Can a 3 way valve be stuck in neutral?

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Sorry if this is long winded. I have other posts about a problem with my britony combi 80 and since I'm Still waiting for my heating engineer to turn return I though I'd fault find.

I won't replace any parts myself but if I can tell him what to look at it might give him a kick up the butt.

After a pressure issue (stable at 1 bar until burner and pump running) and gargling noise coming from the expansion vessel he fitted an external expansion vessel and pump. Still no further forward though.

The problem has been intermittent so I thought about moving parts and the only one i could think of is the diverter. I turned the hot tap on, the fan, pump and burner kicks in and the pipe coming from the chamber gets hot. The pressure then bounces all over and the boiler cuts out and the expansion vessel gargles. As the boiler cuts out the tap water goes warm and then cold again. It's a similar story with the heating.

Could the valve be stuck in a neutral position causing pressure to build, force water into the original expansion vessel and then cause the gargling noise as the pressure drops and water then escapes the vessel?
 
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As already advised your boiler is cutting the pump at the same time as the burner and the pump over run is not operating, it has absolutely nothing to do with your expansion vessel new or old
 
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Just to let you know the boiler has stayed on when i turned the boiler on this morning and the ch is heating up. i'll check for the pump over run once the system is up to temp.

I believe / hope the pump only kicks out at the same time as the burner when there is a problem and the boiler cuts itself out
 
No doubt I'll get a load of abuse for this but here goes.

About 5 years ago I had a similar problem with my Britony 100 when it was under warranty.

The problem started when I was having a shower - suddenly running cold. The intervals of hot got less so I called the installers.

By this time the fault was that bad the boiler refused to fire up at all.

They came out and changed the PCB and a few other bits like the thermistor but the fault remained.

Eventually they gave up and called the rep. He told them it was the incoming water flow switch. One of the engineers grabbed it and it fell to pieces in his hand. (a common occurance apparently).
They changed the flow switch and it's been fine ever since.

Dunno if you have the same issue but it's s simple part to check (physically and electrically) so if I were you I'd have a look at it.

BTW the function of the switch is to send a voltage to the 3 way valve so if it doesn't operate properly - your valve will be 'stuck in neutral'.

Now let's wait for the abuse.
 
Hi all,

The little elf is stuck in reverse, the gearbox would depend on how many gears it has, whether it is a manual or automatic! Can't get back into first gear. Failing that, the diverted valve may be stuck in DHW mode, when calling for CH. Do you get DHW ok? These have been known to explode! BE VERY CAREFUL. There is pump overrun on PCB. Suggest you get a GSR engineer out...

Call Chaffoteaux for a local engineer, simples...

Good one in Sunderland ;)
 
Hi all,

The little elf is stuck in reverse, the gearbox would depend on how many gears it has, whether it is a manual or automatic! Can't get back into first gear. Failing that, the diverted valve may be stuck in DHW mode, when calling for CH. Do you get DHW ok? These have been known to explode! BE VERY CAREFUL. There is pump overrun on PCB. Suggest you get a GSR engineer out...

Call Chaffoteaux for a local engineer, simples...

Good one in Sunderland ;)

I didn't know mackems were called little elf's, now I'm really confused ;)
 
No a direct replacement for the original grundfos. He has been around again today and went over everything he has done so far. Before he started he thought the pump may still be the issue but that it could be a bad electrical connection.

He disconnected everything to the pcb board, checked the jumper settings and then reconnected everything, taking his time to make sure everything went on properly

He has also took the original pump away with him to test as when he replaced it he used the original pump wiring to save disturbing the pcb, just connecting to the black box on the pump.

Everything has been fine since lunch time and I have the boiler set to switch on for every other hour to put it through its paces. I've run the water several times and everything is ok. I'm going to leave the boiler off idle over night since its mild and then fire it up in the morning.

I'll report back, thanks again for the advice so far
 
It always amazes me when people come on to a forum and look for free information and receive it from engineers who have worked in the industry for a long time, admittedly there are different qualities of replies and it is sometimes difficult to decide who to take information from, I worked for C&M for 5 years and I know your boiler as well as anyone , from your video YOUR PUMP OVER RUN IS NOT WORKING it is NOT your expansion vessel , it is not your tacho on your fan, you do not need Chylimaflyonic acid to clean it you need to sort your PUMP OVER RUN
 

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