Block Off Plate Question

[Fire Bug]

Hi Everybody,
I have,(yes another question), this one concerns block off plates.
I have had a Heat & Glow FB Grand Propane Fireplace Insert installed by,(S& T Coombs Inc., Blakeslee, Penna.), in my upstairs existing wood burning fireplace that has a terracotta flue liner.
When the installers put the unit in, they ran a flexible tube to the high wind termination cap on top of my chimney to carry the exhaust outdoors from the insert.
They also ran a approximately three foot piece of flexible tube into the flue for the units intake air.
My question; they did not take of the existing fireplace damper door, they just left it open and stuffed fiberglass insulation around the tubes that go through the damper opening.
As far as I know, no block off plate was installed by them.
My question about block off plates originates from ELK's comment about block off plates on my thread about Overfireing Wood Stoves.
I didn't want to change the subject of that post so I started this one.

Thanks,
John

 

[MrGriz]

It doesn't sound like they installed a proper blockoff plate. I'm not sure about a propane fireplace insert, but my question would be about taking the intake air from the chimney. Maybe I'm interpreting the set up wrong, but that doesn't sound like a good idea to me....

 

[BrotherBart]

Both termination of the intake pipe in the chimney and the use of unfaced insulation to block-off the opening above the fireplace are acceptable installation methods according the the installation manual. The termination cap has an opening that allows intake air into the chimney.

In other words, they did it according to manufacturer's instructions.

 

[MrGriz]

I'm surprised to hear that you can take intake air from the chimney. No matter how hard you try, you learn something new every day...

 

[BrotherBart]

The setup they show in the manual has a top sealing plate on the top of the chimney. There are two short pipes coming down out of the termination cap. You hook a top to bottom flex liner to one of them for exhaust and then have the option of putting in a top to bottom flex for intake air or using the three foot piece that comes with the kit and letting it suck intake air down the chimney from the other short pipe at the cap.

The part that seems wierd to me is that a lot of the intake air pulled in looks like it would be from the exhaust exiting the other pipe. Of course it is that way with regular direct vent pipe also.

 

[elkimmeg]

Let's face it a half a** way of doing it. Pulling a combustion air threw that smelly creosote laiden chimney May be acceptable by the manufacture specs but. I would nebver have that setup in my home. I would have the combustion air feed in its own separate flue and termination cap exit 9" lower that the exhaust vent. I would place material that does not collect the cresote smell and is is water resistant so that normal chimney condensation does not get into the fiber glass weigh it down causing it to sag and loose the block or air passage capabilities.

But that's just me I would never be party to half ass installations/. Taking it one step further I'll bet you gas liner is Alumium Again aceptable code wise but probably withan 8 year warranty and will be useless at the end of the warranty period. I would use Styainless steel and forget about in my life time and not have to pay for 4 additional removals and intsallation of alnmium liner

So what I do with my inspections is make sure the liner warranty is noted in my final notes. You should see the expressions that it will require replacing in 8 years Most homeowners were clueless and wished they had a ss liner. One asked who will know I said it is now entered into public record should you sell the home and the banks or home inspector review the records it is public knowledge. I also have made a list the past 4 years I add to again public records. Most installers have been questioned enough to at least make owners aware of options. They get tired of have to explain themselves when the homeowner is told the limit of the warrranty and prodict life expectancy..

Is this the same jotul you are having so much trouble with? Did the retailer take the time to explain installation options and the reasons behind them? Since the changed the u fuel usage
from wood to gass naturally a full inspection of that chimney was and through cleanning prior to installation as per code?

 

[MrGriz]

The part that seems wierd to me is that a lot of the intake air pulled in looks like it would be from the exhaust exiting the other pipe. Of course it is that way with regular direct vent pipe also.

That was my thought. With the intake air being pulled from the chimney like that, I would think it would be sucking a good percentage of exhaust. The set up Elk describes sounds like a much better idea.

 

[Shane]

923GK termination from Simpson Duravent offsets them pretty well. As for the intake liner being cut off short is actually a preferred install method for installing many DV inserts due to the restriction of intake air that the corrugated aluminum liner causes. Case & point is the 34DVL by FPX. Was having trouble with one not getting adequate air this year and tech had me cut the vent so that it extended past the flue tile and that solved the problem. As for the blockoff plate, in my opinion (after being educated here) it should be there and made of sheet metal. However one has to consider that the AHJ and manufactureres install instructions often play a major part in whether this is actually a requirement for your area.

 

[Fire Bug]

Hi Guys,
Both the insturctions for my H&G Insert and my Jotul Gas Stove show two ways of running the aluminum corrigated liner.
The H&G manual shows using the top to bottom aluminum linner for the exhaust and top to bottom aluminum corrigated linner for the air intake. Both lenghts terminate at the high wind termination cap.
The second method in the H&G Manual shows a full lenght aluminum corrigated linner for exhaust and a at least three foot piece of aluminum corrigated linner for air intake.

The Jotul manual, shows the use of two full length corrigated linner from top to bottom for exhaust and air intake.
The second install method, in the Jotul Install Manual, show another method of using a full length aluminum corrigated linner for exhaust and a minimum of at least three feet of SS Corrigated linner for the air intake with a block off plate.
The Jotul Stove, has the Co Axle Stove pipe going into a terracotta thimble trough my fieldstone wall behind the stove into my chimney.
There is a square plate that attaches to my fieldstone wall that the Coaxle stove pipe goes through. I believe this is the block off plate in this situation.

Both these installations where done by factory authorized dealers, Tall Pines Farms Inc., Kingsley, Pa. for the Jotul Stove and S&t Coombs Inc., Blakeslee, Pa. for the H&G Insert. Neither suggested any other methods of installation or material.

I am try to comprehend how exhaust gases can enter the air supply and hence into the stove through either install method.
If you use two full length liner to the top, it is sealed from top to bottom.
If you use one full lenght linner to the top and one three foot piece into the terracotta flue liner, the terracotta flue linner is sealed at the top by a plate that is sealed with silicone underneath it so where would the unwanted exhaust enter?
The high wind termination caps have the exhaust slots on the top/sides of the cap with the smaller intake slots on the bottom underside of the cap.
I am sure in certain atmospheric conditions, some exhaust can enter the intake slots on the bottom underside of the cap no matter what linner install you have.
I have had my chimneys cleaned by a sweep before these installs, even though S&T Coombs said for the insert install, it wasn't necessary.
When shoping for a stove, one dealer said they have an independent sweep who comes out and washes down the flue with baking soda. I believe this is to neutulize the acid in the chimney linner if your burn coal which, I believe, produces sufuric acid and can be detrametal to a aluminum liner.
I have never heard yet of a dealerthat utilizes SS linner for gas installations of stoves, inserts, or fireplaces, and believe me we talked to many, many, before we made our purchases of these units.
The install prices for these units were, in my opinion, out ot this world and are way over priced usigng aluminum corrigated liners, I could not imagine anyone could afford the SS liner installation even if offered by all these dealers.
We again were never given any other options for install. According to all the dealers, the aluminum corrigated linner was the way these direct vent items are installed.

John

 

[BrotherBart]

Both done by the book by reputable dealers. I don't see the problem with that.

As to life of the liners, I know that Selkirk warrants their aluminum liners for gas appliances for life. Of course it is pro-rated after 10 years and has all of the weasel woods in the warranty that they all use.

 

[jtp10181]

That's how we do 100% of gas inserts. We do make the customers get their chimney cleaned first though.

Fire Bug, the cap has an exhaust and a fresh air collar underneath it. So when then short liner is used for fresh air, the cap allows combusion air into the flue and the fireplace draws it down and into the stubbed up liner.

 

[elkimmeg]

Common alumium gas liners come in two thickness .010 and .012. the 0.12 thickness is usually the 10 year warranty product the 6 to 8 year warranty is for th 0.10 thickness liner

To give you an idea in cost the 0.12 cost about $3 per ft this is for 3"
0.10 3" cost about 2,25 per ft
0.10 4" cost about 3.25 per ft

Actually I stumbled acrost this revelation while searching for a carbon monoxide leak complaint. I was able to isolate the leak to the gas stove. The gas stove was only about 7 years old. The connection at the flue collar seemed good. Finally the stove was pulled out and I aimed a very bright flashlight up the liner. Well ! the light was bright enough to see thousands of tiny pin holes in the alumium liner. It was replaced with a stainless steel liner. Yes that's right ,one can use the same liner used for pellet stoves wood stoves or cloal stoves but 3 or 4"
those liners are also listed for gas stove applications. Most carry a 25 year to limited life time warranty.

 

[jtp10181]

Elk what is this block off plate rules you keep talking about for wood inserts? I cannot find anything about it in our install manuals.

(broken link removed)

Unless this is what you are talking about? (Page 9)

2. Seal either the damper area around the chimney liner
with a high temperature sealant or the fireplace front with
fiberglass batting.

 

[Fire Bug]

That's how we do 100% of gas inserts. We do make the customers get their chimney cleaned first though.

Fire Bug, the cap has an exhaust and a fresh air collar underneath it. So when then short liner is used for fresh air, the cap allows combusion air into the flue and the fireplace draws it down and into the stubbed up liner.

Thanks everyone for your feedback.
I feel a little more at ease with the knowledge that the installations were done in accordance with the Manufactures Installation Manuals even though these might not be the best or most expensive methods.
I definitely would prefer to have SS liners installed instead of aluminum for longevity purposes.
I also would have had the liners exstended to the very top connection on the high wind termination cap but as I have no options in materials or installation methods were made avaiable to me by numerous, potential, installation dealers. They all pretty much had the same installation methods and matierials.
jtp, if I am correct, in your post you said the exhaust is on the top of the termination cap, and the intake vents are on the lower bottom. Am I correct in my interpretation of your post.
If I am correct, even if the intake line was connected to the termination cap, (like the exhaust line), I would still be pulling in exhaust through the intake tube and into my unit the same as if the stub tube is used?
My reason for asking; sometimes I can get a very slight wiff of what to me smells like "spent or burnt" fumes when I am close to the unit. This does not happen frequently but on occasion.
I do have full sofit ventilation on my home and I believe sometimes the spent propane exhaust gases find their way under the eves of my home and enter my attice through the full perforated sofit material and the rafters of my attic.
When I had my wood burner, sometimes I would get a wiff of wood smoke in my home when the wind was just right and carry the smoke from the top of the chimney and curl it under the eaves of my house.
I would have to say, I would rather get a whiff of wood smoke over a whiff of spent propane exhaust. It stinks!!

John

 

[jtp10181]

Yes the exhaust comes out the top of the cap and there are some small louvered slots at the bottom that let the combustion air in.

with the short combustion air liner there is basically a hole at the top of the chimney letting air down into it. It is possible for some exhaust to get into there if the wind is blowing it back down. Heat rises, it should go up instead. But if it did get into the chimney, from there it could come down and leak out around the edges of the surround panel and into the house. If the combustion air liner went all the way up and was attached to the cap anything that came through the cap would only have one place to go, inside the fireplace.

 

[elkimmeg]

To answer you question code requires when removing an esisting piece that an alike piece be used to substiture its replacement since a damper is metal and alike metal peice should be used to replace it. Stove manufactures are wrong listing Fiberglass insulation to substitute a cast iron damper plate First of all fiberglass bats are only certified for wall cavity insulation At no point has the manufactures ever tested and listed it fto be used in any other situttion. IT's heat range can not withstand a chimney fire being around 700 degrees due to aditives used in the manufacturing process It is not a permanent fix as moisture from chimney condensation in the summer weights it down causing it to sag and fall out aand loos sealing but finally here is the code language there is also language about preventing intrusion of room air into the chimney.



2006 direct cut and paste

RESIDENTIAL
CODE®
FOR ONE- AND TWO-FAMILY DWELLINGS

Part V — Mechanical
CHAPTER 18 Chimney& Vents
MECHANICAL

M1803.4 Connection to fireplace flue. Connection of appliances
to chimney flues serving fireplaces shall comply with
Sections M1803.4.1 through M1803.4.4.

M1803.4.1 Closure and accessibility. A rigid noncombustible
seal shall be provided below the point of connection to prevent
entry of room air into the flue. Means shall be provided
for access to the flue for inspection and cleaning

 

[BrotherBart]

It is not a permanent fix as moisture from chimney condensation in the summer weights it down causing it to sag and fall out aand loos sealing but finally here is the code language there is also language about preventing intrusion of room air into the chimney.



2006 direct cut and paste

RESIDENTIAL
CODE®
FOR ONE- AND TWO-FAMILY DWELLINGS

Part V — Mechanical
CHAPTER 18 Chimney& Vents
MECHANICAL

M1803.4 Connection to fireplace flue. Connection of appliances
to chimney flues serving fireplaces shall comply with
Sections M1803.4.1 through M1803.4.4.

M1803.4.1 Closure and accessibility. A rigid noncombustible
seal shall be provided below the point of connection to prevent
entry of room air into the flue. Means shall be provided
for access to the flue for inspection and cleaning

Which is taken care of with the insert surround being sealed with unfaced insulation and the damper being stuffed with unfaced insulation as directed by the UL listed installation in the manual for the insert. The surround is 1.) Rigid 2.) Non-combustible and 3.) Tested to the UL standard the insert is listed for. And apparently meets the local codes the inspector applied.

 

[jjbaer]

It is not a permanent fix as moisture from chimney condensation in the summer weights it down causing it to sag and fall out aand loos sealing but finally here is the code language there is also language about preventing intrusion of room air into the chimney.



2006 direct cut and paste

RESIDENTIAL
CODE®
FOR ONE- AND TWO-FAMILY DWELLINGS

Part V — Mechanical
CHAPTER 18 Chimney& Vents
MECHANICAL

M1803.4 Connection to fireplace flue. Connection of appliances
to chimney flues serving fireplaces shall comply with
Sections M1803.4.1 through M1803.4.4.

M1803.4.1 Closure and accessibility. A rigid noncombustible
seal shall be provided below the point of connection to prevent
entry of room air into the flue. Means shall be provided
for access to the flue for inspection and cleaning

Which is taken care of with the insert surround being sealed with unfaced insulation and the damper being stuffed with unfaced insulation as directed by the UL listed installation in the manual for the insert. The surround is 1.) Rigid 2.) Non-combustible and 3.) Tested to the UL standard the insert is listed for. And apparently meets the local codes the inspector applied.

Well, just because it's written in code some where doesn't mean it passes the "sanity test"........let's look at that: a 3' or so air intake sticking up into a chimney with the exhaust vented out the top of the chimney and the chimney top open so that outside air can enter the chimney and be sucked into the air intake......now, last time I looked, insulation around the surround doesn't stop carbon monoxide or other gases from passing through them into the living room........hence the need for the block-off plate. The plate stops any CO that travels back down the chimney from getting into the living room and it can only go one place instead: into the air intake tube and the stove and back outside.....

lets face it...code fails to address block-off plates because anyone who has put one in knows they are a real PITA...I put mine in and I can vouch for that...and that's why they don't mandate them...but they should....