4 year old Alpha CD24S - where is the leak?

[wildrabbit]

Hello

We had an alpha CD24S condensing boiler fitted January 2006 and have been very pleased with its performance until a fortnight ago.

The previous week I'd topped up the pressure as the boiler didn't fire up in the morning - something that's been very occasional.

We noticed at night that the boiler was dripping water from the bottom and consequently we turned it off and called the service engineer. I noticed that the pressure was in excess of 3 bar and falling as it was turned off. We caught about 200ml of water overnight.

When the engineer opened up the sealed unit the tray was full of rusty water suggesting that it had been around for a while. After drying it up he could not find any obvious leak. He thought that the filler valve may not have been fully turned off leading to excess pressure. The leak maybe coming from a joint he tightened with a quarter turn. He spent about two hours checking everything but could not find anything obvious. He got it running up to temperature for half an hour with no leaks discernible and then put it back together.

This morning the boiler did not fire up as the pressure was too low and I noticed that the bottom of the boiler was slightly wet. I repressurised the system at 8.0am to 0.7bar, it fired up and the pressure rose to 2.25bar over two hours and has remained there until now - 1.0pm.

I'm concerned that we didn't find the original cause of the problem and wondered if anyone had come across it before. Keeping an eye on it now.

Thankyou for any help.

 

[Paul Barker]

Imediately I can say that you need your expanshion vessel checking, recharging if not ruptured renewing if ruptured. You most likely now need a pressure relief valve.

The leak is unlikely to be difficult on this boiler. Rather than nip up I would fit a new fibre washer to the suspect joint. It can only be a standard size which all of us who know what we are doing carry as van stock. If I hadnt the van stock I could do it with what we call a gromet.

There are no known leaky parts on that boiler.

 

[wildrabbit]

Thanks for the reply Paul when I see the engineer next I'll ask whether he's considered the expansion vessel. I remember he did say that the pressure relief valve was intact.