Power vent for a coal furnace

[vandalay714]

I was looking into buying a Harman sf2600ss coal/oil furnace to replace my oil fired furnace. Unfortunately my chimney is 6" and the harman requires a 7" flue. The guy at the Stove store didn't have any suggestions at that point other than $2-3K for a new stainless chimney if it could fit. My HVAC guy mentioned using a power vent thru the side of the house. I know that some coal stoves utilize a power vent but I'm not aware of their usage with a furnace (rated 120K btu). Does anyone have any opinions or comments on going the power vent route for this type of furnace?
Any help is much appreciated!

 

[pybyr]

Vents dependent on power are almost certainly a no-no for this as well as any (or almostt any) other solid-fueled furnace or boiler-- reason being that if power fails, solid fuels keep burning for some time, which leads to a combined risk of overheating of the unit and combustion byproducts leaking into the building.

7" appliance into 6" flue is _sometimes_ OK to do with a reducer -- skip the dealer and call the Mfgr. to ask.

Good luck.

 

[vandalay714]

The Harman rep told my stove guy that using a 6" flue would void the warrantee.
Thanks for the input!

 

[stee6043]

Your "HVAC guy" told you to use a power vent on a solid fuel burning appliance? Me thinks its time for a new HVAC guy....

 

[pybyr]

Speak with Harman directly- for the reason Stee mentions

 

[thecoalman]

Many smaller stokers have been rated for power vents and I believe the smallest Keystoker boiler can even be power vented. The reason being is they have only a handful of fuel burning. If the power fails they'll be out in a very short amount of time.

You CAN NOT do this with a hand fired coal stove or larger boiler like an EFM which can burn for hours without electric.. Check the manufacturer specs.

Having said that I wouldn't be concerned with the smaller flue either...

 

[thecoalman]

The guy at the Stove store didn't have any suggestions at that point other than $2-3K for a new stainless chimney if it could fit.

Missed this before, SS is not that great for coal. They don't last very long, at least for the cost involved. 10 years seems to be about the max. Standard chimney will last you a lifetime.

 

[vandalay714]

OK so I can see how a hand fired coal furnace cannot be power vented. Keystoker has a stoker furnace that also has an oil burner attachment. Is there any reason why this unit with a stoker cannot be power vented? I just want to get some opinions before talking to the guys at Keystoker. They are closed for the day and I'll call them tomorrow but was hoping to get some input here today.
Thanks!

 

[thecoalman]

You'll have to ask them, as I mentioned I *believe* the smallest boiler they make can be power vented. The difference with the Keystoker and something like a EFM or AHS is all the Keystokers use a bed design. Even with the small boiler you don't have a lot of fuel on the bed and probably more importantly the air is cut off for the most part once the power goes out. The EFM on the other hand has a pot with a larger amount of fuel and an air setting.

The oil option is nice but it's my understanding it's not very efficient compared to standard oil boiler. Also keep in mind it's not a matter of throwing a switch. There's a protective cover of some sort that needs to be removed.