M
migoplumber
sorry about the wait for my epic story, didnt realise you get timed out in the writing something section. wrote this earlier so hopefully copy and paste.
Be nice and gentle with me boys, this is how i do it, and how i interprete my results.
ime a commercial guy, and things are a little different but have the same end result.
first thing you must do is know what to expect in your flue gas analysis. the only way to do this is consult the manufacturers instructions.
if you dont know the exact type of boiler you are playing with, then you may as well stay at home and thumb twiddle.
one really annoying thing with the fga is boiler hitting temp and cutting out, be aware of this. try to turn off boiler/s for an hour before you get started.
perfect time for visual checks and basic servicing.
if you know the boiler, and are pretty sure its not been touched by anyone else life is simpler,
if not first thing to do is gas rate appliance, and watch it work for a while. most of my boilers are looked after by me so i have a fairly easy life.
turn on boiler and high fire for 10 mins to get flue temp up.
locate your analyser point and stick probe in hole.
some manufacturers specify the depth of probe insertion - most do not.
first thing i watch for is the co reading. if its rising rapidly at a rate that i know is gonna go high i take probe out and check gas rates and burner pressure/fan assembly (with zero governors)
hate getting more than 2 cells a year for analyser !
remember co levels over 200 ppm the instalation is ID and should be capped. always cap before informing client is my attitude - but technically not correct, you are a proffesional, you should be able
to locate problem before it comes to this.
next ime looking for the specified co2/o2 levels always found in the MI.
most manufacturers i know specify the co2 levels, for me typically around 9%, the broagg manufacturers for example specify o2 to typically 5.4%
now i make small adjustments on the gas valve generally, to obtain this target figure.
a quarter turn is the most i do at one time and wait for 30 seconds for flue to stabilise before i look at readings. NB you will always turn the adjustment screw in the wrong direction first time
thats life.
after a few adjustments your co2/o2 levels will be as per manufacturers instructions. if you are unable to obtain these numbers, proceed to a full strip down service continuing.
next i look at flue temperature, if the reading is above what i am expecting, i would like at flue issues, primarily lack of flow, i always start with termination and work my way backwards.
depending on system could be an issue with the fan, and sometime but not often ventilation.
the last number that i use is the ratio. this is the money earner number ! the cpa1 course shows these numbers and what to do with them, but as a general rule of thumb ( which dosnt exist in gas )
always consult the MI numbers. less than 0.004 means you have a heat exchanger issue. this will require strip down clean, possibly acid bath. a real in depth service. if the number is close to that
then advise the customer because they may wish to wait till next year ( or get somebody else in who hopefully wont notice is what they mean ) but generally ime advised to do what is neccessary at the time.
thats how i interprete the figures that i get in most circumstances. the manufacturer is god and talking to them if you are unsure is vital.
another co note, i carry a portable co detector in plant rooms, better safe than sorry - nearly got me once and i learned my lesson.
most importantly, i do not consider sticking the fga in the hole a "service" or an "inspection" it just does not cut it. always at bare minimum take boiler casing off and visually inspect the thing
running the fga around the casing in room safety mode is a good detector for combustion leaks.
some boilers have a low/high fire system. some have a modulation system from 10% to 100% sometimes the co2/o2 requirements are different for high low fire. if you dont get them spot on for a
modulating boiler all the values from 0 to 90 % will be wrong and you are potentially killing your customer.
also the ignition or low fire co2 values are important for the correct start up of system combustion. incorrect co2 levels at start up can cause sooting of thermocouple/ionisation probes, leading to
unrecognised flame failure signals and lock out. which leads to call outs to non starting boilers. ( hate those ) , they can also cause poor flame with same results or worse explosive ignition
sounds horrible and scares customer !
there is nothing like being sat down in front of your boiler for 30 minutes before you start, watching the flame and listening to the boiler, this will tell you as much about the state of the thing
as the fga results.
good luck.
did a nice one today on a lovely wessex 250 stack, recorded it cos i could ! will post link youtube video as soon as i upload it !
shaun. x
Be nice and gentle with me boys, this is how i do it, and how i interprete my results.
ime a commercial guy, and things are a little different but have the same end result.
first thing you must do is know what to expect in your flue gas analysis. the only way to do this is consult the manufacturers instructions.
if you dont know the exact type of boiler you are playing with, then you may as well stay at home and thumb twiddle.
one really annoying thing with the fga is boiler hitting temp and cutting out, be aware of this. try to turn off boiler/s for an hour before you get started.
perfect time for visual checks and basic servicing.
if you know the boiler, and are pretty sure its not been touched by anyone else life is simpler,
if not first thing to do is gas rate appliance, and watch it work for a while. most of my boilers are looked after by me so i have a fairly easy life.
turn on boiler and high fire for 10 mins to get flue temp up.
locate your analyser point and stick probe in hole.
some manufacturers specify the depth of probe insertion - most do not.
first thing i watch for is the co reading. if its rising rapidly at a rate that i know is gonna go high i take probe out and check gas rates and burner pressure/fan assembly (with zero governors)
hate getting more than 2 cells a year for analyser !
remember co levels over 200 ppm the instalation is ID and should be capped. always cap before informing client is my attitude - but technically not correct, you are a proffesional, you should be able
to locate problem before it comes to this.
next ime looking for the specified co2/o2 levels always found in the MI.
most manufacturers i know specify the co2 levels, for me typically around 9%, the broagg manufacturers for example specify o2 to typically 5.4%
now i make small adjustments on the gas valve generally, to obtain this target figure.
a quarter turn is the most i do at one time and wait for 30 seconds for flue to stabilise before i look at readings. NB you will always turn the adjustment screw in the wrong direction first time
thats life.
after a few adjustments your co2/o2 levels will be as per manufacturers instructions. if you are unable to obtain these numbers, proceed to a full strip down service continuing.
next i look at flue temperature, if the reading is above what i am expecting, i would like at flue issues, primarily lack of flow, i always start with termination and work my way backwards.
depending on system could be an issue with the fan, and sometime but not often ventilation.
the last number that i use is the ratio. this is the money earner number ! the cpa1 course shows these numbers and what to do with them, but as a general rule of thumb ( which dosnt exist in gas )
always consult the MI numbers. less than 0.004 means you have a heat exchanger issue. this will require strip down clean, possibly acid bath. a real in depth service. if the number is close to that
then advise the customer because they may wish to wait till next year ( or get somebody else in who hopefully wont notice is what they mean ) but generally ime advised to do what is neccessary at the time.
thats how i interprete the figures that i get in most circumstances. the manufacturer is god and talking to them if you are unsure is vital.
another co note, i carry a portable co detector in plant rooms, better safe than sorry - nearly got me once and i learned my lesson.
most importantly, i do not consider sticking the fga in the hole a "service" or an "inspection" it just does not cut it. always at bare minimum take boiler casing off and visually inspect the thing
running the fga around the casing in room safety mode is a good detector for combustion leaks.
some boilers have a low/high fire system. some have a modulation system from 10% to 100% sometimes the co2/o2 requirements are different for high low fire. if you dont get them spot on for a
modulating boiler all the values from 0 to 90 % will be wrong and you are potentially killing your customer.
also the ignition or low fire co2 values are important for the correct start up of system combustion. incorrect co2 levels at start up can cause sooting of thermocouple/ionisation probes, leading to
unrecognised flame failure signals and lock out. which leads to call outs to non starting boilers. ( hate those ) , they can also cause poor flame with same results or worse explosive ignition
sounds horrible and scares customer !
there is nothing like being sat down in front of your boiler for 30 minutes before you start, watching the flame and listening to the boiler, this will tell you as much about the state of the thing
as the fga results.
good luck.
did a nice one today on a lovely wessex 250 stack, recorded it cos i could ! will post link youtube video as soon as i upload it !
shaun. x
...... just a correction needed matey ... "....