help - can a low pressure problem be fixed with a new valve

[paulcockerton]

Hi

We've got a worcester bosch 14/19 Cbi installed - about 5 years ago. We've lived at this house for almost 2 years and not had a problem with the boiler until now.

2 weeks ago, in the cold snap, the boiler failed to fire. After leaving it off for a while (5 hours) it then worked fine, lighting up properly. Again, a couple of days ago, coincidentally when another flurry of snow hit London, the boiler failed to fire. This time we haven't been able to get it going and called out staunch and flow, who we've used before to service the boiler and seem pretty good.

After a couple of hours here, the plumber has said that the reason the boiler isn't firing is that the pressure is too low (15) at the boiler. At the meter, which is down the stairs and outside, the pressure is 28. He claims that it's 'probably' due to the size of the pipes and the number of bends. He's suggested that the valve attaching the pipe to the boiler could be replaced, to change the pressure. Partly because the valve is 'old'.

My concerns are - why haven't we had problems before if the problems are with the pipes / valve - it's unlikely (though possible?) that something has started to fail. Should this have been noted at the previous servicing of the boiler? Was it a coincidence that the boiler failed to fire up correctly during the cold snaps? IF the engineer is right, isn't it possible that a new valve may not fix the problem? Could it be a problem with the piping that's developed elsewhere?

Any tips appreciated - for instance could i call transco and say we have a problem with gas pressure?

Thanks in advance!

 

[Gasguru]

I assume the 28 figure refers to the standing pressure which is largely irrelevant. The 15 presumerably refers to the working pressure at the boiler. Although lower than required by regulations it should not pose much of a problem for this boiler. Did he confirm the working pressure at the meter was correct?

If the boiler fails to ignite after several attempts it will lockout and the red light will come on requiring a manual reset before further attempts to light are made.

Did the red light come on at any stage?

The minimum quoted burner pressure (on its lowest output) on this boiler is very low...it should happily light at only 6 mbar so it should be able to operate at very low inlet pressures.

When the weather is cold it is possible for the working pressure at the meter to drop due to excessive demand (due to overloading the gas main in the street) and also due to water freezing in the mains. This can lead to very low gas pressures at the meter. Unless the pipework from meter to boiler is seriously undersized the boiler should cope ok.

I suspect there is another problem.

 

[andytheplumber]

The boiler does not like snow.

 

[Agile]

Hi

This time we haven't been able to get it going and called out staunch and flow, who we've used before to service the boiler and seem pretty good.

After a couple of hours here, the plumber has said that the reason the boiler isn't firing is that the pressure is too low (15) at the boiler. At the meter, which is down the stairs and outside, the pressure is 28. He claims that it's 'probably' due to the size of the pipes and the number of bends. He's suggested that the valve attaching the pipe to the boiler could be replaced, to change the pressure. Partly because the valve is 'old'.

Thanks in advance!

One assumes he was unable to repair your boiler?

I have been called to a boiler where that firm was unable to repair it. I have little respect for firms who fail to repair boilers.

Tony

 

[paulcockerton]

Thanks for your prompt comments.

Yes, the red light came on - we tried to reset the boiler ourselves and even called out transco as I suspected it may be a gas problem. Transco confirmed there was gas going into the property (and that's all they wanted to do).
The engineer did do a full servicing / test of the boiler anyway and couldn't find anything else wrong so almost by default (and after long conversations with worcester) think that the valve needs replacing.

Also, the gas coming into the boiler somehow varies between 11 to 14 which also sounds strange.

All of this is third hand as I wasn't here when the engineer came! But my partner is pretty reliable.

I think we're going to try the valve idea - and then see. Don't really want to replace pipes / boiler! With a young family don't have hardly any cash to splash around