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Heating & Air Conditioning

Time to replace gas boiler?

16 years ago

Just had the gas company in today for the annual cleaning and inspection of our 100,000 btu, 47-year-old gas boiler. Since Jan. 07, they are now required to do a CO check, because a woman in PA died of CO exposure after the gas company was in to do a routine inspection. Findings? Our gas boiler was "yellow tagged," showing it to be a safety concern because the CO monitor found 6 ppm concentration of CO. He said if it were 9ppm, he would need to "red tag" it and shut it off. Readings in the vent were 32ppm, which he said was in the safe range. He said that other than the 9 ppm reading directly above the boiler that the rest of the system seems to be burning clean.

The technician said that the likely cause was the degrading of the cast iron of the boiler (and whatever seal is inside the unit) that is allowing CO to leak from the seams, plus the fact that we created a room for the boiler that was smaller than recommended for the size of our boiler, when we put up drywall to finish the basement and create a utility room. He added that the boiler is quite oversized for the load, since we converted from baseboard radiant heat to a hydronic coil with a second story addition we did last year.

He recommended replacing the boiler, and leaving the door to the utility open in the meantime to provide more fresh air to the system.

Thoughts on the technician's conclusions? How urgent do you see the need to replace the unit?

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Comments (5)

User
16 years ago
Did you make provisions for fresh air intake to the room? I don't recall the sizing recommendations on our brand new 70k BTU boiler, but it was stated that if the boiler is in a small room, intake air must be allowed to come in through large vents at the top and bottom of the room. Even our own municipal code requires a six-inch air intake on our garage because that's where our boiler and water heater are.

47 years is a great life span for a boiler. I just replaced a 140k BTU boiler with a 70k BTU unit. The new boiler is the Weil-McLain GV3. Our heat loss calculation showed that our home should lose about 55 BTU / hour at -10Â°F. But since we haven't been in the house through a winter, we were being cautious.

If you choose to replace it, you'll need a heat loss calculation to size the new one correctly. No doubt that you can find a unit that will be much more economical. I found myself unwilling to go for a new 'modulating' boiler due to my concerns of its reliability, so I went with a unit that's a 15 year old Condensing design. When researching, look into Outdoor Temperature Reset units, which adjust the temperature of the boiler supply water to be in line with the heat loss of the house in warmer weather. (For example, my boiler has been running at around 120Â°F while the temperature outside is hovering around freezing. As it gets to 10Â°F outside, the boiler is gradually ramped up to 180Â°F. This saves a bundle on fuel usage.)
kathi06
Original Author
16 years ago
Thanks for the response braytonak. Gives us some great things to think about if/when we replace.

My more immediate question is whether we need to replace the unit pronto, based on the findings, or whether just adding a louvered door or something will address the concern. We're in the middle of a kitchen remodeling, and a $10,000 bill for a boiler wasn't in the plan right now!

But we certainly don't want to sacrifice safety, if indeed the CO levels are truly a concern.
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bonanza_stu
16 years ago
Replace the boiler. 47-years old is way past it's useful life and is costing you a fortune to operate compared to a new 93% efficient unit.

You should plan to spend more for a HE boiler but, utility cost savings is the gift that keeps on giving.

Good luck,

Stu
heimert
16 years ago
In the meantime, be sure to get a CO detector in your basement and upstairs just in case.
kathi06
Original Author
16 years ago
Thanks for the responses, everyone. We're going to get a few quotes. We've always kept CO detectors on every level of our house...they all read "0". So it doesn't seem that the CO is creating issues in the living space yet. So we'll just see about getting it replaced before it does!

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