We have an Alpha boiler, around 9 years old. It's a combi boiler but not a condensing one.
It came with the house we bought and we noticed the pressure was dropping gradually. Every 10 days or so, I would just top it up with the filling loop and it would be ok. However the length of time has got shorter and shorter between filling. An engineer looked at it today but seemed to pose more questions than answers. Here are the symptoms:
- Pressure drops below minimum and so boiler fails to start up. This usually occurs after a long(ish) period of being unused, e.g. heating off when out all day, or overnight. The frequency of this has become more and more often.
- Pressure still goes up when heating is on. Engineer asked if it gets to the highest extreme, but it only ever seems to each 2 bar when on, sometimes a bit over.
- I did the bag test on the outside pipe. Due to weather and plastic bags having holes in, it's not conclusive but I think there is a slight drip.
- It does not seem to take much refilling to put the pressure back up to the usual 1.2ish bar to fire the boiler up. I would say I hold the valve for a few seconds.
- There are no obvious signs of leaks anywhere, other than the TRV on one of the radiators kept developing a small puddle after I turned it down once. I think I had accidentally loosened the connection to the pipe so I took it off and put it back and not noticed any leak from it again.
- The radiators have started to make a bit of a hissing noise when the heating is on. This has only recently started and probably due to the constant refills creating air bubbles I guess. I don't think this is a cause.
Any suggestions of what could be wrong or what else to look for to help pin point the problem?
The engineer thinks either a leak somewhere, which will be near impossible to find, or a new expansion vessel, which he thinks will be cost prohibitive and may as well get a new boiler, unless we do some kind of bypass (didn't really understand this).
Thanks.
It came with the house we bought and we noticed the pressure was dropping gradually. Every 10 days or so, I would just top it up with the filling loop and it would be ok. However the length of time has got shorter and shorter between filling. An engineer looked at it today but seemed to pose more questions than answers. Here are the symptoms:
- Pressure drops below minimum and so boiler fails to start up. This usually occurs after a long(ish) period of being unused, e.g. heating off when out all day, or overnight. The frequency of this has become more and more often.
- Pressure still goes up when heating is on. Engineer asked if it gets to the highest extreme, but it only ever seems to each 2 bar when on, sometimes a bit over.
- I did the bag test on the outside pipe. Due to weather and plastic bags having holes in, it's not conclusive but I think there is a slight drip.
- It does not seem to take much refilling to put the pressure back up to the usual 1.2ish bar to fire the boiler up. I would say I hold the valve for a few seconds.
- There are no obvious signs of leaks anywhere, other than the TRV on one of the radiators kept developing a small puddle after I turned it down once. I think I had accidentally loosened the connection to the pipe so I took it off and put it back and not noticed any leak from it again.
- The radiators have started to make a bit of a hissing noise when the heating is on. This has only recently started and probably due to the constant refills creating air bubbles I guess. I don't think this is a cause.
Any suggestions of what could be wrong or what else to look for to help pin point the problem?
The engineer thinks either a leak somewhere, which will be near impossible to find, or a new expansion vessel, which he thinks will be cost prohibitive and may as well get a new boiler, unless we do some kind of bypass (didn't really understand this).
Thanks.