Installation Question

I have seen an installed firewood insert, and an installed pellet insert. The collar on both were male and the metal liner then acted as a female in the connection. A metal clamp/tie was tightened to make a solid connection and some sort of high temperature mastic or caulk was coated on to make sure it was air tight.

I went to look at a Hitzer 503 unit that I considered buying. I saw that the metal liner was the male and the exhaust on the insert was female. The manufacturer responded to me saying that the liner rests on the exhaust vent of the unit and provides a sufficient seal for the exhaust (my interpretation of what they actually said). I think there is an implied requirement that the liner is coming directly down onto the insert. My chimney flue jogs a little and any liner I use would be resting at a slight angle onto the exhaust of the unit. I asked the sales guy (who does not work for the manufacturer) about this and he said that a high temperature caulk could be used to ensure a seal. I did not get an explanation of what caulk he was referring to.

Clearly there is a high temperature caulk that can hold up to the exhaust of a firewood and pellet insert/stove, but I am assuming a coal fire is hotter.
Is there a high temperature caulk that would hold up at the exhaust portion of a coal insert/stove?
If so, can you point to a product as an example?

https://www.northlineexpress.com/rutland-600-degr ... 7Aod8jAAmg

Here is an example...

Actually coal stove exhaust is lower in temp than a wood burner. They like to keep wood exhaust higher in temp so creosote does not form. Not sure what pellet stove exhaust runs temp wise.

If you are using a liner, ya really don't need any caulk. Just get a male adapter that fits inside the flue collar. Use 3 screws per junction and you'll be ok. Doesn't matter how many twists & turns are involved. Just remember male down inside the female. Good luck.
Jim

Another thing that should be considered is pressure. A pellet stove has a combustion blower that forces exhaust out of the unit. If the chimney isn't drafting well, the forced exhaust could find a way into the living space thru an unsealed pipe connection. The Hitzer 503 you are considering relies on chimney draft for combustion air intake. This negative pressure in the chimney system prevents any escape of exhaust into the living area (unless chimney draft fails) which makes a perfect seal, not as important.

The biggest fear with chimney draft failure is that of if something would block or reduce the the capacity of the draft to the point that the chimney/liner then becomes positive. Birds, critters or collapse of perforated/corroded liner are some examples of blockages.

> Just get a male adapter that fits inside the flue collar.

I have not seen anything like that. Are you suggesting the manufacturer would have this available? or is it third party?

> Use 3 screws per junction and you'll be ok.

... and ...

> This negative pressure in the chimney system prevents any escape of exhaust into the
> living area (unless chimney draft fails) which makes a perfect seal, not as important.

Part of what I was concerned with is when the unit is not in use.
In the fall and spring, the geothermal heat pump does well, and there is not a big need for a furnace; our kerosene heater does well to top off the living room and family room on the colder days.
In the winter, the backup heat is required, currently that is electric
My concern in this regard is that during the spring and fall, when the unit is not in use, would not cold air in the liner make its way inside at the collar?

It seems to me, that when I read their installation manual, they are assuming that the fireplace would be sealed around the shroud. Which I suppose is solution to my concern, but caulking the collar seems even better.

J F Graham wrote:If you are using a liner, ya really don't need any caulk. Just get a male adapter that fits inside the flue collar. Use 3 screws per junction and you'll be ok. Doesn't matter how many twists & turns are involved. Just remember male down inside the female. Good luck.
Jim

Actually on a coal only burner the male end should point up and the female end point down. Opposite that for wood.

Coalkirk, Hate to disagree; But I stand by my advice!!!
Jim

That's OK Jim. I'll still love you in the morning. It will work either way.

I think I understand the male- female thing, but just to clarify this subject.. As follows, the crimped end (male) goes up with coal,that would have the smooth end (female) pointing down. This is opposite of wood because with wood there is the creosote possibly running down & you then need the male pointing down to prevent creosote running out onto the outside of the pipe,where with coal you want the male pointing up so the coal gases stay in the stack & head out to the ozone layer.This is assuming that we all understand that the male end goes inside the female end.

Its more important for wood that its right, than it is for coal. As long as there is just a smidge of negative pressure in the pipe, coal gas cannot escape it. It can't swim upstream.

Well,now I am confused,i have read numerous times on here that the crimped end goes up.But as you state gas is going to follow the air stream(easy terminology) Thanks for the confusion clarification, Lightning.

Your welcome .... My unit was a multi fuel burning appliance. The collar is designed to take the male end of the pipe, which is correct for wood. If burning coal I would need to turn the whole flue pipe assembly around and use some kind of adapter to make it work. Not gonna happen lol. Just go with the flow. I don't see any deal breaking issue burning coal with the flue pipes assembled for wood burning.