ducting blower fan directly to furnace

Will a blower on a harmon mark III make it more efficient? I use it to heat my basement then it heats my whole house. My oil burner sits right next to it, and is very jelous of the stove. Can I duct the back of the stove where the fan mounts to the stove and pipe it directly to the cold air side of the furnace, or do you think the heat may hurt the furnace fan assembly? Then I want to hook up the fan only swich that is on my oil burner's thermostat to make use of the basement heat.

Sounds like a plan, how about pics? That should generate a plethora of ideas to chose from.

Here are my thoughts on that, after having tried using the furnace system as an air circulator.

While the furnace fan will circulate the air, it also passes the "hot stove air" over the furnace heat exchanger. When the air passes over the furnace heat exchanger, it loses a lot of it's heat to the furnace, probably going out the furnace flue. The end result being, any air coming out of the furnace system is too cool to assist warming the house. "Very inefficient"!

If you were to use a separate fan and plumb the stove heat into the hot air plenum of the furnace, it would probably do a better job.

Edit: It should probably have a return to the stove, as well.

Dallas has it right. the heat exchanger in the furnace will work in reverse, and it will heat the air in the furnace's burn chamber and flue, so it's not a good way to do it.

Put a fan on the MarkIII, this will make it MUCH more efficient, make a duct top like Dallas did for his coal stove, and duct the heat into the upper part of the house.. Put a cold air return duct to the inlet of the distribution fan on the MarkIII, and you will have a little coal burning furnace setup, and working right..

You will still get plenty of radiant heat off the stove's body to heat the basement.

Maybe you can talk Dallas into making you one of his custom stove top heat ducts?? ??

Greg L

Here is Dallas's custom stove top heat reclaimer: Really temperamental stove/draft !!

Nice metal-bending !!

Greg L

I have mine set up with the furnace blower on a thermostat with relays. When thermostat calls for heat stove will come off of idle and blower will not come on until the fan limiter on stove switches on. I have 1 cold air return in the center of the house piped directly to the stove. All cold air returns on the furnace are shut off via a piece of sheet metal over the air filter. Temps blowing out of the vents are lower than directly off stove about 105 deg. but the house is evenly heated.

Butch, where do you have the stove heat entering the furnace system?

through the access cover for the blower. The blower draws the air through the stove then blows it through the furnace and into ducts.

LsFarm wrote:Here is Dallas's custom stove top heat reclaimer: Really temperamental stove/draft !!

Nice metal-bending !!

Greg L

Dallas's heat reclaimer is awesome. It's more than I can make. I will go out to buy the blower for a mark III.

Sounds like something similar to what I plan to do with the Alaska. I'm going to duct the hot air into the hot air plenum after the oil furnace's heat exchanger. I'm sure it won't produce the same effect as the actual oil burner running, but it will supplement the heat from the Harman.