# Refractory cement or mortar?



## NVHunter (Oct 31, 2015)

I am looking for input on what the difference is between refractory cement vs refractory mortar. 

I'm going to line my chimney with a stainless steel liner and the tee (6") will be coming through a 9" hole (thimble) in the brick wall from the chimney. 

There are some spots I'm going to need to fill with refractory cement inside the thimble as the person who made it 40 years ago didn't do a very good job. 

With that being said can I use refractory cement to secure the tee snout in place or does it have to be mortar....?


----------



## RyanStorm (Oct 31, 2015)

I bought Imperial "Stove and Fireplace Cement and Morter". I think you can repair broken firebricks with it, but I was gonna use it cause I have a leak in my stainless steel pipe. My dad put his torch up into flue to heat it, and I realized right where the flame sat, is right on the spot the stove attaches to stove pipe, and on that spot I can see light coming through if I put my flashlight up there.

I am editing this in, I looked into Furnace/Stove/Fireplace Cement has a ton of uses. A quote from below product:  "Fix a crack or seal the collar to the top of your wood stove or seal between your firebricks and prefabricated fireplace. Use this cement anywhere else you need a high temperature adhesive for furnaces, firebrick repair, FILING GAPS, sealing joints or gluing ceramic logs." I'm gonna go buy this stuff to seal my cap outside, if you have 3" gap I don't know if it will work, mine is minimal, like 1/4th"

http://www.tractorsupply.com/tsc/product/rutland-black-furnace-cement-10-1-3-fl-oz

I also have same problem as you, but my Tee piece goes outside as 8" pipe dual layered pipe, but the hole in cement is like 1/4 inch wider, and I got major draft coming in through there and haven't found anything to fill in that gap to stop my draft? I was gonna stuff Roxul around the gap.


----------



## begreen (Oct 31, 2015)

RyanStorm said:


> I'm gonna go buy this stuff to seal my cap outside,


No, use a good quality silicone for outdoor sealing. GE Silicone II will work.


----------



## RyanStorm (Oct 31, 2015)

begreen said:


> No, use a good quality silicone for outdoor sealing. GE Silicone II will work.



I saw that at the store, I actually bought a different one right next to it to seal up all the old sealing around house. But will this GE Silicone 2 be fine touching the stove pipe? Cause the metal piece that is suppose to be cover the extra space I was gonna pull it back and seal between the pipe and cement.


----------



## NVHunter (Nov 1, 2015)

I purchased some Rutland refactory castable cement. Would this work begreen or should I get something different to set the tee in place?


----------



## begreen (Nov 1, 2015)

RyanStorm said:


> I'm gonna go buy this stuff to seal my cap outside, if you have 3" gap I don't know if it will work, mine is minimal, like 1/4th"


There are two different tasks and needs being described here. One is mortaring into a chimney and the other is an exterior application to what should be class A chimney pipe. Silicone is fine for the exterior work. The insulation in the class A chimney drops the surface temp on the pipe considerably. You can also fill the gap with stove gasket as a backer. 


NVHunter said:


> I purchased some Rutland refactory castable cement. Would this work begreen or should I get something different to set the tee in place?


NVHunter, I'm no mason but I think you want high temp mortar or furnace cement and not castable refactory cement.


----------



## jotul? (Nov 1, 2015)

Is your install in a finished space? Any mortar you use to fill a 1.5 inch gap is going to crack or at least shrink back from the tee. Mortar is made to be applied .25 inch thick to .5 inch thick between solid masonry units. Refractory cement is to be applied in .25 inch joints or less.  Aggregate size and material is what determines usage. Mortar or cement classifed as refractory have a very small silica aggregate.  I would fix any holes in the thimble with type N mortar or refractory cement, and not worry about cementing the tee in place. Use a furnace gasket backer and fire stop caulking to seal the gap between the tee and thimble. Anything mortar based will crack from expansion / contraction in that large a gap. The fire stop isn't very pretty though. It's usually orange. Needs to be covered up.


----------



## NVHunter (Nov 1, 2015)

Here's a picture of the thimble hole before I cleaned it out.  I am going to open the bottom of it 2" to fit the tee in.

I guess my question is what material do I use to close this area back up?

Castable cement to build it back up to the snout then use the gasget described above?


----------



## jotul? (Nov 1, 2015)

Castable will work if you set the tee in place and then pour it in so that it flows under the tee. Tough to keep it from flowing out from under the tee in the front and back though. Do you need the masonry for structural support of the tee? If not, you could use regular mortar and lay brick back in there just to close it up a bit for the gasketing. Castable is made to be poured into a form.


----------



## NVHunter (Nov 1, 2015)

jotul? said:


> Castable will work if you set the tee in place and then pour it in so that it flows under the tee. Tough to keep it from flowing out from under the tee in the front and back though. Do you need the masonry for structural support of the tee? If not, you could use regular mortar and lay brick back in there just to close it up a bit for the gasketing. Castable is made to be poured into a form.



I need to build it back up to the tee. I guess I'll build it up with regular mortar and pieces of brick and then use gasket around the snout.

Will this work?

The liner's instructions say mortar the tee snout into place....


----------



## NVHunter (Nov 1, 2015)

This is the refractory cement I purchased....

Says it can fill large holes in masonry and holds its shape while drying.


----------



## jotul? (Nov 1, 2015)

I dont disagree with the manufacturers instructions. You just have that sized opening that is a nightmare to fill without the fill material cracking. The Rutland castable says it will do it though, so I'd say full speed ahead.


----------



## NVHunter (Nov 1, 2015)

jotul? said:


> I dont disagree with the manufacturers instructions. You just have that sized opening that is a nightmare to fill without the fill material cracking. The Rutland castable says it will do it though, so I'd say full speed ahead.



Yea time will tell....

I'll put together a whole thread with pictures of my install as I go through it. 

Stive will be here next week and liner and all are waiting in the garage...


----------



## begreen (Nov 1, 2015)

Are you dropping the tee down the chimney already attached to the liner without the snout? Then attaching the snout through the hole?


----------



## NVHunter (Nov 1, 2015)

begreen said:


> Are you dropping the tee down the chimney already attached to the liner without the snout? Then attaching the snout through the hole?



No because the way my clay flue is positioned. It's 7" x 11" and I'm using an oval liner (5" x 8.15")

The problem is the clay liner is positioned with the 7" facing the opening for the thimble and the oval tees have the snout opening on the major end (11" side) so the tee is being custom made to have it on the minor side (5" and 7" side)...

So the tee is custom made to have the snout on the 5" side but it can only be made with the snout perminitley attached to the tee body, hence why I'm opening up the thimble a little more and need to seal it back up, because I need to install the whole tee from below...


----------



## begreen (Nov 1, 2015)

Got it, bummer. How large a gap will need to be patched afterward?


----------



## NVHunter (Nov 1, 2015)

begreen said:


> Got it, bummer. How large a gap will need to be patched afterward?



2" maybe... Will fined out once the tee gets here. It's going to be a short body tee too which will help with length.

If I mix some of the broken brick into the cement will that help keep it together and keep it from cracking?


----------



## quotejso (Nov 1, 2015)

NVHunter said:


> View attachment 165760
> 
> 
> 
> ...


If u drop the liner down with the tee attached then attach the snout you will have less patch work.


----------



## NVHunter (Nov 1, 2015)

quotejso said:


> If u drop the liner down with the tee attached then attach the snout you will have less patch work.



Can't as the only way they can make the custom tee is to have the snout perminently attached to the tee body... So it won't work that way.


----------



## begreen (Nov 1, 2015)

NVHunter said:


> 2" maybe... Will fined out once the tee gets here. It's going to be a short body tee too which will help with length.
> If I mix some of the broken brick into the cement will that help keep it together and keep it from cracking?



I was wondering the same thing. The gap is not large enough for a partial brick, but too large for stuffing in stove gasket as a backer.


----------



## quotejso (Nov 1, 2015)

Stuff with Roxul  trim outside with metal ring.


----------



## quotejso (Nov 1, 2015)

How are you going to attatch the liner to the tee. That was the hardest part for me and I could reach in the work area inside a fireplace.


----------



## NVHunter (Nov 1, 2015)

quotejso said:


> How are you going to attatch the liner to the tee. That was the hardest part for me and I could reach in the work area inside a fireplace.


Silimar way you did it. I'm gonna use a pull cone and once it's down I'll take it off and slide the tee in place and push it over the liner then tighten the clamp down. 

This is another reason I need to open the thimble up a little more to give me a little more working room. It's going to be a pain in the A$$ I know but there's no other way to do it that I can see...

Just have to orenent the clamp screw head to where it's pointing toward the opening in the thimble. I've rehersed this install in my head a thousand times by now. Just waiting on the short body tee to arrive and the weather to line up with my days off and I'll do it.


----------

