Rebuilding Firebox Before Insert Install

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Aug 9, 2017
11
Ozarks
Hello,

I'm new to the forum, looks like we have a lot of knowledgable folks on here. I like people who know their stuff!

Anyway, the fireplace in our house is in rough shape. The back wall of the firebox has loose fire bricks that can be pulled out easily. It appears that there was never any motor between the bricks to begin with. Also, the damper has rusted out at some point from water damage, so it is totally missing except for the outer frame. So I've decided to install a wood burning insert.

The leaks have been repaired and the chimney has been inspected and been deemed ready to burn as long as the firebox is repaired.

Contrary to some reading I've done around these forums lately, I've had advice to just stick an insert in and call it good. But I want to do this right. I'm going to rebuild the back wall of the firebox before installing a SS liner, block off plate, and insert.

My question today is, if I use refractory mortor to put the fire bricks together when rebuilding, how will I be able to cure the mortor at 500 degrees? I assume I shouldn't be lighting a fire without a damper installed.

The refractory mortors I have looked at have all had this requirement for 500 degree curing. Will the heat from the insert be enough to cure the mortor? Or will it matter at all after I install the insert, anyway?

Thank you to all for your input
 
If the integrity of the entire fireplace and chimney system has been inspected and approved as safe then it's ok to burn without the damper in place. Considering that you are putting in an insert, though the setting up of the mortar is not a show stopper. Will you be putting in a damper area sealing block-off plate? If so, that will keep more heat surrounding the insert and may help cure the mortar better.
 
I will be installing the damper area sealing block off plate.

I guess my main concern is, will I be wasting my work on a wall that will be quickly crumbling again if the refractory mortar happens to not be properly cured by the heat from the insert alone?
 
I will be installing the damper area sealing block off plate.

I guess my main concern is, will I be wasting my work on a wall that will be quickly crumbling again if the refractory mortar happens to not be properly cured by the heat from the insert alone?
No the back wall is crumbling from the same water damage that rusted out the damper. It will be fine.
 
I don't think it will be an issue, but if concerned maybe use a different brand?
(broken link removed to http://alsey.com/products/residential-mortar-indoor/)
(broken link removed to http://www.heatstoprefractorymortar.com/productDetail.php?HEAT-STOP-50-HEAT-STOP-II-1)