In an earlier contribution to this discussion,
Jon Telfer wrote:
Set Square wrote:
In an earlier contribution to this discussion,
Jon Telfer wrote:
Hi,
I've just tried to turn on the central heating after it being off
all summer and there was a flash/bang/release of magic smoke.
I've not made any changes to the system since it was last working
OK. Any ideas/usual culprits? It was serving the hot water OK.
It's a horstmann controller and it's not a combi boiler system if
that's any help.
TIA + not looking forwards to tomorrow's shower,
Jon
We need a few more details about your system - gravity hot water and
pumped CH, or fully pumped? If fully pumped, how many - and what
type - of motorised valve do you have? [Likely either one 3-port
valve (Y-Plan) or two 2-port valves (S-Plan) - see
http://content.honeywell.com/uk/homes/systems.htm]
Seemingly, something which hasn't been used for a while has
developed a fault in the meantime. If it's a gravity hot water
system, I would check the pump. Otherwise, look at the valve(s).
I've taken the controller apart and put some photos online
http://makeashorterlink.com/?F23F249EB
There are various blown components but the most noticeable thing is
that the copper has been melted from the tracks going to output pins
4 and 5.
There's an installation diagram up there too. It's the only
installation method listed by horstmann to contain a three port valve
so hopefully it's OK. Oddly though I have no room thermostat so
presumably this controller wires from pin 4 straight into the valve
- is this the culprit, or am I jumping ahead of myself?
Thanks,
Jon
It's *possible* that there was a fault inside the controller itself -
causing it to self-destruct when you switched the heating on - but it seems
more likely that there was a short in the valve actuator. Unless you can rig
up a means of testing the actuator on its own, the only safe solution is to
replace both it and the controller. If you replace *just* the controller,
and there *is* a fault in the actuator, you stand to write off the new
controller.
--
Cheers,
Set Square
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