Draft install concerns

[enigmablaze]

Hello all, I enjoy this forum very much and have been trying to get a stove installed for months now (can't get a contractor to give me a chimney chase quote...seriously months I've been trying). Due to the issues getting a contractor to do the chase and some logistical issues with the house (intake vents, electric meters etc.) we are considering more strongly a different location that requires no chase or expensive moving of essentials. It is the northernmost corner of our sunroom which is a one-story addition type room to our small 1 1/2 story cape cod.

My concern is, even though the pipe would go straight up (through a rubber roof) and have no turns (other than maybe venting out the back of the stove), it would only be maybe 8' tall (though I'm guessing they can make it taller), the house is going to be blocking air flow from the south and there is a large tree to the southwest of it, as well as trees and a house to the north from our neighbors...I'm just not sure if this is a bad idea or not . The stove that would likely go in that location would be a Morso 1440.

 

[WoodyIsGoody]

Hello all, I enjoy this forum very much and have been trying to get a stove installed for months now (can't get a contractor to give me a chimney chase quote...seriously months I've been trying). Due to the issues getting a contractor to do the chase and some logistical issues with the house (intake vents, electric meters etc.) we are considering more strongly a different location that requires no chase or expensive moving of essentials. It is the northernmost corner of our sunroom which is a one-story addition type room to our small 1 1/2 story cape cod.

My concern is, even though the pipe would go straight up (through a rubber roof) and have no turns (other than maybe venting out the back of the stove), it would only be maybe 8' tall (though I'm guessing they can make it taller), the house is going to be blocking air flow from the south and there is a large tree to the southwest of it, as well as trees and a house to the north from our neighbors...I'm just not sure if this is a bad idea or not . The stove that would likely go in that location would be a Morso 1440.

I doubt 8' of stack would provide adequate draft for good performance.

 

[double-d]

Could you use a Telescoping Roof Support then add a second 4' section of pipe getting you 12' of chimney, still on the short side but better than 8'. Then if needed, you may be able to add another section of pipe, like a 2'. You'll have a better sense of how well it drafts once the colder temps arrive, but you could experiment with a inexpensive galvanized pipe at different lengths, to see what height you need, to get the best draft.

 

[Squirrely]

That's good advice, double-d. Whatever length of flue you choose, I'd also recommend a T fitting for easy cleaning.



Greg

 

[enigmablaze]

The problem with putting some now and adding later is that I don't trust myself to do it correctly so we're hiring a sweep to install it, so I don't want to have to pay them twice if it can be avoided. Is 12' long enough or do I need longer? I might be able to use that bracket thing to get a taller one. What is a good minimum height, or what do people usually do with one-story installations???
I'm definitely concerned that the house's second story might block the air, plus I'm surrounded by trees here, but mostly shorter ones. Though behind the house (to the north of the sunroom) the hill slopes up and my neighbor's house is way above mine, so again, other than a W-E breeze, the south and north areas are blocked by buildings/trees etc :/.

 

[enigmablaze]

That's good advice, double-d. Whatever length of flue you choose, I'd also recommend a T fitting for easy cleaning.

View attachment 198938

Greg

I really like the idea of the T-fitting for easy cleaning...and the venting from the back (as I want to heat water etc. on top), do you find it reduces the draw though? But then I believe your chimney pipe is much taller than mine would be?

 

[enigmablaze]

That's good advice, double-d. Whatever length of flue you choose, I'd also recommend a T fitting for easy cleaning.

View attachment 198938

Greg

Is there any disadvantage to the T-fitting? It seems a great option and I wonder why I don't see them on here more often, just wondering

 

[Squirrely]

I really like the idea of the T-fitting for easy cleaning...and the venting from the back (as I want to heat water etc. on top), do you find it reduces the draw though? But then I believe your chimney pipe is much taller than mine would be?

There's a cap under the T so you can take it off and run a cleaning brush up the flue from the bottom. Out the back is great in that it keeps the top of the stove clear. I don't know if out the back reduces draw because in 42 years of owning stoves I never vented one out the top. Our flue is 24 feet long so draw is no problem. We put the whole thing inside the house in order to reclaim the maximum amount of heat from the flue. From that black ceiling box out the roof the flue is double walled.

A 6 inch flue on a really tiny stove with only a .7 cubic foot firebox is ~way~ oversized. So Morso designed a cast iron cup shaped "one way" restrictor that partially obstructs the potential of any backdraft flow while allowing a smooth unobstructed flow out the stove. As an experiment I burned the stove without it to observe the effect. Stove temps were significantly limited while flue temps shot up.

Is there any disadvantage to the T-fitting? It seems a great option and I wonder why I don't see them on here more often, just wondering

No disadvantages that I know of other than being more bulky looking. I saw one on another stove and thought it was a really neato idea.


Greg

 

[bholler]

I really like the idea of the T-fitting for easy cleaning...and the venting from the back (as I want to heat water etc. on top), do you find it reduces the draw though? But then I believe your chimney pipe is much taller than mine would be?

With a short chimney i would get a top vent stove and go straight off thr top and out. Most stoves are to pull baffles ect to clean from the bottom. And honestly i find it easier to control dust that way than with a tee.

 

[bholler]

Is there any disadvantage to the T-fitting? It seems a great option and I wonder why I don't see them on here more often, just wondering

Yes it is a 90 that reduces draft. Now if you have a rear vent stove absolutly put a tee behind it. But most new stoves are top vent and most top vents beath easier

 

[begreen]

How much stove pipe would be connecting to this 8 or 12' chimney pipe? If the stove pipe is <8' I agree with bholler, top vent it for the best draft.

 

[bholler]

How much stove pipe would be connecting to this 8 or 12' chimney pipe? If the stove pipe is <8' I agree with bholler, top vent it for the best draft.

Yeah i was assuming that height was total height. But you are absolutly right if there is 5 feet of pipe or so that changes things allot

 

[enigmablaze]

How much stove pipe would be connecting to this 8 or 12' chimney pipe? If the stove pipe is <8' I agree with bholler, top vent it for the best draft.

Oh sorry, let me clarify (sorry I'm so green I'd probably form creosote...lol tacky joke).
The room from floor (no hearth required as it is concrete slab floor) to ceiling is just a hair over 8' tall. The roof itself is about maybe 2" thick (just wood planking with rubber roof on top). After that my understanding is that it would only need 2' of pipe above the roof for code since it would be (just barely) over 10' away from the house. Once you subtract the height of the stove I'm guessing that would be about 6' inside and 2' outside...or obviously more if I'm going to need it! I really want this to be correct.

 

[enigmablaze]

Yes it is a 90 that reduces draft. Now if you have a rear vent stove absolutly put a tee behind it. But most new stoves are top vent and most top vents beath easier

I see what you mean. Cleaning it is not a huge consideration to me as we will likely hire a sweep to do it, however being able to warm food/water etc. on top IS highly important to me and a huge component of our decision to get a stove...hence that disk on top for heating becomes pretty valuable on such a tiny stove as the Morso 1440. Does it make a very strong difference to have it in the back? This stove can vent either way but although I prefer the look of venting out the top I would hate to lose that stovetop space. Then again though, if the stove won't fire correctly we won't be using it much to speak of anyway :/. I'm just not sure how much a difference it makes.

 

[enigmablaze]

A 6 inch flue on a really tiny stove with only a .7 cubic foot firebox is ~way~ oversized. So Morso designed a cast iron cup shaped "one way" restrictor that partially obstructs the potential of any backdraft flow while allowing a smooth unobstructed flow out the stove. As an experiment I burned the stove without it to observe the effect. Stove temps were significantly limited while flue temps shot up.

Okay please help me understand, does that mean that the very small size of the stove can get away with less "ideal" draft situations than a bigger stove because the piping is "too big" for it anyway? Or does the smaller size mean my flue will not get as hot and my draft will be even worse than a larger stove with the same flue setup?

 

[bholler]

Oh sorry, let me clarify (sorry I'm so green I'd probably form creosote...lol tacky joke).
The room from floor (no hearth required as it is concrete slab floor) to ceiling is just a hair over 8' tall. The roof itself is about maybe 2" thick (just wood planking with rubber roof on top). After that my understanding is that it would only need 2' of pipe above the roof for code since it would be (just barely) over 10' away from the house. Once you subtract the height of the stove I'm guessing that would be about 6' inside and 2' outside...or obviously more if I'm going to need it! I really want this to be correct.

Well you would need to be 3 feet above the roof penatration

 

[bholler]

Okay please help me understand, does that mean that the very small size of the stove can get away with less "ideal" draft situations than a bigger stove because the piping is "too big" for it anyway? Or does the smaller size mean my flue will not get as hot and my draft will be even worse than a larger stove with the same flue setup?

Draft could be worse with a smaller stove. Combine that with a short chimney and you are going to need all the help you can get. Which is why i think top venting would be best.

 

[enigmablaze]

Well you would need to be 3 feet above the roof penatration

Oh, of course...I was thinking about having to beat whatever is within 10' by 2'. So looks like 9' of pipe/chimney in total. I just read in the manual that this stove recommends but does not require 16' total.

Is it acceptable or wise to have more like 6' of chimney above your roof?

 

[enigmablaze]

I should mention that we were going to do Class A chimney

 

[WoodyIsGoody]

Okay please help me understand, does that mean that the very small size of the stove can get away with less "ideal" draft situations than a bigger stove because the piping is "too big" for it anyway? Or does the smaller size mean my flue will not get as hot and my draft will be even worse than a larger stove with the same flue setup?

The second idea is correct. A larger flue has more surface area and dissipates more heat resulting in lower flue temps and less draft.

Are you sure Morso requires a 6" flue? I would install the smallest one that meets all approvals. I would also use tripod roof supports to extend the flue so it is at least 12' if not more.

 

[bholler]

Is it acceptable or wise to have more like 6' of chimney above your roof?

Yes you just have to check the support requirements of the chimney system

 

[Squirrely]

Are you sure Morso requires a 6" flue? I would install the smallest one that meets all approvals.

Consider the BK Princess with a 2.8 cu ft firebox. That's four times larger than a Squirrel firebox, and yet it uses the same size 6 inch flue. The Squirrel comes from the factory with a 6 inch collar, but from operating it I believe it would work just fine with a reducer, a 4 inch flue, and with the internal restrictor removed.

I'd email Morso and ask them. They'll know for sure.

Greg

 

[bholler]

Consider the BK Princess with a 2.8 cu ft firebox. That's four times larger than a Squirrel firebox, and yet it uses the same size 6 inch flue. The Squirrel comes from the factory with a 6 inch collar, but from operating it I believe it would work just fine with a reducer, a 4 inch flue, and with the internal restrictor removed.

I'd email Morso and ask them. They'll know for sure.

Greg

That internal restrictor is to help hold heat in the firebox to increase heatoutput. The increased firebox temps also gives you more complete combustion and allows the secondary combustion to happen. You dont want to remove it. And in europe many stoves run on flues close to 5" very very few run on 4" i doubt yours would work well at all.

 

[enigmablaze]

The second idea is correct. A larger flue has more surface area and dissipates more heat resulting in lower flue temps and less draft.

Are you sure Morso requires a 6" flue? I would install the smallest one that meets all approvals. I would also use tripod roof supports to extend the flue so it is at least 12' if not more.

Rats, I was hoping I'd have an advantage there .

Yes, I read part of the manual today and it specified the 6" flue...it appeared to me...though it's possible I did not recognize something.

 

[enigmablaze]

Yes you just have to check the support requirements of the chimney system

This might be ridiculous, but if 16' is ideal...would it be crazy to have 10' of chimney above the roof??? Would it be too cold being that tall outside?

Seriously, what do people usually do with single story installations? Am I missing it?