Top or Rear Vent - Suggestions?

[Waulie]

I have a Woodstock Progress on order, which can be top or rear vented. My current thimble is centered about 20 to 21 inches above the top of the Progress. I need to upgrade my hearth R-value before installing the new stove and it has crossed my mind that raising the hearth 7 to 8 inches would be nice. However, that would not give me much height between the top of the stove and the thimble (about a foot). I think this would look strange and I think I've heard that at 24 inches of height is best before turning into the chimney. So, here are my options:

1. Just upgrade the hearth R-value and top vent the Progress into the existing thimble giving me about 20 inches of height from exhaust to thimble.

2. Raise the hearth 7 to 8 inches and top vent into the existing thimble giving me about 12 inches of height from exhaust to thimble.

3. Raise the hearth 7 to 8 inches and cut a new thimble into the chimney, seal up the old one, and rent vent the Progress.

I think I like option 3, especially when most of the cost of the thimble work would be offset by needing a lot less stovepipe. I spoke with my chimney sweep today (who would do the chimney work), and he said he would never recommend rear venting straight back into the chimney. He said even with a rear vent stove, he really likes to get 24 inches of vertical stovepipe before entering the chimney. He's been cleaning my dad's chimney for years and said he's never like how his Hearthstone II vents straight back into the chimney.

He also said he would never recommend a Cat stove, because it costs about $500 with all the labor required to change one out. :roll:

Woodstock doesn't think there is much benefit with top or rear venting either way.

What do you all think?

Thanks!

 

[HollowHill]

Hi, Waulie, I'm also getting the Progress and will be rear-venting into my existing fireplace. According to WS, only need a 1/4" rise every foot if going horizontal. It's going to be a tight fit, so that's about all I'll be able to do. Got my hearth finished last Friday, .41 R value with Durock Next Gen and 1/4 inch porcelain tile. Are you getting the ashlip to reduce needed R-value or are you aiming for the .8 R-value? Of the 3 options, I think I like 3 the best. Any word on when they will be shipping? Good luck!

 

[Waulie]

If I don't raise the hearth, I think I'm just going to do the 1/2" durock and tile and go with the ash lip. If I raise it, I will go all the way to 0.8. I just don't want to create too much of a toe stubber.

Last email I got from Woodstock said my stove was delayed and was scheduled to ship the week of November 7th. That was obviously a while ago. I asked last week and they wouldn't even give an estimate. So, I have no idea when it will be coming. I don't want to do the hearth work now and have to wait weeks for the stove. I would have to get new pipe lengths for my existing stove, move it off, move it back on, or burn propane. Neither of those options are great.

 

[begreen]

I think your sweep is probably a good and capable guy, but with limited exposure to cat stoves, he is blowing some smoke. Woodstock has made it pretty easy to remove the cat for regular cleaning and a new one is less than $200.

Regarding rear or top exit: On one hand, at this point we have no idea how the Progress operates in real world conditions, I'd be hesitant to recommend the straight-thru rear vent, especially for non-cat burning if it turns out that the Progress is draft sensitive in this mode. On the other hand, the direct rear vent will eliminate one 90 deg turn in the smoke path. I think that it will depend on what the stove is connecting too. If the flue is tall and has an insulated liner, maybe this is a moot point? Have you spoken to Woodstock about this question?

 

[Waulie]

Regarding rear or top exit: On one hand, at this point we have no idea how the Progress operates in real world conditions, I’d be hesitant to recommend the straight-thru rear vent, especially for non-cat burning if it turns out that the Progress is draft sensitive in this mode. On the other hand, the direct rear vent will eliminate one 90 deg turn in the smoke path. I think that it will depend on what the stove is connecting too. If the flue is tall and has an insulated liner, maybe this is a moot point? Have you spoken to Woodstock about this question?

Yeah, I should have said my chimney is 6.5 X 7 ish ID, clay lined masonry. It's about 25 feet tall and interior. I'm going to see how it goes this year before springing for a liner. Woodstock says top or rear vent shouldn't make a big difference. My dad is also getting one and he will be rear venting straight back into a 7X11 chimney. I told him to be ready to spring for a liner, but Woodstock told him they would try it first and see. His is also 25 feet and interior.

Do you have any experience with sealing an old thimble or cutting a new one? Maybe I could handle this myself?

 

[Todd]

Your stove is a much different animal but I've gone back and forth on one of my Keystone's between top and rear vent and can tell you there is a difference for me, top venting gives me a little stronger draft but rear venting works good enough and gives me a better look. My new Supaflue chimney helped the rear vent draft even more so I doubt I'll go back to top venting.

I would try option #1 first and see how it goes, less cost and work. A 20" rise on top of the stove would look fine imo. Maybe instead of 1 90 elbow connect 2 45's together to make a larger less restrictive turn towards the thimble. Double wall pipe may help a little as well.

 

[BrowningBAR]

I have a Woodstock Progress on order, which can be top or rear vented. My current thimble is centered about 20 to 21 inches above the top of the Progress. I need to upgrade my hearth R-value before installing the new stove and it has crossed my mind that raising the hearth 7 to 8 inches would be nice. However, that would not give me much height between the top of the stove and the thimble (about a foot). I think this would look strange and I think I've heard that at 24 inches of height is best before turning into the chimney. So, here are my options:

1. Just upgrade the hearth R-value and top vent the Progress into the existing thimble giving me about 20 inches of height from exhaust to thimble.

2. Raise the hearth 7 to 8 inches and top vent into the existing thimble giving me about 12 inches of height from exhaust to thimble.

3. Raise the hearth 7 to 8 inches and cut a new thimble into the chimney, seal up the old one, and rent vent the Progress.

I think I like option 3, especially when most of the cost of the thimble work would be offset by needing a lot less stovepipe. I spoke with my chimney sweep today (who would do the chimney work), and he said he would never recommend rear venting straight back into the chimney. He said even with a rear vent stove, he really likes to get 24 inches of vertical stovepipe before entering the chimney. He's been cleaning my dad's chimney for years and said he's never like how his Hearthstone II vents straight back into the chimney.

He also said he would never recommend a Cat stove, because it costs about $500 with all the labor required to change one out. :roll:

Woodstock doesn't think there is much benefit with top or rear venting either way.

What do you all think?

Thanks!

The Heritage top vents and has two 45s before it hits the 90 in the chimney and goes straight up. The Vigilant is top vented with no bends, just straight up. The Encore rear vents to a T and goes straight up.

For me, all three stoves are very different, and all three have very good drafts.

 

[Backwoods Savage]

I have a Woodstock Progress on order, which can be top or rear vented. My current thimble is centered about 20 to 21 inches above the top of the Progress. I need to upgrade my hearth R-value before installing the new stove and it has crossed my mind that raising the hearth 7 to 8 inches would be nice. However, that would not give me much height between the top of the stove and the thimble (about a foot). I think this would look strange and I think I've heard that at 24 inches of height is best before turning into the chimney. So, here are my options:

1. Just upgrade the hearth R-value and top vent the Progress into the existing thimble giving me about 20 inches of height from exhaust to thimble.

2. Raise the hearth 7 to 8 inches and top vent into the existing thimble giving me about 12 inches of height from exhaust to thimble.

3. Raise the hearth 7 to 8 inches and cut a new thimble into the chimney, seal up the old one, and rent vent the Progress.

I think I like option 3, especially when most of the cost of the thimble work would be offset by needing a lot less stovepipe. I spoke with my chimney sweep today (who would do the chimney work), and he said he would never recommend rear venting straight back into the chimney. He said even with a rear vent stove, he really likes to get 24 inches of vertical stovepipe before entering the chimney. He's been cleaning my dad's chimney for years and said he's never like how his Hearthstone II vents straight back into the chimney.

He also said he would never recommend a Cat stove, because it costs about $500 with all the labor required to change one out. :roll:

Woodstock doesn't think there is much benefit with top or rear venting either way.

What do you all think?

Thanks!

Sounds like that sweep is old school all the way. There is nothing wrong with rear vent so long as you have some rise in the pipe. 1/4" is code but more I think is even better. We went 1/2" or thereabouts. This lad also knows little about cat stoves!

Sometimes folks get set in their old ways and it is difficult to get new knowledge into them....