low operating pressure on Turbomax pro

[markadams]

Hi,

I went to service a valiant turbomax pro 28, gas rated it using hot tap got 17.5 then checked operating pressure at the boiler and only got 12.3 mbar and 20.47 at the meter, checked the pipework and found it under sized, 20m of 22 to the boiler and hob then a further 20m of 15 to a fire.

I still thought that 12.3 was too low considering I retested it with only the boiler on.

I re-piped replacing the 22 for 28 and half of the 15 for 22.

retested it and to my surprise I got the same readings.

I was going to install a test point on the pipework but regardless of this do you agree that it needs a new gas valve?

 

[Stoney Ground]

Vaillant lose a lot of pressure through their gas valve.

 

[markadams]

12 mbar seems very low.

 

[markadams]

MI says it should be 20 mbar, so it does not comply with MI by a long way.

 

[ShaunCorbs]

you replace the pipework from the meter direct ?

 

[markadams]

yes 28mm from meter union to upto 1/2 meter of boiler which is 15mm

 

[ShaunCorbs]

yes 28mm from meter union to upto 1/2 meter of boiler which is 15mm

why not run it in 22mm to boiler ?

 

[GrahamM]

You checked the gas valve not full of carp and restricting gas?

 

[markadams]

I left the last 1/2 meter of existing 15mm pipe which connects to the boiler. As mentioned I am going to connect a test point just before the boiler to see if this is blocked. It will be a pain to replace the last bit as it is behind a kitchen unit which is why I wanted to confirm it was the problem first.