burner pressure probs

[dwb78]

hi guys, right here it is.. i serviced a water heater the other day which turned out to be a vokera flow master or somethin, thing is i had been called out to fix a prob wit this that had been ongoing for ages and nobody seemed to b able to fix it, it kept cutting out very regular, so i stripped it down and found sulphtes in the pilot pipe and cured the problem that plagued it for so long,, but thing is for the hell of me i couldn get the burner pressure up to 10.5 it just wouldn go any higher than 7. any 1 any ideas i do believe that the heater is quite old. but the inlet pressure was spot on for ng.. just want to hear some ideas please

 

[kirkgas]

if you serviced then repaired you would have gas rated, so did the gas rate equal the HI, i have seen the test point section partially blocked which effects what is being recorded at the last 1" of the test pipe not actually what is being burnt but as i gas rated and found it spot on i knew what was going on

 

[marfyboy]

to start if you could not get the burner pressure to Manufactures instrutructions of 10.5 mb i would class it as AR incomplete combustion? and shut off .is the gas pipe big enough or gas valve u/s?

 

[tamz]

As long as it meets the manufacturers minimum specified burner pressure or input rating it should be classified as NCS.

Unless it effects the flame stability or combustion when AR

 

[marfyboy]

As long as it meets the manufacturers minimum specified burner pressure or input rating it should be classified as NCS.

Unless it effects the flame stability or combustion when AR

also true 🙂
unless we are on site avin a look belts and braces every time

 

[buckley plumb]

i questioned one like this and it is not clear in the gas safe book when they say manufacturers min gas rate they mean 5% of the max normal gas rate not as some think(includibg me before i phoned gas safe) how its worded gives the impression they mean the minimum gas rate a range rated boiler can be set at or modulates down too.but when you sate minimum burner pressure do you mean the burner pressure stated by the manufacturer as they dont normaly give a range they just normaly state the what the pressure should be.i find this area very grey myself can anyone put it clear in my mind for once and all

thanks ant

 

[GrahamM]

i questioned one like this and it is not clear in the gas safe book when they say manufacturers min gas rate they mean 5% of the max normal gas rate not as some think(includibg me before i phoned gas safe) how its worded gives the impression they mean the minimum gas rate a range rated boiler can be set at or modulates down too.but when you sate minimum burner pressure do you mean the burner pressure stated by the manufacturer as they dont normaly give a range they just normaly state the what the pressure should be.i find this area very grey myself can anyone put it clear in my mind for once and all

thanks ant

If it’s a spot rated appliance then the Manufacturer will normally recommend a burner pressure which is normally the nominal burner pressure the appliance has been designed to operate at. If the manufacturer specifies max. 10.1mbar then in practice set it to 10.0mbar and if it is modulating you will have set the low fire pressure independently. If you were to set the nominal pressure to the low fire pressure the boiler would never reach the correct high fire temp. as it was designed for as you will have restricted it. It will never hit its optimum temp. and will give little heat.

If it is a range rated appliance such as a Bermuda back boiler the Manufacturer will specify a burner pressure range for you to set taking the installation conditions into account. In normal practice this is set to the middle range.


A system should never be installed so as it will only ever meet it's minimum settings. It should be installed so as to reach it's design parameters and if required may then be turned down to mid setting if required.