Draft Question?

[Cap-n-Cray]

Hi,

First post, but I have researched here before, lots of good info. I just installed a Pacific Energy Summit Insert into a zero clearance fireplace surround. Basically a brick wall with an enclosure inside. The original zero clearance fireplace had draft problems. It had a triple walled 10 inch ID stack pretty much straight out the roof. I was able to connect to the original stack using a 45 degree 6 inch SS Simpson Dura-Vent pipe turned almost straight from the stove and a 60 inch flexible SS Simpson Dura-Vent pipe with an adapter to the 10 inch triple walled stack.

Everything is working great and the performance of the Summit is better than I could believe. And here is the but. But I am wondering if the draft is not what it should be. When I open the door slowly sometimes I get a small puff of smoke. Can that be a sign of not enough draft? It also takes some time to start.

Two thing that might be contributing to the problem. The 6 inch to 10 inch connection and the over all length of the stack. The total length of the stack is about 13 feet. Is that too short? Does the increase in size from 6 inch to 10 inch reduce the draft? The cap is a wind directional cap.

Should I increase the length first at the top of the roof by adding more 10 inch pipe or run 6 inch pipe all the way inside the 10 inch pipe? I believe there is plenty of combustion air. On the other side of the enclosed space there is a pellet stove and there is plenty of vented air that can be sucked in from both rooms.

TIA for any advise.

Cary

 

[begreen]

Yes, you have dramatically increased the cross section of the pipe which is reducing draft. Also, ZC fireplace flue pipe is not rated the same as required by the woodstove. The insert should be installed as directed in the manual with a full 6" liner for the ZC installation. See page 6 of the manual:

A full stainless steel rigid or flexible flue liner meeting
type HT requirements (2100°F) per 1777(U.S.) or ULC
S635 (Canada) must be used for both safety and performance.
The liner must be securely attached to the
insert flue collar and the chimney top.

13 ft is marginal. Is there room to insulate the 6" liner? If at all possible, do that for added safety and increased draft. The flue will stay hotter which will help it stay cleaner too.

 

[PunKid8888]

I agree, anytime you increase cross sectional area you decrease velocity. 6in dia approximately 28insq, while 10in dia is 78insq. so you have effectively increased your pipe by almost 2.5 times. I don't think adding any height will help, only reducing that cross sectional area will

 

[Backwoods Savage]

Welcome to the forum.

Along with the above, do make sure you open the draft full and wait a minute before opening the firebox door. This will start the smoke and gasses shooting up the chimney to create more draft so that you won't get that puff of smoke when you open the door slowly.

 

[LLigetfa]

I don't think adding any height will help, only reducing that cross sectional area will

While there's merit, I don't fully agree. Reduced diameter helps if there is too much heat loss during the ascent. Increased height will give better draft if there isn't significant heat loss it the upper section.

Opening the draft shortly before opening the door does help to get things moving by heating the chimney but if you have an OAK and negative pressure situation, it can also worsen the puffing as the OAK will push smoke into the room. Make sure the house pressure is balanced.

 

[Cap-n-Cray]

Thanks for the answers. I was told by the shop I bought the stove from, even after showing them photo of the existing stack, that it would be OK to tie into the existing pipe. They even sold me the adapter. It has always made me nervous. I have used a infrared temp gauge to read the pipes temp. It does not get that hot, but still didn't seem correct.

I am going to run new 6 inch Dura-vent SS Double walled rigid liner in the old 10 inch stack pipe keeping it spaced to the center. I plan on using the new existing 6 inch Dura-vent SS flex and 45 Degree to connect to the new straight sections. Would it be necessary to insulate the flex because it is not double walled? It is at least 20 inches from anything, but does get hot.

The insert's manual says a minimum of 15 feet for the chimney height. With the new pipe I would be at 11 feet. Would that be OK? If I add 4 more feet it would be sticking up really high (6 feet) above the almost flat roof. I plan on remodeling the house someday so this is a temporary fix.

Also is a clean out "T" necessary?

Thanks,

Cary

 

[Cap-n-Cray]

I ordered two 4 foot 6 inch Dura Vent SS double walled pipes which I will run inside the 10 inch stack with a new cap and flashing. That makes a total of 13 feet stack height. Any guess if that will be enough? It will be 2 feet short of what the manual recommends. I don't want to go too high above the almost flat roof. It will be a little less that 4 feet higher above the roof.

Thanks,

Cary

 

[Backwoods Savage]

Cap, 6' above the roof should not be a problem other than that you will have to support it.

On the 13' chimney rather than 15', you might get by with it. It will somewhat depend upon the lay of the land and other buildings and trees in the area. Sometimes it works and sometimes not. I am about 2' short too but get along just fine.

 

[begreen]

I ordered two 4 foot 6 inch Dura Vent SS double walled pipes which I will run inside the 10 inch stack with a new cap and flashing. That makes a total of 13 feet stack height. Any guess if that will be enough? It will be 2 feet short of what the manual recommends. I don't want to go too high above the almost flat roof. It will be a little less that 4 feet higher above the roof.

Thanks,

Cary

Is this class A pipe? You don't need DuraVent. If Simpson, DuraLiner is what you need. ClassA is not required and will create additional issues with weight and support. DuraVent is not designed for this application.

 

[Cap-n-Cray]

Thanks for your input BeGreen, I am a general contractor, but all this stove/fireplace stuff is new to me.

The pipe I ordered is DuraLiner or at least that is what the catalog calls it. The problem I have is the brick faced wall that the original fireplace was in. The original owner did not do anything to code. I am trying to put an insert into a brick wall. My main source of information has been the dealer that sold me the stove and he is on the other side of the pond (Sound) so to speak.

I am also trying to plan for the future as I will be remodeling and I want to reuse the stove and pipe again if possible.

Thanks,

Cary

 

[begreen]

If the insert is going into an approved ZC fireplace and it's getting connected to DuraLiner, you're ok.

 

[Cap-n-Cray]

BeGreen,

That is part of the problem. The stove is in a brick faced cavity. Two brick walls front and back inside the house. There is a pellet insert stove offset on the other side of the cavity. I have made the cavity fire proof with a cement floor to bring the floor height up to the outside brick hearth. I have lined the inside with backer board to fire proof it where needed. Also the cavity is mostly brick on a slab foundation.

I have used the pellet stove for over a year with no problems. It is in the place where originally there was a zero clearance fire place that was removed and replaced with a propane insert. The propane insert was not adequate for heating the house and very inefficient. The propane insert was installed in the cavity. So it was replaced with the pellet stove insert.

The second original fire place was a zero clearance, but it did not function correctly and had draft problems. Nothing would fit into it because of the way it was design, so it was removed. I can actually get inside of the cavity while both the pellet stove and fire place insert are running. I have check temperatures with an infrared temp gauge. No surface has ever read above 90 degrees, other than the stoves and exhaust stacks. There is no chimney other than the existing two 10" tripled walled stacks that go up through a box on the roof.

I have attached some photos of the set up. The whole set up is kind of a hybrid. As I have said this is temporary till I can remodel the house. I just need it to work and be safe till the remodel. It is the only heat for the house other than a second free standing pellet stove.

 

[Cap-n-Cray]

Here are some more photos:

 

[begreen]

Oy, this is a quandry. The pictures put a whole different light on this subject. Thanks for posting them.

I was assuming that a) the ZC unit was still in place and b) the ZC flue was still connected to the ZC fireplace. Liner is not supposed to be used in this circumstance. It is no better than single wall pipe in that cavity. And from the looks of things up top where it enters the 10" pipe, clearances are less than the 18" required for single-wall. Also, the insert is not approved for this type of installation. The insert is only approved to go into a full masonry fireplace or an approved ZC fireplace. This is not the place for an insert installation unless the ZC unit is put back in place and the 10" pipe correctly reconnected. Then the liner would be shielded when run up in the 10" pipe.

As things stand, I'd be tempted to a) replace the insert with a freestanding, rear-vent stove b) remove the old 10" pipe and replace it with 6" class A, then run a double wall connector from the freestanding stove up to the new Class A pipe. But perhaps others will have some alternative suggestions.

From the PE Pacific Manual:
Your Insert is designed to be installed into a masonry or
factory built zero-clearance fireplace. The masonry fireplace
must be built according to the requirements of the Standard
of Chimneys, Fireplaces, Vents and Solid Fuel Burning
appliances, N.F.P.A. 211 (Latest Edition) or applicable
National, Provincial, State or local codes. The installation
shall conform to CAN/CSA-B365, Installation Code for Solid-
Fuel-Burning Appliances and Equipment. The factory built
zero-clearance fi replace and its chimney must be listed per
UL 127 or ULC S610 standards.
Warning: Under no circumstances is this heater to be
installed in a makeshift or "temporary" manner.

 

[stoveguy13]

dont use that unit the way it is now you are sitting on plywood from the looks of the pic that install is not even close to meeting code!

 

[DAKSY]

HOLY SH******T!
That bad boy has the word DEATH written all over it!
You'd better consult a hearth professional before you light a fire,
& get a safe install...
Your neighborhood will thank you...