I think it's "more efficient" only if you are
running a system where the heating is on 24/7 - like a nursing home
etc.
If - like us - you just want a blast of heat
when you come home a night it's not good. We have radiators upstairs
(thankfully) so we can heat the bedrooms at night easily.
Last winter I tried running the UFH
constantly, like you are supposed to. My oil bill over the winter was
40 quid a WEEK!!!!!!!!
Sounds like you need better
temperature control - maybe some DS1820s(?) using up some of that spare
CAT5
(you have got some spare haven't you?) to allow HV to provide additional
control for each zone valve. With some clever programming, I'm sure
you can set a temperature of say 15C overnight, and then up it during the
day and evening when you're in, and lower it slightly when you're out
(Comfort).
The problem seems to be the
'inertia' in getting the floor mass to a working temperature, if you switch
the heating off (at night for example) then the floor will cool and in the
morning the UFH will have to start with a cold floor again. If you
could maintain a low floor temperature overnight, then it should be more
responsive in the morning. That's based on MY understanding, so might
be complete nonsense.
I've just added a programmable
thermostat to my system, and it's now much more flexible.
James
H