Underfloor Heating Issue

[bermudasun]

I have just bought a new flat from and I am having problems with m

underfloor heating. I believe from the builder that it is a cabl system. There are 2 zones in the flat one covering the kitchen an living room and the other covers the bedroom and hallway. The heatin in the living room and kitchen is fine and I can get the rooms warm. My problem is with the bedroom and hallway . The floor feels war however there the actual rooms are cold and never seem to get warm. have tried running the heating over night to no avail. I have trie setting the temperature on the thermostat in these rooms to maximum bu it never gets warmer than 20 degrees celcuis in the rooms. Can anyon help and give me some advice?

-- bermudasun

[Aidan]

Put it in writing to the builder, get him to fix it. The problem will be worse in 10 or 11 months when it is colder.

Inadequate heat output, able to maintain the steady-state heat losses from the rooms at the design temperatures? Floor coverings insulating the radiant floor? Unoccupied, unheated flats adjacent? New flat, damp plaster, screed & mortar, higher ventilation rates required to dissipate the moisture? etc., etc., ?????

If it's too cold now, it will be colder in very cold weather.

20 degC can't be far off the design. Most UFH installed in screed needs to be run continuously, the heat up time for the floor slab mass is too long to operate intermittently like conventional radiator heating. The air temperature can be lower with UFH, whilst still being comfortable, due to the increased radiant output from the floor, i.e., the air is cooler, so heat losses from you to the air are higher but heat losses from you by radiation are lower, so you still feel comfortable.

[The Natural Philosopher]

Mine takes about an hour to an hour and a half to be up to temperature.

20C would seem to be Ok ish for a hall area..I suspect its just under-specced.

[Jonathan Pearson]

By cable I assume that you mean an electric system - we use a similar system in our kitchen, and hidden in the settings is a maximum temperature which the floor is allowed to get (I'm pretty sure I can set a temp higher on the front end of the control, but it gets overridden by the max temp setting), maybe they have set this too low? - Also these system unlike conventional radiators are designed to be on all the time - we have ours set to 16 deg during day and night, and increase it to 21 deg in mornings and eves.

Jon