I have a problem with a boiler not turning off via the programmer. It turns on fine with the programmer (CH or HW) but will only turn back off via the programmer when done so within a few seconds of turning on, left any longer and it just won't turn back off at all by the programmer or thermostat. Also there is no hot water even though the boiler fires up when the hot water is turned ON, on the programmer. To turn the heating off, the power to the boiler has to be turned off or the programmer unplugged. I have tried a new programmer but still the same. It is an old boiler but had been working fine previous.
> I have a problem with a boiler not turning off via the programmer. what sort of boiler/system is it?
sounds to me like the 3 port valve, there is a constant live to it and if its malfunctuating, it will give live to the boiler and pump when not being called for.
its usually in the hot water cupboard, but it could be under floor, if you know where the pump is, it will be near it.
Checked the 3-port valve and it is always getting driven to the CH postion no matter what, even if only HW is called for. It is a siemens MA-V3 valve. I tried a replacement motor on the valve but again as soon as the boiler is on the motor drives to the CH position and will not turn back off again. Could it still be the valve body at fault, which I quote has the "electrical and mechanical drive mechanism unit" or could the fault lie else where??
we're running out of options here now, new programmer, new valve motor, its best to call some one in with a multimeter, theres something not right and it will take an engineer to find it,
I'm looking for the cheap option, I have a multimeter and am competent enough to use it, just need some pointers in the right direction.
there is no cheap option, you have bought a programmer and 3 port motor and still you need to spend more, an engineer would have nailed it by now and saved you money,the wiring is complex on this system, it could be that one of the parts you have bought is faulty ( happens often ) , or you could have wired the programmer wrong, possibilities are many, call someone in.
I haven't done anything to the system prior to the fault, everything had been working fine for years and no wiring has been changed. All components I've tried have been new and refundable (no money wasted) and unlikely to be faulty because they have had no effect to the fault. There must be one component faulty in the system, either still being a the 3-port valve end or with the boiler.
my moneys on the 3 port, when you say you changed the motor, do you mean the full head wiring and all? thats that is what i think is at fault, i don't think the boiler is.
No just the motor was changed, the valve body still holds a micro switch and circuit board and has not been changed, was just trying a process of illimination with the motor. Plus I wouldn't know where to start with changing the valve (i.e. isolation, draining, refiling and bleeding the system)but I'm still willing to have a go with guidance.
well i think thats your problem, the head will come off without draining , but you will have to rewire it and there are 4 wires that will need nimble fingers, cos inside the wiring centre there are many connections, so best to undo and connect each wire one at a time so you don't get mixed up. red to red blue to blue etc etc, make sure the power is off at the switched spur, as there is i live one inside there, good luck.
I'll change the valve like for like, the wires go to a junction box with easy access so thats not a problem, how come I will not need to drain before the valve is taken out, one port comes into the side of the valve from the pump, the CH pipe goes down from the valve, and the HW pipe goes up to the tank located above it.
sorry i thought the head came off, you will have to drain off, turn water off , connect hose to a drain point and drain system, change valve,refill and bleed upstairs rads,
Forums
Facebook
Twitter
You Tube
Instagram
Shop