New to Me Harman Magnum. Questions

I am turning my Keystoker 90 into a mini furnace. I did not get the duct ring in the top from the factory but will now weld one in. I ran a Buderus hand fed for years in the basement family room, and supplemented the heat with a few hundred gallons of fuel oil. Well, in comes the Keystoker 90, and knocks the socks of my previous arrangement. Last 2 years thermostats where turned off for the oil fired Buderus. I did a redneck hookup to the Keystoker gathering the air off the front and feeding my air distribution blower of many years and all of a sudden the house was equally warm. Cold weather was forcasted last nite so out came the redneck setup. This morning my bride of 32 years said " I was wondered why the house has not been that warm? Now you hooked up that tube and everything is better Tis weeekend it will be warmer and I will sell the new duct ring into the top, showing the cleaner and more efficient connection of the convection blower to the distribution blower. The Keystoker Koker should kick your install up a notch or two if installed into your existing furnace. I only wish this site and my knowledge I have now was here 30 plus years ago All in all I never went off half cocked and did anything stupid with my install. Everything is still pleasing to the eye, and very functional as well.

The Koker will definitely do what you want. I have mine connected in series with my oil furnace and only use the oil furnaces' blower to push all the heat throughout the house. A hand-fired stove won't work any better than the stoker you have now, in fact the hand-fired will require more work as you'll need to tend to it more often.

I finally got around to cutting a return vent in the floor and it has helped some. I am thinking I am going to have to use the duct on top of the stove in order to get the amount of heat that I want upstairs. I really don't want to cut another hole in the floor so I think I am going to just use one of the existing supply vents. It is much easier to disconnect one of them from the main system than to cut another hole. Any thoughts??? Also, If I use the duct on top of the stove, will the radiant heat be enough to keep my basement somewhat warm?

I have a mag stoker in my garage workshop with the vent coming off the top ducted to the upstairs. The workshop is only 20x24 and has insulated floor, walls & ceiling, however, there is a 5' opening to the 24x24 garage that is closed off with only hanging plastic. The workshop will get to 80* just off the radiant heat from the stove as well as the duct that runs across the ceiling to get to the upstairs vent. I am sure your basement is larger and may not be insulated as well so your heat loss would be greater. But I still think you would get plenty of heat off the stove to keep it comfortable.

Make sure you don't place your duct off the stove too tight to anything combustible! The duct going across my ceiling gets hotter than the flue pipe. I have a 1" air gap from the ceiling and I'd be worried if I didn't!

kirtdog wrote:Also, If I use the duct on top of the stove, will the radiant heat be enough to keep my basement somewhat warm?

Depends on how big the basement is, how well insulated, etc. What I found with my stove was after I ducted it to the upstairs the basement became comfortable. Very comfortable. Before ducting, my basement was near 80* and upstairs was in the high 60s. Once I ducted it the basement dropped to the low 70s and the upstairs came up to the low 70s. No more roasting in one place and freezing in another. Everyone's house and set-up is different, of course, but it worked really well for me.

I haven't given up on the magnum yet. This may be a dumb question but how big (high) should the flames be? I don't want to overfire the stove and mess something up. I am still trying to avoid using the takeoff on the top of the stove so I want to make sure that I am burning the stove to its full potential without doing damage. Any help is appreciated.

When mine is firing the flames will be touching the top of the triangular baffle. I think that flame height would be a result of quite a few variables like the combustion air volume, coal quality, grate holes clean or not, fly ash under grate, etc. I watch a couple things are more closely than flame height, though.

The first is that you aren't pushing more air into the firebox via the combustion fan than you can exhaust out the flue. If you are then the exhaust will look for other ways out of the stove and into your living space via the hopper or around the glass. My combustion fan plate is only open 3/4" from the flat part of the plate to the edge of the fan cage arc. You can compare the firebox draft versus the flue pipe draft with a manometer to make sure you are balanced correctly.

The second thing I watch are the temps on the stove body and the exhaust. The flue body gets to about 600* (mag thermometer on top-front corner of left sidewall) when firing for about 1/2 hour and the corresponding flue temp is 250* (probe thermometer about 18" from stove exhaust port). When idling for the day, the side temp settles to about 350* and the flue temp is at 125*. I have a baro on mine that keeps the flue draft at about 0.04.

I am about to give up. I can't get the heat upstairs. I thought the heat would come up through the basement stairs and circulate through the house. I did cut a return vent at the opposite end of the house thinking that it would pull the heat. It isn't working. I am trying to avoid putting more holes in my floors. I may just have to suck it up and run the duct off of the top to the first floor.

This is a VERY common complaint, trying to make a stove into a furnace..
Go to the venting, chimneys forum and do some reading, there are many threads on this subject..

I'll tell you what WORKS.. You HAVE to remove cold air from upstairs.. just having a vent in the floor will not
assure that cool air from that floor will fall into the basement.. You MUST use a duct, like a dryer hose from that
vent in the floor over to the inlet of your circulation fan.. this way you are PULLING cool air from the upstairs, and
then the flow of air up your stairs will increase noticably.

Think about a furnace, it has cold air return ducts, and hot air out ducts, they open into each room upstairs.. so you
can't expect to heat the house well or evenly with just the staircase as your 'ductwork'.. Many staircases end up having
cool air flowing down, and hot air along the ceiling of the stairway flowing up... but they get mixed, the flow is not separated
by rooms or walls or ducts, so it doesn't work well..

We've had several forum members who installed the clothes-dryer vent from a floor vent to the inlet of the stove's fan, and had great success getting a much better air circulation in the house..

It can be done, you just have to figure out the airflows in your house, or create the ones you want.

Hope this helps..
Greg L

As Greg said the air circulation issue is the most common problem heating with stoves. Some folks have found that just cutting a hole in the floor for a vent only allows more heated air at the basement ceiling to go up through this vent rather than allowing the cold air to drop. The fix is to have a duct from this vent to the basement floor.

I have a 6" flexible duct on the one floor supply vent in the back bedroom that drops to the basement floor. I can feel the cooler air flowing out of this flex duct. You should definitely try this before cutting more holes in the floor.

And if you could end the piece of dryer vent right adjacent to the inlet of the circulation fan of the stove, you would 'almost' have a closed circuit.

Forum member WNY hooked up cold air returns to his Hyfire in his basement, he already had hot air ducts in place.. he was able to raise the upstairs temperature around 10* if I remember correctly.

You can't push hot air into a room, you have to remove cool air, and hot air will replace it.. It just works better this way.

Greg L.

i actually did run a duct and it still doesnt seem to be working. The duct isn't the whole way to the floor. It is about 16" or so from the floor. Should I extend it down further?

Take a look at this link, Forum member Qball did it right.

About halfway down page 2 there is a series of photos showing his ductwork.

Cold Air Return?

Greg L

I had good success running a duct from my Harman in the basement to the two coolest rooms upstairs on the other side of the house. (Actually I built a sleeve around the stove so I have two ducts coming off it). I did have to install two two inline duct fans to help with the flow, however. I also used hard ducting vs. the flexible stuff. I used flexible originally but it gave off a stink when the stove temp got high and the flow wasn't great either. After I upgraded to metal duct the flow was improved. As a bonus I pulled the plastic lining out from the inside of the flexible duct and slid the insulation over top of the metal duct.

The setup works well but you have to keep the room doors cracked and the basement door cracked or else those rooms heat up too much. Also, if you put in duct fans, make sure they are good quality or the heat will kill them. I found that out the hard way after going through three Home Depot pieces of poo. I have Tjernlund duct boosters now and they've been good for a couple years so far. One got a little noisy but has been that was for over a year now and continues to work fine. I suppose you don't have to worry about that aspect if you are using duct fans to pull cold air out of a room.

I have on of these older Magnum Stokers,, I didnt get the deal you did I had to fork over $800 for mine but I know I even got a great deal. I live in a 28 x 52 Ranch style house sitting on a full superior wall basement. When I bought my house it has a wood burner in the basement with a "tent" over the stove that connected to duct work that ran to 4 registers. When I got my magnum I took out the top vent plate and plugged up the front vent. I used a 3ft piece of duct work from the top vent directed up into the tent. In thew top of that tent is a squirel cage fan from an old trailer furnace. I hooked that fan into a 30amp dimmer switch that I placed at the top of the basement steps. I can control how much air comes upstairs. The only change I want to make is I want to put a switch like the switch on a forced air furnace air handler that only turns on when it hits a certain tempature then shuts off on its own, thats just to help with the electric bill. My poor stove has been thru 3 floods with the last one ending with the water at the very top of coal stove. After each flood I dissasembled the fans and wd-40'd the crap out of them. They will get replaced for next year as well as a new hopper ,I had to reinforce that a few days ago. also read somewhere about running the combustion fan all the time for a better burn of the coal which I have done for a short time to see and it does burn better but with everything my poor stove has been thru I don't want to keep that motor running.