Start-up Bangs & shut-down pops AFTER service.

[GasAt300Bar]

Start-up Bangs & shut-down pops AFTER service.

Potterton Boiler C50/15 (circa 1972?)

Our Potterton stopped firing and we had a GasSafe bloke diagnose a new Honeywell V4400 valve & thermocouple. Fitted these and now it fires-up, silently.

I can hear the boiler stat click. Yet, every 10-15th ignition, (so not consistently) you’ll hear a real ‘Wompf!”.

On shut-down, as much as 5-6 secs later you’ll hear a little “Pop”. But I think it always did “Pop’ at shutdown, but I’m not sure.

I got the impression our GasSafe bloke had never seen a Potterton before, I don’t think he had experience. But I watched him strip it down, There’s not much else in there.
It’s a valve. Do we:

1) Call him back to sort this, he clearly has no clue?
2) Call in another bloke?

I’m worried about option 1) I want a bloke that knows more about this thing than me. I feel i shoudl cut my loses and go with 2) but how do I find the right bloke?

 

[Last Plumber]

It should not pop, bang or Woomf at all.
You need - as you stated really - an ‘experienced’ Engineer to come and set it up/check it over.

I doubt the Gas valve needs replacing.

 

[GasAt300Bar]

Yes, a new valve it won't need. Just had that. (says Honeywell V4400 on box) New valve cured the initial non-firing fault. I am looking for another bloke now. GasSafe registered deson't mean what it should. Watched last bloke put a meter on the valve so i know he 'tried' to set it up. I am guessing the issue is still set-up.

 

[Chalked]

Sounds like co2 not set up right.

 

[Chuck]

GasSafe registered deson't mean what it should.

The boiler is 46 years old, I'm surprised you found anyone willing even to look at it!

 

[Wetbandit]

I don't think it's fair to assume that gas safe doesn't mean anything these days.

Your boiler is 40 odd years old and the engineer may not have come across one of this age before so stripping it down may have been different to what he is used to, also he did diagnose the fault correctly I think you should speak to him about the noises and not be so harsh on the guy.

Wet bandit

 

[GasAt300Bar]

The boiler is 46 years old

Ah... he nearly did walk away! He was querying its set-up, and didn't want to sort it.

Sounds like co2 not set up right.

Managed to find the Burner rating plate 17mBar, he was happy. I'm guessing CO is much like a car and its Lambda O2 mixture. I watched him meter to 17mBar.

I'll give him a call. He did diagnose correctly, but then it's got a stat, a valve and a thermocouple in there. Three things. The pilot stayed lit, so it doesn't leave much?! I reckon I could have dazzled you with my brilliance for that.

But my concern is, I don't know if he knows what he's doing.

 

[Pickwickpick]

Also don't take this the wrong way, but it can be really disconcerting & distracting having someone hovering behind you watching your every move when you're trying to get a job done, especially if you're working with an unfamiliar ancient system. By all means have a chat, find out what's being done and why and make sure the jobs done properly before signing off on it, but I think you will generally get a better job done if the tradesman doesn't feel pressured and is given some space. Just my 2cents from personal experience.

 

[GasAt300Bar]

That is true. Can't have helped, never having seen one. I will give him a call.

 

[GasAt300Bar]

Well, got to the bottom of it. My GasSafe bloke left the burner clogged with scale. The drain-cock was weeping. He repaired the drain-cock, but didn't clean the burner.
The first of the four burner-rows you can see was completlely clogged, the second is still white with scale.

Because it sits near the pilot assembly, scale formed. This scale block caused the 'Wompf' effect. Not sure why he couldn't diagnose this. Cleaned and it runs. No 'Wompf'. Frankly, if a GasSafe bloke can't see this, I'm left wondering.