Glowworm Ultimate 50FF & pilot light

[blade1212]

Hi, I really hope you guys can help me out.

I have this Glowworm Ultimate 50FF boiler. The pilot ignition keeps sparking even after the pilot light comes on. The fuse then blows on the PCB after about 10 seconds.

I've just received and fitted a new PCB today and the problem is still there..... arggghhh

any ideas ?

tia

 

[ollski]

Reverse polarity?...had any electrical work done in the house??

 

[blade1212]

Hi, thanks for the suggestion, but no electrical work/changes.

 

[gasgeezer]

Does the pilot go out,if it stays on all the time gas valve faulty.Maybe trying to ignite when permantley on

 

[ChrisR]

Can you measure the resistance of the gas valve coils?
On many of them it's a 3 pin connector with blue brown and black wires, blue being common and the coils 2-3k Ohms, though some are higher.

 

[blade1212]

gasgeezer - the pilot stays on but the fuse blows after about 10 -15 seconds of constant ignition so then it all goes out. If I switch off teh power after about 5 ignition clicks, this prevent the fuse from blowing and can retry the procedure (this hasn't help fix anything mind you)

Chris - I'll try to find the connections and measure the resistance at the weekend. If the resistance is significantly higher or lower, what component does that point to and is it typically located within the boiler housing or next to the hot water tank upstairs ?

thanks guys.

 

[gasgeezer]

Check the ignition lead it could be shorting on the case check connection to pcb

 

[ChrisR]

Gas valve connector is the leftmost connector usually.
Is the spark reaching the electrode? The glass thingy on the pcb is supposed to flash, by the way. If so the wire would be ok.

Does the board have one, or two, fuses?

 

[gasgeezer]

The pcb has some neons on it, 4 i think they light at different sequances. Should tell you how far up the ignition it is going.I think there are two fuses on the board one is for the pump not sure which one, s/be a wiring diagram on the boiler case.If the pilot is lighting and it continues to spark it sounds like the rectification circuit is at fault could be the aps not switching properley and blowing a fuse unlikely to be new pcb assuming you have wired the new board correctly.The only time i have seen sparking after the pilot has lit is when the pilot does not shut down after externals are off.When they call for heat again because the pilot is already alight it does not bring the main burner on just sparks,did not blow any fuses though.Check the aps tubes, try linking out the aps to see if that stops the fuse blowing.If it is disconnect the pump ext.controls run a lead temporarily to boiler to see if the fuse still blows

 

[geoff@cetltd]

Check the ignition lead it could be shorting on the case check connection to pcb

An ignition lead short would not cause a fuse to blow

nothing to do with the APS either

However, I don't have an immediate answer as to why it should blow a fuse after 15 seconds

an outsider ... insulation gone in the fan windings

is it the version with or without the pump overrun ?

 

[corgiman]

Check the ignition lead it could be shorting on the case check connection to pcb

An ignition lead short would not cause a fuse to blow

nothing to do with the APS either

However, I don't have an immediate answer as to why it should blow a fuse after 15 seconds

dont think that geezer meant a short as such, but the iginition leads on these do tend to fray where it enters the combustion chamber and the spark earths on the case rather than at the electrode

know what I mean harry??

 

[geoff@cetltd]

Check the ignition lead it could be shorting on the case check connection to pcb

An ignition lead short would not cause a fuse to blow

nothing to do with the APS either

However, I don't have an immediate answer as to why it should blow a fuse after 15 seconds

dont think that geezer meant a short as such, but the iginition leads on these do tend to fray where it enters the combustion chamber and the spark earths on the case rather than at the electrode

know what I mean harry??

doesn't make any difference, the spark is derived from the HT transformer (which is totally insulated from the mains) and powered by the energy stored in a capacitor. If you conneceted the spark output directly to earth, it still wouldn't blow a fuse

 

[gasgeezer]

If the thermister blows as chris said it takes the board out,but you still have power/fault lights you will have to bite the bullet and get a corgi out as it seems very likely the gas valve is faulty, silly thought is the gas isolater on the previous engineer may have turned the gas off.

 

[gasgeezer]

Ignore previous post wrong boiler If it continues to spark after the pilot is established it could be a fault on the ign. lead not rectifying the fuse blowing could be due to ext. controls/pump the aps is made to start the sparking process and has 240v through it so coud blow a fuse if wiring is faulty. if it was making and breaking would the spark come on and then try to spark regardless of the pilot being on the. The ign. lead often arcs on the casing.The fuse blowing is a mystery you may have two seperate faults. p.s not being argumetitive correct me if wrong about aps.

 

[ChrisR]

Plain boring old dirty pilot jet could give a poor pilot flame not enough for the flame detection to recognise, so it would keep sparking.
Can't tie it up with a fuse blowing, though as gg implies - anything with live on it can blow a fuse! Pump fuse is the one on the right - unless you've got the board which has only one fuse. Glowworm seems to fit the "wrong" one sometimes according to the manuals..

Test from the lives to earth with the power off on highest Ohms range, though normal meters won't always see a partial short mains will.
Try disconnecting the pump, just to see if the fuse doesn't blow. The boiler will overheat but should run for 15 seconds!
If you have AC ammeter you could check current to fan.
Sniff things - short circuits usually get hot and smell funny.