Best Way to Do DHW

A Coal stoker furnace or stove controls most operations including automatically feeding the coal. They are quite similar to any conventional oil and gas units and easily operated for extended periods of time. They commonly use rice coal but may use larger sizes like buckwheat. They can be used as primary heat, supplementary heat or have a dual set up with your existing oil/gas furnace.
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dave brode
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Posts: 478
Joined: Fri. Jan. 15, 2010 5:47 pm
Stoker Coal Boiler: Keystoker KAA-2
Hand Fed Coal Boiler: used to have a 5 section Red Square
Coal Size/Type: rice anthracite
Location: Frostburg, Maryland [western]

Post Sun. Nov. 24, 2013 6:00 pm

1st pic shows the change to the piping from the side arm down to tank. You can see green tape on the ell and the cap where that pipe used to connect.

2nd, 3rd and 4th shows where the pipe leading down now connects at a tee at the bottom of the tank to gravity loop piping.
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I love my Kaa-2. It replaced a small 5 section Red Square, and Iron Fireman, burned bituminous for 20 yr.

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dave brode
Member
Posts: 478
Joined: Fri. Jan. 15, 2010 5:47 pm
Stoker Coal Boiler: Keystoker KAA-2
Hand Fed Coal Boiler: used to have a 5 section Red Square
Coal Size/Type: rice anthracite
Location: Frostburg, Maryland [western]

Post Sun. Nov. 24, 2013 6:12 pm

Pics from other angle, might show the side-arms [heat exchangers] better. Well water comes in from the well, can be routed right down to tank for summer, or sent on to side arm, through both of those, and then down to tank. Well water goes the the return pipe side-arm where the aquastat is located. Said aquastat senses the temp there, and calls to the TT in 8124 any time water is drawn.

Note that the drain on the 'jumper pipe' from return pipe side arm to supply pipe side arm is to drain any sediment or other crap that might gather in the heat exhangers.

Also, the term "sidearm" comes from the fact that most heat exchangers like mine stand vertical beside the hot water tank.

Hope this helps.

p.s. - note the way that the Tee is oriented at the bottom. Run direction is to the coil. Branch is to the tank. A "throttle" valve could be used on the pipe feeding the bottom of the tank, which would force more of the water through the coil, but it works pretty darned well as is. Now, the water from a faucet will cool just a bit after a few minutes, but then it seems to stay the same for the duration of the draw [20 min+ showers]

Dave
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I love my Kaa-2. It replaced a small 5 section Red Square, and Iron Fireman, burned bituminous for 20 yr.

kinnscience
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Posts: 29
Joined: Sun. Nov. 24, 2013 11:06 am
Stoker Coal Boiler: EFM 700
Stove/Furnace Make: efm 700
Stove/Furnace Model: 700

Post Tue. Nov. 26, 2013 9:28 am

Just installed an efm 700 and have the 7 gallon DC running into the water heater. Calculations from our end showed that it was better to run electric during the summer, but only slight difference with coal. Previously had the DC on the oil boiler running into the HWH, with bypasses to use only the HWH during summer months. During Fall and Spring it was a toss up and will probably run the boiler from October through the first half of April .. maybe all of April. Your mileage may vary, especially with smaller Coal burner units.

One piece of advice given to me via Rob Roy, make sure if you run the DC into the HWH that you have a bypass if you are shutting down the coal burner in the summer. It is not a good idea to run cold water through your DC.


Pacowy
Member
Posts: 2731
Joined: Tue. Sep. 04, 2007 10:14 pm
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite
Location: Dalton, MA

Post Tue. Nov. 26, 2013 10:00 am

kinnscience wrote:Just installed an efm 700 and have the 7 gallon DC running into the water heater. Calculations from our end showed that it was better to run electric during the summer, but only slight difference with coal. Previously had the DC on the oil boiler running into the HWH, with bypasses to use only the HWH during summer months. During Fall and Spring it was a toss up and will probably run the boiler from October through the first half of April .. maybe all of April. Your mileage may vary, especially with smaller Coal burner units.

One piece of advice given to me via Rob Roy, make sure if you run the DC into the HWH that you have a bypass if you are shutting down the coal burner in the summer. It is not a good idea to run cold water through your DC.
I agree with Rob's advice, and would add that for a similar reason you should lean toward running the unit all summer rather than letting it sit. It's not easy to get all of the ash out of a 700, and ash + summer humidity is not a good formula for the boiler.

If you are going to run a 700 for DHW, I'm not sure why you'd want to use the HWH at all, especially in the summer. With an appropriate tempering valve (thanks, Sting :D ), you should get abundant DHW from the large reserve of BTU's in the boiler water and the formidable power of the stoker. And when doing any calculations regarding summer use, you might want to consider the benefits of the coal boiler as a dehumidifier. When we used a 900 to make DHW in the summer, the draw of air for the stoker, the chimney draft and fugitive heat from the boiler let us retire our conventional dehumidifier and the portion of the electric bill it created.

Mike

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dave brode
Member
Posts: 478
Joined: Fri. Jan. 15, 2010 5:47 pm
Stoker Coal Boiler: Keystoker KAA-2
Hand Fed Coal Boiler: used to have a 5 section Red Square
Coal Size/Type: rice anthracite
Location: Frostburg, Maryland [western]

Post Tue. Nov. 26, 2013 4:11 pm

Guys,

How much heat are you getting in the house during summer, burning for DHW? Mine would add a pile imo.

I want to get an add-on heat pump water heater for summer. 6K BTU cooling and dehumidifier while it's running. Said to cost 2/3 ish of what a twin 4500 watt elec costs to run. http://water.nyle.com/residential/

Dave
I love my Kaa-2. It replaced a small 5 section Red Square, and Iron Fireman, burned bituminous for 20 yr.

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Rob R.
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Posts: 11343
Joined: Fri. Dec. 28, 2007 4:26 pm
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Tue. Nov. 26, 2013 4:31 pm

My basement is usually 75-78 degrees in the summer, depending on how hot it is outside and how much the boiler runs. My boiler is insulated with about 1.5" of fiberglass between the boiler and sheet metal jacket.


Pacowy
Member
Posts: 2731
Joined: Tue. Sep. 04, 2007 10:14 pm
Stoker Coal Boiler: H.B. Smith 350 Mills boiler/EFM 85R stoker
Coal Size/Type: Buckwheat/anthracite
Location: Dalton, MA

Post Tue. Nov. 26, 2013 4:43 pm

In our old house we made DHW year-round using an uninsulated EFM 900, and had no issues with excess heat. We got basically infinite hot water running against a lower limit of (IIRC) 160.

Mike

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Rob R.
Site Moderator
Posts: 11343
Joined: Fri. Dec. 28, 2007 4:26 pm
Stoker Coal Boiler: EFM DF520
Hand Fed Coal Stove: Hitzer 50-93
Coal Size/Type: Lehigh Rice
Other Heating: Dad's 1953 EFM Highboy
Location: Chazy, NY

Post Tue. Nov. 26, 2013 5:55 pm

Naturally the size of the basement and insulation on the walls is a huge factor. A large basement with field stone walls will absorb a ton of heat...a modern basement with foam inside & outside the walls will have a higher room temp. under the same conditions. My brothers house is a good example, even with foam insulation and jackets on the boiler the basement stays close to 80 in the summer.

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