should i install a block off plate?

nick060200 · Dec 30, 2014

i've been reading a bunch on block off plates from this forum. when i got my stove installed they wouldn't do it. said i didnt need it. they used a 5.5" liner thru an existing 8x13 terra cotta chimney. its not insulated, but its sealed at the top of the chimney.

i have an exterior chimney, 2 story colonial home, built in the 50's, 1900 sq ft. not the best insulation.

got the stove insert installed and have been using it for about a week now. i have good draft. i have oil heat, and got the insert to supplement my heating. i keep my heat on 64 for my wife during the day, and we turn it down to 61 at night.

with the insert, the downstairs will get to 67 pretty quick and then reach 69-70 after the insert has been loaded 2-3x. this is plenty warm for the both of us. she is happy and so am i. i can seriously see myself using wood as my primary heat with the way its going. i should note that the thermostat is not in the same room as the insert, so it is a few degrees hotter in my living room.

my concern is if i do a block off plate will it get much hotter in the house? i dont know that i want it much hotter.
but if a block off plate will help burn less wood, then i might do it.

i guess im asking, if im satisfied with the heat this thing is putting off, is there other benefits to adding the block off plate? i see most people who add the block off plate do it because they are not happy with the heat they are getting.

can anyone recommend a pot for a humidifier? the air is warm but really dry. i ended up with a hampton HI300.

thanks, and be easy on the new guy.
Nick

mellow · Dec 30, 2014

Well, you are sending BTUS to the outside via the back of the fireplace and up the chimney. I would recommend installing the block off plate and Insulating that fireplace to keep those BTU's in the firebox and out via the fan on the insert. You will see longer burns, plus you can always use more heat, especially since it hasn't really gotten that cold yet, you will want those extra BTU's when it is in the negative with the wind blowing, if it gets too hot then turn on some fans and distribute the heat.

jatoxico · Dec 30, 2014

There will be no down side to insulating well and adding a block off plate. There are a number of benefits. My installer didn't want to do it either and took some pressuring to get them to do Roxul, which when I re-did the setup I found to be wanting. They don't want to do it because it's harder (or they are ignorant to the benefits) not because its better to not have one.

WoodpileOCD · Dec 30, 2014

I agree with jatoxico completely There will be no down side to insulating well and adding a block off plate. Keep all the heat you can in the house. If it gets to hot in the house, build smaller fires. 64 during the day? Really... My wife would be freezing wrapped in blankets at that temp. We have gotten used to 70 - 75 downstairs. Upstairs bedrooms are a different story. Low 60's at night which is where we like it for sleeping. Do a block off plate, you won't regret it. Several plans here for fairly simple ones.

Dix · Dec 30, 2014

What J said.

You've had the stove for a short time, and not had really cold temps.

Insulate,and add the block off plate (especially with an exterior chimney ).

You won't regret it when it hits 0F with the wind chill.

Welcome to the forums !

jatoxico · Dec 30, 2014

Nick just to give you idea, I have a very similar setup to you. Outside chimney, 2 stories so about 28' of chimney. Before I insulated (properly) and added a block off plate, on a 30 deg day I measured the temp of the outside brick at the level of the old damper and smoke shelf and it was 80 deg.

That's heat that was unavailable to heat the living space and/or lost chimney heat meaning I was not keeping my flue gasses as hot as possible increasing their condensation in the liner (creosote).

Since insulating and adding the plate the temp difference relative to outside air temp is < 5 deg and the stove holds it's heat better. That translates to better secondaries and a cleaner firebox.

Enjoy your new stove this year, there's no rush but if you can add the plate in the spring or over the summer you won't regret it.

nick060200 · Dec 30, 2014

Thanks. I'll do it. I don't think I would able to insulate the liner. Will it be ok to leave the liner uninsulated and the top sealed off?
I'll start messing with it this weekend. I've read all the threads about everyone's project and have a good idea of how I'm going to tackle it.

jatoxico · Dec 30, 2014

nick060200 said:
Thanks. I'll do it. I don't think I would able to insulate the liner. Will it be ok to leave the liner uninsulated and the top sealed off?
I'll start messing with it this weekend. I've read all the threads about everyone's project and have a good idea of how I'm going to tackle it.

My liner isn't insulated either. Naturally it would be better if it was but it performs fine and as I posted I'm no longer experiencing the severe heat loss I was before. I did what I could from the bottom to get insulation as high up as I could. Using a piece of square stock I pushed Roxul up and around the liner. Then fully filled the smoke shelf and on down to the block off plate.

Since you have an exterior chimney and while the box is out, insulate the side walls with Roxul, Durock or both. I only had room to do the back with Roxul and left over sheet metal but if you have space around the insert, do all the sides you can.

cableman · Dec 30, 2014

Installed the same stove for a buddy, insulated liner, roxul whole fire place and block off plate. He wanted to have "them" install it with no insulated liner and no block off plate or firebox roxel. Couldnt amagine it performing like it does heating a void....

weatherguy · Dec 30, 2014

For the small cost of materials and the time it will take might as well go ahead and do it, why heat the outdoors, you may want that little extra heat when it goes down to zero.

Hogwildz · Dec 31, 2014

Why didn't they install the proper 6" liner. Should be enough room. Yes install the block off plate. Your installer is an asshat.

mellow · Dec 31, 2014

nick060200 said:
Thanks. I'll do it. I don't think I would able to insulate the liner. Will it be ok to leave the liner uninsulated and the top sealed off?

Unless you are getting smoke rolling out when you open the stove door I wouldn't worry about insulting the liner if the installer thoroughly checked the terracotta for cracks and found none.

Here is a link to my insulated fireplace thread to give you some install ideas: https://www.hearth.com/talk/threads...lating-my-fireplace.75755/page-2#post-1635483

Sons924 · Dec 31, 2014

i skipped the block off plate and just jammed tons of roxul into the opening. It made big difference in the heat output. As stated above, you can always burn smaller fires if you want less heat, but when it gets cold you might wish you had more heat.

RickBlaine · Dec 31, 2014

Nick, glad you will install a block-off plate....

Do you NEED a block off plate? No. Your insert will still work. But a block-off plate took this newbie just 2 hours to build ($25 for materials at Home Depot) and install, and it is the right thing to do. I insulated my liner, and installed Roxul on top of the block-off plate, the smoke shelf, and underneath the top plate.

I have an outside brick chimney with a short run- so I wanted all the draft help I could get.

I am happy to say that I measure ZERO degree difference in the bricks on the outside chimney- all the way to the top. The bricks are the same temp as the outside air. A few times it got too hot in the house, I just opened a window. The point is- I am in control because of the block-off plate and insulated liner.

The reason I did this myself rather than hire a company is that the first two companies each told me that I did not need a block-off plate. Warning, Will Robinson! I'll do it myself and leave the no-talent arse clowns to their B.S.

nick060200 · Jan 2, 2015

i got my materials yesterday, gonna do it this weekend. its going to be warmer. and you guys were right. i think i posted this a little too soon, with it really being cold in the 20's i can't get the downstairs up to 70 any more with the thermostat in the other room like i described.

one question: i bought some "3m fire barrier sealant" its rated for over 1200+ deg can i use that around the block off plate? or should i oatley stove cement? thanks

Hogwildz · Jan 2, 2015

Silicone caulk around the perimeter of the block off plate, door rope gasket to fill any gap between the liner and the block off plate. Furnace cement will dry, harden, crack and fall off.

nick060200 · Jan 4, 2015

It turned out to be a little bit more of a project than I thought. Ran out of time. So I ended up with roxul all around insert and up around the smoke shelf. I really packed it in as much as I could. I used about 3/4 of what you get in a pack. And with just That I can tell a difference. Everything heated up quicker and I'm already at 72 where my t-stat is located. and I only started burning at about 3pm. I think with the roxul it's a significant difference. I'll have a better idea after burning all day tomorrow what real gains I have made with just the roxul. Happy with the improvement thus far.

Galesville · May 12, 2019

I'm sorry if this question has already been answered: do I need a block off plate if I'm using outside air?
I have an exterior chimney, lined with pre-insulated stainless liner.
Installing a Pacific Energy Super Insert.

bholler · May 12, 2019

Galesville said:
I'm sorry if this question has already been answered: do I need a block off plate if I'm using outside air?
I have an exterior chimney, lined with pre-insulated stainless liner.
Installing a Pacific Energy Super Insert.

Do you need one? No. But will installing one help get more of the heat made by your stove into your house? Absolutely.

begreen · May 12, 2019

Galesville said:
I'm sorry if this question has already been answered: do I need a block off plate if I'm using outside air?
I have an exterior chimney, lined with pre-insulated stainless liner.
Installing a Pacific Energy Super Insert.

It's not a necessity, but it will improve heating output. If there's room consider adding a bit of non-combustible insulation (micore, roxul) behind the insert too.

should i install a block off plate?

New Member

Resident Stove Connoisseur

Minister of Fire

Minister of Fire

Minister of Fire

Minister of Fire

New Member

Minister of Fire

Minister of Fire

Minister of Fire

Minister of Fire

Resident Stove Connoisseur

Burning Hunk

Burning Hunk

New Member

Minister of Fire

New Member

New Member

Chimney sweep

Mooderator

Similar threads