Hot Air of Stove Into Which Plenum of Oil Furnace?

Would the heated air from the coal stove be ducted into the hot or cold air plenum of the oil furnace? We ordered the coaltrol device(CM2-4) with dry contacts so we could turn on the oil furnace blower. If it is ducted into the cold air, heat would come out of the cold air ducts unless the blower ran all the time. If ducted to the hot air plenum, the sensor in the plenum would turn on the blower when needed. Which way is best? Thanks in advance for info, Jim

Would the heated air from the coal stove be ducted into the hot or cold air plenum of the oil furnace? We ordered the coaltrol device(CM2-4) with dry contacts so we could turn on the oil furnace blower. If it is ducted into the cold air, heat would come out of the cold air ducts unless the blower ran all the time. If ducted to the hot air plenum, the sensor in the plenum would turn on the blower when needed. Which way is best? Thanks in advance for info, Jim[/quote]

First, what kind of stove are you hooking up?
Do you have a heat jacket or the vents on the stove to hook into the Return?

It depends, most installs go into the cold air and let the furnace blower pull the hot air from the stove. But if you have big enough blower on the stove like a koker, you could probably hook it either way.

Jim:

There is something to consider with ducting your coal stove into the return of your oil furnace.
1. With high temperature air bathing the blower motor in the conventional furnace, the motor's life expectancy is reduced.
2. The high temperatures may also trip the thermal overload switch in most blower motors, turning off the blower. These first two problems do not arise if the blower motor is outside the air flow.
3. The blower motor in the conventional furnace may create negative pressures or suction inside the coal stove's jacket. This will draw smoke out of any cracks or leaks, and this smoke will then be blown into the house.
4. Reverse air flow is more likely during power failures, resulting in dangerously high temperatures in the return air ducts.
Systems in which the cold air input to the supplemental stove that comes from a basement or utility room space, instead of a ducted return air system, can lead to difficulties with air distribution.

I would recommend ducting into the supply of the conventional furnace and use spring dampers(also known as back-flow preventers) or adjustable, manual or electric motored, dampers in the supplies, If you plan on the parallel or semi-parallel set up you are inquiring about.

Thanks doug!! Better explaination...I seemed to have forgotten a few things.

We recommend people install so that the coal stove dumps its heat into the coal air return line of the oil furnace. With the blower going the air temp hitting the furnace blower is not hot enough to be a problem. We've also not heard of any problems with doing this. In this configuration you need to either use a hot air jacket or remove the convection fan of the stove to free up air flow. If your stove has two convection blowers on it, many people will only remove one of them and leave the other one attached in order to blow heat into the basement off the stove when the furnace blower isn't on.

Some do go the route Doug suggested and pipe it into the supply side of the furnace and use dampers to prevent back flow. A lot of people don't have enough room to do that kind of install though, especially if they have a split off the top of their furnace hot air outlet and/or have an AC unit installed. It can also make using the oil furnace as a backup more difficult, particularly if manual dampers are used.

Hi, guys. I'm usually in the solid fuel central furnace heating mode. So, I may have overlooked the fact, that the stoves heated air temperature going into the conventional oil furnace is going to be much lower and at a lower volume than I was thinking for a central air solid fuel unit. Most conventional furnace blower fan motors can handle 160 degree inlet air temperature with out any effect. Some up to 250 degrees, but they are belt driven blowers. Therefore Paul,( pvolcko )I stand corrected regarding the hot air from the stove, NOT the hot air from the furnace. I think I read the question wrong. It's a stove not a furnace. Going into the return of the oil furnace should be fine for the lower temperature output from the stove. DOUG

Does anyone have any pictures of their install tying their Keystoker to their existing forced air ducting? I am taking delivery on a new Keystoker 90 Bottom Direct Vent. I had Keystoker add an 8" Collar on the top of the stove and upgraded the standard convection blower to a 500cfm fan. I'm not familar with coal-trol, but have become more interested in how I might make this work for me. I have plenty of clearance to go into either the cold air inlet or the hot air outlet of my propane forced air furnace. I know that the furnace has a blower greater than the 500cfm fan on my Keystoker and that air volume will be less, so I can't decide on where the best place to tap into my existing duct work. I read a thread in another post that there is an external relay that I could get for coal-trol to trigger my furnace fan to assist, but don't know what the best route is. Better yet, which coal-trol unit would best fit my application? I'm also concerned over a) backflow back to my keystoker if I were to tie the coal stove into the warm air outlet in my plenum if in the event I need to use my Propane Furnace or b) backflow of heated air from my Keystoker (tied into the furnace plenum) down through the furnace creating loss of volume to the warm air ducts.
Any and all assistance would be greatly appreciated.

tullybrewing
You would/should put in the back flow prevents in the duct lines when/if you tie it into your furnace, so you don't get the air going the wrong way....

I only used the stock blower (365cfm) on my keystoker and an 8" vent, but it wasn't powerful enough to heat the downstairs of the house (running it in the basement).

Also, the blower on the furnace might be too powerful and all you would do is blow cool air.

How big is your house?

New 2200 sqft Colonial. 50% Hardwoods on first story. Hoping that the heat in the basement alone will make the first story floors more comfortable. The additional air through the ductwork would add to the first and second story comfort levels. We currently leave our heat @ 67 during the day and bought the coal stove to add to the comfort of our home. My wife is home with two young ones and 67 can be a little on the cool side with the chilly hardwoods.

tullybrewing
It might make a little difference on the floors, depends on your basement and how well it would maintain the heat.
Also, if you have a basement door, you might leave it open and help circulate the warm air upstairs.

I would try and just hook it to one area of your duct work, it may not have enough heat output to pull it all the way thru your duct work with the built it blower. You may have to experiment with different hookups. The stand alone stoves don't work like furnaces, they only heat the back and top of the stove, so you will loose a lot of radiant heat from the sides into the basement.

Most furnaces are at least 1500CFM and that may just suck/blow cool air from around your stove, you would have run it much hotter than normal to get the heat upstairs.

I just bought my Alaska Channing III just last week and hope to get it installed in the next 7-10 days. I asked the dealer about ducting into the cold air return and use the blower from my gas furnace to circulate are throughout the house. He said it's quite likely that it would pull the air so fast through the stoker it wouldn't have enough time to really heat the air, resulting in cool/cold air coming out the vents. It seems logical as that fan really moves so much air that I get golden retriever furballs rolling across my hardwood floor!

On the other hand, would ducting into the warm-air side of the duct work be any different? One advantage I have ducting there is that my 2nd floor is on a separate warm-air duct, and I don't heat the upstairs anyway as I like to sleep in a colder room.

So...

Would it be "reasonable" to put a manual damper in the duct FROM the coal stove to the warm air side of my gas furnace? That way, I could limit the airflow being sucked from the stove so that what comes out is hot. Or, would "plan B" be better and simply put in a manual backflow damper on the warm-air duct and let the blower on the stove do all the work?

I am burning with a keystoker koker and have it ducted into cold air return. cold air return is on the lower/ bottom side of furnace and draws in to the blower area of the fha furnace. it is working very well,furnace blower is not wired to convection blower it just cycles on with the fan limit control of existing fha system.i did adjust the fha fan limit control down @10 * on high and low seems to work better,more heat. convection blower on koker is still running and feeds air from koker into fha plenum. it is of my own design and seems to work! also connected cold air return of fha system to convection blower on the koker. I had it hooked to hot air plenum of furnace last year and although it did work I was getting a very short cycle on the fha blower it would only run for about 25-30 sec.shut off for 1min.then back on due to blower on furnace over powered the convection blower and would cool the fha plenum very quickly and overpowered the convection blower from the koker.i didn't have cold air return to convection blower connected last season but mant will suggest that this should be done,instead of drawing cold air from basement area. my $.02 worth is that system works better connected to cold air return side,much more consistent heat.

A standard Keystoker 90K Stove with a 265-365CFM blower, may not move much air once you get it hooked up to your duct work, you need the volume to maintain and push the hot air.

These are stoves, not furnaces. I tried with mine with just the 8" duct and it couldn't keep up at all trying to only heat the first floor from the basement. You also loose a lot of radiant heat on the sides in the basement.

Even my Hyfire I with 130K BTU, dual blowers and heat jacket even struggles a bit to maintain a good temperature upstairs from the basement when it below Zero outside.

Tulleybrewing...here's a pic of my keystoker into the plenum...running parallel to my oil furnace with backdraft dampers in place. Questions just ask!