combi bolier overflow dripping

mitchb

I have a sabre 24 combi boiler that was experinceing a build up of pressure and the overflow was contstntly running.

This was diagnosed as a faulty heat exchanger and i got this replaced.

Since then their has been a drip from the overflow pipe, its not a lot of water probably less than an egg cup a day. At first i thought it was just rsidual water from the pipe but its went on for around 3 weeks.

Any idea why it would still be dripping?

EliteHeat

It is not an overflow pipe, it is a pressure relief discharge pipe. The reason it is dripping is because the pressure relief valve has not reseated itself properly following the over-pressurisation.

This might be because you have a dirty system, but you could try operating the PRV manually a few times to see if you can get it to seat itself.

Your manual should explain how to do this.

saintlee

unlikely a faulty heat exchanger would cause the pressure relief to start dripping. Tow most common faults to cause this are either the expansion vessel has failed (or is blocked) or the filling loop is letting by and pressuring your system.

If your pressure relief pipe is still dripping you need to see whether the pressure on the system is still high or not. If it is above 2 bar, the original fault is still occuring (probably for one of the reasons I've just stated)

If the pressure is normal on the system it will be the pressure relief valve itself that is faulty. This is quite common if it has been operated, and often starts to leak when being checked as part of a service.

EliteHeat

saintlee wrote: »

unlikely a faulty heat exchanger would cause the pressure relief to start dripping. Tow most common faults to cause this are either the expansion vessel has failed (or is blocked) or the filling loop is letting by and pressuring your system.

If your pressure relief pipe is still dripping you need to see whether the pressure on the system is still high or not. If it is above 2 bar, the original fault is still occuring (probably for one of the reasons I've just stated)

If the pressure is normal on the system it will be the pressure relief valve itself that is faulty. This is quite common if it has been operated, and often starts to leak when being checked as part of a service.

It will happen when the plate HEX perforates letting mains water pressurise the system side. Had this few times now.