Will a 5" chimney liner work in this scenario?

jdanswers

Saw a closed thread that doesn't quite answer my question, so I'll try here. I replaced my old boiler with a Dunkirk hot water boiler WPSB-4D outputting 94,000 BTU. I have gradually noticeable condensation in the chimney since the install in Dec. 2007 causing interior ceiling damage. There are no leaks around the chimney. I had it pointed and resealed. 6 feet of the chimney runs through a cold attic and 3 feet is above the roofline outdoors. I am in Erie, PA where winter is pretty severe. Temps below freezing much of the time.
1. chimney height - 17' 6" top to bottom.
2. clay lined cement block chimney, straight, no bend. Inside dia 8"x7" sloppy mortar joints inside.
3. boiler has a 6" exhaust through a 5' up-angled run to chimney.
4. hot water tank also vents into the chimney, not sure of btu output. (Sorry)

I am considering an insulated flue liner but using a 6" won't fit the chimney as is. The 6" liner has an OD of 7.25. I could get away with a 6" liner not insulated but I am concerned about the extreme cold we have most of the winter.

A 5" insulated liner has an OD of 6.25 and likely would fit but will it give enough draft to expel gasses safely? My installer can't answer my concerns.

I turn to your expertise.
Thanks
JD

Robert O'Connor_12

I'd use a standard stainless 6" liner. When you put a liner in an existing tile lined chimney, you have (according to the tables) created a B Vent. You could break out the original tile liner to fit an insulated one which can be a fairly labor intensive to do. It's also possible you can go down one size, but be careful. This should be supported by your heating pro, applicable according to the B vent tables & be okay with the AHJ. In NJ you need a permit to install a liner and must submit supporting documentation & verification of chimney by heating pro when changing appliances.

vaporvac

I'm curious why you had the brick chimney sealed? Was it originally? On older houses this can cause problems as the brick is meant to breath and a sealant keeps all the moisture inside.

jdanswers

Robert O'Connor said:

I'd use a standard stainless 6" liner. When you put a liner in an existing tile lined chimney, you have (according to the tables) created a B Vent. You could break out the original tile liner to fit an insulated one which can be a fairly labor intensive to do. It's also possible you can go down one size, but be careful. This should be supported by your heating pro, applicable according to the B vent tables & be okay with the AHJ. In NJ you need a permit to install a liner and must submit supporting documentation & verification of chimney by heating pro when changing appliances.

Thanks for the response. I was hoping to not have to call a local HVAC person for advice since they could try to steer me into an expensive solution. I figured you guys would give me the straight story.

jdanswers

vaporvac said:

I'm curious why you had the brick chimney sealed? Was it originally? On older houses this can cause problems as the brick is meant to breath and a sealant keeps all the moisture inside.

I think you are responding to another query. My problem does not seem to fit your answer. (ex: no blocked chimney)

vaporvac

"I had it pointed and resealed. "

This is what I was referring to, sealing the exterior of the brick, not sealing up the chimney.

jdanswers

vaporvac said:

"I had it pointed and resealed. "

This is what I was referring to, sealing the exterior of the brick, not sealing up the chimney.

Sorry. I see. "Resealed" meant the chimney flashing not the bricks and mortar.

Any advice about the flue liner size/type I should use?

JD

icesailor

"" A 5" insulated liner has an OD of 6.25 and likely would fit but will it give enough draft to expel gasses safely? My installer can't answer my concerns.

I turn to your expertise.
Thanks ""

Your installer should have the knowledge and expertise to answer that question. Otherwise, IMO, he is no better than those that hand around HD looking for work.

And if you have a gas boiler, the chimney needs to be lined, and the "installer" definitely needs to know how to calculate flue sizes and chimney sizing.

Concrete Block chimney's with clay flue tiles are terrible. Most so called "Mason's" couldn't build a chicken coop out of bricks and not have it leak. The tiles are never set properly so they leak at the joints and the tiles crack.

Any heating person that thinks that Power venting is a bad idea, has never built a chimney or laid bricks. Or finally figured out why all the brick chimneys they dealt with had such bad draft, and how you had such good consistent draft with a Power Venter.

ChrisJ

I'm NOT a professional and as others have said this should really be handled by a professional in person that can see everything.

From what I recall when I attempted to have my chimney lined the size of the liner goes by the height of the chimney and the boiler's input BTU rating. The manufacturer of the liner should have a chart that shows what the liner will handle under those conditions.

For example from this website,
http://www.chimney-liner-central.com/chimney-liner-size-guideline.html



This chart should only be used as a rough idea as you should always follow what the manufacturer of the exact liner you are using says as well as local codes.

jdanswers

"With all due respect, nobody on this site can possibly recommend that you utilize anything less than 6" because that size is the recommendation by the manufacturer of the boiler." Thanks for all your input. I guess I need to call a local HVAC company to look at my situation. I thought, by providing all the info here, I could get someone to calculate what liner could fit my situation. I have read elsewhere that there is some leeway in calculating liner size. Apparently those opinions are wrong.

Thanks again, everyone.
JD

ChrisJ

jdanswers said:

"With all due respect, nobody on this site can possibly recommend that you utilize anything less than 6" because that size is the recommendation by the manufacturer of the boiler." Thanks for all your input. I guess I need to call a local HVAC company to look at my situation. I thought, by providing all the info here, I could get someone to calculate what liner could fit my situation. I have read elsewhere that there is some leeway in calculating liner size. Apparently those opinions are wrong.

Thanks again, everyone.
JD

Ahem...

Did you read my reply?

jdanswers

ChrisJ said:

jdanswers said:

"With all due respect, nobody on this site can possibly recommend that you utilize anything less than 6" because that size is the recommendation by the manufacturer of the boiler." Thanks for all your input. I guess I need to call a local HVAC company to look at my situation. I thought, by providing all the info here, I could get someone to calculate what liner could fit my situation. I have read elsewhere that there is some leeway in calculating liner size. Apparently those opinions are wrong.

Thanks again, everyone.
JD

Ahem...

Did you read my reply?

I did read it and it made no sense because I'm an idiot when it comes to tech jargon. My boiler is a Dunkirk hot water system. But, hey, thanks for responding. I appreciate your effort to help.

JD

ChrisJ

jdanswers said:

ChrisJ said:

jdanswers said:

"With all due respect, nobody on this site can possibly recommend that you utilize anything less than 6" because that size is the recommendation by the manufacturer of the boiler." Thanks for all your input. I guess I need to call a local HVAC company to look at my situation. I thought, by providing all the info here, I could get someone to calculate what liner could fit my situation. I have read elsewhere that there is some leeway in calculating liner size. Apparently those opinions are wrong.

Thanks again, everyone.
JD

Ahem...

Did you read my reply?

I did read it and it made no sense because I'm an idiot when it comes to tech jargon. My boiler is a Dunkirk hot water system. But, hey, thanks for responding. I appreciate your effort to help.

JD

Na, that doesn't make you an idot.
All you need is to know the input btu of the boiler, which is on the tag on the boiler. If you give us the model we can help look it up.

You then take that, and look at the chart and wherever the size liner you want intersects with how high your chimney is is the largest boiler that liner can support.


You said a 5" liner at 17 feet so the closest thing is 15 feet. That gives you a maximum INPUT btu of 119,200.

Chances are, your boiler will work with that, but we need to know the actual input btu of the appliance.

But as was said, this all must meet local code as well.

todd_ecr

Per the NFGC, it is permissible to reduce the vent size 1 pipe diameter. You must carry the boiler's 6" vent all the way to the chimney connection(do not reduce it right at the boiler's vent damper.)
The WPSB-4D' s input is 112,500. As others have mentioned, you must remain within the capacity of the liner. Add the water heater's input to the boiler's. If this total is not less than the maximum capacity of the liner for a given height and diameter, then it is not permissible.

ChrisJ

todd_ecr said:

Per the NFGC, it is permissible to reduce the vent size 1 pipe diameter. You must carry the boiler's 6" vent all the way to the chimney connection(do not reduce it right at the boiler's vent damper.)
The WPSB-4D' s input is 112,500. As others have mentioned, you must remain within the capacity of the liner. Add the water heater's input to the boiler's. If this total is not less than the maximum capacity of the liner for a given height and diameter, then it is not permissible.

I missed the comment about the water heater.
Thanks for catching that.

RobG

You could also replace the water heater with an indirect tank to exclude it from the BTU factor.

jdanswers

todd_ecr said:

Per the NFGC, it is permissible to reduce the vent size 1 pipe diameter. You must carry the boiler's 6" vent all the way to the chimney connection(do not reduce it right at the boiler's vent damper.)
The WPSB-4D' s input is 112,500. As others have mentioned, you must remain within the capacity of the liner. Add the water heater's input to the boiler's. If this total is not less than the maximum capacity of the liner for a given height and diameter, then it is not permissible.

Excellent! Thanks for taking the effort to give me this info. Yes, boiler is 112,500. The water heater is 35,500 (40 gal). This is 148,100 total. So, I need a liner that can vent this input based on length of liner and proper sized diameter. The length needed would be a minimum of 17.5 feet. It's still the diameter to be determined taking into account the clay lined chimney is 8"x7" inside dimensions with some sloppy mortar joints. The house is 60 years old.

RobG

Once again, if you abandon the water heater and use an Indirect you should be able to get by with a 5" liner. (I am just going by the specs above).

Robert O'Connor_12

If you use a 6" liner, and without knowing the connector rise so I'll assume (with Odd Couple Theme in my head) it's 1 feet (R)
Now, using table G2428.3(2) {two or more Cat 1 appliances with single wall metal connectors}
without interpolating height and use 15' (on the table)
You get 116,000 btu's.
Now, reduce it by 20% based on G2428.3.15
or
92,800. This is max based on code when using a liner.

ChrisJ

This is actually the reason I ended up with a power vent heater.

icesailor

Its the input of the appliances, the length of the flue and the size.

Being too big and too short is as bad as being too small a flue and too long. Everyone is different. Today, you have to calculate it.

Its all in the NFPA codes to look up. The whole intent is to get the flue hot, and the gasses pass at an acceptable rate. 100 MPH isn't acceptable, nor is 1" per hour.

You have to calculate it. Its on the gas code books and in the oil codes.

Replacements are a whole other issue. They must meet standards too.

I don't make the rules. I just had to work by them.

j a_2

It will work if the local code says it will..Bigger or smaller is equally as bad..

Mikey Lasagna

vaporvac said:

I'm curious why you had the brick chimney sealed? Was it originally? On older houses this can cause problems as the brick is meant to breath and a sealant keeps all the moisture inside.

Maybe true with older brick not true with newer brick or new wall systems eg: cavity walls

The engineers would rather have the wall sealed and have weep holes to drain any condensation.

Mikey Lasagna

icesailor said:

"" A 5" insulated liner .

Concrete Block chimney's with clay flue tiles are terrible. Most so called "Mason's" couldn't build a chicken coop out
of bricks and not have it leak. The tiles are never set properly so they leak at the joints and the tiles crack.

Any heating person that thinks that Power venting is a bad idea, has never built a chimney or laid bricks. Or finally figured out why all the brick chimneys they dealt with had such bad draft, and how you had such good consistent draft with a Power Venter.

I think you left out the hack chimney liner company's that "repoint" your chimney and repair the wash on top. I can't tell you how many times I'm called to a house to repair what did.

jdanswers

I want to thank everyone for advising me. I got three estimates from local pro's after discussing the finer points many of you made and those I learned in my online research. I have chosen one to do the work. I'll let you know if I chose wisely.

Thanks again!
JD

icesailor

@Mickey Lasagna:

And someone thinks that THAT is better than a Power Vent?

Not in MY experience.

Out of sight. Out of mind.

ChrisJ

j a said:

It will work if the local code says it will..Bigger or smaller is equally as bad..

If local code says it will work but the liner manufacturer says it will not, what happens?

I ask, because I always hear local code out ranks everything else.

icesailor said:

@Mickey Lasagna:

And someone thinks that THAT is better than a Power Vent?

Not in MY experience.

Out of sight. Out of mind.

In my opinion a B-vent is better than a power vent.
No moving parts, no noise.

I installed a power vent Bradford White 50 gallon water heater. Part of me wishes I didn't, part of me likes it.

The part of me that wishes I didn't is the part that gets annoyed by the sound, annoyed by not having a water heater when the power is out, and the part of me that knows sooner or later I'm going to have to replace that expensive beast. Expensive when compared to an atmospheric vent heater and yeah, it's more efficient but there is no way it will ever pay for the price difference.

Other than that, the noisy isn't that bad and it really seems like a good heater. It's just there are some cons to them.

icesailor

After April 1, 2015, you don't have a choice on larger sized gas water heaters.

Buy an unsold grandfathered one and save it until you need it.

ChrisJ

icesailor said:

After April 1, 2015, you don't have a choice on larger sized gas water heaters.

Buy an unsold grandfathered one and save it until you need it.

Is that in MA or all of the US?
What is "larger" ?

Na, I don't dislike it enough to hoard one.

vaporvac

I think it's over 50gal? I bought my Rheem atmospheric recently and it's so quiet and much more efficient than the old one due mainly to insulation and the piping. We have outages here all the time; having no heat is bad enough, I'd be sunk with no hot water.

icesailor

ChrisJ said:

icesailor said:

After April 1, 2015, you don't have a choice on larger sized gas water heaters.

Buy an unsold grandfathered one and save it until you need it.

Is that in MA or all of the US?
What is "larger" ?

Na, I don't dislike it enough to hoard one.

FEDERAL.

Nothing to do with Massachusetts other than Massachusetts is covered along with every other jurisdiction in the USA,

"Larger" means it has a larger diameter and height for additional insulation.

Bob Bona_4

New DOE mandates. Is going to be a real problem for installs that are tight already. Condos, etc.

SWEI

Straight from the CFR:


How long 'till we see the first 55 gallon model?

j a_2

ChrisJ said:

j a said:

It will work if the local code says it will..Bigger or smaller is equally as bad..

If local code says it will work but the liner manufacturer says it will not, what happens?

I ask, because I always hear local code out ranks everything else.

icesailor said:

@Mickey Lasagna:

And someone thinks that THAT is better than a Power Vent?

Not in MY experience.

Out of sight. Out of mind.

In my opinion a B-vent is better than a power vent.
No moving parts, no noise.

I installed a power vent Bradford White 50 gallon water heater. Part of me wishes I didn't, part of me likes it.

The part of me that wishes I didn't is the part that gets annoyed by the sound, annoyed by not having a water heater when the power is out, and the part of me that knows sooner or later I'm going to have to replace that expensive beast. Expensive when compared to an atmospheric vent heater and yeah, it's more efficient but there is no way it will ever pay for the price difference. Chris, the local code,defers back to the manufacture installation instructions…Any and all appliances/fixtures must be board approved…Anyway thats how it is here in Mass...

Other than that, the noisy isn't that bad and it really seems like a good heater. It's just there are some cons to them.