Worcester oil boiler - not working for water

[gmg0987]

Hi all,

Just wondering if anyone has come across a similar issue?

Boiler is Worcester greenstar utility 32/50.

A few monthes ago the boiler stopped coming on when the hot water is turned to on on the control unit (Drayton). Just doesn't make any noise and doesn't fire up.

It fires up no bother when the heating is turned to on. At this point I can get the water to heat up also. The heating has to be on for the water to heat up!

I am not 100% convinced it's the boiler but the service engineer suggested to replace the oil pump but way I think then surely the pump would affect both the water and the heating.

Any tips or help would be much appreciated, even to get me in the right direction!

 

[Johntheo5]

If a non combi have you got a S system with two or more motorized valves or a Y system with one 3 port mid position valve?

 

[gmg0987]

Hi, it's a oil boiler, heats bother water and heating. Approx 10 years old. That's the valve set up in the photo.

 

[Johntheo5]

That's a S system so looks like the HW motorized valve is not giving a run signal to the boiler but is opening as you get HW when you request both CH & HW, its probably the micro switch in the valve actuator isn't supplying 230V from the permanently live grey wire to the orange wire, you need a multimeter to check it out.

 

[gmg0987]

Thanks. What valve is the hot water one? Is it possible to but a replacement actuator? Screwfix maybe

 

[gmg0987]

Just to confirm, the valve with the white plastic actuator is working when I select HW on and off, as you said boiler not firing up though.
Is this wire you suspect to be faulty going from the programmer?

 

[Johntheo5]

Just to confirm, the valve with the white plastic actuator is working when I select HW on and off, as you said boiler not firing up though.
Is this wire you suspect to be faulty going from the programmer?

No, not that wire, you should have 5 (certainly 4) wires to that actuator, a earth wire (the 5th one), a brown, blue, grey & orange, the brown wire gets 230V via the programmer and cylinder stat and powers the motor which opens the valve (blue is the neutral from the motor), the actuator contains a set of contacts, one side has a permanent 230V from the grey wire, when the valve opens the contacts close and 230V is then switched via the orange wire to fire the boiler, if the valve is opening (which it is) then you are not getting 230V to fire the boiler, it does fire when you open the CH because this also supplies 230V via its permanent (same) grey wire and its own orange wire. looks like the HW contacts arn't closing, even a phase tester should be enough to carry out a few simple tests.

 

[Johntheo5]

WHat make/model is the white actuator, should be able to get a replacement actuator but better to do a few simple tests first.

 

[gmg0987]

Hi. Nipped to screwfix and got a replacement actuator. Same Drayton one but newer style. I have wired that in. Set the programmer to water on, the new actuator is operating as it should be still no boiler coming on!

 

[Johntheo5]

Have got a phase tester or better again a m.meter? At the junction box where you connected in the wires or at the actuator itself, with power switched on but HW not programmed on check for voltage at the grey wire, if you have voltage there, programme HW only on and check for voltage on the orange wire.

 

[gmg0987]

Yes got a multimeter here.

So there is 0.00 reading on the grey wires with HW/CH program to off.

The orange wires reading between 14.00 and 16.00 with both HW/CH.

When I select HW on still 0.00 on grey wires.

When I select CH to on the grey wires then read 16.36 jumping back and forth to OL (not sure what that means).

I have attached a photo of the junction box. Both grey, orange, blue and earth go to the same ports.
The brown on the HW wire goes to a separate port as does the CH. In the CH there is a white wire that goes to nothing.

 

[gmg0987]

Photo of JB

 

[Johntheo5]

Yes got a multimeter here.

So there is 0.00 reading on the grey wires with HW/CH program to off.

Ensure 500V AC or nearest selected on M.meter, you should get 230V between grey(s) and neutral. With HW only on you should get 230V between orange(s) and neutral or earth, if not switch off HW, switch on the CH and check for 230V between oranges and neutral or earth.
Also identify the HW (NEW) cable.

 

[gmg0987]

The new HW cable is the right side black one on the bottom of the photo.

With HW and CH off at programmer, the grey reading is 0, orange is 240.

With HW on at programmer, the grey reading is 0, orange is 240.

With CH on at programmer, the grey is reading 240, orange reading 240.

 

[Johntheo5]

Whoever wired it seems to have used the orange wires as the permanent supplies to the micro switches and these are then switching the grey(s), shouldnt be a problem IMO, the new HW actuator doesnt seem to be switching the supply to the boiler, seems very unlikely that there is also a problem with this new actuator but its possible that the valve is sticking and preventing the actuator going hard over to close the micro switch. Suggest first, with HW only selected, check for 230V between terminal8 and neutral, this ensures correct valve, next, switch off power, remove actuator with wires still in the terminal block, switch back on the power, select HW only and see does boiler fire up, if not check again for 230V between orange & grey. If it does fire up, shut it down immediately and check that the valve spindle turns freely, it should move with or almost with finger pressure, then get a adjustable spanner or a pliers and move it back and forth firmly up against the open stop, reassemble and test again.