"Grimly Curmudgeon" wrote in message
...
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Mike
saying something like:
Thanks for the replies. Is it normal for UFH for each floor to have a
single giant heating pipe circuit or is it more normal for each room
to have its own set of pipes and temperature controlled valves, kind
of like a big underfloor radiator per room ?
Have a look here...
http://www.earthnrg.co.uk/ufh-principles.php
Basically, the second part of your question is the answer - each room is
a seperate entity, connected back at the manifold, but part of the zone.
There's a limit to the size of the individual loops - about 15~20sqM, so
a bedroom generally won't push the limit. Small rooms may be combined,
as you suggest above.
Each zone would be fed from and back to a manifold, the supply to each
manifold being controlled by a zone valve to suit time of day, demand
for heat from stat, etc. Within the zone would be the downstairs rooms
or the upstairs bedrooms, and so on. The return water from the UFH zones
is blended with the incoming hot water to cool it to an acceptable
temperature for UFH.
There's no limit to how much control you put on it - you could have, if
you wanted, individual control of bedroom temperature, with the addition
of stats and zone valves for each room, but that's a bit overkill.
I've never tried a thermostatic valve on the input to a room UFH, but I
see no reason why it wouldn't work - just a question of mounting the
valve with an input pipe to and from it.
It's a very effective system and perfectly suited to lower-temp inputs
like ground heat recovery or solar heat banks, but running it off an oil
or gas boiler can be expensive - not that it needs to be pricey, just
that it can be.
I'm thinking of one I did a couple of years ago - 60sqM of UFH in a barn
conversion - cost an arm and leg to run over the winter, but the owner
was pushing 90 and felt the cold. It was a beautiful job, but there was
nothing I could do if he insisted on having it on all the time. Besides,
the old bugger was loaded and could well afford it.
--
Dave
GS850x2 XS650 SE6a
"It's a moron working with power tools.
How much more suspenseful can you get?"
- House
A Keston Qudos boiler with integral outside weather compensation can be
used. Have a primary loop top the manifold(s). Have a high limit stat on
this loop, set to 55C to protect the UFH pipes. Then set the weather
compensator curve to give no more than 50C max and the system runs itself.
The Keston has a directly attached cylinder stat that will run the boiler to
maximum temperature when DHW is called. A three-way "divertor" valve should
be used to divert the water from the boiler to the rapid heat recovery coil
cylinder, or DHW heat bank, preferably a direct model. Also Keston make a
combi version of the boiler. So when DHW is called no heat to the UFH and
instant DHW at the taps. then it reverts back to the UFH when taps are off.
The great thing about this system is that no blending valves need be at the
manifold(s). The manifolds can be made up of cheap 2-port zone valves
operated by local room stats. Or no zone valves at all and a central room
stat or sensor) that modulates teh boiler (UFH) temperature down, or boiler
off. Only one pump is needed. It is a very cheap and effective system. The
weather compensator on the boiler ensures the right UFH temperature.
Centrral romm temperature control or individual room or zone control.