFE tape round the threads of compression fittings.
2. Because heating pipes expand and contract it is usually accepted that any fittings are more susceptible to coming loose except for soldered fittings.
3. If he doesn't do press fit he should have used a wet and dry vacuum cleaner to suck all the old water out. And then used soldered fittings.
4. I doubt he could have soldered to the pipe from the radiator. It looks like stainless steel. I'd accept a compression fitting there but fitted just below the surface in a piece of sleeving to provide access.
5. What he has done may well be OK, but take the advice of others above to make sure the joints are accessible with minimal disruption.

 

[AdrianUK]

Well it could be chrome plated copper..... but that's usually more shiny/polished.

If it is stainless steel there might be an issue with the brass olives not 'biting' into the stainless, which is much harder than copper.

And you cant solder stainless steel with 'normal' plumbers solder!