Boiler does not turn on for hot water

robshak

matt_drummer said:

robshak said:

Just pressed the reset button and unfortunately, nothing happened..now reading the manual myself..and looking for the cylinder thermostat replacement

I think there are two.

There are two immersion heaters and they both have thermostats. One of them sends a signal to your boiler.

Do you know which one is which?

I would imagine it is the one in the middle of the tank, not the lowest one.

matt_drummer said:

robshak said:

Just pressed the reset button and unfortunately, nothing happened..now reading the manual myself..and looking for the cylinder thermostat replacement

I think there are two.

There are two immersion heaters and they both have thermostats. One of them sends a signal to your boiler.

Do you know which one is which?

I would imagine it is the one in the middle of the tank, not the lowest one.

I don't think any issue with immersion heaters..they heat water fine when I turn it on but they cost a fortune..

I have a question on the thermostat temp control dial. Is it the maximum for how warm water should be when heated or the minimum temp under which it sends signal for boiler to fire..probably daft..

matt_drummer

robshak said:

I don't think any issue with immersion heaters..they heat water fine when I turn it on but they cost a fortune..

I have a question on the thermostat temp control dial. Is it the maximum for how warm water should be when heated or the minimum temp under which it sends signal for boiler to fire..probably daft..

I wasn't suggesting that the immersion heaters are faulty or need replacing.

There are two immersion heaters and both have thermostats.

One of those thermostats tells your boiler to heat the water.

I don't know which one it has been connected to but I would expect it to be the one in the middle of the tank.

That is why I suggested checking the reset button on both thermostats.

The thermostat sends a live signal to the boiler all of the time that the tank temperature is below what is set on the thermostat.

When the tank has reached the set temperature the thermostats stops sending power to the boiler and the boiler stops heating.

The boiler will only fire when the tank is below the temperature set on the thermostat and your programmer is in an on period for hot water.

You should be able to make sure that the terminal on your thermostat that tells the boiler to heat is live as your tank is below the temperature set on the thermostats.

matt_drummer

You should have a wiring centre somewhere that your programmer is connected to.

You could test there to check that the input from the tank thermostat is live.

FreeBear

matt_drummer said:

You should have a wiring centre somewhere that your programmer is connected to.

The wiring centre is probably that white box on the floor in front of the boiler. But invariably, none of the wires will be labelled, and they'll all be one of three colours.

matt_drummer

FreeBear said:

matt_drummer said:

You should have a wiring centre somewhere that your programmer is connected to.

The wiring centre is probably that white box on the floor in front of the boiler. But invariably, none of the wires will be labelled, and they'll all be one of three colours.

There might be a wiring diagram inside the cover?

QrizB

matt_drummer said:

FreeBear said:

matt_drummer said:

You should have a wiring centre somewhere that your programmer is connected to.

The wiring centre is probably that white box on the floor in front of the boiler. But invariably, none of the wires will be labelled, and they'll all be one of three colours.

There might be a wiring diagram inside the cover?

There's a diagram of how it *should* be wired in the HW tank instruction manual!

matt_drummer

QrizB said:

matt_drummer said:

FreeBear said:

matt_drummer said:

You should have a wiring centre somewhere that your programmer is connected to.

The wiring centre is probably that white box on the floor in front of the boiler. But invariably, none of the wires will be labelled, and they'll all be one of three colours.

There might be a wiring diagram inside the cover?

There's a diagram of how it *should* be wired in the HW tank instruction manual!

I know, I have read it.

The manual seems pretty good.

Those diagrams won't necessarily match the wiring centre used and won't necessarily tell them which terminal of the wiring centre is the tank thermostat.

I have wired a few Honeywell wiring centres in the past and the terminals are numbered on a diagram and it tells you which terminals to bridge depending on the desired functions.

Qyburn

FreeBear said:

you appear to have an S plan system, so you don't have diverter valves, just regular zone valves - One less port, but the mechanics of operating is still the same.

The two port valves normally have a microswitch, which is what actually what switches on the boiler and pump. The programmer opens the valves as required, but power to the boiler/pump comes through those switches and not from the programmer. The valves are spring loaded closed, there is normally a lever to manually open but the latched position doesn't necessarily hold it open enough to close the switch.

 If the switch has failed, then you would get hot water by manually opening the DHW valve while the boiler is running for heating. This would also over ride any cylinder thermostat.

glennevis

robshak said:

FreeBear said:

robshak said: If the diverter is at fault, think I'm going to call in expert as don't want to start fiddling with plumbing..

you appear to have an S plan system, so you don't have diverter valves, just regular zone valves - One less port, but the mechanics of operating is still the same.

As for fiddling with stuff - You should really be a Gas Safe registered engineer to remove the cover on the boiler. There is usually a seal around the casing panels that need to be checked as there is a (very small) risk of fumes leaking out. Interesting to note that there are only three pipes entering the boiler at the bottom - Two for the central heating, and one for gas. No sign of a DHW heat exchanger, so the boiler is certainly a heat only model.

There was no seal, just a latch at the top and two screws at the bottom to take the front panel out..I know my limits ha ha.. and I am now beginning to understand it may not be a simple fix e,g. a wrong setting somewhere,as I anticipated..so may be this is where I rest..your suggestions have been really educational for me..thanks..

Freebear is right, WB cover should only be removed by a Gas Safe engineer.

For your information, it's a known fault with WB combi boilers that the diverter paddle can stick if the stepper motor controlling it goes faulty, causing no DHW.

The motor is located behind the green cover which if you were permitted to remove it would reveal a small stepper motor attached to a plunger that should move up and down as the diverter switches from DHW to CH mode. My guess is this is not moving which would be the root of the issue. Get the Gas Safe engineer to remove and clean the diverter paddle as well as replacing the motor as it might be sticking due to a bit of crud.

robshak

 

Thanks for your advice..and everyone else's too..I have accepted that this is not a straightforward and easy amateur house owner fix due to a wrong setting somewhere.

I will soon book a gas engineer to have a look. Hopefully all troubleshooting I have so far carried out will assist them in getting to the root issue quickly.