AA 260 rewire

AA 260 rewire

PostBy: Rick 386 On: Thu Jul 03, 2008 10:54 pm

I'm looking for advise.

I don't how it works but our unit works fine in the winter. The way the controls are wired have me scratching my head.

However we seem to be getting too much unburnt coal in the summer using the AA for DHW only.

So it appears that I will be rewiring this weekend. I want to follow the AA instructions and include the timer. Years ago we installed a DPDT switch that I believe controls the circulators whether we are on oil or coal.

The AA260 is hooked up parallel to the oil burner. I have 2 zones each controlled by their own thermostat and circulator.

I currently have 3- L8214 A,C control units, 2- R 845 A relays, and 2 L 6006A aquastats to be installed anywhere on the 2 boilers. The current setup has 1 L6006 as the high limit on the AA, 1 L6006 as a low limit control for the circulators, 1 L8214 on the oil burner, and both R 845A's connected to control each zone's circulator.

My question to the gurus here: I can follow the AA wiring diagram to wire the coal, but how will I wire the oil burner to also operate the 2 zone system ????

My ideal setup would be to be able to throw the circuit breaker to turn on the AA and have it work as it has following their diagram. But if I want to use the oill, I would like to just throw on that breaker, turn off the coal and have it operate the same.

We really don't to switch over to oil but I do want that option made easy.

Any suggestions ????


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Rick
Rick 386
 
Stoker Coal Boiler: AA 260 heating both sides of twin farmhouse
Hot Air Coal Stoker Stove: LL Hyfire II w/ coaltrol in garage
Coal Size/Type: Pea in AA 260, Rice in LL Hyfire II
Other Heating: Gas fired infared at work

Re: AA 260 rewire

PostBy: LsFarm On: Fri Jul 04, 2008 10:55 am

Hello Rick, my AA260 also has more unburnt coal in the ashpan in the summer than I'd like... The problem is that there is a LOT of coal in the firepot, the firepot is large in diamerter [~15"] and the boiler just isn't running enough to burn the large quantity of coal completely... The short runs on the timer just barely run it enough to 'shake' the ashes from under the fire... the fresh coal comes out of the feed tube, rolls down the 'cone' and to the outer perimeter of the fire, where the water jacket is cool enough to keep the coal from burning right up against the steel.. so you get unburnt coal.

In the summer, you need to look at the ashpan,, and figure out just how much unburnt coal you REALLY have.. after 7-9 days of idling along,, I was away and the timer was all that ran,, no hot water used, so the ashpan got to about 3/4 full... I hand picked the shiney unburnt coal from the ashpan,, sifted out the pieces... and only had about a gallon of unburnt or partially burnt coal.. it LOOKED like a hell of a lot more,, and since coal is such a chore for me to get, store and pay for out here in Michigan,, it really bothers me to throw any out with the ashes...

BUT, the gallon or so of reclaimed coal [normally tossed out] is a fraction of the cost of propane right now,, so I'm not concerned...

I think you will find that starting a fully burning fire in the AA260 will be very difficult in the summer or fall.. you will need to put a large BTU load on the system, and burn it without fresh coal for a few hours, to get a full-diameter firepot burning.. Unless you are heating a swimming pool.

The wiring diagram from AA is good, and it is the way to set up the AA boiler.. but interfacing it with your oil boiler,,, well I can't help, maybe I could help if you had an accurate wiring diagram of the oil boiler's system.

Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: AA 260 rewire

PostBy: Rick 386 On: Fri Jul 04, 2008 11:17 am

Greg,

Are you near your cell phone ????

I think I still have your number. No access to a scanner right now to post the diagram.


Rick
Rick 386
 
Stoker Coal Boiler: AA 260 heating both sides of twin farmhouse
Hot Air Coal Stoker Stove: LL Hyfire II w/ coaltrol in garage
Coal Size/Type: Pea in AA 260, Rice in LL Hyfire II
Other Heating: Gas fired infared at work


Re: AA 260 rewire

PostBy: LsFarm On: Fri Jul 04, 2008 11:27 am

Rick, check your PM's

Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: AA 260 rewire

PostBy: Yanche On: Fri Jul 04, 2008 11:45 am

I'm seeing a lot more unburnt coal in the ash with my summertime use of my AHS 130 also. It's just the operational characteristic of the boiler. I don't think there is much that you can do about it. Perhaps switching to a lower Btu content coal, like re-cycled coal would help. The lower Btu content would in theory make the boiler fire more often and longer resulting in a more complete burn across the fire column. My theory is most of the unburnt coal comes from the sides of the column or at least the side that's the coldest.

The fundamental problem is that the boilers are over-sized for just summertime domestic hot water heating. Still cheaper to heat DHW with coal than oil. In my case approximately $2 vs $3 per day. I have significant heat loss in my installation. My oil and coal boilers are in series. So in addition to the radiation heat loss off the coal boiler I have the additional heat loss of the oil boiler acting like a heat emitter. My inter-connection piping is not insulated so there is more heat loss there. I've consider re-piping to a true series-parallel pipe so there oil boiler is out of the circuit completely, but then the coal boiler would burn less frequently, perhaps resulting in more unburnt coal. I think the Bureau of Mines report on the A-A showed more unburnt coal in summertime use.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea


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