My DIY block off plate installation

[OhioBurner©]

I had another thread going about some questions and problems but since I have worked through it and finished I'd like to document the whole project FWIW.

Starting from the top, what’s the reason? Well it seemed like my unit wasn’t throwing off as much heat as I expected. Of course this is completely arbitrary, it’s my first insert I've ever had and really haven’t been around others during heating season either. But based on others opinions of the insert (Jøtul C 550 Rockland) and how large of a house they were heating with it, I felt I should be able to heat the addition to my house. The addition is 22x36, 792 sqft, 2 story (1584sqft) but half of that is open (large great room) so not sure how you factor that in. As it is right now if the temp dipped below 40ºF the insert could not keep the average temp at 70ºF. That’s not near what I hoped. I run the stove hot also so don’t blame it on my burn methods; usually cruise at 500-600º and often up to 700º. Many have suggested that block off plates prevent heat from being wasted up the chimney, and some have reported large increases in the temperature of their surrounds by the heat being trapped around the stove and not going up the masonry. I'll try to record these increases a document them as well.

Next was to design a plate that would work, and I had several problems. The big issues was that the block off plate would hold the stovepipe in a fixed horizontal plane (and vertically too if you seal it with stove cement like the article on here states). I must have a not so common stove setup since with the pipe fixed like this it would be impossible to install the insert or later remove? I guess other folks stove must have a good length of more pliable pipe to allow for installation and removal, but where my plate would go was approximately 3-4" above the stove top - so the rigid angled connector that goes into the flue collar of the stove was the same piece in the hole of the block off plate - it has to be able to move. I tested a theory and it worked - I went to the rooftop and was able to lift the entire 6" SS liner up and block it a few inches high to allow the stove to be moved into place, and then dropped back down later and inserted into the collar. So the standard design would work, I just need to be able to lift up the flue for installation and removal.

I took the measurements of the opening, and traced it all out on cardboard:

Almost all these pics have supplemental craftsman 19.2V lighting... the great room is large and dimly lit. My flash on the camera is also broke (long story, ran over the camera with my F350...)

Mocking up the cardboard cutout. This pic is before raising the flue, so you can see how close the insert will be and how the connector is still rigid at the point it passes through the block off plate.

Tracing everything out on sheet metal now:

Test fitting the final product:

I want to trap as much heat as possible and also cut down on air leak without using sealants so I went to the hardware store in search for 'rock wool' they handed me Roxul AFB. Doing a search here turned up others have used this same stuff so figure it is what I was looking for.

Done. Used a few masonry screws driven half way in to tack in place.

Not pictured: to help seal around the hole where the connector passes through I wrapped a few inches wide strip of rock wool around the connector, and secured with a piece of#12 bare copper wire (just using what I had on hand), as the pipe is lowered into the opening the wrapping contacts the block off plate with a layer or rockwool already on it, and helps seal it even thicker.

Unfortunately I wont know for several days how it turns out, its in the 50's today and tomorrow and working the next several days anyhow making it difficult to monitor things even if I was burning it. But next week I have off and I'm sure this warm weather won't last too much longer...

Like I said I haven’t run the stove yet, so this is also a chance for anyone who might see some potential problem to speak up before I use it for the first time.

 

[southbalto]

Looks fantastic!

Very tight seals all around.

 

[Joey]

Thats awesome......great work for a self proclaimed amateur..!!

 

[Rudyjr]

Ohioburner, Good job looks like it will work well. Everyone that I have done has had to be done differently just the nature of building something for a hand built fireplace, the cardboard template always works well. Let us all know what you think about the heat output. Happy New Year, Jim

 

[OhioBurner©]

...Everyone that I have done has had to be done differently just the nature of building something for a hand built fireplace...

Yeah that seems to be very true, each one is different. Which is probably why installers dont seem to either know anything about it or dont want to do it. of course they block off at the top, but the tops are usually standard sizes and a lot more accessable!

 

[Rudyjr]

...Everyone that I have done has had to be done differently just the nature of building something for a hand built fireplace...

Yeah that seems to be very true, each one is different. Which is probably why installers dont seem to either know anything about it or dont want to do it. of course they block off at the top, but the tops are usually standard sizes and a lot more accessable!

Yeah and they can buy the top cap with the liner for whatever size clay tile that is there, no fabrication skills needed and no time required.

 

[BrotherBart]

Makes me want to throw rocks at my ugly block off plate. Great job.

 

[Renovation]

Awesome!

Functional and clean--you earn major DIY points with that one!

Thanks for the recap, and inspiration.

 

[JeffT]

Nice freestyle fabrication. :coolsmile:

 

[afptl]

Thanks for posting the pictures! It helped me think here how to get my new stove hooked up!

 

[iceman]

That is an awesome job! I coulda never done that so neat!

One sugg/regret I have is put more rockwool.. if it is possible try to put one more layer on the inside.. it does make a difference...

 

[OhioBurner©]

Well I am overdue for an update but have not had many true tests to get a feel for what change the block off plate had. Without the blockoff plate that side of the house could no longer hold 70ºF running on just the insert when the outside temps dipped below 40ºF. Since then though we have been running the freestanding stove as well, except for one day in the 30's. I forget the exact temperature but we still couldnt get it to 70º and with falling temps forecasted by the end of the day we had the other stove going again. I left the house today with the temp at 32º and just the insert going, but... I'm working nightshift and gone for 14 hrs. I wont get any good info out the runs today/tomorrow and garunteed the stove will be out when I get home and a cold house.

What I can say is the block off plate has insulated around the stove, the surround has got much warmer. It went from barely being 'warm' to the touch to nearly burning you upon touching, the IR gun has shown the surround at 160's on a good hot burn and I think I have seen in the 170's once. The bricks immediately above the surround are also very warm and were not noticably warm before. It also may be no coincendence that I overfired the stove withing a few days of installing the block off plate. I reloaded in the 300's and left the door cracked just for a minute until flames had fully caught (well I probably didnt need to leave the door cracked - must stop doing that when not needed). Reloaded the other stove as well and then set the timer which is usually set to 10 min but it had 12 on it and I didnt feel like resetting it. Well at about 11 minutes I heard a bang and came into the room to check the insert. Center of the stovetop was at 940º!

Another thing I have noticed is the stove stays warmer longer after burning out. I made another change though at the same time which might be part of this, I blocked off the zipper air (I think its called). After the stove dieing out before waking up in the morning, I noticed by noontime the box was still quite warm. I opened up the air to wide open and saw ashes instantly rustle around. I opened the door and it was very warm. Stirring the ashes up I uncovered many hot embers. Got it lit off with some kindling, ~6-8 hrs after all visible coals were white powder. Does that cound as burn time? If so that would be a good 14-16hr burn.

So was it worth it? Well I dont know. I can't really say it made a noticable difference in heating the house. But I enjoy diy stuff and would do it regardless, even if it only helped a little, which I am certain it helped atleast a little. Being used to freestanding stoves I think I just over anticipated the capability of an insert heating that side of the house.

 

[Jotul_Rockland]

Hi,

How do I turn off this zipper air and how will this be of help? I have a Rockland insert as well.

 

[OhioBurner©]

Hi,

How do I turn off this zipper air and how will this be of help? I have a Rockland insert as well.

This is what I read, from the "Jotul c550 Rockland tips thread": https://www.hearth.com/talk/threads/24713/

In a nutshell though its two small air ports that are in that buldge in the bottom front center facing into the firebox. They are open air leaks you cannot control, to burn down the coals faster I beleive. I like to have coals left, even if they do go completely out I am am left with unsightly black chunks instead of nice white powder its no big deal, I relite the stove and they burn next time.

 

[stejus]

Nice job! If you lived closer to me I'd ask you to help me do mine!