sabre he combi boiler

[DOGMAR]

hi my combi boiler has a problem it has high pressure on pressure
gauge just over 4 bar and only pump and fan start up no ingnition
of boiler this is the same if in hot water only or heating and hot water
any ideas please

 

[gas4you]

Firstly the PRV should have blown at 3 bar, either this is faulty or your pressure gauage is.

I would check the tubes fron the fan to the air pressure switch first for splits or blockages and possibly the fan venturi. If these check out ok then I would suspect the APS its self as it does not appear to be detecting the fan spinning.

 

[DOGMAR]

ok thanks

 

[Agile]

Make sure the filling loop is not left open!

Tony

 

[DOGMAR]

filling was open now closed how do i get pressure down

 

[gas4you]

The boiler usually has a drain off under it, or look for one under a downstairs rad.

 

[DOGMAR]

ok have had a look and am still looking i thought that might be the case
is this why the boiler wont fire is it a lock out because of the high pressure

 

[gas4you]

No, high pressure doesn't usually cause this

Go back to checking fan and aps first.

 

[DOGMAR]

poo ok thanks Dave

 

[billtfish]

HELLO
i just had a similar problem my heating system was filling up through my hot water (heat exchanger damaged ) if pressure goes down when you open the hot tap it could be this.(blow off should kick in at 3 bar)

 

[bengasman]

If you can’t find a drainpoint, take out half a litre from bleeding screw on a rad

 

[Agile]

poo ok thanks Dave

What have you been saying for him to answer like that Dave?

Tony