Replace Chimney with what type of vent

DavewB

My house was built in 1910, the chimney (small) has had it, I'm planning on tearing it down to the basement. Its in bad shape all the way down. I only need to vent the Oil furnace. What type of vent pipe (an size) should be installed ? Ive searched and cant seem to find anything specific - dual wall, same size pipe that exits the furnace ? Prior owners went thru less then a tank of oil a season - I'm in MA. I'm planning on installing a wood stove & building a DIY solar heating system. So the oil heat will get less use. No gas to the house. I need to replace the roof by Winter, so planning on replacing the chimney as a vent at that time. Thank you - Dave

STEVEusaPA

What's the make/model number of the furnace?
You can probably power vent it, or you may be able to direct vent it through the wall.
If you're rebuilding a masonry chimney, just for this appliance, terracotta lining and a stainless steel chimney liner, properly sized for your equipment. I doubt you need more than an 8x8 terracotta for the masonry and a 5" or 6" liner. But like I said, properly sized. What's going to be the total height of the chimney-from where the chimney connector enters to the top of the chimney?
Even though I'm an oil person, if you're using less than 1 tank of oil up in MA for the winter, you're doing better than most. You could probably change the outdoor unit to a heat pump, then you would only need oil on the coldest days (or if your out of wood).
Keep in mind modern heating oil's main drawback is that it doesn't store well. I recommend additives in the end of the season and filling the tank.

DavewB

Looks like I have to use L-Vent for oil.

DavewB

I do not see L Vent in 6" size, looks like its usually used for Pellet stoves and 3-4". Guess I will need to rebuild the chimney from inside the attic thru the roof. Then cleanup & remortar the chimney in the basement, then put a sleeve in.

STEVEusaPA

DavewB said:

Looks like I have to use L-Vent for oil.

Based on what?

DavewB said:

I do not see L Vent in 6" size, looks like its usually used for Pellet stoves and 3-4". Guess I will need to rebuild the chimney from inside the attic thru the roof. Then cleanup & remortar the chimney in the basement, then put a sleeve in.

Also, based on what?
Once again, What's the make/model number of the furnace?
and
What's going to be the total height of the chimney-from where the chimney connector enters to the top of the chimney?

Bob Harper

Olympia Chimney Supply makes L vent in 6" but its air cooled and not really be best choice if the chimney must run up the exterior. If interior, its great. Outside, you want to use factory built chimney, commonly referred to as "class A" or "All-fuel". This is a double walled listed chimney with a stainless steel inner liner, stainless steel or galvalume outer and insulated with a ceramic fiber or solid pack mineral fiber insulation and carries typically a 2" clearance to combustibles. Their L-vent carries a 6" lateral clearance even with oil. If you feel you must rebuild a masonry chimney it must meet the current code. This includes maintaining clearances to combustibles, firestopping, etc. You don't need both terra cotta (which is an obsolete material) and stainless steel. Just build the chimney then drop a listed liner to its listing. As Steve is asking, you need to refer to the listed installation instruction for that appliance for vent type and sizing then cross-check with your state codes. Taxachoosets is run by the plumbers and their codes can be quite different from the International Codes observed by most of the rest of the country so do your due diligence. I recommend consulting a local chimney pro. Also, look to the warranties. A masonry chimney carries a curbside warranty. A pro liner, however, typically carries a transferrable lifetime or Forever warranty. Most class A nowadays is a non-transferrable lifetime warranty. That Olympia product line is a transferrable Forever warranty on all their listed liners, L-vent, and factory chimney. You will also need to figure on your connector pipe to the vent or chimney so again refer to the appliance listing. There's usually a chart in the appliance cabinet next to the rating plate and in the instruction manual.

Steamhead

If the house is that old, the chimney structure may be supporting some of the house's framing. This is no longer permitted under most Codes, and would have to be corrected if the chimney is removed and/or rebuilt.

countryroads99

If you go with a 316L class a chimney, you could use it for oil and if you decide you want to change to a wood burner down the road, then you don't have to change the pipe. https://www.rockfordchimneysupply.com/chimney-pipes/class-a-insulated-chimney-pipes/rock-vent-class-a-chimney-systems/rock-vent-class-a-chimney-pipe-316l-inner-430-outer.php You may not have to take the chimney all the way down. You could take it down some and then transition to a class a chimney. You would have to run a stainless flex liner down the masonry part that you keep though. This would same you some money if half the chimney is still good.

GBart

Steamhead said:

If the house is that old, the chimney structure may be supporting some of the house's framing. This is no longer permitted under most Codes, and would have to be corrected if the chimney is removed and/or rebuilt.

Agreed, also note that old brick is valuable, someone will buy it. If it's just gone on the interior you can reline with SS.

Jack

I would not make another masonry chimney. Factory built far outperforms masonry. Use either the Dura-vent or Selkirk UL-103HT chimney. L-vent is tested to 1700* and was found lacking for use in wood and the 103HT product was developed to the 2100* level. The HT product gives you the most latitude for future use whether oil or wood. The factory built chimney is simple to assemble and installs quickly. Now, if you want to convert the space from the old chimney to living space and can't get a new flue up in the area, then you can power vent the oil equipment. If it is less than 1.25 gal firing rate I would use the Tjernlund SS-II

DavewB

Hi, IM posting form work when its slow, I don't have the furnace model at present. It is about 20 years old. The chimney is in the middle of the house, no fireplace & its a small square chimney that does not support the house. Its a 1 story house, so from where the pipe enters the chimney from the furnace, to the exit point on the roof is maybe 14' Max, then add 3' more to clear the roof per code. It exits at the exact center of the roof. I'll have to look in the attic, but I know the exterior chimney above the roof needs to be rebuilt. And the base in the basement needs to be cleaned & re-mortared. If in between is in decent shape then a sleeve may be the way to go. I've only run B vent for a gas HW heater & stove pipe for my wood stove. So I was looking for what direction to go/materials to use. Thank you for the input, tomorrow I will check the rating on the furnace. I do not trust the chimney to go thru the Winter, so I am looking into this in advance, Its been in the 90's, too hot to go in the attic to check that part of the chimney

Bob Harper

L vent is listed to UL 641 rated for 570°F max. for oil and CAT I gas. 1700°F rated factory chimney is listed to UL 103. 2100°F chimney is listed to UL 103HT and thus often referred to as "all fuel" meaning gas, wood/ coal or oil. He can demo the stick chimney and replace it with 103HT chimney up the center of the house, which will warm the chimney and provide a more stable draft. Just use all the listed components required, esp. supports, firestops, and transition to single walled connector. No need to put a stinky sidewall venter in if you have the vertical option but hey, you can kill the shrubbery and stink out the house if that's your thing. A lot to go wrong with power venter and must be terminated well above snow line. Yes, use 316L inner wall and 400 series outer. Terminate 3/2/10 rule above roof.

DavewB

Ive been working from home, had the link at work. Chimney is not as bad as I thought, so sleeve is the best method I think. Hot air Oil fired furnace Unicell model DBUA96 - D3. 55, Input 119,000 btu an hour, .85 nozzle , Beckett burner. I do prefer to go up & not out the side. Thanx

DavewB

Took the chimney down to the roof level today. Its OK below the roof line, just loose where exposed to weather. So Im going to rebuild it, then sleeve it & install a SS cap