Boiler loses pressure and 1 rad is not getting hot

[janus]

Hello. I have an Alpha HE SY25 boiler system in my small single floor house. I have noticed that the boiler keeps losing pressure to zero many times a day and switches to the red light. Also, in one of the rooms ( not the farthest from the boiler) one single radiator stays permanently cold, and bleeds cold water without air. After reading another post I decided to turn all the other radiators off and leave the cold one on, and turn the boiler temp right up. But with all the other radiators turned off, the boiler switches off, as if not recognising this radiator at all. Please help. tia.

 

[aggis]

System might need cleaning if no flow to your rad, also sludge might have blocked the feed pipe to the expansion vessel or the exp vessel might have lost it's pressure, causing the safety relief to blow off when heating on. Get a Gas Safe engineer to look at it.

 

[Alpha man]

Has the non working rad have a TRV on it?

As for losing pressure daily, could be a leaking pipe/rad/valve or a component in the boiler, IE AAV, PRV etc

 

[janus]

System might need cleaning if no flow to your rad, also sludge might have blocked the feed pipe to the expansion vessel or the exp vessel might have lost it's pressure, causing the safety relief to blow off when heating on. Get a Gas Safe engineer to look at it.

Not quite sure what a trv is!

 

[rw1]

system may have a leak or prv is letting by, the radiator could have a build up of sluge, could surgest to remove radiator flush it through and change the valves either side of the radiator, power flush could help depending on the age of the system, if the system is to old then a chemical flush would be advisable, if the expansion vessel lost pressure the pressure gauge would rise causing the prv to blow out, check the external side of the prv to see if it is wet or sighns of blowing out, problem is easy solved

 

[Alpha man]

Not quite sure what a trv is!

Thermostatic Radiator Valve

 

[Copperkid]

Expansion vessel might need a pump up regarding the pressure loss check the pressure relief pipe isnt dripping when you top the boilers pressure up??