Osburn 2400 Insert Overdraft??

[slefoll7]

We installed an Osburn 2400 insert last week - it puts out a very impressive amount of heat. We are having some difficulty controlling the rate of burn, though. It seems to burn very hot, even with the vent control turned all the way down. There is a some dampening of the fire noticeable when we close the vent all the way, but it still burns through 3 or 4 large logs in about 2 - 3 hours. When we load it up completely at night, we feel that it is over-firing.

We have a 30 feet masonry chimney, in the interior of the house, with a 30 foot insulated SS liner, 6" diameter. The flue diameter is 8 inches.

One additional note: there was already a flat, square stone cap on top of the chimney, set on four little brick columns that extended above the main opening at the top of the chimney. So, we (myself and the chimney sweep who installed everything) did not put an additional cap on the top of the liner. So, the liner is basically open, terminating maybe 6 inches beneath the stone cap. This effectively keeps the rain and weather out, but could this setup be creating an overdraft? (ie. - does the cap on top of the liner restrict the draft somewhat?)

Could the addition of a liner cap solve the potential overdraft? Or, maybe a barometric damper?

Please help! We love this stove, but we need a longer burn ... we are burning very dry, hard woods.

Thanks.

Scott

 

[Swedishchef]

Welcome to the Forum Scott.

Glad to see a fellow wood burner using an Osburn product They are under rated stoves.

It sure does sound as though you have a bit of an overdraft problem. That is a massive insulated chimney! Did you ever think of attempting to install a damper?

The cap may help deduce draft however I think that the primary reason for a cap is to prevent precipitation and some critters from getting in.

I am partially new to wood burning. Hopefully some of the "pros" will chime in on this topic.

Andrew

 

[oconnor]

Start off by damping it down earlier - you can cut back the air so long as you still have full flame in the firebox. If you wait too long to turn down the air, you can get lots of draft built up in the flue that can't be shut down. That has happened to me from time to time.

Given your flue, you may benefit from a restrictor of some sorts - not likely a standard damper plate, but something similar that is fixed in place - there is an SBI rep on the forum here, hopefully he chimes in. Otherwise, give thier tech support a call and see what they recommend.