I have what looks like regular Satchwell thermostats on the wall (DRT-3451's for anyone interested), but inside they are just a potentiometer, the setting of which is read by the computer which controls my heating. The computer can be set to read them or to use some specified setting and ignore them, so I can effectively override the wall stat setting. That might be a way to resolve this;-)
Alternatively, buy another wall stat and stick it to the wall with double-sided sticky pads without connecting it to anything, and tell the rest of the family that's the new thermostat:-)
Autolycus coughed up some electrons that declared:
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the "1 other" that may be of interest. Not available[1] in the UK due to Honeywell UK thinking that we're all too stupid to read the manual for such a beast.
[1] But is available as part of a full installation service for lots of wonga plus silly markup on the components.
Also available from
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HTH
Tim
PS Not tried it but read the specs, it looks pretty good.
ARWadsworth coughed up some electrons that declared:
I have holidayed in a couple of such flats in Riga and Vilnius. Big central boilers on each estate and, as you say, unlimited heating. There was talk in Riga of putting usage metering on the rads and hot water though.
Same system in China, but sometimes you don't get the how water, just the central heating.
Just dealt with two such stuck valves. Take the head off (the dry bit only), then see if you and push the pin in (not too hard mind).
If not, try a sharp tap with a light metal tool, eg pliers or pin hammer. You are looking to invoke a small shock to crack the stuck valve open, not to hit it so hard you damage it, or upset the compression/screw fittings.
Worked on both of mine. Then put the head back and turn on and off a few time, which should finish the job.
If that doesn't work, don't get any more violent or you might get wet, in a black yukky magnetity sort of way. Buy a new valve and fit when convenient.
The house is at the north end of a terrace. It's never been an issue in this house. Actually, being a solidly build 1900 house, it stays lovely and cool in the summer, unlike modern houses with no heat capacity.
If it is an issue for you, that would point to a different zoning scheme being more appropriate.
My flat is long and narrow, bed one end, kit/liv the other and split 2 zones, 2 x CM67. Two rads in the hall one on each zone, bathroom radiator is the bypass. Works brilliantly and is economical too.
Sadly though I can't help think that many so-called pros would have walked or quoted a mega price if asked to do something like this.
FYI I had a lockshield valve that was stuck t'other day whilst changing a rad. Mole grips around the valve body, big adjustable on the flats of the valve - and the bugger snapped clean off at the base of the flat.
New lockshield only £2:80, system drained so no real problem, but it could have been.
The additional constraints that have made me consider this fully-zoned system are:
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
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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.
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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.
With full multi-zoning like this using simplified controls that don't have synchronised demand you can find the boiler firing just to service a call to heat for a one small room, leading to frequent boiler cycling. When I designed my own system I plumbed it so that heat from the large H/W cylinder could be stolen to meet light C/H demands, as with a thermal store. The boiler would then only fire to top up the thermal store (when operating on light loads). The extra components are a second pump and a non-return flap valve to stop back flow through the boiler and of course extra control to detect light loading. This phase of the project has yet to be implemented as I have the 7 zones configured in 2 control banks (4+3) and the need for such fine control hasn't been required. The control for the light loading would be simple logic but proprietary.
An alternative is not to fire the boiler until either 2 or more rooms call for heat or 1 room plus a fixed delay had timed out. The effect of this is to try and force the zones into some sort of synchronised demand but again this requires proprietary control.
I like the concept, but I'd decided to do away with a cylinder completely since there's only no bath and only one shower, and the present cylinder is a Fortic.
I see that some (all?) modern combis claim to have short-cycling prevention systems. Vaillant make a thing of it in their blurb, but looking at the various state codes, it seems that Ultracom and Flexicom Glow Worms have it too. I must investigate which others have it - I've not decided on the boiler yet.
What they don't explain is how exactly it works: presumably, if there's too little heating load for even the lowest burner modulation setting, the boiler stops firing but the pump continues running. If the call for heat ceases, then the pump over-run kicks in for its preset period, but otherwise the boiler will not fire up until the defined "anti-cycling period" has elapsed. It's unfortunate that although both Glow worm and Vaillant allow the installer to set these periods within wide limits (2 - 60 minutes), neither give any advice on why one should deviate from the factory defaults. Glow worm do, however, insist on both a minimum flow through the radiator the user can't turn off (or presumably the smallest one in a fully-zoned system), defined in terms of temperature rise through the boiler, _and_ a minimum total flow, including that which goes through the bypass. Since there's no way of measuring this directly, I can only think that you have to work this out from the pump and bypass characteristics.
All this talk of short cycling and part loads makes me think that more emphasis should be placed on the minimum output a boiler can be modulated to, which varies widely from type to type. A Flexicom 30cx goes down to 9.3kW, an Ecotec 831 goes to 8.7, but an Ultracom 30cx goes to 4.95.
And this is without considering any of the newer "intelligent" stats that communicate their every need to the boiler some mysterious way. My brain hurts.
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