No gas at burner pressure test point?

[Agile]

Doing a service earlier this week I found that there was no pressure at the burner test point.

It was a SIT 845, actually on a vaillant, but the problem could be on any boiler with that valve.

Yes, the U-gauge showed nothing, the burners were alight, the screw was loose, LDF showed nothing, the air compensation tube was on the correct point, yes I seemed to be able to suck gas out of the valve.

I was unable to get the screw out with blue-tack.

Has anyone else experienced this problem with that valve?

Tony

 

[gazthepottertonengineer]

no

 

[rumplestiltskin]

you're a pretty clever dude Tony so I hesitate to reply but just in case it helps.......some condensers may read zero as they tend to "suck" from the gas valve

 

[ollski]

you're a pretty clever dude Tony so I hesitate to reply but just in case it helps.......some condensers may read zero as they tend to "suck" from the gas valve

They will read a negative pressure on a u gauge though and Tony was seeing no movement

 

[chrishutt]

The SIT 845 is a normal gas valve with electric modulation (i.e. not a gas/air one for condensing boilers) and so the above comments would not apply.

 

[Agile]

Yes, Chris is correct, its a normal gas valve.

Rumple, its not only condensing boilers, many other premix boilers use zero pressure gas valves. Ideal Response for example.

I met another one today but was able to get screw out completely and that then cleared whatever was blocking it.

Anyone else had this problem?

If you did meet it what would YOU do about it?

Tony

 

[ollski]

If you did meet it what would YOU do about it?

Tony

Gas rate it and fsd check it at the meter.