Old Boiler, Combustion and Co2

debbyg

Hi All, I have a Burham boiler that I'm estimating to be from the mid 80's. Up to this point, with maintenance it has worked well. I had it cleaned and at the end of the appt, the tech checked the CO2 reading and he got 7ppm and told me he needed to turn off the boiler and recommended we replace it.

I had another tech from a different company come out today, his first concern was the need for fresh air in order for proper combustion to occur, and he said it is important to keep the small vented window in the enclosed boiler room open, so that the needed air wasn't being drawn from the room, but instead was being drawn from the outside.
This made sense to me, with the limited amount of knowledge I have about combustion. When he took the CO2 reading with the window open it sat between 0-1ppm. He also stated that older boilers may emit a small amount of CO2 over time, due to age.

When I called the first company back and told them the reading was 0-1, they stated it was only because the window was open, bringing the fresh air in, and if we closed the window, the Co2 level would most likely return to 7 or above.

The boiler is located in an enclosed 5 x 10 closet along with a water heater

So here lies my dilemma and questions-
+Is the fresh air from the window required for proper combustion?
+Is the fresh air from the window somehow masking a higher level of Co2?
+Is an older unit with a CO2 reading of 1ppm safe or should it be replaced?

I appreciate your opinions and knowledge!

Thanks, Debby

STEVEusaPA

Let's get the nomenclature correct. CO2 is a percentage measurement of Carbon Dioxide and CO is a PPM measurement of Carbon Monoxide. I'm assuming you mean CO.

Your first tech is not a professional technician, just a hack salesman. Same goes for his company.

If he's reading 7ppm CO in the flue you're fine. In fact with proper combustion you could read 0. I'd like to see the rest of the combustion numbers.

Now if he's reading 7ppm in the room, now you need to investigate.

If it's a boiler, then some of the reasons for high CO are poor combustion, not properly cleaned, blocked flue pipe, leaking door/burner gaskets.

debbyg said:

I had it cleaned and at the end of the appt, the tech checked the CO2 reading and he got 7ppm and told me he needed to turn off the boiler and recommended we replace it.

Crap

debbyg said:

I had another tech from a different company come out today, his first concern was the need for fresh air in order for proper combustion to occur, and he said it is important to keep the small vented window in the enclosed boiler room open, so that the needed air wasn't being drawn from the room, but instead was being drawn from the outside... When he took the CO2 reading with the window open it sat between 0-1ppm. He also stated that older boilers may emit a small amount of CO2 over time, due to age.

Again, are we talking about CO or CO2? At least tech #2 is thinking. Never heard of older boilers emitting small amounts of CO (sic) over time, due to age. I've heard of combustion getting a little less efficient.

debbyg said:

When I called the first company back and told them the reading was 0-1, they stated it was only because the window was open, bringing the fresh air in, and if we closed the window, the Co2 level would most likely return to 7 or above.

More crap. Tell them to come out and prove it.

debbyg said:

So here lies my dilemma and questions-
+Is the fresh air from the window required for proper combustion?
+Is the fresh air from the window somehow masking a higher level of Co2?
+Is an older unit with a CO2 reading of 1ppm safe or should it be replaced?

1. Yes. Proper amount of air is needed for combustion. This is known by doing a little math regarding the firing rate of the boiler, and the cubic feet of the room (the available amount of air for combustion). If it's not enough, then you would need to introduce more air for combustion. Also, if your boiler is in the same area as a high efficiency dryer, that dryer is sucking all the combustion air out of the house (let alone the room).
2. No, again CO, not CO2 However, if the room were running out of combustion air as the boiler was firing, then yes, CO could rise. But unless you're in a very small room, you wouldn't notice it in 10 minutes. Or, like I said above, a dryer or even an exhaust fan can change the pressure of the room, affecting combustion and draft.

So to sum up, determine the amount of combustion air needed, including factors for infiltration, exhaust fans & vented clothes dryers.
If it's not enough, opening a window would help, but bringing combustion air right to the burner would be best.

debbyg

Hi Steve, Thank you for replying- Also-Thank you for the clarification, we are talking about Carbon Monoxide/CO

The 7ppm reading was taken in the closet that the boiler and water heater are enclosed. It was not taken in the flue but within a foot of the flue. At the time it was taken the window venting the closet was closed. The only air was from the surrounding room.

When the 0ppm reading was taken today, it was taken approximately the same distance as the tech yesterday, but the window venting the closet was open.

I will have to calculate if the closet is providing enough air for proper combustion.

NY_Rob

Sounds like it's time to invest in a decent CO tester & meter and investigate the potentially dangerous situation yourself...

https://www.amazon.com/Tough-Waterproof-Made-USA-Monitoring/dp/B004YUEPBW/ref=sr_1_8?ie=UTF8&qid=1508977872&sr=8-8&keywords=sensorcon+inspector

debbyg

You read my mind Rob, that's exactly what I did today.

captainco

Combustion air is measured by measuring draft. You can't pull air out if there is no air to pull in. Just having openings does not guarantee combustion air is getting to the equipment. However oil burner have a fan a suck plenty of combustion air.
If there is CO in the closest it might mean the flue or sections are restricted but then you would probably have a smoke smell. Some hand held CO detectors are heat sensitive and will read CO just because of heat and shouldn't be used near a heat source.
It is always better to check around and in the equipment with a combustion analyzer. These are used by professionals. Hacks don't use them!!!

NY_Rob

debbyg said:

You read my mind Rob, that's exactly what I did today.

That particular CO meter helped to pinpoint a CO leak originating from the back of my 1960's era boiler.
After a long call for heat (usually at the 6am t-stat morning activation)- my basement would read in the 12-15ppm CO range. I took the Sensorcon and orbited it around the boiler- keeping it about 6" away from the metal surfaces at all times. Near the back side of the boiler the readings jumped up to 60-70ppm and when I finally zeroed in on the point of the co leak (turned out to be a 2" length of deteriorated gasket between boiler sections) the reading spiked to 325ppm! Luckily, the leak was directly below the draft hood, so the majority of the CO was getting pulled up and into the draft hood into the flue pipe.

FWIW- I leave the Sensorcon on 24/7/365 now since we have a gas oven and even though our new mod-con boiler is direct vented, it makes me feel safer just knowing the meter is there (along with several CO detectors scattered around the house) just to keep an eye on CO levels.

Good luck with the investigation!

captainco

There is no way a gasket leak will produce 325ppm of CO. However, a boiler not venting properly will cause a gasket leak from stress and heat. I am betting that a combustion test on your boiler would have shown CO in the thousands of ppm range. Hopefully repairing the gasket was not the only repair.

NY_Rob

^ Thanks Cap...

That 325ppm reading happened when I placed the sensor of the Sensorcon right up to the leak area on the boiler... I guess I was just hitting the CO "stream"... as soon as I moved it a few inches away the reading went down to 60ppm or lower.

There could have been other leaks too, but when I dismantled the old boiler sections before the mod-con install I took note of the gaskets (still about 1/8" thick after 50yrs in service) and there was a 2"+ section where the gasket was completely missing.

captainco

My question is why was the boiler making 325 ppm of CO in the first place? Not from a gasket leak.

Jamie Hall

@captainco knows his marbles very well -- pay attention! To put it another way, however, a boiler which is properly fired -- correct air/fuel ratio, correct draught, all that -- shouldn't be producing anywhere near that level of CO. Something is wrong with the combustion setup.

EBEBRATT-Ed

With a 5 x 10 boiler room with a water heater and a boiler and no combustion air opening, window and door closed equipment operating I would be surprised if you could get 0 Co ppm in the boiler room outside the flue

You will positively have Co in that room with no make up air. Equipment running will pull the room into a minus condition until one of the flues starts to backdraft.

Best bet to keep from freezing the room is a small permanant opening sized for just the water heater. An additional opening with a damper with an actuator with an end switch wired to the boiler

debbyg

Thanks to everyone for the suggestions/opinions, much appreciated!