Defiant Cat-C Fireback Gasket Replacement

[Wood Axe]

I have a Defiant 1975 CAT-C installed in the spring of 2020. We love it and use it alot during the burning season.

When I was removing the CAT to clean it, a 1 1/2 inch piece of the fireback gasket was laying on top of it.

A new gasket and gasket plates are on order, but I don’t have a service manual or instructions to remove the fireback and install the new parts. Are there detailed instructions available on line? Or does anyone know where I get a copy?

There are multiple Owners Manual sources out there, but where can I get a Service Manual for this model?

Right away, I can see that freeing the fireback from behind the baffle assembly is going to be an issue. Any hints on what to look out for?

 

[arnermd]

I have a Defiant 1975 CAT-C installed in the spring of 2020. We love it and use it alot during the burning season.

When I was removing the CAT to clean it, a 1 1/2 inch piece of the fireback gasket was laying on top of it.

A new gasket and gasket plates are on order, but I don’t have a service manual or instructions to remove the fireback and install the new parts. Are there detailed instructions available on line? Or does anyone know where I get a copy?

There are multiple Owners Manual sources out there, but where can I get a Service Manual for this model?

Right away, I can see that freeing the fireback from behind the baffle assembly is going to be an issue. Any hints on what to look out for?

All you have to do is ask.... I got these from the factory when I rebuilt mine. Pretty sure I have them posted on this forum somewhere. But here they are again. Mine is a model 1975 but not the Cat C. Pretty sure there are no significant differences, except you have a cat temp probe included.

 

[Wood Axe]

Wow. This is great. Thank you so much.

Just curious, why remove the top? It doesn’t seem necessary. I’m thinking, as this is a factory manual, maybe it isn’t sealed yet at this point of the process. It looks to me like the CAT engine can be removed without doing that and risking a bad seal after reassembly.

 

[arnermd]

You are very welcome, glad to be of service....

You need to remove the top so you can re-install the damper assy..... I found out the hard way. I got the damper out with the top on but was unable to reinstall it with the top on.....

It is not that hard....

Good time to replace the damper gasket too if it is looking a little ratty.... Easier with the damper assy out of the stove.

How does your refractory look? Show us some pics.

Do you have a cat temp probe? Or just the dial indicator? Curious if you have been expeiencing runway cat temps like most of us with the larger Defiant.

I have never had a gasket chunk fall out, but the plate does move side to side on me over time. I just slide it back with a screwdriver blade. I have thought about doubling the flat gasket there but have not tried it.... The metal plate is proably warped and buckled, so good call ordering a new one.

 

[Woodsplitter67]

You are very welcome, glad to be of service....

You need to remove the top so you can re-install the damper assy..... I found out the hard way. I got the damper out with the top on but was unable to reinstall it with the top on.....

It is not that hard....

Good time to replace the damper gasket too if it is looking a little ratty.... Easier with the damper assy out of the stove.

How does your refractory look? Show us some pics.

Do you have a cat temp probe? Or just the dial indicator? Curious if you have been expeiencing runway cat temps like most of us with the larger Defiant.

I have never had a gasket chunk fall out, but the plate does move side to side on me over time. I just slide it back with a screwdriver blade. I have thought about doubling the flat gasket there but have not tried it.... The metal plate is proably warped and buckled, so good call ordering a new one.

Your a stud my man..

Funny thing is I did the same thing. I posted my manual for my stove and cant for the life of me figure out what I did with it and where its posted

 

[Turbo89]

Thanks for sharing! I have the encore CAT-C, but the assemblies look almost the same!

My CAT access door is a little loose (I shimmed it up to keep it closed), always looking for pics to see if that’s actually impacting performance.

 

[arnermd]

Thanks for sharing! I have the encore CAT-C, but the assemblies look almost the same!

My CAT access door is a little loose (I shimmed it up to keep it closed), always looking for pics to see if that’s actually impacting performance.

Maybe you already know.... don't shim it too tight! you want things a little loose there for thermal growth. Other wise bad things happen....

I assume it was so loose the top was falling out? Was it always like that or did something "move" / break?

 

[arnermd]

Your a stud my man..

Funny thing is I did the same thing. I posted my manual for my stove and cant for the life of me figure out what I did with it and where its posted

Here maybe?

https://www.hearth.com/talk/threads...-for-rebuild-instructions.199415/post-2740925

 

[Woodsplitter67]

Here maybe?

https://www.hearth.com/talk/threads...-for-rebuild-instructions.199415/post-2740925

I posted it once like 3 years ago.. Don't know where it is. I have the rebuild manual on paper but dont have the PDF anymore

How you making out

 

[Wood Axe]

Your a stud my man..

Funny thing is I did the same thing. I posted my manual for my stove and cant for the life of me figure out what I did with it and where its posted

Well, I finally got around to replacing the fireback gaskets. I had to wait until a few warm days to do it. You were right, the top had to come of to do it right. I did replace the baffle assembly gasket as well.

The top came off with little difficulty with one exception…whether because of a casting/drilling issue, 5/32 allen screw at the front of the stove was bound up and difficult to remove. But after bit of dremmel tool grinding, the install was much easier. The top gasket was pristine, so I didn’t have to replace that.

As an added benefit, I was able to reposition the blower and baffle after vacuuming everything out to fix a long standing intermittent rattle when the blower was turned all the way up.

This forum was very helpful and helped me to avoid many possible pitfalls. Many thanks.

 

[Turbo89]

Maybe you already know.... don't shim it too tight! you want things a little loose there for thermal growth. Other wise bad things happen....

I assume it was so loose the top was falling out? Was it always like that or did something "move" / break?

Just noticed this response, sorry. Lol

I bought it’s this way and didn’t know, but I paid very short money for the stove. So it’s always need like this since I’ve owned it. It doesn’t stay shut and it’s sort of loose (I can see the CAT glow around the top of the door sometimes).

I’ll try to snap a picture, I hate having to shim it, but the stove works fine with the shims.

 

[Wood Axe]

Yeah. The old refractory gasket fell down in pieces when I went in to clean the CAT. Hard to know why. During the replacement, I found part of the factory installed baffle gasket was out of place, which might have allowed the CAT housing to get too loose at the top. The tension blocks holding the bottom were plenty tight, though. The stainless plate looked burned where the missing parts were, but it was not warped. I replaced it anyway since I had a new one.

 

[arnermd]

Just noticed this response, sorry. Lol

I bought it’s this way and didn’t know, but I paid very short money for the stove. So it’s always need like this since I’ve owned it. It doesn’t stay shut and it’s sort of loose (I can see the CAT glow around the top of the door sometimes).

I’ll try to snap a picture, I hate having to shim it, but the stove works fine with the shims.

Seeing the cat glow around the top is normal, I see it on mine frequently. Nothing wrong with shimming I think, you just want it a little loose around the edges for thermal growth. If it is working for you then its good.