Metal chimney liner needed for gas boiler conversion?

jesmed1

We're considering whether to convert two 200,000 oil burning boilers to run natural gas via conversion burners. Both boilers vent into a common masonry chimney with terra cotta liner in good condition. I'm in the Boston suburbs, and spoke today with our town building inspector about chimney liner requirements. He said he would ask us to have a chimney sweep inspect the chimney and advise us on whether or not it needs a metal liner. So it seems the inspector will go with whatever the chimney sweep says. So can I just hire a chimney sweep and hope he says our terra cotta liner is in good shape and we don't need a metal liner? Because I'm guessing the chimney sweep is going to have some incentive to say we need a liner.

Steamhead

A stainless-steel liner is a great idea no matter which fuel you burn.

jesmed1

Steamhead said:

A stainless-steel liner is a great idea no matter which fuel you burn.

All home improvements are great ideas until you have to convince 3 other members of your condo association to pay for them.

Steamhead

Well, it's cheaper than having to rebuild the chimney.....

jesmed1

There's a local chimney sweep with a good reputation for honesty and not trying to upsell unnecessarily. I'll try to get him over and see what he says.

Mad Dog_2

Its a good idea to have them install an insulated liner or pack in Vermiculite in the annular space between the Terracotta & the liner if you can.  Mad Dog 🐕 

HVACNUT

Exterior chimney?Going from oil to gas and downfiring both boilers? The chimney is going to rain.

jesmed1

HVACNUT said:

Exterior chimney?Going from oil to gas and downfiring both boilers? The chimney is going to rain.

No downfiring. You all beat me into submission. And Carlin requires that their gas burner BTU output be set to within +/-5% of the boiler spec. So I would have the gas burners set to run at the full 200MBTU/hr.

So with one boiler running that's 200MBTU/hr, and with both it's 400MBTU/hr. That's a lot of heat keeping the water vapor in the vapor phase and not condensing in the chimney.

Also, the chimney is indoors through the basement and two upper floors before going through the attic and roof.

pecmsg

jesmed1 said:

HVACNUT said:

Exterior chimney?Going from oil to gas and downfiring both boilers? The chimney is going to rain.

No downfiring. You all beat me into submission. And Carlin requires that their gas burner BTU output be set to within +/-5% of the boiler spec. So I would have the gas burners set to run at the full 200MBTU/hr.

So with one boiler running that's 200MBTU/hr, and with both it's 400MBTU/hr. That's a lot of heat keeping the water vapor in the vapor phase and not condensing in the chimney.

I would listen to the experts and not speculate that your right!

jesmed1

pecmsg said:

I would listen to the experts and not speculate that your right!

I will. I'm trying to get a local chimney sweep over to take a look. If he says we need a liner, we'll price that into the job.

HVACNUT

Interior chimney and fired at the correct input it might be OK, but yes, get it checked.

ChrisJ

@Bob Harper

random12345

Yeah, in the Boston area as well. If you live in a 4 condo building, the estimate for that liner is going to make you cry...I don't know for sure, of course, but all the sweeps I've spoken with over the years the quotes for a two family were as high as a boiler replacement...I'm sure they have their reasons but it just doesn't seem fair that sliding a piece of metal tubing down a chimney would cost that much.

jesmed1

random12345 said:

Yeah, in the Boston area as well. If you live in a 4 condo building, the estimate for that liner is going to make you cry...I don't know for sure, of course, but all the sweeps I've spoken with over the years the quotes for a two family were as high as a boiler replacement...I'm sure they have their reasons but it just doesn't seem fair that sliding a piece of metal tubing down a chimney would cost that much.

I was afraid of that. I just checked Rockford chimney supply, and just the materials for a 40-foot liner, 10" diameter costs more than both the gas conversion burners and associated bits and pieces I was hoping to install. Add in labor, and yeah, it's going to be expensive.

pecmsg

jesmed1 said:

Yeah, in the Boston area as well. If you live in a 4 condo building, the estimate for that liner is going to make you cry...I don't know for sure, of course, but all the sweeps I've spoken with over the years the quotes for a two family were as high as a boiler replacement...I'm sure they have their reasons but it just doesn't seem fair that sliding a piece of metal tubing down a chimney would cost that much.

I was afraid of that. I just checked Rockford chimney supply, and just the materials for a 40-foot liner, 10" diameter costs more than both the gas conversion burners and associated bits and pieces I was hoping to install. Add in labor, and yeah, it's going to be expensive.

What’s the cost of replacing the chimney due to the boards cheapness?

jesmed1

pecmsg said:

What’s the cost of replacing the chimney due to the boards cheapness?

Well, this is only a 4-unit building, so we don't even have a condo "board." We have 4 different owners with different expectations about how long they may or may not be owners here.

If an energy efficiency improvement project has a payback period of 5 years or less, I can probably get everybody on board. Longer than 5 years, probably not. So if gas conversion is too expensive up front, there won't be any gas conversion, and the chimney will still be here in another 20 years with its original terra cotta liner.

Mad Dog_2

You're paying the Chimney company's insurance premiums and the risk & danger of climbing ladders, roofs, pulling liner down  mad Dog 🐕 

jesmed1

Mad Dog_2 said:

You're paying the Chimney company's insurance premiums and the risk & danger of climbing ladders, roofs, pulling liner down  mad Dog 🐕 

Oh, I understand. Last year I saw a roofer working on a house across the street and asked him if he'd be able to come over with his ladder and climb up 2 stories to look at a leaky gutter. He said he had to charge me $375 just to set his ladder up in order to pay for the insurance. And our condo building's master insurance policy went up 18 percent last year. In one year.

realliveplumber

Mad Dog_2 said:

You're paying the Chimney company's insurance premiums and the risk & danger of climbing ladders, roofs, pulling liner down  mad Dog 🐕 

Not to mention the blood, sweat, and bricks that need to be removed to get around the offset that the drunk mason layed up at the end of the day.

Mad Dog_2

Extremely dangerous work.  Not alot to tie off to for a harness, either...Almost all those guys "work without a net." In my own 1899-1900 Victorian Farmhouse,  the Interior chimney that picked up a Pot Belly stove on each floor, I had a bad blockage. I  Removed many old Beer Cans without the pull tabs..you punched it with a Church Key. Many Oldtime Chimney Guys and plumbers drank all day long.  I caught the tail end of those Hard men:  Break time "Hey  kid...get me a Six of  B-16s (Bud Tall Boys) will ya?? Make sure the foreman don't see ya!"  They always threw ya a few bucks.  They might be a little Rocky by quitting time, but they banged out alot of qaulity work...its just the way it was.  Alot of foreman smoked cigars, looked and acted like Fat Tony Salerno, and probably knew him.  Mad Dog 🐕 🤣 

Bob Harper

You need a Level II inspection per NFPA 211. That includes an internal video camera. this will undoubtedly reveal failure of the joints in the flue tiles at minimum. The oil soot will undoubtedly have eaten the terra cotta tile up. Plan on relining it. I've never seen one that met the std. in >40 yrs. Ask the sweep to size a listed liner. A smoothwall liner does not have to be derated 20%, flows better and does not collect soot on oil burners.

Waher

Is the chimney on an outside wall or in the middle of the building?

If it is on an outside wall you'll need a liner because terracotta will eventually fail from a combination of the acidic condensate and frost spalling. A good stainless steel cap is worth it too. The good news is that many of the liners have lifetime warranties if they are regularly inspected. If one starts to fail, the material at least is covered for replacement. Some warranties from the liner manufacturer's include labor. You'll have to read the fine print and make sure you have all the paperwork to collect on one of those though, so it'll become a regular responsibility of the board to keep the records in order.

jesmed1

Thank you @Bob Harper and @Waher. Our town building inspector trusts the inspection work of the chimney sweep we're using, so the sweep will know what the inspector wants to see. I expect he will have an internal camera, and I expect we'll have some joint failures at a minimum.

This is an internal chimney, fortunately, but due to the economics of our condo association, if a liner is in fact required, it's going to put us over budget for the gas conversion and we'll have to scrap that idea and stick with our existing oil burners. We probably will get a stainless steel cap anyway, because I can see that rain coming down the chimney is causing efflorescence in the mortar at the bottom.