DuraVent masonry reline assistance please.

[sadpanda]

I'm shopping for a new liner and need help with some transitions.

Application is a free standing wood stove, alcove installation in old open hearth with fabricated block off plate. I am thinking 5in DuraLiner for the main run and DVL or Durblack welded seam for the stove to block off plate connection.

Here is a diagram:



The main run would be suspended from above with their cap kit and the slip section at the block off plate to allow for expansion.

It appears the damper(s) can be used as appliance connectors so from the stove up:

Damper (6DVL-AD/6DBK-DSW)​

(2) 45s for offset section​

Vertical slip section up to plate​

The transition from 6>5in AND from standard pipe to the DuraLiner is where things get tricky.

• The only 6>5 transition I'm seeing is 5DLR-R6 which has the twist lock on the 5in side and a standard flare on the 6. This should allow direct connection to DVL/Single wall but some other adapter would be needed to get a flange for mounting to block off plate. Possibly 6DLR-MTSC1 or some other fabricated solution.
• My original thought was to use a support box/anchor plate as a transition for the plate (ie 5DT-RCS / 5DT-AP) but Duravent claims they are not compatible with Duraliner

Any other ideas?

Thanks!

 

[begreen]

This is overcomplicated. What stove is this for? Why the transition to 5" instead of sticking with 6"?

 

[sadpanda]

I agree 6in would be easier but old setup (6in insulated flex liner) was overdrafting like crazy ( 0.10 to 0.11 in/H2O). I have to use zero clearance insulated liner so the only options to scrub off CFM/draft is to add a damper (already did on old stove) and drop down to 5in liner.

 

[SpaceBus]

I think decreasing liner diameter will increase the speed of draft, but not the volume of air moved. You may want to look or an alternative method.

 

[sadpanda]

I think decreasing liner diameter will increase the speed of draft, but not the volume of air moved. You may want to look or an alternative method.

These theories have been batted around before but no official word from any mfg... I suspect liability issues.

My googling yielded draft flow equation, combined with my burn logs I was able to calculate average flue temp. I used weather.com average temperature for winter months for external air temp. This resulted in:

• 5in liner = 256 cfm
• 6in liner = 368 cfm

The manual indicates 0.05 inH2O with 6in liner however running those through a basic duct flow calculation gave a much smaller number (175 cfm).

While trying to pull back up the links I used, I found this document that seems much more complete with regards to calculating actual exhaust volume etc. If anyone is curious, I will can make an excel spreadsheet.

 

[begreen]

How tall is the liner? To test the effectiveness of throttling down, have you put a 6" to 5" reducer on the top of the liner and run the insert?

 

[sadpanda]

28-30ft. The chimney is near the center of the house too.

I installed a standard key damper last year.... Only way to get the draft in range was to barely nudge it off of full close.

 

[SpaceBus]

28-30ft. The chimney is near the center of the house too.

I installed a standard key damper last year.... Only way to get the draft in range was to barely nudge it off of full close.

Our friends had an install like that at their old house, but the wind was the reason, not chimney height. If what you are saying is true then I don't think the 5" reducer will do much. I would go with a second damper.

 

[begreen]

Yes, before going through the hassle I would restrict it at top with a reducer. If that makes the desired difference then the 5" liner should work. If that is the case I would use single-wall pipe to connect to the liner.

 

[sadpanda]

I think decreasing liner diameter will increase the speed of draft, but not the volume of air moved. You may want to look or an alternative method.

Our friends had an install like that at their old house, but the wind was the reason, not chimney height. If what you are saying is true then I don't think the 5" reducer will do much. I would go with a second damper.

Wind definitely makes it worse. I'm considering other measures as contingency but trying to change one thing at a time

Yes, before going through the hassle I would restrict it at top with a reducer. If that makes the desired difference then the 5" liner should work. If that is the case I would use single-wall pipe to connect to the liner.

+1 on the single wall up to the block off plate. Hence the Duraliner > Single wall adapter question

I'm not going through the hassel just trying to fix the draft... I recently added on to the house and had to add 5ft to the chimney so I technically needed a new liner last year. Hoping the damper would do the trick, I cobbled together an extension so I could get data and limp through the season. Ideally yes, I would try to start this season on the old liner with the damper and a restrictor at the top however I do want to risk the dodgy patched liner a second year especially now that the new space is occupied.

Being that the damper helped but had to be essentially shut, I'm fairly confident a smaller liner won't HURT the situation.


So back to the original question, anyone with Duravent experience have any insight on making that 5>6 Duraliner>single wall transition at the plate?

 

[begreen]

If using Duraliner, just stick with their system. They make a 6" to 5" flue collar adapter (5DLR-R6). From their use their 5" Duraliner flex (5DLR-36F) to connect to the rigid DuraLiner in the chimney above the damper.