Photo Cell lasted only 3 weeks

Wearb

I replaced a photocell in an ENVIROMAX C44 three weeks ago due to an intermittent not firing problem, but motor running continuously. The photo cell has given up the ghost again. Is this unusual? What might be the reason for this?
I attach FGA details of the same burner that I measured after replacing the last photocell. Everything seems OK there, seeing as it is due its annual service in April.

Dtp79

Wearb wrote: »

I replaced a photocell in an ENVIROMAX C44 three weeks ago due to an intermittent not firing problem, but motor running continuously. The photo cell has given up the ghost again. Is this unusual? What might be the reason for this?
I attach FGA details of the same burner that I measured after replacing the last photocell. Everything seems OK there, seeing as it is due its annual service in April.

Them boilers have issues with sooting and overheating due to the fact the heat has to go down before it can go up. I've seen baffles destroyed and the condensate trap melted a few times. Maybe this killed your photocell

Wearb

Just popped home after having a look at it (I need to collect a control box). I jumped to the wrong conclusion about the photo cell, seeing as the symptoms were exactly the same as last time. I now think its the control box. No power being given to solenoid even after changing the photo cell. Will keep you updated.

Wearb

New control box did the trick. Seems tough on the owner to have both cell and control box go within the same month.

Them boilers have issues with sooting and overheating due to the fact the heat has to go down before it can go up. I've seen baffles destroyed and the condensate trap melted a few times. Maybe this killed your photocell

I did notice signs of heat on the service cover. I will investigate further on the next service. But as you mention, it might be an inherent problem with this upside-down boiler.

shane0007

Wearb wrote: »

I replaced a photocell in an ENVIROMAX C44 three weeks ago due to an intermittent not firing problem, but motor running continuously. The photo cell has given up the ghost again. Is this unusual? What might be the reason for this?
I attach FGA details of the same burner that I measured after replacing the last photocell. Everything seems OK there, seeing as it is due its annual service in April.

CO2 is way too high for this boiler. Bring it down to 11.2.
Also drop the nozzle size down to a 1.10 & increase the pump pressure to 8.0 bar or just above.

Wearb

shane0007 wrote: »

CO2 is way too high for this boiler. Bring it down to 11.2.
Also drop the nozzle size down to a 1.10 & increase the pump pressure to 8.0 bar or just above.

Shane, your reply prompted me to look over my records for this burner. I attach image the boiler plate which I now find confusing. It says C44 but the 26kw box is ticked. The manual lists 35 to 44kw firing range for the C44 any thoughts on this.

shane0007

Wearb wrote: »

Shane, your reply prompted me to look over my records for this burner. I attach image the boiler plate which I now find confusing. It says C44 but the 26kw box is ticked. The manual lists 35 to 44kw firing range for the C44 any thoughts on this.

Which RDB is on it?
What was the nozzle size in the burner?
The CO2 will be the same for both but obviously nozzle & pressure will be different if boiler is a C26.
The printed documentation on the boiler is C44. Handwritten tick is human so most likely human error.
How big is the house?

Dtp79

shane0007 wrote: »

CO2 is way too high for this boiler. Bring it down to 11.2.
Also drop the nozzle size down to a 1.10 & increase the pump pressure to 8.0 bar or just above.

Not questioning your knowledge Shane but it says CO2 in manual to be 12 per cent @ 8.5 bar. Now I know this is from the same crowd who can't diagnose their own faults on the upside down boiler!! Is reducing the nozzle size the key?

Wearb

RDB 2.2 Firebird C26 90K
I haven't serviced it yet. I was not the last person to service it. I don't know the size of the existing nozzle. I have the job of the next service in April. So far I have just been to 2 breakdowns on it. I took some photos on the first breakdown and did a FGA test after replacing the photocell to to check that it was working close to recommended parameters. Recommended CO2 for all of those is 12%
Pump pressure is about 9 bar I think. I did a pressure check on it at intermittent first breakdown to make sure pump was working OK.
Way over sized for the house. It is a bungalow of about 2000 to 2500 sq ft with one third let as a flat and this is supplying the flat. Sime boiler supplying the rest. I didn't fit either. Says done this way as future plans are (whenever flat end not needed to be rented) to have the Firebird heat the whole house.

shane0007

Dtp79 wrote: »

Not questioning your knowledge Shane

Why not? You are perfectly entitled to question me or anybody else. I am not some higher force, so question away!

The reason manuals state 12% is for efficiency purposes. Their boilers get a higher SEDBUK rating.
I will try to explain. Look at excess air. On average at 11.5% CO2, excess air will be circa 35%. Sounds at lot but XS air is 100% air but only useful 21% oxygen. So really that 35% XS air is only 7% spare O2. Reduce that XS to say 20%, then O2 is now 4%. Depending on the day you commission the burner, it could be a nice high pressure day. Easy to for the burner to burn. But tomorrow is a heavy low pressure day. Burner struggles to grab that O2.
I can run that boiler at a perfect burn with zero XS air so the efficiency is at its most. This would have a CO2 of well over 13%. This would be stupid because weather pressures fluctuate as does the ability to extract that all important O2.
The upside down burner creates a poor throughput within the combustion chamber. Outside air pressure becomes greater than with the flue & the result is a sooty boiler. Bring the CO2 down to 11.2% with this particular boiler reduces this risks. Lowering the nozzle size to allow a higher pump pressure will increase the throughput without lowering the kw output of the boiler.

@Wearb: if the burner is that, then it is a C26 and the printed material is incorrect. Bold FB! It will have a 0.65 80ES nozzle set to 9.0 bar pressure. Drop to a 0.55 80ES and increase to 9.5 pressure.
Tip: I would not be sticking my analyiser into an unserviced boiler, smoke tested or not!

jimf

so if called to commission a c26 from new shane would you recommend dropping nozzle size

increase pressure .5 bar approx

fga to 11.2 co2


i have used your advise above and cured a particular problem boiler where 2 others failed i was as proud as ****e if only they knew where i found out

shane0007

jimf wrote: »

so if called to commission a c26 from new shane would you recommend dropping nozzle size

increase pressure .5 bar approx

fga to 11.2 co2

Yes if you do not want to be called back until it is due its first service.

jimf wrote: »

i have used your advise above and cured a particular problem boiler where 2 others failed i was as proud as ****e if only they knew where i found out

I am afraid as I have said before, I cannot take credit for that knowledge. I learned it from DGOBS, a far higher force than I. For me, that is what this forum is about, helping others that care!

Wearb

shane0007 wrote: »

Why not? You are perfectly entitled to question me or anybody else. I am not some higher force, so question away!

The reason manuals state 12% is for efficiency purposes. Their boilers get a higher SEDBUK rating.
I will try to explain. Look at excess air. On average at 11.5% CO2, excess air will be circa 35%. Sounds at lot but XS air is 100% air but only useful 21% oxygen. So really that 35% XS air is only 7% spare O2. Reduce that XS to say 20%, then O2 is now 4%. Depending on the day you commission the burner, it could be a nice high pressure day. Easy to for the burner to burn. But tomorrow is a heavy low pressure day. Burner struggles to grab that O2.
I can run that boiler at a perfect burn with zero XS air so the efficiency is at its most. This would have a CO2 of well over 13%. This would be stupid because weather pressures fluctuate as does the ability to extract that all important O2.
The upside down burner creates a poor throughout within the combustion chamber. Outside air pressure becomes greater than with the flue & the result is a sooty boiler. Bring the CO2 down to 11.2% with this particular boiler reduces this risks. Lowering the nozzle size to allow a higher pump pressure will increase the throughput without lowering the kw output of the boiler.

@Wearb: if the burner is that, then it is a C26 and the printed material is incorrect. Bold FB! It will have a 0.65 80ES nozzle set to 9.0 bar pressure. Drop to a 0.55 80ES and increase to 9.5 pressure.
Tip: I would not be sticking my analyiser into an unserviced boiler, smoke tested or not!

He only wanted to get it going and not serviced until April. I only did the analyser test to check that there were not any dangerous emissions. What is the danger to the analyser using it after a smoke test?

re: your co2 explanation; here are some notes I took off somewhere:

=== 1% in rise in Co2 as the
ambient temperature rises
by 20°.
Therefore:
In the cold of Winter aim for
lower Co2%. Perhaps -0.5% if temp lower than zero.
In warmer times of the Year set
the Co2 higher.Co2% Perhaps +0.5% If temp 20C or there abouts. ====

Cant find my corrections for pressure and altitude changes, though in a country with relatively small variations in altitude, I dont think it needs to be taken into account for domestic burners.

btw Shane, thanks for the tips on tuning the Upside-down boiler.

jimf

well thanks to dgobs and yourself for sharing this knowledge with us

its great to have somewhere to go to get this type of info i know i have got at least 3 services from the recommendation of this particular customer

Wearb

Just been looking at the manual and I see that I can identify the boilers potential output from measurements. There is a difference in size between the C26 and C44. I guess that it is a C26 from what Shane said after reading the size of the burner, but can confirm it at service time.

shane0007

Wearb wrote: »

He only wanted to get it going and not serviced until April. I only did the analyser test to check that there were not any dangerous emissions. What is the danger to the analyser using it after a smoke test?

Boiler could be over-aired & therefore high CO. A high CO hit to your analyiser will damage or shorten the life of its CO cell, thus costing you money. An over-aired boiler will have clean POC's.
A dirty boiler will most likely have a dirty flue. The smoke pump may not disturb this soot but the analyiser probe being longer may disturb it unknowingly.

Probably fine, it's just OCD I have. If I am there, why not. If only a couple of months since its last service, I would at least open up the combustion chamber to inspect it. It can tell a lot about whether the issue is combustion based or flue based.

jimf

im not 100% sure but have i seen the rating marked on the baffles ??????

JohnnieK

The flue way's at the back of that boiler are a joke, I've said it a thousand times you just wouldn't get that with a grant:)

shane0007

TBH you will know the minute you see the boiler. There is a huge difference in their sizes.

TPM

shane0007 wrote: »

Tip: I would not be sticking my analyiser into an unserviced boiler, smoke tested or not!

I made this mistake once, two weeks after the analyser was serviced and new sensor fitted, lets just say I wont be doing it again.

Wearb

shane0007 wrote: »

Boiler could be over-aired & therefore high CO. A high CO hit to your analyiser will damage or shorten the life of its CO cell, thus costing you money. An over-aired boiler will have clean POC's.
A dirty boiler will most likely have a dirty flue. The smoke pump may not disturb this soot but the analyiser probe being longer may disturb it unknowingly.

Probably fine, it's just OCD I have. If I am there, why not. If only a couple of months since its last service, I would at least open up the combustion chamber to inspect it. It can tell a lot about whether the issue is combustion based or flue based.

Did have a look at the air settings before using the smoke pump and analyser. I would prefer to damage a cell in my FGA than walk away from a boiler producing high CO. Perhaps I am being too mean in not wanting to give a full service when the customer only wants the burner put back in working order.
Thank you all for going to the trouble of explaining all of those issues to me. I may have to rethink my ideas about breakdowns. It would not be the first time that my reluctance to do a service ON THE CHEAP prolonged my fault diagnosis.

shane0007

Wearb wrote: »

Did have a look at the air settings before using the smoke pump and analyser. I would prefer to damage a cell in my FGA than walk away from a boiler producing high CO.

The air setting on the burner will give you no accurate measure of how the burner is running. A HE Warmflow will have air usually turned nearly to nothing but a Vortex will be around 3. An Environmax could be anywhere!
Damaging a cell is an expensive lesson & you most definitely will only do it once.
It usually only takes a couple of minutes to remove 4 x 13mm nuts to have a gander in the combustion chamber. If it needs a service, I am sure most homeowners would prefer to have the boiler running at its most efficient rather than losing approx 10% efficiency for every coupe of mm's of soot in the boiler.

Wearb

shane0007 wrote: »

The air setting on the burner will give you no accurate measure of how the burner is running. A HE Warmflow will have air usually turned nearly to nothing but a Vortex will be around 3. An Environmax could be anywhere!
Damaging a cell is an expensive lesson & you most definitely will only do it once.
It usually only takes a couple of minutes to remove 4 x 13mm nuts to have a gander in the combustion chamber. If it needs a service, I am sure most homeowners would prefer to have the boiler running at its most efficient rather than losing approx 10% efficiency for every coupe of mm's of soot in the boiler.

I did, during first call see the combustion chamber and blast tube and saw no signs of sooting. So perhaps I wrongly assumed that it was previously running running OK

But I will remember your advice. I don't want to have to send back my FGA until next year. Thank you all for your advice and help.

corkgsxr

TPM wrote: »

I made this mistake once, two weeks after the analyser was serviced and new sensor fitted, lets just say I wont be doing it again.

expensive enough to do it every year.

calibrated every second year

cell every other year

works out not far off 200 a year to keep the feckers going

agusta

shane0007 wrote: »

Boiler could be over-aired & therefore high CO. A high CO hit to your analyiser will damage or shorten the life of its CO cell, thus costing you money. An over-aired boiler will have clean POC's.
A dirty boiler will most likely have a dirty flue. The smoke pump may not disturb this soot but the analyiser probe being longer may disturb it unknowingly.

Probably fine, it's just OCD I have. If I am there, why not. If only a couple of months since its last service, I would at least open up the combustion chamber to inspect it. It can tell a lot about whether the issue is combustion based or flue based.

Shane,how would i know if a boiler is over-aired before i put my analyser in the flue.I have done a boiler before and it had a zero smoke reading with the smoke pump.I then put in my anton analyser and got very high co,i was just lucky i spotted the co rising rapidly.the boiler was severly over-aired.thanks

shane0007

agusta wrote: »

Shane,how would i know if a boiler is over-aired before i put my analyser in the flue.I have done a boiler before and it had a zero smoke reading with the smoke pump.I then put in my anton analyser and got very high co,i was just lucky i spotted the co rising rapidly.the boiler was severly over-aired.thanks

Obviously you must put the analyiser in at some stage otherwise if you could see that the boiler is set up with the correct fuel to air ratio, then we would not require an analyiser! I just prefer not to put it into a boiler without doing a few simple checks first if not servicing it. At least then, I am limiting the chances of costing me money.

Wearb

agusta wrote: »

Shane,how would i know if a boiler is over-aired before i put my analyser in the flue.I have done a boiler before and it had a zero smoke reading with the smoke pump.I then put in my anton analyser and got very high co,i was just lucky i spotted the co rising rapidly.the boiler was severly over-aired.thanks

Perhaps when you get a reading of zero (you dont know how far beyound zero it has gone) on the smoke pump, you could try restricting the air a little until you get a reading of one or two on the Bacharach scale and then re adjust for a reading of between 0 and 1. That way you will know that it is not way over aired. Then you can start using your analyser.
Perhaps some of the more experienced guys can confirm or contradict this.

agusta

thanks