Does burner pressure equal heat input

[fusion]

Hi, I am doing my ACS and just want to understand something more clearly.
- I have a Baxi solo 2 40 PF.
- M.I's state max heat input 14.65 kw and min heat input 11.36 kw.
- Max burner pressure 16mbar and min 10mbar

My question is if the recorded burner pressure was at the lowest eg. 10 mbar would the gas rate when taken equal the min heat input of 11.36 kw. And if one where to increase the burner pressure to 16 mbar, would the heat input when taking the gas rate be equal to 14.65 kw. (Assuming that the injectors where correctly sized and clean.)
In other words does the set burner pressure correlate to a specific heat input in KW?

 

[stevetheplumber]

Hi, I am doing my ACS and just want to understand something more clearly.
- I have a Baxi solo 2 40 PF.
- M.I's state max heat input 14.65 kw and min heat input 11.36 kw.
- Max burner pressure 16mbar and min 10mbar

My question is if the recorded burner pressure was at the lowest eg. 10 mbar would the gas rate when taken equal the min heat input of 11.36 kw. And if one where to increase the burner pressure to 16 mbar, would the heat input when taking the gas rate be equal to 14.65 kw. (Assuming that the injectors where correctly sized and clean.)
In other words does the set burner pressure correlate to a specific heat input in KW?

Yes in this scenario the burner preasure is linked to the heat output this is a range rated boiler the same applies to modulating boilers where the burner preasure is modulated to match demand automaticly. However a different boiler could have the same burner preasure and give a different output due to the burner design so there is no definate link between BP and out put
gas rate however is applicable to any burner/ appliance if its getting a set amount of gas it will produce the same heat hope this makes sense

 

[fusion]

Thank you for your reply!

 

[kirkgas]

the relationship between them SHOULD work like that, but a good thing to look out for is to measure burner pressure AND calculate/check heat input to confirm the burner is clean and burning the correct amount of gas to supply the correct heat, imagine a set up where you measure burner pressure and it is perfect, BUT the customer complains the house is colder than it used to be, why? the clue is the appliance is say 5 years old and has never caused any bother (therefore has never been looked at in 5 years)

 

[dboi78]

could u have a scenario where gas rate is high but burner pressure correct, assuming u tightness tested and their is no leaks ?

 

[diamondgas]

could u have a scenario where gas rate is high but burner pressure correct, assuming u tightness tested and their is no leaks ?

Yep this'll happen when you have an enlarged injector...

 

[fuzzy]

could u have a scenario where gas rate is high but burner pressure correct, assuming u tightness tested and their is no leaks ?

yes, this would indicate a problem. Incorrect injector size or similar

 

[GrahamM]

As mentioned an incorrect injector size will give you incorrect burner pressure vs gas rate readings.
A not too uncommon scenario is where a boiler is interchangeable between NG and LPG and the injector has not been changed for the correct fuel.

 

[kirkgas]

i cant believe the amount of guys who will do a burner pressure test but not a gas rate which is mental, one without the other is only half a job, i often ask "if the burner pressure is supposed to be 17mb, and when you check it you find it is 17mb, but why does the fire not supply as much heat as it used to" the amount of guys who simply dont equate this to a fire needing its injector and/or burner cleaned is staggering, and on the flip side, if you check burner pressure and gas rate and find both to be spot on you dont need to strip and clean the injector or burner as they both must be clean, but some guys simply dont know how to do the job properly and always say they only gas rate every 5 years at ACS

 

[GrahamM]

Lack of understanding, complacency and laziness. Take your pick!

As per section 26 GSIUR:
(9) Where a person performs work on a gas appliance he shall immediately thereafter examine -
(c) its operating pressure or heat input or, where necessary, both;

If you want to confirm correct operation of an appliance, where possible you should always be carrying out a Burner Pressure & Gas Rate.
A lot of BG guys in particular, do not realize this. They are only concerned with one or the other.

 

[stevetheplumber]

Lack of understanding, complacency and laziness. Take your pick!

As per section 26 GSIUR:
(9) Where a person performs work on a gas appliance he shall immediately thereafter examine -
(c) its operating pressure or heat input or, where necessary, both;

If you want to confirm correct operation of an appliance, where possible you should always be carrying out a Burner Pressure & Gas Rate.
A lot of BG guys in particular, do not realize this. They are only concerned with one or the other.

thats what bg insruct them to do burner preasure if possible if not gas rate im sure there legal dept has worked out the minimum requirements
if they do a burner preasurs they have to do it at full rate then reset to original position if the boiler doesnt make full rate its AR now not NCS