Safety concerns and replacement options for a 140 co ppm 35 year old boiler

tzuhsianglin0110

I am a new homeowner in Mass and inherited a 35 year old Burham low pressure boiler.

During my Mass save energy assessment, the co reading in the flute reached 140 co ppm, greater than the recommended 100 co ppm, and I was recommended to lower the reading for any mass save rebates such as insulation.

I have a few technicians/sales come over and provided me some opinions

1. The energy assessor mentioned that it is not leaking, so no need to over worry about it. We can have the boiler serviced to lower the co readings. After looking on the web saying CO readings could kill us, my wife and I installed co detectors and did not turn on the boiler.

2. Then I called in an HVAC technician on yelp. He took a look at the boiler and said there's nothing he can do. The heat exchanger looked clean. The boiler is simply old and not much parameters he can do. He also took measurements and the readings were at 400 co ppm in the flute. Later he texted me saying he discussed with a colleague and thinks that the heat exchanger must be broken due to the high readings.

3. We then called an HVAC sales guy for boiler replacement. Dude seemed knowledgeable and has been in the trade for long. He said the 100 co ppm rule came from Canada and applies to the newer models, while my old boiler since it was manufactured older, is simply not energy efficient. And a lot of the newer HVAC dudes started scarying older folks off their old boilers in cold winters while their boilers just worked fine. Told me to turn on the boiler since it wasn't leaking and I had co detectors around. Also checked the boiler and said it looked clean. Mentioned that some of the gas valves can be tuned to lower the co readings but might result in insufficient heating for the home.

I am at a dilemma here. The high co meter readings prevents my home from receiving mass save insulation rebates, since Mass save rebates are all tied to high efficiency initiatives. We live in our home and would like to get our attic insulated to reduce energy bills. At this moment, I am guessing the 400 co reading is due to us not turning on the boiler for a few days. By turning on boiler I meant turning on all thermostats in my home.

I live in a 2b 2.5b 3 level townhome. Since my water heater is 10 years old and AC is also 35 years old, I am considering the following options, ranked from cheapest to most expensive:
- 1) Do. nothing
- 2) Get the boiler serviced again to reduce co readings, then get insulation done.
- 3) Replace with another low efficiency gas boiler with low co.
- 4) Replace with a high-efficiency gas boiler.
- 5) Replace with a combi-boiler that also replaces my water heater.
- 6) Get a whole home heat pump to do both heating & cooling. There are heavy rebates on this, but online calculators say the electricity bill will be higher even than a 80% efficiency boiler. So I am less inclined towards this.

Is my current boiler safe? What are the usual recommendations in low efficiency vs high efficiency boilers with water heater in play? Thanks.

ethicalpaul

I'm not saying that a heat pump is what you should get but I saw a flaw in your thinking about their costs.

but electricity seem to cost more than gas no matter what. So I am less inclined towards this.

I'm not sure what you're basing this on, but a heat pump moves heat instead of creating it, so it is able to perform at the equivalent of 200% to 500%+ efficiency, which you can't get close to with gas.

There's a lot of math and variables and again, I am not saying you should get a heat pump, but you should understand a bit more about what "efficiency" means for each fuel type.

tzuhsianglin0110

Totally got you. I based my heat pump vs boiler calculation on this calculator: https://c03.apogee.net/mvc/home/hes/land/el?utilityname=eversource&spc=hcc.

After input the gas/electricty costs from my last bills, it says that newest electrical heat pump costs more than my existing 80% gas boiler in utility bills.

EBEBRATT-Ed

Some of the information you have been told is correct and some is incorrect.

CO readings in the flue are recommended to be "Less than 100PPM" is ok to run, less than 50 PPM is recommended.

Since you have a boiler the heat exchanger is not broken. If it was you would have water leaking out of it.

Also the boiler should be run at "steady state" meaning its all warmed up before readings are taken.

Put a cold pan of water on a gas stove burner and it will make CO until the water is warm.

Your are right to be concerned about the CO level but I would not panic about it. As the MA Save auditor told you it is apparently not leaking CO into the house it is going up the flue.


The tough part is finding a knowledgeable technician. It could be a little soot on the burners or a burner knocked out of alignment or a minor gas pressure adjustment could fix this issue. There is no way to know the answer until someone works on it.

Post your location in MA. Someone may have a recommendation for a service tech.

tzuhsianglin0110

Thank you! Your comments are educative and insightful!  

I live in Newton, MA.   If anyone knows of a good technician please let me know!   I also have a technician recommended by a colleague who will be coming over tomorrow morning who seem familiar to how mass save auditors raise high co ppm issues in people’s homes.  Will see how this goes… 

Derheatmeister

I would call NCI (National Comfort institute) to check who can help you in your area.
here is a link. https://nationalcomfortinstitute.com/

pedmec

What is the maximum allowable CO in flue gases?
400 ppm
The ANSI Z-21 maximum CO level is 400 ppm air-free. Oct 19, 2020

What does this mean? It means as long as your flue is drafting you are ok. you ain't violating any codes or in any danger. Key word is air free. Most techs don't use the air free number to determine actual CO levels but it is the most accurate depiction of CO in your flue gas.

Do I want to have 400 ppm air free. No, not really. What I want is zero but that's a hard number to reach. That's why all manufacturers will give you a maximum level. HTP munchkin boiler at high fire will operate at 135 ppm CO at manufacturers specifications.

A Burnham atmospheric boiler should not be that hard to bring your CO levels down below 100 ppm. I find that cleaning the burner tubes of dust easily will bring the CO number down. Dust, dryer vent lint, and spiderwebs all contribute to high CO. I have done a couple of hundred Burnham's boiler combustion test and just cleaned the burner tubes and orifices and brought the levels down. And if the burner tubes are defective they can be ordered.

Steamhead

If I had to guess, I'd say the burners are over-fired. But you'd need someone with an analyzer and the know-how to use it, to verify this.

Here is a list of contractors in MA. Not sure who is closest to you, but there are several whose work I'm familiar with:

https://heatinghelp.com/find-a-contractor/state/MA/

SuperTech

It should be something fairly simple to fix, if there actually is a problem. Readings might have been taken while the boiler was cold. I agree that you just need a better tech who is familiar with combustion analysis. Maybe NCI knows someone in your area. Too many techs these days will just say "it's old and needs to be replaced " because they either don't know how to fix it or just want to sell you a crappy mini split system and collect a commission. 

Jamie Hall

Try Ryan at New England Steam Works

Mustangman

I get that you are dealing with CO in the exhaust gasses. What about CO in the house? May not be a bad idea to pull the smoke pipe and check the chimney base. If you think about it, it is a 35 year old boiler. It doesn't owe anyone anything. I tell people if you can get 25 years, you are way ahead of the game.

ChrisJ

@tzuhsianglin0110

Is this a steam boiler or hot water?
Does it have a gauge glass on it showing the water level?

TheUpNorthState88

I would find another company more knowledgeable and have it serviced. It took me dealing with two crap companies before finding company 3 who had no issues servicing my 87 year old boiler. They have been great to deal with. So many HVAC companies are becoming sales based over repair based. A couple hours of labor and the issue can be resolved, nowadays they will say, "there's nothing we can do, but replace the system."

I got that recently because my pilot light was going out. My new tech fixed things in 30 mins the other guy didn't want to do.