Another block off plate question

[buckeye]

I have my heritage sitting in front of my fireplace and I have a stainless steel shroud that fits snug around the blower and covers the fireplace opening. I dont have it sealed around the opening, but it is relatively snug and should help to stop most of the stove heat from going back up into the chimney. If the block off plate is only about 2' above the top of the stove, how much good is that doing? My liner is about 35' long, so that means that 33+/- feet are above the block off plate. I am keeping most of the heat from my stove in the living area with the shroud correct?

 

[edthedawg]

if the shroud that "covers the fireplace opening" is essentially part of the blower housing itself, it would seem you likely are losing stove heat up the un-blocked chimney. I would consider adding the block-off plate.

Sounds like we have similar setups - 35' of 6" SS liner running up from a tee that sits not even 2 feet off the back of our Heritage. The blockoff plate is just sheetmetal - sits maybe 18" up from the tee. We've done nothing to really seal it up beyond just tapping the metal to fill the various voids. No sealants or insulation (yet - thinking about it...). I just added an inline damper right off the back of the stove (between it and the tee) and we are seeing remarkably better burn control. HAD to slow down that chimney.

 

[buckeye]

I have had a damper in line pretty much from the get go. I guess Im just trying to understand what heat a block off plate is keeping in. Like I said, I that shroud covering the fireplace opening, it seems as if I would be keeping most of the heat from the stove in the house with that. The top of my chimney is capped and I would think the ss liner would be warming most of the chimney. It is an exterior chimney with a clay lined flue. Therefore, if the block off plate is 2-3' above the T, the liner would still be heating the other 35'.

 

[edthedawg]

Is the liner insulated in that exterior chimney?

I think the premise of the blockoff plate is so that the heated room air doesn't draft naturally up into the chimney, around the liner. I believe there are other code-related issues too, but it's early in the day so forgive me

A couple photos of your setup may help folks here figure out whether you have the shroud doing what you hope or not.

 

[Summertime]

It will keep the heat around the stove instead of it heating the chimney, It should also keep heat loss to a minimum especially if you have a exterior chimney.

 

[JotulOslo]

Here's how I did my block off plate in my fireplace with Jotul Oslo. https://www.hearth.com/talk/threads/3251/#
It's held in place with emt conduit clamps machine-screwed to the plate. I used stove cement between the plate and the cast iron damper throat. Works a charm.

JotulOslo