Worcester 28 SI II

[micky p]

Has anybody had any dealings with this model. I went to look at one today that was taking ages to light. I narrowed it down via the fault finding diagram in book to either PCB or Gas valve.... Thing is They are 2 very expensive parts to replace. I could just replace the PCB and if the problem persists the book sugests changing to gas valve if that is the case. Boiler is only 3 years old (approx).
The fan runs on high speed then slows down to low speed then it trys to light (spark) but no gas is coming throught to the burner. Eventually it did light up after about 2 mins of waiting. Any sugestions???

 

[ChrisR]

Is there a voltage on the gas valve before it opens?
Sparks?

 

[BOB.DOLE]

was it sparking for the two mins then did it light up

 

[micky p]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

 

[BOB.DOLE]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

i think that the valve on the gas valve seating is sticking if your getting the right ohms to the solanoid and then the the valve opens now and again , sounds like the gas valve to me, might be the criap transco uses

 

[micky p]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

i think that the valve on the gas valve seating is sticking if your getting the right ohms to the solanoid and then the the valve opens now and again , sounds like the gas valve to me, might be the criap transco uses

could be the gas valve sticking you may be right or a dodgy tempremental PCB. I think the customer may be better getting worcester out to it as the charge £180 and i think they will replace any 3 major parts for that money so it may work out cheaper than me doing it.

 

[BOB.DOLE]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

i think that the valve on the gas valve seating is sticking if your getting the right ohms to the solanoid and then the the valve opens now and again , sounds like the gas valve to me, might be the criap transco uses

could be the gas valve sticking you may be right or a dodgy tempremental PCB. I think the customer may be better getting worcester out to it as the charge £180 and i think they will replace any 3 major parts for that money so it may work out cheaper than me doing it.

if you get the right ohms when a demand is selected the pcb is doing its job

 

[micky p]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

i think that the valve on the gas valve seating is sticking if your getting the right ohms to the solanoid and then the the valve opens now and again , sounds like the gas valve to me, might be the criap transco uses

could be the gas valve sticking you may be right or a dodgy tempremental PCB. I think the customer may be better getting worcester out to it as the charge £180 and i think they will replace any 3 major parts for that money so it may work out cheaper than me doing it.

if you get the right ohms when a demand is selected the pcb is doing its job

i was testing the ohms on the gas valve not on the pcb. i wouldn't know where to start as for testing pcbs out.

 

[BOB.DOLE]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

i think that the valve on the gas valve seating is sticking if your getting the right ohms to the solanoid and then the the valve opens now and again , sounds like the gas valve to me, might be the criap transco uses

could be the gas valve sticking you may be right or a dodgy tempremental PCB. I think the customer may be better getting worcester out to it as the charge £180 and i think they will replace any 3 major parts for that money so it may work out cheaper than me doing it.

if you get the right ohms when a demand is selected the pcb is doing its job

i was testing the ohms on the gas valve not on the pcb. i wouldn't know where to start as for testing pcbs out.

sorry i meant voltage when a demand is made

 

[micky p]

i never tested to see if there was voltage as the flow diagram never asked in the book. I have test resistance on the 2 coils on the valve like the book says and they are both under 100ohms which is correct.

It sparks then it stops ....then it trys the sequence again then it stops...eventually it fires after quite a few attempts.

when u first turn the power onto the boiler the fan runs at high speed then goes on to low speed and i can here relays clicking on and off. i think the pcb is a bit tempremental but a bit costly at £150 + vat if it isn't that.

And the book is pointing towards pcb or gas valve which isn't much use.

i think that the valve on the gas valve seating is sticking if your getting the right ohms to the solanoid and then the the valve opens now and again , sounds like the gas valve to me, might be the criap transco uses

could be the gas valve sticking you may be right or a dodgy tempremental PCB. I think the customer may be better getting worcester out to it as the charge £180 and i think they will replace any 3 major parts for that money so it may work out cheaper than me doing it.

if you get the right ohms when a demand is selected the pcb is doing its job

i was testing the ohms on the gas valve not on the pcb. i wouldn't know where to start as for testing pcbs out.

sorry i meant voltage when a demand is made

i never got that far as the book only asked if there was a resistance of less than 100 ohms on both coils. But like you said that doesn't tell you if the valve is sticking. The flow diagram in the book is pretty vague IMO. Im quite supprised at the price og the parts on this boiler as worcester are one of the cheapest for spares.

 

[micky p]

just an update on this fault. The customer ended up getting worcester out to it and i think you might of been right . The gas valve was partly blocked so when you test the inlet pressure it is correct but it wasn't getting throught the valve properly.