Downdraft - Found about this right before selecting a fireplace

[Yeager]

Hello all,
I have been in process of building a 4 season porch (with exception of past 2 days where its been -45 with windchill) and need some help on making a decision on a fireplace.

My 4 season is 18x20 where the fireplace chimney would be roughly 15 feet away from the 2 story house. The porch is on the east side of the house and is below my master bedroom. The peak of the main house is about 30-35 feet away with a height of around 33-35'.

I have been building this porch around the idea of a fun room that could be used for overflow dining, reading a book, etc with a cozy wood fireplace with crackle and smell. We have 2 other "gas" fireplaces and miss the wood fireplace I've had in the past.

I had selected a fireplace (Heat n Glo Rutherford 42) and was about ready to purchase it when last minute the store mentioned that there was risk of downdraft and that I might need to make the chimney very high and even then there was no guarantee. Staring out my master bedroom to see a chimney 15 feet out doesn't sound that good, but my view isn't really great anyway.

I am confused as to what is the best option for me. Should I:

- switch to a sealed unit to avoid risk of smoke puffs coming through?
- switch to another fireplace where the vacustack could attach to? (the fireplace installer said that it didn't appear to be compatible - didn't that make sense to me)
- give up on wood and go to gas (I don't want to do this, but don't want to spend thousands and have an unusable unit.

Appreciate any advice!

thanks

 

[Yeager]

Here's the plan with a ~20' fireplace to give some context. Its about 14 feet from chimney to roof edge.

 

[Yeager]

any thoughts on this?

thanks!

 

[owingsia]

First off if that is a prefab "sun room" "Sun porch" 4 season room" the roof is usually aluminum and Styrofoam for insulation. The walls are 100% vinyl with Styrofoam insulation (Assuming there is any at all, Many will say 4 season rooms and they use air for insulation).

The sales rep will tell you all kinds of good things about the room and how you can but in an open fire pit if you would like to (Hey you can open the windows to get the smoke out) Whatever it takes to sell you that room!

I used to sell and build those and when most people found out about them they went with stick build (traditional add on with bigger windows etc....) Most manufactures will not allow a wood or gas fireplace in the room at all.

Be very very careful about what you are wanting to do. Should you do this I would double if not triple the none insulated clearances for the stove and then I would shield the heck out of the wall. Meaning if the stove says 20 inches from a wall (Without shielding) I would put it at 45-60inches and put the shield on. Your plastic wall may not catch fire but it will melt (I have seen it and they were using a small kerosene space heater 24 inches from the wall.

Just my thoughts before you even pick out a stove.

When selecting a stove its going to get hot in that room unless you get something extremely small. You are talking about 360sqft of space.

Maybe a small gas stove would be a little bit more your speed. Wood Stock makes a small mini Franklin that might just do the trick and can be direct vented to the outside of the room. It has almost a zero clearance.

 

[Yeager]

Hi owingsia,
It is a traditional 2x6 wood wall construction. Its more of an addition than a sun porch (just lots of windows!). The fireplace and chimney will have the needed clearances from all combustables and things that can melt! My question is really about the down draft. I spoke with a tech at Vacustack (really great guy) and he felt very bullish that this would be a good candidate for Vacustack and shouldn't have a problem. Any other thoughts out there?

thanks,
Yeager