zero governors / burner pressure's

[gary50]

would i be right to say its just the older boilers eg. ones with piolit lights where you see the flame and non- condenser's where you have to do the burner pressure?

would i then be correct in saying all new boilers condensing combis etc....have zero governors and therefore you cant take burner pressure just inlet pressure.

also the regs state 1mbr drop alowed in pressure between meter and appliance but some boiler m.i state a inlet pressure of as low as 17mbr is allowed which would surley bring it out of the 21 mbr +1 or -1 ??

hope some one can help clear my head...cheers!

 

[Toddyplumb]

If you have more than 1 mBar drop on your pipework then your pipework is out of spec.
Have a search on here there are quite a few threads on inlet pressures to zero governors

 

[ljrgas]

you cannot take burner pressure from boilers with zero governors
you are allow 1 mb drop from meter to appliance with appliances at full rate.
however im pretty sure that as long as the applainces are working correct as per mi's
undersized pipework is ntcs (correct me if im wrong)

 

[diamondgas]

Hi gary50,

-There are still sight glass's fitted to modern condensers but yeh, in general you don't get to see the flame from the customers view point.
-"Burner pressure" is still important on zero compensating gas valves. Zero is still a pressure they need to achieve. However it is important to check the supply pressure.
- ljrgas is correct regards more than 1mbar drop being NTC. However on a new or replacement installation you HAVE to install as per current standards and more than 1mbar drop doesn't wash with Gas Safe Inspectors (As I found out to my cost)

Hope this has been of some help

 

[GQuigley67]

although with new boilers you do loss alot of pressure in the gas valve, so if it is say 17.5mb then it should be fine as there would be about 2.5mb lost in the gas valve itself. Some people fit test points before the boiler to confirm that they have 20mb to the appliance.

 

[bobgarden]

although with new boilers you do loss alot of pressure in the gas valve, so if it is say 17.5mb then it should be fine as there would be about 2.5mb lost in the gas valve itself. Some people fit test points before the boiler to confirm that they have 20mb to the appliance.

Damn expensive tho for a simple test point. Anyone got anything they use to check?

 

[Billy Bob Bob]

would i be right to say its just the older boilers eg. ones with piolit lights where you see the flame and non- condenser's where you have to do the burner pressure?

would i then be correct in saying all new boilers condensing combis etc....have zero governors and therefore you cant take burner pressure just inlet pressure.

also the regs state 1mbr drop alowed in pressure between meter and appliance but some boiler m.i state a inlet pressure of as low as 17mbr is allowed which would surley bring it out of the 21 mbr +1 or -1 ??

hope some one can help clear my head...cheers!

your right regarding band a take a fga/gasrate reading,regarding band b burner pressures/gasrate
regarding pipework,more than 1 mb drop its ncs,mi,s may ask for 17mb inlet but if that boilers going full rate to dhw what happens to the gas hob with no ffd?always design pipework to 20mb inlet on all appliances with them all running

 

[GQuigley67]

Damn expensive tho for a simple test point. Anyone got anything they use to check?

a couple of £ for a brass isolation valve with a test point on it ?

 

[bobgarden]

a couple of £ for a brass isolation valve with a test point on it ?

Got a link mate.

 

[Toddyplumb]

BES for test points

 

[bobgarden]

local merchants wanted £15 each.

found this place doing them at less than £5 ea, anyone used this firm before?
Gas Testpoint Ball Valve | 15mm x 15mm Compression | LPG and Natural Gas

 

[BLOD]

I've bought stuff from Hamilton gas products before and found the goods were good quality and the delivery was quick.
(i'm nothing to do with them by the way).

 

[yo1]

Why not check the inlet at the inlet test point on the gas valve?

 

[Blackcatgas]

Why not check the inlet at the inlet test point on the gas valve?

You can lose 3mb across the valve between where the pipe enters the valve and the test point (worcester Bosch have admitted this themselves and as such aloow for a lower "inlet" pressure.

 

[capitanpugwash]

local merchants wanted £15 each.

found this place doing them at less than £5 ea, anyone used this firm before?
Gas Testpoint Ball Valve | 15mm x 15mm Compression | LPG and Natural Gas

Hi bobgarden

Just got my FGA off them and they were about the cheapest including delivery. Very fast delivery and good packaging. I think they are based in N.Ireland as they have a 028 phone number....

HTHs

 

[Pluk]

Zero governors are not the only gas valves fitted in condensing boilers . Just fitted Baxi duo tec condensing boilers . They gave an operating mlb and a burner mlb . Did check burner presure on Baxi only to see if they were all running the same or because of modulating gas valve average presure . Contract was more concerned on meter to boiler drop . At meter 21mlb and to boiler plus or minus 2mlb . Also in manual it says no need to analyze boiler because factory set . I checked them to be on safe side and found most of them were out . They needed to be minimum of 9.4 co2 and max 9.7 co2 . At to set them because they were running at 11.4 co2 . Manual not alway correct so please check . Any way to clear things up and hope this is correct ? I believe most modulating gas valve are designed for similar uses . The difference is there is a Venturi fitted in them which mixes the air/gas ratio . Not exactly sure but it depends on where the Venturi is fitted in gas valve . If fitted before the burner testing point you will get a reading . If fitted after the burner test point you will get a zero reading . Or visa versa . Hope this is right ?