BTU rating vs Square Foot specs

[jcouncil]

I'm confused by the relationship between BTU and square foot ratings. I'd expect them to have some correlation, but for example, I was trying to compare

Harman PC45 multifuel - 50,000 btu - 1400 sq ft
Enviro M55 multifuel - 55,000 btu - 2500 sq ft.

I was just told by a dealer the sq ft rating is based on testing AT THE MANUFACTURERS LOCATION, ie the Harman heats up 1400 sq ft in Wisconsin, while the Enviro heats up 2500 sq ft in British Columbia.

So would the Harman likely heat 2300 sq ft in British Columbia? Would both of them heat nearer 3000 sq ft, down here in Oregon, way west of Wisconsin and south of Canada?

We have 800 Sq ft - poorly insulated - old wood cabin. So we thought 1400 sq ft Harman gave us some extra umph without going WAY too big - (just run it on low unless we want to heat the house up from cold). Now I'm starting to wonder if we are going to end up living in an inferno.

Thanks all in advance!

(PS - no suggestions on other stoves thanks, a) we're limited to local dealer brands, b) we've looked at the rest of the Enviro and Harman range, c) we'd really like a multi-fuel or at least all 3 pellet grades stove).

 

[HEMI]

I'm confused by the relationship between BTU and square foot ratings. I'd expect them to have some correlation, but for example, I was trying to compare

Harman PC45 multifuel - 50,000 btu - 1400 sq ft
Enviro M55 multifuel - 55,000 btu - 2500 sq ft.

I was just told by a dealer the sq ft rating is based on testing AT THE MANUFACTURERS LOCATION, ie the Harman heats up 1400 sq ft in Wisconsin, while the Enviro heats up 2500 sq ft in British Columbia.

So would the Harman likely heat 2300 sq ft in British Columbia? Would both of them heat nearer 3000 sq ft, down here in Oregon, way west of Wisconsin and south of Canada?

We have 800 Sq ft - poorly insulated - old wood cabin. So we thought 1400 sq ft Harman gave us some extra umph without going WAY too big - (just run it on low unless we want to heat the house up from cold). Now I'm starting to wonder if we are going to end up living in an inferno.

Thanks all in advance!

(PS - no suggestions on other stoves thanks, a) we're limited to local dealer brands, b) we've looked at the rest of the Enviro and Harman range, c) we'd really like a multi-fuel or at least all 3 pellet grades stove).

PC45 is rated 45,000 BTU........maybe look into the Enviro mini rated at 30,000 BTU

 

[littlesmokey]

Usually the ratings are based on maximum output. Hopefully, you will not be operating a stove at Max, all the time. As for square footage, have your home analyzed for it's environmental efficiency. Here the gas or electric company offers it as a service. They test the amount of insulation, thermal wrap of the house, efficiency of the window insulation, doors, etc..... They will at the end give you the reasonable amount of Btu's to heat "your" home. Coming from Oregon, they are about the most efficient in doing the analysis. They will also make suggestions for improving your efficiency and what gets you the best bang for the buck. Here the utilities do the leg work, but it is a state program. You could contact the city or county and see what is available in your area. Then you will know the hard data. From that you can decide the size and configuration that best applies in your case.

 

[jtakeman]

The square foot rating is deemed by the Manufacturer. Some over rate and some under rate there stoves. Why? I am not sure. Same goes for the BTU ratings. Both those stoves are over rated or Idea conditions of a lab. Ever stove that is Qualified for the tax rebate. Has sent them to an EPA testing lab. The numbers from there are less than Ideal.

Real world is much less than Ideal! If you look at the mini(just as an example) You see Enviro rating of 30,000 BTU's The you see the 22,584 just below it. That was the EPA rating. There ratings are better than real world but closer to reality.

http://www.enviro.com/fireplace-products/pellet/freestanding-fireplace.html#mini

The M55 use's 6.5 lb/hr and if you used a pellet of 8500 BTU's per lbs. That would be 55,250 Max BTU. (I am only using the Enviro spec's because I know where to fine them. But I am sure Harmans does the same) The M55 low feed rate is 1.5 lb/hr with an 8500 BTU pellet that's 12,750 BTU's on low THe average pellet is not 8500 BTU's more like 7800 BTU or so.

As for the Max square foot of handling you would also have to consider the amount of max cfm the room fan will move. The M55 is 200 CFM The PC-45 is 135 cfm. That could be the difference in total area heated.

Both of these stoves will easily handle you heating task. I would go and see them both run, Find the one that is quietest for you. Also look at ease of maintaining and for most ease of use. How easy is it to adjust and is it over complicated. Some find the Harman's to be tricky to adjust. Personally I like the Enviro because its a simple control and not awkward as they say. New digital control easy to adjust and read. Once the damper control is set(done by installer) the other changes are on the board. Simple easy push of a button.

I am not sure how low the Harman will go. I can't find there feed rate spec's. I would post them if I knew where to find them. Curious to see how low the feed rate will go myself. Then you could figure the minimum BTU output.

Hope this helps
jay

P.S. One other thing. You really don't need to run the stove 24/7. Both these stove will run off a Thermostat(Harman has a room temp probe) just like a furnace. Only on when needed. Off and ready when not. The Harman's have some issue's with there ignitors lately. Just a head's up. It will be covered by warranty if there is an issue.

 

[jcouncil]

thansk jtakeman - I think the PC45 has a min feed rate of 0.75. Cant' find it in the brochure (where they call it 0-5lb per hr - since it turns off rather than run on low when the room is at temperature), but I got that from somewhere!

 

[jtakeman]

thansk jtakeman - I think the PC45 has a min feed rate of 0.75. Cant' find it in the brochure (where they call it 0-5lb per hr - since it turns off rather than run on low when the room is at temperature), but I got that from somewhere!

So If you set the Harman on stove temp(stove doesn't go off). .75 lbs per hour x 8500 = 6375 BTU per hour Min. 5 lbs per hour x 8500 - 42,500 BTU's max(don't know how they got 50,000 unless it has Turbo mode).

There is one other thing on the Max BTU loss. That is the efficiency of the heat exchanger. You will get some heat loss here as well. The manufactures don't figure this in. But the EPA did I believe.

Did you happen to get the max EPA efficiency for the PC-45?