How to connect cold air return to Koker

Last fall you guys helped us with the info and direction to install our Keystoker Koker furnace. We did not at that time connect any cold air returns to the Koker but want to do that within the next couple of weeks. We got lots of black dust/soot in our house, not sure if it was from not having a sealed system, or shoveling into the hopper. The Koker is installed next to the forced air propane furnace and using the ductwork to send the heat from the basement to the house, 2000 sq/ft, 2 story, built in 1873. It heated the entire house very well, was toasty warm all winter but sick of the black coal layer even on the second story. Can anyone offer advice?
thanks !

Could you post some pictures, you shouldn't be getting the kind of dust your talking about. If you check on past posts there are plenty of pictures of kokers & both hot & cold air tie ends.

I've been running a Koker for the last few years and have not experienced any black dust/soot in the house. I did see dust in the basement when I got careless handling bulk coal. I suggest what's happening in your home is due to loading the hopper when the Koker blower motor is running and the dust created during the loading is being sucked into the open convection fan and blown through the house.
For what it's worth, I'm including some photos of my installation. I encourage you to connect sealed ducts between your Koker blower and your cold air return system. Also, install a removable damper in both the hot and cold air sides to prevent a circulation "loop" with your furnace. We're heating an 1800 sq ft ranch with only the Koker blower with no problem.
Regarding the manometer, I recommend you get on permanently installed. Most importantly, it will give you the ability to always know what's going on with your draft.
By the way, I have a direct vent unit, so the vent is different than yours. Disregard that system.
I hope this is some help to you. Good luck with yours.
Here are the photos:

Here are two photos.
Thanks so much for the pictures, they are exactly what we are looking for and want to do with our system.
What size pipe is your return ? Also, where do you find 12 x 12 filters? We have a problem finding them here.
It looks like you have a piece of sheet metal attached with either some kind of tape or screws to the outside of the filter frame and then the ducting into that. Would that be a correct theory? We have not done anything with ours yet because different folks have told us just box in the whole blower motor and tap cold air return ducting into that, but that would eliminate using the filters, which we don't want to do.
Your help is greatly appreciated !!!
PS.......shoveling coal while the motor is running is what is happening. Guess it would also help to seal EACH seam with a duct tape as well.

Rick, I have seen the filters at our local walmart, I have been blowing mine out with compressed air but now that I found some I'll get a couple new ones & keep the old for spares. (just in case my puppy decides to discover if they come out as easy as the furnace filter did)

I used 10" dia 30 ga sheetmetal ducts for my cold air returns between the basement ceiling and the motor. In the ceiling I sealed off the space between the floor joists to act as a duct.
At the motor I already had a 12" air filter frame screwed onto each side. I simply fabricated a connector out of a 12" square piece of sheetmetal and a 10" dia crimped starter collar and fastened it to the frame.
You are right about sealing the joints. As a separate project I went thru my entire heating system and sealed ALL the joints, heat and return. It made a huge improvement in the efficiency of the system.
Regarding the filters, I picked them up at a Home Depot in Houston and brought them home. I've had a hard time finding them around here but I did see some in Lowes locally.

I order MERV 7 and 11, 12x12 filters depending upon the price and change both 3 times per year.

Very low cost online.

No dust in my house either since I have been using Merv 7 or 11. (3 years now)

Stay away from the Fiber Merv 3/5 filters as they are useless for Coal Dust.

http://filtersdirect-online.com/polyester_air_filters

thanks for the link, but it is no longer there?

Yeah, I see that...looks like I am looking for another source also!!

Here is how I connected mine. I used 14" round duct and tied the oil furnace blower in series. The oil furnace blower blows into the Koker.







Here you can see where I split the cold air return side of the oil furnace...