Jaguar boiler - driving me mad...

[Harry Palmer]

Hi

I have a Jaguar boiler that has a problem (I know, they're rubbish so what do I expect...). Basically, when the boiler switches on, it 'ignites' for a few seconds, then cuts out. Then tries again ad infinitum. The pressure bar thing is also very high (after draining the system a bit, it keeps rising from 1.5 ish to about 4.0).

British Gas have been out three times to try and sort this out, and everytime it works for a few hours after they've been and then it all starts to go wrong again. On their last visit, the engineer pointed out that the valve on the filling loop was the wrong type (apparently it's a mains valve). I've noticed that when I drain some of the system and dropped the pressure back don to 1.5ish, the boiler seems to work okay - until the pressure reaches 3.0+.

What I want to know is:

Could the incorrect valve on the filling loop be causing the pressure to constantly rise?
Is this probably causing the boiler to stop working?
Is this something I could fix myself and if so, how?

It's very cold in my flat, and I'm having to use a kettle/friend's houses for hot water. Any help would be greatly appreciated.

 

[kevplumb]

is the filling loop disconnected

 

[Harry Palmer]

When you say 'disconnected', do you mean is the valve turned off, or do I need to physically remove the loop?

(edited for poor spelling!)

 

[kevplumb]

it should be removed

if the valve drips thats what is increasing the pressure

 

[Harry Palmer]

Sorry to sound stupid, but if I remove it, would water not come out of the pipe it was attached to?

 

[Nige F]

Not if both valves...one @ each end are shut and holding.should be left disconnected anyway.(water regulations).any relation to Michael Cain

 

[ChrisR]

nb pics in the "for reference" section

 

[meldrew's_mate]

Could the incorrect valve on the filling loop be causing the pressure to constantly rise?
Is this probably causing the boiler to stop working?
Is this something I could fix myself and if so, how?.

Yes, no*, and yes.

*Unless the safety relief valve is also passing, causing the pressure to drop too low as it cools, on the digital display models the pressure display flashes when it's too low.

Do what has been suggested and remove the filling loop to check valves.

Most probably the expansion vessel has failed, or needs the air ballast topping up, even BG should be able to manage that I presume that you have a contract with them.
As for the start-stop operation you may have poor pump performance or a poor fan/pressure switch.

 

[Agile]

These are perfectly reasonably boilers when properly installed on a clean system.

BG people will have difficulty because they are not specifically trained on these models.

The problem is most likely associated with the combustion process.

I am quite happy to give free telephone advice to a BG engineer attending your property.

Tony Glazier