My "Back-Up" Resistance Boiler Is Back up and Running, ...

lsayre · Post by **lsayre** » Mon. Sep. 15, 2014 6:05 am

... complements of a fine member of this forum who made the trip and worked a whopper load of electrical magic to restore it to functionality. If he wishes to come forward and identify himself he is welcome to do so, but otherwise he will remain anonymous (though his accomplishments will not).

After pulling the cover it was discovered that the resistance boiler that I had assumed (based on the cover panel) to be a 5 stage 22.5 KWH boiler is actually only a 3 stage 13.5 KWH boiler. That is only 46,000 BTU's. It's all good though, since:

On the coldest day last winter when it was -17 deg. for the low and +4 deg. for the high (mean temp = -6.5 deg.) we burned 110 lbs of coal.

110 lbs x 12,150 BTU's/Lb. x 0.80 efficiency / 24 hours = 44,550 BTU's per hour

Resistance boiler revelation: Only 3 x 4,500 Watt elements = 13,500 Watts/Hr

13,500 Watts/Hr x 3.412 BTU's/Watt = 46,062 BTU's per hour

Looks like a decent match for our homes heating needs.

Sting · Post by **Sting** » Mon. Sep. 15, 2014 7:03 am

LIKE!

mozz · Post by **mozz** » Mon. Sep. 15, 2014 12:22 pm

What you're saying is your coal boiler is 3 times as big as it needs to be?

lsayre · Post by **lsayre** » Mon. Sep. 15, 2014 12:44 pm

mozz wrote:What you're saying is your coal boiler is 3 times as big as it needs to be?

Yes, but it has a very small footprint that fits into my boiler room. The KAA-4 (the only boiler I'm aware of with lesser BTU's that was available back when I ordered my boiler) has a larger footprint (to my knowledge) and would most likely not fit in my limited space. Besides, I can't readily get rice in bulk where I live (at least from my closest supplier, who is about 25 miles out), but I can always get bulk pea. My next closest supplier is 80 some miles out, and depending upon his mood and the alignment of the stars he either will or will not deliver coal to me (at a nice upcharge for the distance). It varies by the year....

I've said before that I wish AHS made a smaller Coal Gun, but alas, they don't.

The EFM 520 would fit into my boiler room, but it is about a 175,000 BTU (or likely larger) boiler.

No problems with the Coal Gun. It takes things in stride. Nice to know that it will keep my house warm down to -80 degrees F.

And I have the sneaking suspicion that I'm not the only one out there with a well oversized coal boiler. To broaden the scope of this, regardless of the fuel, most homes main heating appliances are well oversized, be they forced air furnaces or boilers. How many of us burned more than 110 lbs. on the coldest day last year. And if so, and they doubled it to 220 lbs., they would only have been delivering 89,000 BTU's. That's just outside of the range of the KAA-4.

And on the flip side of the spectrum nearly all hand fired stoves are at least touting twice or more their actual BTU output capability. I would not want to be on this side of the fence and discover the hard way that my stove can't heat my home when its really cold outside.

Remember that all of the heat you will ever get out of the coal is in the coal to start with. If you are not burning it (meaning here in massive quantities), you are not getting the heat out of it that you think you are. But it's all good!

mozz · Post by **mozz** » Mon. Sep. 15, 2014 4:38 pm

Actually I think the aa130 style has more output than the efm520, was rated at 540 sq whatevers to the efm rated at 520. Mine hasn't really kicked on yet with the thermostat, the timer is keeping the first floor 68-70 even with it going to 40 degrees which I had this morning. Pretty soon the pipes will be banging.

lsayre · Post by **lsayre** » Mon. Sep. 15, 2014 5:12 pm

If I would have ever used my brain, I would have figured out years ago that my resistance boiler was only 13.5KW, as its breaker at the main panel is only 60 amp.

240V x 60 Amps = 14,400 Watts = 14.4KW max

As it is there is but a slim margin, as at 13,500 Watts that comes out to 56.25 amps of actual current flowing through a 60 amp breaker.

13,500 Watts / 240 Volts = 56.25 amps.

Post by **Lightning** » Mon. Sep. 15, 2014 5:23 pm

Yeah wow.. that is just marginal.. a 50 amp is recommended for my hot tub.. with all the pumps running, lights on, and heater running it draws around 8 KW per hour..

Scottscoaled · Post by **Scottscoaled** » Mon. Sep. 15, 2014 10:08 pm

Doesn't that change all the comparisons you did referring to cost to make domestic hot water during the summer?

lsayre · Post by **lsayre** » Tue. Sep. 16, 2014 5:45 am

Scottscoaled wrote:Doesn't that change all the comparisons you did referring to cost to make domestic hot water during the summer?

No, because electricity is 100% efficient, and because I was comparing the coal boiler to our electric hot water tank and not the resistance boiler (though it shouldn't matter).