Finally got around to insulating my fireplace

[theDokes]

Mellow -
How did you get the Roxul to stay in place on the top block plate?
I have my 4" pipe coming down through what is left of my old damper with Roxul stuffed into the remaining cavity - nothing on the side walls.

 

[mellow]

On the top, I made a block off plate out of my extra concrete board. The Roxul sits on top of that as an extra insulation.

 

[mellow]

They say pictures are worth a million words so I thought I would let them do the talking.

Took these on Saturday, outdoor temp was in the lower 40's. Insert was cruising at around 1000 on the cat and 300 on the flue.

Overview shot of my exterior chimney:


This is a picture of my baseline temp, outside temps. 41


This is a picture of right above where the insert sits, heat rises so this was the warmest spot I could find, 43
I can live with 2 degree difference. Before insulating, this spot would have been around the same temp as the picture below around 15-20 degrees warmer than surrounding spots, quite a bit of BTU's going to heat the outside brick.



Just for reference to show heat loss I have not insulated the area above where my liner goes into the terracotta. 55



Just another picture for reference, I have an insulated liner but still outputs quite a bit of heat.




Hopefully this will help people to understand the importance of insulating your fireplace if you have an exterior chimney with both Micore or concrete board AND Roxul, otherwise you are contributing to Global Warming Just kidding

 

[Nelson]

Great pics!

I had my PE Summit Insert installed in November. Unfortunatley, due to time constraints and the installer I was using, I was unable to get Durock and Roxul on my fireplace prior to the install. However, I am planning to shut the stove down at some point this winter and get the work done. For the price of materials, it can't hurt to try. Certainly isn't going to make things worse.

One question I had was around secondary air - any concerns that as you tighten things up in the fireplace that you might somehow be affecting the amount of air available for secondary intake? Maybe it isn't as air tight as I'm thinking it would be and, therefore, not an issue.

Either way, I'm planning to do work similar to yours (Durock on sides, Roxul and Durock in back and then Durock blockoff).

I will try and get some temp data on my outside chimney before and I after to report back.

 

[mellow]

One question I had was around secondary air - any concerns that as you tighten things up in the fireplace that you might somehow be affecting the amount of air available for secondary intake?

Secondary air input varies from insert to insert, the Jotul 450 I had it was in the back, some is on the lower sides, my Appalachian doesn't have secondary air so it all comes from the front door. Depending on the insert I would provide an airspace for the secondary air, or even install an insulated OAK if you can. My XTD insert had secondary air on the lower right so I made sure I had airspace on that side to the front surround so air could flow cleanly.

 

[lml999]

Great write up. I recently installed Roxul and a blocking plate above my insert. I have spare Roxul and am planning on insulating behind the stove. Not sure whether I'll use durock or light sheet metal in front of the insulation. The sheet metal is so easy to use...

 

[Clyde4]

Hi Mellow,

Sorry if I missed your answer. How did you secure the durock to the back of the fireplace without really compressing the Roxul?
I'm trying to figure out if it should attache metal studs first?
I have a hearthstone Clydesdale and a really big fireplace opening. It barely heats 1 room.
Scene:
Outside chimney
Heavy-duty SS liner, capped at the top, stuffed with Roxul around the damper only.
I'm going to install a block off plate soon. I hope that helps, though my installer says it won't help much because he capped the top of the chimney.
Chimney is 25ft+
The back wall and floor of fireplace are cold. 49 degrees (using IR gun)
The fireplace opening is 5ft wide at the front. I'd like to insulate like you did but also put Roxul on the sides since I have the room for it

 

[Jags]

I hope that helps, though my installer says it won't help much because he capped the top of the chimney.

I will wager that your installer is wrong.

 

[Schmev]

Roxul is great and i never heard of it until i joined this site. At the very least you can make a double layer block off plate with that stuff and be much better off than what some installers are doing.

Honestly, now that i think about it i wish i could have wrapped my SS liner with it instead of the .5 inch insulated wrap it came with.

 

[mellow]

View attachment 151493How did you secure the durock to the back of the fireplace without really compressing the Roxul?

I have a metal fireplace box so I drilled and tapped my holes then installed long bolts, you could do something similar using a 4" or 5" tapcon going into the brick.

Install a block off plate, you are sucking more heat up that chimney than you think.

 

[Clyde4]

Thanks for your reply. I'll do the block off plate first and then try insulation.

 

[Clyde4]

I'm waiting for the metal to come in. Going with 24ga galvanized sheet. Tonight I had the fire going and took a few temp readings.
The flue collar was 550. About 30" above the insert the brick wall is 75 degrees. The rest of the room is 69-70 degrees. The fireplace floor behind the insert not even 12" away is 60 degrees.
I think it's safe to say I desperately need a block off plate.

 

[Clyde4]

I just installed the block off plate this weekend. I left the roxul that was stuffed in the damper, and then put 2 layers of Roxul R23 on top of the block off plate. I pinned it in place with tapcon screws, and then caulked the perimeter with hi-temp silicone. Around the liner I used the stove mortar to seal that gap.

**One thing I would highly recommend when following these block off plate instructions is to make sure you take the measurements SHORT exactly like it says. I tried to make mine too exact and had to trim/bend/play with it etc. the flaps will leave enough room to make up a distance, and you will have to caulk around it anyways.

It has definitely helped. the room its in gets warm all around, and the surrounding rooms don't get cooler (like they used to). Now my problem is moving that heat to other rooms. I've been playing with a fan on the floor blowing cold air towards the fireplace. That works a little, but not great. One room however just doesn't get heat. on one side of the doorway its warm, and on the other its cold. The headers above the doorway are about 16" down from the ceiling. I imagine that's not helping. I may try the small fans in the corner of the doorway.

my burn times are longer and more complete now. after putting 2 splits on a bed of coals and returning 2.5 hours later, I have this (see pic).

I've been able to close the air damper to about 20% open. I have gotten some lazy blue flames around the log on a bed of coals (not in this pic).

anyone have better luck with top of door mounted fans vs. floor fans pointed at the fireplace?

 

[mellow]

Glad to hear you are getting the benefits of insulating that fireplace.

Search the forum about fans, many threads dedicated to that already.

 

[msjones2452]

Hey there, fairly new to the site. Were getting ready to purchase an insert, if we can make up our mind which one! I've been following this thread and am very interested in insulating my masonry firebox. I have an exterior wall masonry fireplace/chimney. Definitely insulating the liner and installing a block off plate.

Mellow, I have a question for you - actually everyone who has insulated their firebox. Has anyone experienced any issues with their inserts? Things like overheating of the insert/stove adaptor/liner etc. any failures of the inserts themselves. I'm kinda gathering no one has as it hasn't been mentioned here yet but I thought I'd ask. The insert at the top of my list is a hybrid w/a catalyst, I would think as long as I left some airspace around the insert things should be fine. I was shooting for around 2" on the sides/back and 4" on top. I have no idea how hot the outside walls of an insert get. Is there any concern with getting Roxul and Durock too close or tight to the stove adaptor? I would figure that would be the hottest part of the stove next to the catalyst itself. Also, does one package of Roxul usually cover the whole project?

Thanks for any info.

Matt

 

[mellow]

I would talk to whoever makes the insert you are thinking of buying and get their blessing first. See if they are OK with roxul touching it or if it needs clearances. The most important part to leave an air gap is on the top, the sides do not get as hot IMHO.

1 pack of roxul will do your fireplace and a couple neighbors fireplaces.

 

[msjones2452]

I would talk to whoever makes the insert you are thinking of buying and get their blessing first. See if they are OK with roxul touching it or if it needs clearances. The most important part to leave an air gap is on the top, the sides do not get as hot IMHO.

1 pack of roxul will do your fireplace and a couple neighbors fireplaces.

Thanks for the info Mellow. My dealer doesn't think it's a problem - at least what I've described to him with leaving an air space around the entire stove. I'm not going to physically touch the insert at all. Basically I'm just making my masonry firebox a little "smaller". My biggest concern was the Roxul/Durock touching the liner w/in a few inches of where it connects to the insert. I know the Roxul can handle the heat but I wasn't sure whether or not the actual liner would become so hot it would cause a failure.

We finally pulled the trigger and ordered the Hampton HI400 w/a heavy wall SS flex liner. I ordered the Roxul last night. Everything should be here sometime next week.

 

[Dmitry]

Why do you ,guys , concerned about Roxul touching the insert? The melting point of Roxull is 2150 F. I'm actually thinking about placing Roxul on a top of my insert to prevent heat loss to masonry and keep insert warm longer, It runs around 500 at start and then drops to 400 F on a top of inner box. Temp well controlled. Don't see reason not to do it . If it will start to overheat I can always remove it

 

[Oldman47]

The only issue I can see with using Roxul is that the thing it is insulating may not be designed for a situation where it cannot shed heat. If I design something and expect a 1 inch air space next to it I may make assumptions about how much cooling that inch of air will provide. If you take away that cooling is my material going to survive? That is the only down side I can see to better insulation.

 

[Dmitry]

I've looked at the manual and it says nothing about how much air space should be around the insert. I suppose they not going to recommend to insulate it like this because people would do crazy things , like over fire their stoves and then hold manufacturer liable .

 

[etiger2007]

In my opinion its best to get the blessing from your stoves manufacture for insulation. I called SBI and they said go ahead and insulate the sides and back but do not do the top as it could cause an overfire situation. If you dont get their blessing and you warp tubes or baffles good luck getting them to stand behind their warranties.

 

[jatoxico]

Personally I would not (did not) put insulation tight to my insert. Just makes sense for me to maintain a small amount of clearance. Depending upon where your inset pulls secondary air from you want to be careful not to obstruct any inlets as well.

 

[msjones2452]

Why do you ,guys , concerned about Roxul touching the insert? The melting point of Roxull is 2150 F. I'm actually thinking about placing Roxul on a top of my insert to prevent heat loss to masonry and keep insert warm longer, It runs around 500 at start and then drops to 400 F on a top of inner box. Temp well controlled. Don't see reason not to do it . If it will start to overheat I can always remove it

I'm not so worried about the Roxul. That stuff will withstand way more heat than the average stove should dish out. I'm more worried about an "overfire" or "overheating" of the other components. Like Oldman47 said, "may not be designed for a situation where it cannot shed heat." Also, once I get the insert in place, I will not have the ability of just removing any insulation easily. While my firebox is fairly good size, the opening the insert must fit into is not. I will have very little clearance on the top of the stove at the opening - not very conducive to removing insulation in short order while the stove is still hot. I would feel a lot more comfortable maintaining some airspace around and above the insert. However, my plan is to have Durock/Roxul approximately 4" above where the liner mates to the top of the stove. Due to that being one of the hottest parts of the system, I was curious if there would be an issue with direct contact? Again, not so worried about the Roxul, more concerned with overheating other components.

I'm going to contact my salesman for more input. Unfortunately, the manufacturer does not have any direct consumer contact information. They rely on their dealer network.

 

[mellow]

The whole idea is to have the firebox insulated to keep the heat IN the insert. Back is CRITICAL on an exterior chimney. Sides are OK. Top is CRITICAL with a Block off Plate installed. No need to have the insulation on top of the insert if you have a proper insulated block off plate installed.

Don't get lazy and just put Roxul on top of the insert thinking that will solve the issue.

 

[HappyCamperMan]

Sorry for jumping in on a thread that is nearly 1 year old. However, do the answers regarding insulation change if the chimney is an internal chimney? I have fieldstone interior chimney that runs up through the upstairs master bedroom (is sheet rocked in upstairs). I was not home when my insert was installed so I have no idea if there is a block-off plate or insulation in my firebox. I could take off the face and find out but have not done that. I'm wondering if it would make any sense to pull off the face and stuff Roxul in the firebox for an internal chimney?