Ravenheat HE 85T combi boiler sudden stop

[psarinuk]

Hi all
I've a 3 year old Ravenheat HE85T combi boiler which has had new dry clip on CH and wet pocket type DHW therminsters, diverter valve, microswitch and fan PCB in the past.

This morning the boiler starter fine in the morning at 6:30 am and then at around 7 am, when DHW was started, the boiler stopped with RED overheat light ON. the fan was still running.
I checked the pressure which was slightly less than 1 bar, so I topped it up to 1.5 bar but it was of no use.
I've also checked the condensing pipe for any blockage and there was none. I've infact left it open all day to get rid of any moisture.
But there is still no DHW or CH.

I've reset it so many times now (power reset) but every time I start up the fan starts but I can't hear the pump starting (sound of a second motor which is a little bit more noisy and sounds more powerful than the fan one). The pump does not start for DHW or CH. RED light comes after some time.

I've checked the resistance of thermisters and they are fine, even put new ones on and still the problem is there/ no effect.
I've cheked the main PCB/ ignition board FUSE and that is intact. The microswitch and the knobs for DHW and CH (winter/summer mode) are also working along with the timer.

I've checked the power supply to the water pump after opening its microswitch and its 240V there, I've wiggled the capacitor on pump and some wires on PCB (reconnected all connectors) but all invain.

Is it safe to assume now that my water pump is gone and I need to order a new one (0009CIR01011/1)? Are there any more tests that I should do now?
I presume pump is an easy thing to replace or should I be careful about something? Do I need any new washers while replacing the pump?

Sorry for the long post and many thanks in advance to all the kind souls for their helpful replies..

Kunal

 

[twgas]

Check for a power supply to the pump.

 

[psarinuk]

power supply to pump has been checked and its there, any other checks?

Ta

 

[twgas]

If you have power to the pump and it doesn't run it could well be nakkered, try removing the end screw and starting it manually with a small screwdriver - you may need an old towel as water may escape when the screw is removed.

 

[psarinuk]

I removed the screw off the black microswitch type thing attached to the pump to show up the capacitor and wires inside. I checked the voltage at the end of these wires. Few drops of water did come out when I removed the screw.

How do I start the pump manually? Could you please explain?

Thanks.

 

[twgas]

There is, either a big silver screw or a big black nut on the end , undo that. Screw type - you will need a small screwdriver to try to spin pump. black knob - loosen then pull outslightly (a few mm) when engaged turn knob.

 

[psarinuk]

Hi

Update: Unscrewed the large bleed screw in front of water pump, air was coming out forever, and then noticed that there are no pressure in combi.

Topped to 1.5 bar and some ml of water came out. Started for CH and tuned the knob with a small screwdriver many times: clockwise as well as anti-clockwise.. pump does not come on.
The blades, although heavy seem to move without restriction but the pump does not come ON. Tried the same for DHW mode and same result!

So is the pump gone for good?

I've another issue now. Yesterday, the pressure was too high after top up (when I changed DHW thermister), so I turned the pressure release valve (with the red cap) slightly to get rid of some water (that goes outside through pressure release pipe).. Now the trouble is that it won't stop dripping at the pipe outside and water is constantly flowing out of that pipe. Turned over the pressure release valve (it makes a noise as if something is getting shut and falling into place) but water is still leaking outside, so pressure is going down..

How do I fix this?