Augmenting Existing Propane Forced Hot Air System With a Coal Stoker

I'm a former "coal cracker" now living in New Hampshire. I have a 7 year old 4000 sq ft, 2 story colonial with a propane forced hot air system. Stop laughing, the system made sense back when energy was cheap...

My local Harman dealer suggests augmenting my existing hot air system with a second hot air furnace. Basically, he proposes adding a second hot air furnace; and, route the hot air output of furnace #2 to my existing hot air ducting---probably to zone #1 (the first floor) since warm air rises, the second floor upstairs (zone #2) will eventually benefit... Since the first floor floors are insulated using my existing hot air ducting to move hot air around the house makes sense.

I haven't talked to a HVAC contractor yet. I just wanted to see if this proposal makes sense. Seems like I'll need dampers to isolate airflows from both furnaces to keep air flowing in the right directions. My existing furnace #1 has power dampers to control air flow between the two zones.
I'm concerned about the output of furnace #1 blowing into furnace #2 and vice versa... Since airflow will follow the path of least resistance...

My dealer also suggested not to worry about my cold air return; again, basically leaving my existing cold air return intact, connected to my primary furnace #1 (the propane unit). Essentially the proposed furnace #2 would rely on "ambient" air in the basement for its cold air supply---filtered of course...

Does this make any sense??

Any recommendations out there for a good stoker hot air furnace??

Appreciate your help in advance.

I would recommend a stoker boiler, and water to air heat exchangers, simpler to install in the existing ductwork, everything flows the same.

Greg L

I concur. You will get your domestic hot water for zip too.

The distance your at, I would plan on 25 ton loads right from the breaker. That should hold you about 4-5 years. I'll guess $5-6,000 tops?

watkinsdr wrote:I'm a former "coal cracker" now living in New Hampshire. I have a 7 year old 4000 sq ft, 2 story colonial with a propane forced hot air system. Stop laughing, the system made sense back when energy was cheap...

Sorry couldn't help myself... I had a customer in similar situation on gas. He added a 120,000 BTU hot air Keystoker and was just about able to heat the whole house with 10 tons a year. Went from $600 + gas bills a month to about $100. Most of that $100 bucks was probably for hot water, don't think he has a jacket. Anyhow I figured I'd mention that to give you an idea.

I'm concerned about the output of furnace #1 blowing into furnace #2 and vice versa... Since airflow will follow the path of least resistance...

Just a suggestion because I'm not familiar with ductwork but I'd imagine they must have something similar to a check valve such as they have for water. If not hold that though while I run to the patent office.

Any recommendations out there for a good stoker hot air furnace??

The trouble with that question is you won't find anyone to say what they purchased is junk. That's like asking in a computer forum what's better Windows or Mac? They are all well built American products and anyone that has one will tell you that regardless of manufacturer. Here's a basic list in no particular order, I may leave someone out:

Keystoker, Harman, AHS, EFM , and last but not least Leisure Line. LeisureLine has a forum below and is a member here you can visit there website here: http://www.leisurelinestoves.com/

One thing I will suggest is make sure you have access to the fuel before considering this endeavor. the farther you get away form Northeastern PA the harder dealers are to come by.

Our fearless leader forgot to mention my favorite, the Axeman-Anderson Anthratube. I feel it is the best unit available (they all are good units as the leader said), and the most pricey. However, for the additional $2,000 you'll spend, I'm sure Peter Axeman will throw in a copy of the "Yanche Report".
All in all a pretty good deal.

There is a coal dealer in Pelham and one in Derry, I would check out price and availability first locally. I still think if you go with coal you should buy in bulk from the breaker, "tons" of savings at your distance.

While it's possible to make coal fired furnace work with you existing system it will take a knowledgeable A/C duct designer to do the job. Manual air flow dampers will work for switching between systems. You will need lots of room for the duct work. Stay away from anyone who doesn't include a ducted return to the coal furnace. As others have said the coal boiler with a boiler water to air heat exchanger is the way to go. Especially if chimney location, space and long ducts all conspire to make a design difficult. A boiler can be located almost anywhere since you only need to pipe the hot water to the air exchanger located above your existing furnace. Look at my post it this thread: Forced Air Setup; Boiler or Furnace.
It will give you a link to McQuay water to air heat exchangers.

As "coaledsweat" says line up your coal supply first. Investigate the coal quality and if you buy a trailer load have some contract that assures quality coal. You don't want 25 tons of junk coal!

Yanche

heehee asking which is the best is like asking a group of guys who makes the best pickup truck - Ford, Chevy, or Dodge. hehe I have looked at all the available options but the bottom line is I like my Keystoker dealer, he's an honest guy and I would rather give him my money than anyone else if I decide to buy a new unit, of course the used market might make another model "better" for me depending on the savings.

Boilers are easier to control and generally last a lot longer than furnaces. Oh, and don't forget your hot water. You may as well get 1/2 off that too!

harmon only makes hand fired hot air furnaces at least that is all I see. Based on the size of your house you would be much better off to use the boiler with a heat exchanger. Hot air coal furnaces especially hand fired are much more difficult to regulate. Also by the time you get crteative with your ducting you could probably make up most of the price difference between that and the boiler. probably the most economical boiler for your size house would be Keystoker's KA-6 or KB-8 but that would depend on your heat loss analysis.

My Harman coal furnace use the same ductwork as my poropane furnace.
That includes cold air return ducting too.
I am able to isolate the the propane furnance with a hand damper but have found that it isn't necessary in my situation.
It all works to perfection.
The only downside for some would be the normal disadvantages involved with a handfired furnace.

Thank you all for your help WRT solving my home heating problem. I have two contractors stopping by tomorrow (Good Friday 4/6) to quote adding a boiler and heat exchanger to my existing propane FHA central heating system. Although, I'm leaning towards another solution right now...

I've actually located three sources of coal. The "going price" seems to be $275 - $300/ton for bagged coal up here in NH right now. I know it sounds expensive; but, still significantly cheaper than any other source of energy---except "free" wood that 'ya work your tail off for...

Since I estimate the cost of the boiler/heat exchanger combination is going to be high ($10K to $12K installed), I'm seriously considering the following heat source combination:

1) Harman MAGNUM coal stoker in the basement (with domestic hot water coil). I have a couple of ideas concerning this domestic hot water solution. Any of you folks out there have any good domestic hot water designs??

2) Harman P68 pellet stove on the 1st floor west end of house.

3) Harman fireplace pellet insert stove on 1 st floor east end of house.

Pellets are clean and the "going" price up here is currently $210/ton.

My goal is to run all three heat sources, leaving my central propane FHA system as a "backup" only... This way nothing is disturbed, the system will still work fine for A/C in the summer. And adding the three stoves will total about $8500 installed. I roughly figure a three year payback, worst case.

And I'll be burning fuel that's completely isolated from OPEC! Oh what a feeling!! I'll be WARM again too!!!

You guys probably don't like pellets; but, I was pretty impressed after seeing these stoves in action at my local Harman dealer.

Again thank you for your help. I'm planning a trip to NEPA this weekend to pick up my first ton of coal. I have a 3/4 ton Dodge. Hope to find a good price on bagged rice coal.

Have a great Easter weekend!

watkinsdr wrote: Since I estimate the cost of the boiler/heat exchanger combination is going to be high ($10K to $12K installed), I'm seriously considering the following heat source combination:

My goal is to run all three heat sources, leaving my central propane FHA system as a "backup" only... This way nothing is disturbed, the system will still work fine for A/C in the summer. And adding the three stoves will total about $8500 installed. I roughly figure a three year payback, worst case.

I hate to be a curmudgeon, but your savings of about $2,000 is going to add up to a lot of work for you. And a lot less comfort and a great deal of mess. I would still go with the boiler as I don't see how that would interfere with the AC. With that plan you will be humping coal and ash constantly.
Tending three stoves will be a chore not unlike the "great wood adventure".

watkinsdr wrote: I've actually located three sources of coal. The "going price" seems to be $275 - $300/ton for bagged coal up here in NH right now. I know it sounds expensive;

Locally bagged is about double the price, this price difference gets smaller as you get away from the area but you still might want to look into getting it in bulk if possible. Many of the members make a trek to the area and pick it up themselves, if you have access to a larger truck your set and it will be well worth it. Might take you all day but over a 5 tons your talking roughly $1500+ .

As far as the multiple stoves I'd have to agree with coaledsweat that's going to be quite a chore.

As for the domestic hot water there are quite a few threads in the maintenance forum. The basic method is to run your supply to a T, check valve on the supply and another check valve on one end of the T. You loop it through the hot water heater and the stove. The hot water naturally will expand into the tank. The first check valve on the supply insures it doesn't back into the supply the other is to keep it looping in the direction you want it to go.

That'll give you what amounts to an unlimited supply of hot warter, the hot water heater essentially becomes a storage tank. You can run it directly to the hot water supply but it will be extremely hot and you're just asking for someone to get burned.

watkinsdr wrote:
I've actually located three sources of coal. The "going price" seems to be $275 - $300/ton for bagged coal up here in NH right now. I know it sounds expensive; but, still significantly cheaper than any other source of energy---except "free" wood that 'ya work your tail off for...

Pellets are clean and the "going" price up here is currently $210/ton.

If you think of the cost of fuel in terms of dollars per million BTU coal is less expensive in your area than pellets because the BTU content of a ton of coal is more that one and a half times the BTU content of a ton of pellets.

I agree with the other posters that tending three stoves will get old in a hurry and will not provide the even heat that a boiler/heat exchanger into your existing air distribution system will.

A much more comprehensive energy heating fuel comparison calculator is at: http://www.eia.doe.gov/neic/experts/heatcalc.xls

It uses geographic location for determining heat pump operating efficiency. Be sure to look at all four of the sheets. Many, many links to energy price forecasts, heat content in fuels and equipment efficiency, etc. A wealth of information. Worried about your investment in coal burning equipment? Just compare projected coal price increases to other fuels. It's all there just analyze away.