Underfloor heating alterations

[MarthaPie]

We moved into a house which doesn't have a bath in the main bathroom, just a shower. The room has underfloor heating. We'd like to add a tub but that would involve digging into the floor to access the hot water pipes. Any ideas how much this would cost or what potential problems could arise?

[TheTeaFairy]

Bumping for you as I'd like to know the answer to this too

[PigletJohn]

is it a concrete floor?

How old is the house?

[MarthaPie]

Hi PigletJohn, yes, it is concrete flooring with tiles and the house is five years old.

[PigletJohn]

digging up a concrete floor, and relaying it, is so expensive that it is not usually considered feasible (it is also amazingly noisy and dusty) .

If you're building a new house or extension, and laying a new floor anyway, that's the only time it's considered worthwhile laying wet UFH.

Digging up your floor is pretty certain to damage your old pipes, and you don't want a repair or join buried in the concrete, as it is much more likely to leak, and will be uneconomic to dig up again.

[PigletJohn]

p.s.

run your new bathwater pipes above or just below the ceiling. They can be boxed-in in a corner, or maybe passed through from an adjacent room, perhaps concealed by kitchen cabinets, saving you thousands.

[MarthaPie]

Thanks for your detailed reply. Not sure how they can connect new pipes to the hot water system unless they run them outside of the house into the air source heat pump as the whole house has UFH. Shame they didn't put a bathtub in as they built the place.

[PigletJohn]

you mean the pipes for the hot taps? These are quite separate from the pipes that carry the circulating water for the UFH and any radiators you may have, whose water never mixes with tapwater.

Do you have a hot-water cylinder? What colour?

[MarthaPie]

Ah right, so the pipes needed for the taps aren't related to the UFH. Sorry, I'm completely new to this. I'm not sure what colour the cylinder is, will find out ASAP. The cylinder is contained within a heat pump unit.
The shower has taps coming out from the wall so I'm guessing it's possible to do the same with the bathtub - access the pipes from behind the wall tiles. But then they would still need to dig in to the floor for a new drainage point. Do you think that's possible without potential damage to the UFH?

[PigletJohn]

probably not.

but start by finding the route the waste pipes, and the tapwater pipes, follow.

you can get a fair idea of where UFH pipes are by turning it off for a day or more, so the floor is cool, then praying it with water, then turning the heat on. The floor will dry out first in the pattern of the pipes. The nearer they are to the surface, the easier it is. It is actually easier to do it on concrete than on tiles, because the colour change is so dramatic.

A UFH engineer may use a thermal imaging camera to do the same thing.

[MarthaPie]

Thanks for your info, now I have a better understanding of the process