I have idem, and it is actually a very nice type of heating, plenty of advantages, but it does tie one to the electric power co.

FWIW, they are not run by a room thermostat like radiators, becos they do not work like that !

Perhaps the first thing he needs to do is have a specialist check out his controller: there should not be any lag.

Then an electrician to check the continuity of the cables, especially if the installation is elderly.
(Repairing breaks is a specialist and pricy operation...).

I did all of the above, then retired the floor by removing the fuses then having the power co derate my main breaker, thus saving about 90 Euros a year for starters on the standing charge. Not to mention a bunch of killerwatts (ours) on the bill.

Then abandoned the UFH for a wood stove of the same power. (Also replaced all windows...).

We certainly do not miss the radiant floor. "The best type of heating being the one you don't have to use".

gg

For a couple of years, on and off, I've been looking at Air to Air heat pumps as a means of CH for my own home. The main driver has been the fact that my, - still perfectly good biomass boiler system won't last forever, and the time will come when I have to decide on a replacement biomass or something else. Increased insulation has reduced the overall house load but I still need some form of CH.
After those two years of wavering I'm convinced they are the way forward, and I'm about to start fitting one in time for the next heating season. I'm getting supply quotes at the moment for a ducted system.

"Why Ducted?"
My ducted system is going to supply warm air to a fairly large living room as a straightforward split. Wall hung indoor units were a possibility but only on interior walls, and yes, I could have installed mini condensate pumps inside them but together with visible supply pipework I felt it was going to be a bit messy.
On the other hand I have empty loft space available, its a bungalow, so ducted is the way forward, together with fairly short duct runs and aesthetically more pleasing too. I'm not bothered about noise, provided I get the right duct size and airflow right, together with some nice diffusers I'm sure it will be OK. I like the idea of all the working bits being out of sight.
I'm using this first install as a bit of an experiment. If it's OK after a year or so then I may install another multi-split at the other end of the house. There the interior is more conducive to interior wall hung units.