We've got a problem with our CH/DHW which I think is likely to be a wiring issue.
The system consists of an (original, 15 yrs old) timer-switch, original 15 yrs old thermostat, original wiring centre next to the (7 yr old) pump, and 6 year old Remeha Avanta 18v boiler.
We found the CH to be OK but never really toasty, whereas the DHW was always HOT. Turns out that the cylinder stat was broken, I recently replaced it myself - easy job. All running OK, CH seems hotter now (as I think the mid-position valve was probably always sending water through the cylinder coils before?).
However there's another weird fault that seems more obvious now that the rest of the system's working well. Sometimes the boiler stays OFF even though the house is cold and the thermostat is indicating demand.
The thermostat does seem to have an effect, as most of the time, once the house is up to temperature the boiler and pump goes idle for a while.
Is it possible that our system is simply wired up wrong? So that perhaps it is coming on only for DHW demand, when it should come on for DHW OR CH?
When it's OFF, the boiler has T1 and T2 readings for inlet and output temperature, these fall from the usual 70C+ running, down to around 30C, as you'd expect, with around 5C difference. There's no error messages on the boiler.
Before I get the CH guy out to look at it, are there some simple checks I should do? According to the boiler installation guide, there are Y, W and S wiring-plans. Without opening it all up, I don't know which plan we have.
Edit: One more thing: Cycling the power off & on at the wall isolating switch, puts the boiler into its usual 4 minute purge cycle, then often it fires up and the CH comes on. Sometimes it's taken two off-on cycles, but it always comes back (so far).
Edit2: The mid-position valve has telltale neons. They are showing correct switching, i.e. CH, HW or both.
The system consists of an (original, 15 yrs old) timer-switch, original 15 yrs old thermostat, original wiring centre next to the (7 yr old) pump, and 6 year old Remeha Avanta 18v boiler.
We found the CH to be OK but never really toasty, whereas the DHW was always HOT. Turns out that the cylinder stat was broken, I recently replaced it myself - easy job. All running OK, CH seems hotter now (as I think the mid-position valve was probably always sending water through the cylinder coils before?).
However there's another weird fault that seems more obvious now that the rest of the system's working well. Sometimes the boiler stays OFF even though the house is cold and the thermostat is indicating demand.
The thermostat does seem to have an effect, as most of the time, once the house is up to temperature the boiler and pump goes idle for a while.
Is it possible that our system is simply wired up wrong? So that perhaps it is coming on only for DHW demand, when it should come on for DHW OR CH?
When it's OFF, the boiler has T1 and T2 readings for inlet and output temperature, these fall from the usual 70C+ running, down to around 30C, as you'd expect, with around 5C difference. There's no error messages on the boiler.
Before I get the CH guy out to look at it, are there some simple checks I should do? According to the boiler installation guide, there are Y, W and S wiring-plans. Without opening it all up, I don't know which plan we have.
Edit: One more thing: Cycling the power off & on at the wall isolating switch, puts the boiler into its usual 4 minute purge cycle, then often it fires up and the CH comes on. Sometimes it's taken two off-on cycles, but it always comes back (so far).
Edit2: The mid-position valve has telltale neons. They are showing correct switching, i.e. CH, HW or both.
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