Thread: TRV stuck
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Autolycus[_2_] Autolycus[_2_] is offline
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Default TRV stuck


"Andrew Gabriel" wrote in message
...
In article ,
"Autolycus" writes:

snip
Guess who's in the process of designing a heating system and wants it
fully zoned - 5 rooms - and adjustable to real, understood,
temperature
values, and set without grovelling on the floor, trying to move a
valve
between four-and-a-tiny-bit and four-and-a-tiny-bit-and-a-gnat's.


I suspect that maybe OTT.

I designed and installed central heating about 6 years ago.
I split into downstairs and upstairs zones with separate control.
I did accurate heatloss calculations for each room and sized the
rads appropriately.


snip

The additional constraints that have made me consider this fully-zoned
system a

1) It's a bungalow: the dining room has a small kitchen directly off
it, and has a large, south-facing window, but the lounge is north-facing
with a small window on the west wall, and has previously been found to
work well with two radiators. One bedroom faces north, one south.

2) It will be occupied by an elderly couple, who may wish to use the
rooms fairly flexibly (study-bedroom, etc) and who will almost certainly
want to be able to vary the temperature in odd rooms at odd times. I
think that only the bathroom is really amenable to a normal programmable
room stat, though they could be used in the other rooms.

3) They don't really want to be crawling round faffing with trvs,
especially since most are so coarsely calibrated that you can't easily
return them to a "standard" position. Remote heads for trvs seem to
have gone out of fashion. A dial, or a display, that they can set to
21, or 18 (or even better, 70 or 65) will be much more likely to be
used.

Thanks to Tim for the link, and to Thomas who emailed me

http://www.conrad.de/goto.php?artikel=560618

as a source of radio-controlled actuators. I wonder how long the
batteries last in the actuators? These would be an interesting
alternative to trvs in a system controlled overall by one roomstat, but
I can't at the moment see how to use a number of them to links as OR
inputs to call for heat from the boiler.

http://www.conrad.de/goto.php?artikel=611275 seems to be a similar
device to the Sauter AXT111, but isn't available with an auxiliary
switch.

In the system I envisage, when the room stat calls for heat, two things
will happen: the relevant valve(s) will open; and the boiler will get a
call for heat. This can be achieved using normally open actuators, and
an SPDT room stat, or by NC actuators and a bank of relays, or, easiest,
perhaps, by using conventional two-port motorised valves with auxiliary
switches. The latter have the further advantage that the boiler won't
be woken up till the valves are open, whereas with thermal actuators the
boiler will fire before there's anywhere for the hot water to go.

Boiler choice can be another thread ;-)

--
Kevin Poole
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