Oil-fired boiler, power-vent, outside combustion setup

House has an oil-fired boiler with a powervent flue, and someones home-grown attempt at supplying outside air for combustion (4" flex hose that was shoved over the end of the air intake on the burner head).
If it makes sense for this to have an outside air intake for combustion, I'll have it done properly (the hose slipped off this past weekend and revealed itself for the kludge it is), but since it has a power-vented flue and is therefore sucking large amounts of indoor air through the damper and out the flue, what sense does it make to worry about the small amount of air the combustion intake is going to pull out of the house?
Or, is the power-vent flue setup done wrong as well?
Dave
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Get the proper kit for whatever brand burner it is. Doesn't cost that much at a supply house...
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But, is there any benefit to using outside air for combustion when so much inside air is being pulled through the damper?
-D
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: But, is there any benefit to using outside air for combustion when so : much inside air is being pulled through the damper? : : -D : That's going to depend on a few different things, including how air tight the house/basement is. I respectfully suggest you should have someone in to check it out. Negative pressure in the basement can pull gases from the fire into the air and thus into the ducts. It's hard to quantify without being t here.
Pop
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Unless I do not understand your system, the air pulled through the damper and out the flue by the power vent IS combustion air. Combustion air can be supplied from the inside ambient air or from outside. An outside air supply should prevent any inside air from going outside, except for various air leaks, of course. Don Young

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I'm not saying this setup is correct, its just what was there when I bought the place:
The flue has the typical round weighted swinging damper-door arrangement, and when the power vent is active (when the boiler is firing) the damper door swings wide open and lots of my garage indoor air gets sucked outside by the power vent, along with the flue gases of course.
So, with all that inside air getting pulled outside, what's the point of trying to use outside air for combustion?
The unit is maintained, cleaned, and inspected by a local oil company, but I don't know if they knew the outside-air intake was homegrown or not.
Dave
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I did not understand before that you damper was that type. If your power vent is pulling a lot of air in excess of what the furnace needs it would seem that reducing the venting would solve the problem. It may not be reasonably practical to do that. Outside combustion air would still reduce the total amount of heated air lost. You might try to estimate how much air enters the furnace compared to how much enters the damper. I suspect it may be a minor loss compared to the cost of eliminating it. Don Young

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