Can I Add a Combustion Fan to a Harman Boiler SF-260 ??

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efo141
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Post by efo141 » Sat. Sep. 19, 2009 8:52 am

A friend wants his Harman to work like my New Yorker does with a combustion fan controlled by the aquastat. Is there any reason he couldn't replace the electric draft control on the ash door with a small combustion fan?

 
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Post by coaledsweat » Sat. Sep. 19, 2009 9:47 am

Yes but. He may have to change the Johnson Controls aquastat to control it.

http://www.harmanstoves.com/doc/Trident%20Boiler% ... l%20R4.pdf

 
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Post by efo141 » Sat. Sep. 19, 2009 11:12 am

Thanks for the link. Looks like the draft control runs on 120vac. Here are the specs. on the combustion fan he has. Do you think this will work with the Johnson control?

Voltage 115
Hz 60/50
Phase Single
Full Load Amps 0.49/0.42
RPM 3030

 
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Post by coaledsweat » Sat. Sep. 19, 2009 8:55 pm

The automatic draft control on there now is rated for 6.5 watts, I don't think the JC can handle the amp load of the motor, if I am not mistaken is close to 10 times that.


 
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Post by coaledsweat » Sun. Sep. 20, 2009 6:50 pm

I'm not an electrician, maybe one will chime in. Thinking about this, maybe he could use the JC output to a relay (cheap fix, about $10) and trigger the fan that way. The relay would take the amp load for the fan motor off the JC's output and put it on its own circuit. He would have to make sure the output is continuous on a call for heat. I have no idea how that existing draft control works, whether it is pulsed or continuous. :gee:

 
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Post by efo141 » Sun. Sep. 20, 2009 9:55 pm

Thanks for the info. He has a buddy thats a electrician that will have to solve this one. Sounds like the relay idea will work but I am not the one for that job.

 
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Post by JB Sparks » Sat. Sep. 26, 2009 6:01 am

I have a Trident SF 160 and rigged up a combustion blower last season. It worked good... sending all the heat up the chimney. Took it off and sold it to a guy that wanted to use it as a convection fan . I then installed a 30 minute timer in parallel with the Johnson A350 aquastat. Now to liven up the fire before loading I set the timer for 10 or 15 minutes and go have a cup of coffee, when I come back the fire is livened up and ready for reloading. I'm thinking that Mr. Harman didn't put a combustion blower on the Tridents cuz they don't need one. Just my two cents worth. :)

 
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Post by coaledsweat » Sat. Sep. 26, 2009 9:45 am

JB Sparks wrote:I have a Trident SF 160 and rigged up a combustion blower last season. It worked good... sending all the heat up the chimney.
I'm thinking that Mr. Harman didn't put a combustion blower on the Tridents cuz they don't need one. Just my two cents worth. :)
Proper sizing will be critical as any draft you force on the fire will have reduction in its efficiency. Properly sized however, a forced draft will give a much faster recovery rate and a higher total output. The key is in the CFM rating, I would size the blower in the range of similar BTU output appliances.


 
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Post by efo141 » Sat. Sep. 26, 2009 1:57 pm

When I set the baro at the draft setting that Harman reccomends it would fall behind when calling for heat. He had to run the baro at almost closed and his stack temp was high. He bought the same combustion fan New Yorker uses on there 90 and 130K boilers. I thought this would allow the boiler to run at a lower draft and still keep up with the demand with a call for heat. My New Yorker 90k boiler has this set up and works real good. JB Sparks, Did you use the wires that run the draft damper on the clean out door to run the combustion fan?

 
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Post by JB Sparks » Sun. Sep. 27, 2009 4:53 am

efo141, No, I ran a seperate circuit through a reostat and then tied onto the A350 output terminal...if I recall correctly. With the reostat at it's lowest setting I would get stack temps. up to 600*. I found the timer worked much better. Now having said all this, I do have a very good draft so I had the baro set to around .03 with a stack temp running around 125* to 150*.

Last season was my first year burning coal so, I'm still learning.

This is a pic of how I mounted the blower.

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Post by coaledsweat » Sun. Sep. 27, 2009 10:15 am

Does that chain regulate the draft door too?

 
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Post by JB Sparks » Sun. Sep. 27, 2009 10:56 am

Coaledsweat, It did, but I took the blower off and put it all back together in the factory set up. I think you are right about sizing being critical, I think this blower was too big for the job.

 
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Post by efo141 » Sun. Nov. 08, 2009 7:03 pm

Just an up date on this. The fan runs fine off the same feed wires for the damper. He runs the shutter only about a 1/2" open with the baro set to .03-.04 with stack temps way down.

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