dampers....

[got wood?]

I'm about to start cleaning out my family room stove (older Lopi Endeavor) which is single wall up 3', 90 degrees into the wall 1.5', 90 degrees up on the outside in a SS flue. It's always been a strong drafting stove so I've never questioned its setup. When I had a fella out to give me a quote on a sweep, he mentioned it might be a good idea to put a damper in this flue to help slow down/prolong my burns.

My question is: How do you know when you *need* a damper and do they save a fair amount of wood? This stove is at one end of the house and really is almost too much for that room at times...is a damper the way to go? Will it cause unwanted side effects (more creosote)?

 

[Todd]

How tall is your chimney including stove pipe? Do you have a manual? It might suggest using a damper if your chimney is over a certain hieght.

 

[got wood?]

The SS chimney/flue is probably 20'...the manual doesn't mention in line flue dampers at all (http://lopistoves.com/TravisDocs/100-01161.pdf). Do most folks use dampers here or are they the exception?

 

[begreen]

Dampers tend to be the exception with modern stoves. But I have benefited by them with a more controllable stove and longer burn times.

What are the typical stove top temps that you run at on this stove? Has it been checked for gasket leaks? Is the stove hard to regulate? For example, do you find the stove tends to burn hot all the time, even when the air control is closed down?

 

[got wood?]

I must admit the gaskets do need to be replaced (was suppose to do that mid season last year, never got around to it), so that could be it too. BeGreen, it is hard to regulate though, but again it could be poor conditions of the gaskets.

Could all stoves benefit from a damper, or are they only necessary when drafting is too strong? I usually run this stove pretty hot...around 500-600 degrees.

 

[begreen]

No, on some short stacks a damper would be useless or even have a negative effect. In your case, I'd get the gaskets replaced and see how it goes. 500-600 is a pretty normal stove top temperature range. If the stove is easy to regulate after the gasket replacement, I wouldn't add a damper.

note: on this stove that would be the stovetop's lower step surface.

 

[Larry H]

I changed out the gaskets on my little Lopi Patriot after about three seasons of use. At the time it still passed the dollar bill test, but the door was quite a bit more snug after the replacement. It seemed to me that while the gasket hadn't failed, it certainly was no longer performing up to par. Once the replacement was done it went back to perfectly controllable just like new. I hadn't really noticed the decrease in stove controlability, but did the change anyway and was surprised by just how much of a difference there was.

 

[Gooserider]

Lots of folks "guesstimate" about the need for a damper based on the flue height and other such factors, but this is mostly an estimate. Based on your description, I'd say you have a decent stack height, but not exceptional - you are supposed to subtract 5' for each 90* bend, which means you have an effective stack height on the order of 13' (20' outside + 3' inside - 10' for the bends) which is actually around the minimum reccomendation for many stoves, plus it's an outside chimney which is going to hurt your draft to some degree. Thus I'd tend to think you should be getting good draft, but nothing unusual enough to rate needing a damper. I would concentrate first on fixing your door gaskets, then making sure that all your pipe joints are properly tight and sealed, only then would I even consider adding a damper, and then only if the stove was hard to regulate down to a low burn. Doesn't sound like the case from what you've said so far.

The "technically correct" way to decide if you need a damper is to have an actual draft pressure reading done with the correct meter - a "Magnehelic" or equivalent - a good sweep might have one, so should most HVAC guys. Not all stove makers give exact specs, but IIRC at least some suggest that you add a damper if you have MORE than 0.30" of draft pressure, and not if the pressure is less. Probably a good general rule.

Gooserider