Backpressure?

[Shane]

There are lots of questions about direct venting pellet stoves and the general concensus around the hearth is that it is not the best method. I want to explore the other extreme, backpressure caused by pellet chimneys that are too tall and not large enough in diameter. My main question is how do you installers balance backpressure issues with not wanting to soot up the side of a house? Do you feel that all backpressure issues are alleviated by staying within chimney height and diameter guidelines? When I was an installer I didn't really run into any backpressure issues. Are they extremely uncommon?

 

[hearthtools]

There are lots of questions about direct venting pellet stoves and the general concensus around the hearth is that it is not the best method. I want to explore the other extreme, backpressure caused by pellet chimneys that are too tall and not large enough in diameter. My main question is how do you installers balance backpressure issues with not wanting to soot up the side of a house? Do you feel that all backpressure issues are alleviated by staying within chimney height and diameter guidelines? When I was an installer I didn't really run into any backpressure issues. Are they extremely uncommon?

We have always ran 4" if more than 15 feet or if we are going to have more than one T and a set of 45 deg offset.
Most inserts we run 3" around the damper then run 4" Duravent L vent the rest of the way.

The only time I have seen a problem with back pressure is
I went to check out a old Jamestown that a local Sweep installed for someone.
He ran 23 feet of 3" flex up the chimney. the stove did not work worth a crap. (Could have been because it was a Jamestown LOL)
Anyway. there was a Ash clean out on the outside of the chimney about 6 feet up just above the smoke shelf (never seen one like this before)
The stove was running on low the pipe pipe was about HOT! RED hot and discolored.
The customer did not want to pay to have the pipe changed to 4"
2 years latter they bought from us a EF4 insert and paid to have New 4" liner put in.
that was 8 years ago and the stove is still working great today with Annual summer service.

 

[stoveguy2esw]

rod's right , (as usual) expanding the pipe diameter for long runs is (or should be) in most manufacturers specs, we do ask for expanded pipe to 4 inch at 15 ft mark and i usuallly recommend runing the whole vertical in 4 inch instead of transitioning at 15 ft mark due to the possibility of ash setting in the transition , as well as a cleaner look.

 

[hearthtools]

rod's right , (as usual) expanding the pipe diameter for long runs is (or should be) in most manufacturers specs, we do ask for expanded pipe to 4 inch at 15 ft mark and i usuallly recommend runing the whole vertical in 4 inch instead of transitioning at 15 ft mark due to the possibility of ash setting in the transition , as well as a cleaner look.

Yes we use a 3-4 t when we can or a 3-4 adapt at the stove
but on inserts it makes it easy for us to install past the damper or between Heatform tubes if we use 3" flex.
At it saves the customer a few dollars.
Well it if is an Avalon Astoria we have to use all 4" because the stoves have 4" outlet to start.

 

[hearthtools]

I still dont know why Enviro put a 3" connection on the new large 60 and 70 K BTU stoves they are making now?
I got on the Engineer about it he just said "they are working fine"