Repairing/retaining Underfloor heating following works

Kincora2017

Our house has underfloor heating throughout the ground floor, installed before we moved in. It’s divided into zones, approx. 50m2. There’s no rads downstairs. We think the floor build up is screed (with underfloor heating), on insulation, on slab. We’re now thinking of changing the layout, which would mean moving the kitchen and all the plumbing - sink/waste/dishwasher. We may also remove a structural wall which may mean a new pad being cast for a new post. The existing and proposed kitchen location are not adjoining, and new plumbing connections would need to be brought to the new location. I don’t see anyway this can be done without substantial intervention to the existing floor.
Is there anyway we can retain the existing UFH system? Can the existing pipes be reconnected and rerouted around the new plumbing? Is the only option if we want UFH in the new layout to remove the screed everywhere and re-lay the whole thing?

Thanks.

Water John

Not a chance, the screed and piping comes out. That's not a disaster, Almost certainly the loops, probably 3 come in a door. It would be take out screed and piping and after the rejig relay new pipe, screed and connect. It would be much better if you could take the loops back to the manifold but if not possible put joints at the door.

Kincora2017

Water John wrote: »

Not a chance, the screed and piping comes out. That's not a disaster, Almost certainly the loops, probably 3 come in a door. It would be take out screed and piping and after the rejig relay new pipe, screed and connect. It would be much better if you could take the loops back to the manifold but if not possible put joints at the door.

Yeah, I thought it was a long shot. In terms of cost, would there be much between new UFH & 50m2 screed vs the cost of new rads everywhere?

Water John

You'll be ripping up the screed anyway to to do the new kitchen plumbing as the UFH pipes are in the way. So you'll be relaying a floor screed anyway.
New underfloor piping won't cost a lot. The rads would have to be alu as the water from the UFH is only 40C.

It would be great if the manifold is nearby and take the pipes all the ways back to it. Avoid underfloor joints if at all possible.

Kincora2017

Water John wrote: »

You'll be ripping up the screed anyway to to do the new kitchen plumbing as the UFH pipes are in the way. So you'll be relaying a floor screed anyway.
New underfloor piping won't cost a lot. The rads would have to be alu as the water from the UFH is only 40C.

It would be great if the manifold is nearby and take the pipes all the ways back to it. Avoid underfloor joints if at all possible.

Thanks John. Good advice. It’s a bit of a sickener to rip up a perfectly good system for the new layout. I’ll get a few quotes

Water John

Whoever is taking out the wall could take out the floor too at that time. Waste water pipes etc have to go well down into the insulation.

I'd say 3/400m underfloor pipe, in 3/4 loops. Each loop no more than 100m and spaced in 150mm rows. Screed 75mm, that's less than 4m2, half a load.

Kincora2017

Water John wrote: »

Whoever is taking out the wall could take out the floor too at that time. Waste water pipes etc have to go well down into the insulation.

I'd say 3/400m underfloor pipe, in 3/4 loops. Each loop no more than 100m and spaced in 150mm rows. Screed 75mm, that's less than 4m2, half a load.

New manifold as well presumably?

Water John

Is this only part of a groundfloor? If the heating source is A2W then it's a simple manifold, oil or gas heat source will have a mixer unit.

Kincora2017

Water John wrote: »

Is this only part of a groundfloor? If the heating source is A2W then it's a simple manifold, oil or gas heat source will have a mixer unit.

The new layout would be 3/4 of the ground floor. But the entire ground floor has UFH. It’s a gas boiler.
The previous renovation was about 15yrs ago so probably due a new boiler soon. No HRV either

Water John

The original manifold should do, as I say take the new pipes back to it if possible.
There is a mixing system on that to bring down the water temp to 40c. The other thing there is a thermostat for the room, connected back to the manifold. This either then acts as a master control and turns on/off all the heating to the temp set on it or turns on/off the 4 loops feeding the room through actuators which open/close the water feed to the pipes.

Calahonda52

Given that the existing UFH system is a sunk cost, bar the manifold.

As an example only
https://www.variotherm.com/en/products/modular-wall-heatingcooling.html
Do with a heat pump and keep the gas for hot water if you want.