Augmenting Existing Propane Forced Hot Air System

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 Harmon 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?

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: http://nepacrossroads.com/viewtopic.php?p=8860#8860
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 Harmon 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; 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.

http://energy.cas.psu.edu/ENERGYCOSTS3.XLS

Here is a link to an excel spreadsheet put out by Penn State University that will allow you to change the numbers on the spreadsheet to match your area. And it will compute the fuel cost according to price and appliance efficiency.