Outdoor woodburner ductwork questions.

I have a friend who had an outdoor unit installed, The supply duct was ran to the bottom of the existing gas furnace with a temp switch installed at the outlet of the supply dust to turn on the fan in the gas furnace when the air got to 120 degrees from the woodburner. The lady can not keep the house heated with just the woodburner she thinks by changing the supply from the woodburner to go into the top of the gas furnace and not running the fan in the furnace it would heat the house. Thoughts on this?

Hey Ed,
I would assume that your friend likely won't get much of that warm air circulating her house if the fan is not used. I would question whether a damper should be installed between the gas furnace and its return ducting and maybe partially closed? Perhaps it is easier for the fan to recirculate the cooler air in the house than to draw on the warm air from the outdoor burner? Just a thought keeps us updated with your successes and woes.

The outdoor wood burner does have it's own fan. The return of the gas furnace is basically a closet with openings cut thru 2 walls with grilles on them. then the furnace sits an a wodden box made about 2 feet off the floor. the woodburner supplies it's air into this closet below the furnace and wher it mixes with air from the house.

outdoor forced air units are notorious for losing heat before it gets where you want it. Usually they have big flex duct running from the unit to the house that gets holes and leaks and is not insulated well enough anyway.

Check that ductwork first. Either patch it and add insulation or replace it with insulated hard ductwork.

Any way you could post a pic or two so we can see what we are dealing with?

I had to turn the woodburner the installer had it facing directly north so I turned it to facing east. redid the pipe outside the return is only 4' to the house and the supply is same but then goes under the house. It is fairly new and never worked right. manufacture also sent her a bigger unit. Question should the combustion fan on the unit blow all the time when the tstat is calling or should it cycle off when the temp rises and turns on the blower? I will see if she will send me some pics.

Well definitely make sure any outside ducting is well insulated and then water proofed because wet insulation is worse than no insulation. As for the combustion blower it will always be on when the unit is burning or at least I would assume. That's how a typical boiler works. I know we aren't dealing with a natural gas boiler but it would make sense to me being that its job is to provide air for combustion.

That is what I thought cause I do hvac work also, But one thing that could cause the unit to lose heat is too much going up the flue, thus maybe the comb fan needs to shut off when i arrived it was shutting off when blower came on I rewired and confirmed with the distributor that that was correct. But?
I am trying to get the homeowner to join and get in this conversation and add some pics.

Ya that sounds plausible. Especially if it had been cycling originally.