Advice on block off plate

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RSNovi

RSNovi

Feeling the Heat
May 12, 2010
421
Michigan
Hello All,

I have searched and read many posts on the block off plates. The fabrication should be the easy part. I have a whole bunch of Roxul too.

My problem is getting the stove out and back in. From what I recall the installers had to drop the liner down once the stove was in. I also have a offset box as well.

Can you compress a flexible liner enough to pull the stove out? Here is what I have from the outside. I am tempted to rip it all out, but I have a lot invested in this setup.

ImageUploadedByTapatalk1415908302.722659.jpgImageUploadedByTapatalk1415908332.344342.jpg
 
If clearances are tight it can be challenge. From the description I think I would leave it alone.
 
Yeah, the surround does come off pretty easy. I tried to stuff some insulation around the liner where it enters the chimney. It was too tight to even get much of that done.
 
RSNovi said:
From what I recall the installers had to drop the liner down once the stove was in. I also have a offset box as well.
Click to expand...
how did they secure it though the offset box if they dropped it in after the stove was slid in? That would concern me way more than the lack of a blockoff plate
 
I was considering the same thing for a long time. Finally I pulled off the surround to take a look and saw that it wouldn't be too bad. My insert sits in a rather large fireplace opening, so there was a fair amount of space to work in. I disconnected the chimney liner, and was able to push it up and inch or so, enough to get the insert out. Mine is in a raised hearth, so I built a little box to hold the insert while I worked. That way I didn't have to lift it at all. Just slide it out of the fireplace, and onto the box, then slide it back in when finished. I didn't fab a plate. I just stuffed a bunch of Roxul into every nook and cranny until I was satisfied. I think it has made a significant difference in the amount of heat I get out. But I am reserving final judgement until I run it a little more.

-Jim
 
Just a guess but most offsets made for a flex liner have the adjustable ring you tighten down to the flex liner on top, if they dropped the liner down then reached in and wiggled it in the offset box top and tightened that ring then slide the insert the rest of the way in at an upward angle and then attached the offset box to the insert with the L brackets. Not a job I would want to do, I am getting a hand cramp just thinking about it.
 
I know there are some long straps from the offset box that go into the stove and those straps are bent against the roof of the stove. I am not sure how the liner connects to the offset box. I think I remember them getting some screws in the liner to the box. It is tight and I can't even get my head in there to look at anything. I had to use a mirror when I was trying to get the Roxul in there. I know the installer didn't want to use an offset box, but he thought it was the only way.

To clean it I shove a vacuum up in the box because it catches all the debris after cleaning with a soot eater.
 
Last edited:
mellow said:
I hate offset boxes with a passion, usually you have to have a 25+ ft chimney to get a half way decent draft with one of those things hooked up.

How are you cleaning the offset box currently?

My vote would be to leave it alone, the roxul will help keep some of that heat in the ZC.
Click to expand...
The chimney is about 30'. I cleaned it for the first time this year. It drafts quite well.

Thanks for all the thoughts. Maybe I should try stuffing more Roxul on top of the stove.
 
You don't have to take the liner off to do a block off plate, just do it in two pieces, I did my first one that way, no way I was going to wrestle with the liner again to make a one piece, the two piece works just as well. Make it out of cardboard first then trace it on to a piece of sheet metal. I attached mine with magnets I bought a HD. Since I removed the insert for a new stove I made a one piece but the other one worked just fine.
 
I honestly think in your case roxul stuffed in the gap is enough it is not like a masonry fireplace where there is a large area to cover. i dont really see a need for a hard block off plate.
 
Is it ok for Roxul to directly contact the top and back of the stove?

I could put more Roxul on the top of the stove.
 
I would not pack that area full just pack between the liner and old flue. and make sure you don't interfere with any of the air inlets on the old zc unit when you put the surround back on. I personally don't like this type of install at all but yours is already done so i just want to make sure you have it as safe as possible.
 
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