Poor Man's Block off plate - II

[Danno77]

Hmmm... makes me wonder if it could be held up with magnets,

Not sure, but I think heat causes a loss of magnetism. Someone on this site will know for sure....

It does, but not at these low temps. Many a flu thermometer is held on with magnets. I overfired once and my magnet gave out a little and never recovered. It kinda slid down the pipe. Now it sits on the stovetop. Still sticks, just not like it did.

 

[mhrischuk]

magnets and heat don't mix

 

[begreen]

My understanding is that magnets don't lose their magnetism until north of ~900F. If your lintel is hotter than this, call 911!

 

[NCredneck]

If you have an existing damper assembly and have to cut or notch some of it out for the liner, can't the remaining damper be used as a block off plate? I was originally going to construct one but I got to thinking the damper could be used for the same thing. I guess the biggest issue would be how hard it is to get the roxul up there but figuring that out might be easier than constructing and mounting a plate.

 

[rakuz66]

I get so many conflicting reports on these block off plates. Not trying to create drama, just some things people have told me.
1. Don't use insulation in the chase if you have a blower, it will only blow the nasty stuff into ur house.
2. Not necessary if you have an insert with surround panels and a positive connection( full ss liner)
3. Could create a fire hazard.
4. Won't give you back as much as it takes to install.
5. You want warm air in the chimney to help decrease creosote build up.
6. Just for free standing stoves.
7. No need if you have an interior chimney.
8. If ur draft is working fine, don't mess with anything.
9. Block off SS liner at top of flue with insulation and your fine.

 

[begreen]

It is confusing, especially when confounded by conjecture. Welcome to the internet.

 

[EJL923]

One thing is for sure, you want to block air flow around the exterior of the liner. Some people do it at the top, some at the bottom, some both. I have been going back and forth about sealing the top. My installers originally siliconed the top plate to the top of the clay tile, like a lot of people do. I read through my Jotul manual, and they say specifically not to seal the top. Even though the flue will be be warmer when sealed from the top, i tend to agree with the manual and the issue is safety. What if something were to happen to the liner, and gases were allowed to escape? They would have nowhere to go. I am guessing that is the reason for this. My top cap has since slightly seperated from the top clay, but still has flanges to keep it water proof. I am hesitant to seal this back up, which is why i made the poor mans block off.

I went back to edit this post, when i realized they were talking about amount a prefab fireplace. I did end up sealing at the top, no problems.

 

[mhrischuk]

10. Keeping the heat in the room/house with insulation and a blockoff plate keeps insulation from getting into the room and keeps heat from leaving the room through convection into the chimney space. Heat rises, cold air falls. Convection occurs. The masonry in your chimney will absorb the heat and won't give it back. By not allowing convection to occur, more heat is available for your room/house.

I read this in a rocket science book.

 

[NCredneck]

Is there a problem with using the existing damper as a block off plate, providing you can get the insulation above situated well enough to stop air flow?

 

[DanCorcoran]

"I read this in a rocket science book. "

Kudos! I'll be using this myself, but just want to give credit here.

 

[EJL923]

no problem using the damper as a block off plate, but it is much easier to cut sheet metal than the extra thick damper in the existing fireplace.

 

[rakuz66]

10. Keeping the heat in the room/house with insulation and a blockoff plate keeps insulation from getting into the room and keeps heat from leaving the room through convection into the chimney space. Heat rises, cold air falls. Convection occurs. The masonry in your chimney will absorb the heat and won't give it back. By not allowing convection to occur, more heat is available for your room/house.

I read this in a rocket science book.

I'm not trying to be a smart a**, just trying to figure out what might work best in my situation.

 

[mhrischuk]

Then make 10. the only answer. You don't have to do it at all. As we all have read on here many installers just put in a bare flex and go home. I hate it when the word "professional" or "professionally installed" is used as it often means the cheapest way at the highest price and they pocket the difference. Professional crooks.

Disclaimer.... not all dealers and installers are like that so it's important to become educated before talking to them. You can pick out the good ones that way.

Insulating the liner takes care of the cold air in the chimney issue. That's the whole point of insulating the liner. Now why would you want to use your stove heat to heat the chimney masonry if you already have the liner insulated?

 

[rakuz66]

So, #10 would be????

 

[mhrischuk]

So, #10 would be????

https://www.hearth.com/econtent/index.php/forums/viewthread/80548/P22/#967702

 

[rakuz66]

Yeah, probably right, it's just gonna be a beeeach to make one in my chase.

 

[mhrischuk]

It's an option, not a necessity.

 

[rakuz66]

I f you don't mind me asking, whereabouts in SE Pa, do you live? because I live in SE Pa as well.

 

[mhrischuk]

I'm in Delaware county in Bethel Twp. I'm just on the PA-DE border not far from where I-95 goes into Delaware.

 

[rakuz66]

Cool, you can buy me discounted wine.

 

[mhrischuk]

Total Wine is right down the road.

 

[stejus]

I did mine with the stove in place. Without pics I have no idea whether or not you can. It was tight, but I managed.

Here's a view of what I am against. I can reach up there and stuff Ruxul in there like you did. My bigger challenge is putting in the plate. I don't have much room to measure for the right cut. Can I support the Roxul with stips of metal just layed in there like your support strips? I'd love to get the plate in, but Im not sure I can get up there. Any tips?

 

[begreen]

The best job with the least hassle will be to disconnect the stove and slide it forward to give yourself working space. You can put some blocks or planks down on the hearth extender, then use a plate of metal to slide the stove on to make it easier.

 

[atcomo]

Read this thread and today I installed the poor man's block off plate. What a horrible ...disgusting...job
The Roxul (like fiberglass insulation) is horrible to handle. Anyway its done.
Only question I have.....it only took about 3/4 of batt....should I have stuffed more into the smoke chamber?
I only laid a single batt above the damper plate.
Have not finished with sheet metal yet. Still trying to decide if I should add more Roxul. What are your thoughts?

 

[mhrischuk]

I got about 3 batts up there. I had full access though as the stove wasn't in place yet. The more the merrier.