nasty glowworm compact 80 - lockout!

[Chris-T]

Hi Guys.
Need your help with this boiler. Been Ok for past couple of months since we moved in - until now.

Boiler fires up ok but then 30 secs or so later it locks out. This happens on hot water or heating. THe heating pipes stay cold. I have also noticed that the demand light for hot water is always on even when the hot taps are off (have checked)

I've taken the front cover off to have a look. Seems to be overheating. THe pump and the rectangular metal box that heats the water was red hot. When it cooled down i checked the pump and it is working and spinning. I've also had a look at the diverters (though i'm no expert). When i took the switch off the hot water diverter the light (green)went off on the panel. Then 'pin' on this one moves out but not back in. I can push it back in easy enough. The pin on the heating on is out and will not move at all.

After this 'faffing' i did get hot water for a while so tried for heating. THe heating pipe on the left side got red hot, i could hear the boiler overhreating and it locked out. Its as if the water is stuck and has no-where to go.

What on earth has happened here. Is this an easy fix or do i have to raid the kids piggy banks for a new pcb.

Chris

 

[Gasguru]

For starters replace

DHW flowswitch
DHW diaphragm
DHW diapgragm brass cover and gland assembly

Very common fault on this model.

 

[Chris-T]

For starters replace

DHW flowswitch
DHW diaphragm
DHW diapgragm brass cover and gland assembly

Very common fault on this model.

Thanks for the advice but i think i'll get a local corgi in to do this for me All those things sound hard to fit

Would this part also affect the heating side which is also going no-where (other than heating the frist foot on the flow)

Chris

 

[Agile]

For starters replace

DHW flowswitch
DHW diaphragm
DHW diapgragm brass cover and gland assembly

Very common fault on this model.

I thought that I had been drinking!

Now I wonder if ( exceptionally ) you have as well Geoff !

I admit that I did a West End boiler repair this evening and then met some friends at the Spaghetti House for a lovely meal. Three of us had 1500 cc of their good house red! Since I got home I have had a glass or two of SA wine as well.

However, in spite of my alledged state, I still think that this model has a turbine flow switch on the right behind the pump to create a DHE demand on a four pipe heat exchanger arrangement!

Perhaps I am worse than I think I am and need to take a boilerlizer test?

Tony




PS Only one of these spellings is likely to be correct! DHW diaphragm
DHW diapgragm

 

[Chris-T]

Gasguru is right. I've just had a look at the manual and can see what he means. The small brass assembly with a microswitch on. Sits just to the left of the pump.

 

[Agile]

Isn't that the low pressure switch ???

Below and to the left of the pump ???

Better not to fiddle with boiler if you dont know what the bits do!

Surely I am not drunk after only 600 cc of red wine over four hours? Will have some cheap Baileys and augment it with rum in a moment! Perhaps that WILL make me confused?

Tony

 

[Rob]

Surely I am not drunk after only 600 cc of red wine over four hours? Will have some cheap Baileys and augment it with rum in a moment! Perhaps that WILL make me confused?

Tony

Got a headache this morning, Tony?

Anyway your thinking of the pilot version which is a completely different boiler to the electronic version, which it appears the OP has.

 

[Gasguru]

Tony you really are confused here's a reminder

And the left diaphragm being the pump differential pressure switch.

I'm guessing "...later it locks out" means it's the DBI version of the Compact....and "diverters" are the brass diaphragm covers.


Unusually it is also locking out perhaps due to overheat. Despite finding many Compacts with the DHW switch jammed on I have not found they lockout. Perhaps the burner pressure on these rubbish gas valves has drifted upwards somewhat as they have a tendancy to do causing
overheat lockout.

And to Chris, if the boiler thinks there is a hot water demand (if the pin is stuck out) despite the taps being off the boiler will sit there constanly hot and the rads won't work. If you get a suitable Torx scredriver or bits the job can be done blindfold. Even Tony in his inebriated state could do it blindfold.

Top Tip...use the old screws - don't risk cracking the plastic by fitting the screws that come with the brass cover (they sometimes a different thread pitch).[/b]

 

[Chris-T]

Hi Gasguru

Followed your advice and today i changed the DHW flowswitch. A local parts centre had the whole assembly and the microswitch. I reused the old screws as you suggested.

However, still got the same problem. Have managed to get it running for hot water and i let it run for 10mins.

Then i tried heating and the b***er locked out again (overheated). Flow pipe red hot. --the heating water seems to be going no-where. I took the switch off the diveter assembly on that side and the pin was out. Its stuck out and doesnt move backwards. Would this prevent the heating side from circulating?? Let it cool and tried for hot water and after 20-30 secs it overheats and lockout again??

 

[Gasguru]

So the parts have solved the problem with the hot water demand light being on even if the hot taps are closed. So I presume the the light now funtions correctly and only comes on when a hot tap is opened.

I think the part you are calling the diverter is the pump differential pressure sensor. It looks similar to the hot water pressure assembly you have just repaired and is located on the left side plastic manifold. The pin should only move out when the pump is running. When the pump is off the pin should retract. It is one of the safety devices the boiler uses to determine pump operation with sufficient water.

Are you saying the boiler only locks out in heating mode and the hot water side is now ok? Your post is very confusing. When you mean flow pipe whereabouts. Is this the flow pipe under the boiler when in heating mode or within the boiler?

 

[Chris-T]

So the parts have solved the problem with the hot water demand light being on even if the hot taps are closed. So I presume the the light now funtions correctly and only comes on when a hot tap is opened.

I think the part you are calling the diverter is the pump differential pressure sensor. It looks similar to the hot water pressure assembly you have just repaired and is located on the left side plastic manifold. The pin should only move out when the pump is running. When the pump is off the pin should retract. It is one of the safety devices the boiler uses to determine pump operation with sufficient water.

Are you saying the boiler only locks out in heating mode and the hot water side is now ok? Your post is very confusing. When you mean flow pipe whereabouts. Is this the flow pipe under the boiler when in heating mode or within the boiler?

1. Yes. Replacing that part sorted out the problem with the light being on all the time. That pin now moves freely. I did get hot water running no probs and left it running hot for 10 mins. Then i tried C/H

2. Ah, i see, that pin senses the pump is running. Cant get that pin to retract at all.

3. Tried the boiler in heating mode after sucessfully running hot water for 10 mins. Boiler overheated and locked out in heating mode. heat exchanger was red hot, flow pipe (running under the boiler in 22mm copper was red hot for first 12 inches, pump was very very hot. Let it cool down and tried hot water but boiler locked out again.

 

[Gasguru]

So even if the boiler is switched off the pin does not retract?

Perhaps the diaphragm is clogged with debris or the pin is siezed in the gland seal.

Normally lack of flow to the radiators would not cause an overheat lockout...the burner should modulate down and then off so perhaps a temperature sensor is at fault...are they still all connected/clipped on.

Have you touched the flow/return isolating valves? If so perhaps the plastic lever has broken and a valve is still closed.

 

[Agile]

Is this the plastic one similar to a dreaded Saunier Duval with a diverter valve motor at the left where the diverter valve shaft has seized and is not allowing the diverter to move to the CH position?

Tony

 

[Chris-T]

Is this the plastic one similar to a dreaded Saunier Duval with a diverter valve motor at the left where the diverter valve shaft has seized and is not allowing the diverter to move to the CH position?

Tony

Yes, i think it is..

Is the diverter valve shaft difficult to replace??

 

[Agile]

You just have to drain boiler and open each end and then clean each part one at a time and ensure all the particles of dirt are removed so the two moving parts are free to move.

May be the motor end gland is seized. If so then clean it with wire wool and grease with silicone.

Easy job as they go!

Tony