Harman Magnum Stoker - Hot Water Coil Hookup for Hot Water?

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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beatle78
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Post Tue. Oct. 16, 2007 8:25 am

that makes perfect sense.

Man, I def do not have any out of the box thinking when it comes to this stuff!:idea:

Thanks!!!!


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coaledsweat
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Post Tue. Oct. 16, 2007 9:42 am

Be sure you size the fitting it is going in is large enough, don't put a 1/2" well in a 1/2 or 3/4" pipe. Go big around the well. The ebay picture shows the aquastats, it does not appear that there are any wells with them. The probe slips into the well which has to be screwed into whatever pipe you have chosen to install. The well seperates the probe from the liquid so you can service the probe without losing water from the system. I would see if the unit comes with a well, as you need one with it.

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beatle78
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Post Tue. Oct. 16, 2007 10:42 am

coaledsweat,

Thanks, this unit does not come with a well. I will need to get one. Will home depot have something like that?

Bare with me, I'm a little slow.

What do you mean "go big around the well"?

Do you mean that for my 3/4" system that I need a well fitting bigger than 3/4"?

I was going to do what matthaus suggested and put a 3/4" T near the output from the stoker and put a well in the 'T'.

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LsFarm
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Post Tue. Oct. 16, 2007 10:52 am

The probe for the well will act like a finger sticking into the fitting or pipe. Provide a lot a room around the probe by using [for example] a 1" fitting instead of 3/4" so that the probe of the well will not restrict the water flow.

Once you get the well and try it into a few fittings you will see how restrictive it could be in a fitting that is 'just big enough'.

Greg L
Burning Pea/Buckwheat through an antique stoker [semi retired SSboiler],
Running an Axeman-Anderson 260M boiler burning Pea, About 150-250#per day
Farming, Fixing, Fabricating and Flying: 'spare time' what's that?

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Yanche
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Post Tue. Oct. 16, 2007 11:06 am

Some photos of installed plumbing temperature wells. These are in 1-1/2 copper supply lines with appropriate reducing fittings to accommodate the well thread size. The one in the straight run "tee" was intended to sense the water temperature of my underground supply line as it enters my home. The idea was to have a independent control if the temperature in the underground lines got close to freezing. I would then turn on the pump and circulate some water. Never needed because I buried and insulated my supply and returns lines so well they never get close to freezing even with no flow. The 90 degree turn "well" is atop my oil fired boiler. The idea was to sense boiler water temperature independent of the boiler's aquastat so I could default to the oil boiler as a backup if the coal boiler failed. Not yet implemented because with my single flue chimney it's an either or operation. Coal in winter, oil in summer. Note in each the length of the well stub is cut so that the sensing end of the bulb will be in the water flow. The third photo is a typical Honeywell sensor switch that's inside a aquastat. Separate high, low and differential (hysteresis) set knobs. The copper bulb next to the measuring scale is what goes into the "measuring well", the apparent opening at the top. It's not really open, just a cavity to accept the sensing bulb. Well's are available in 3/4 or 1/2 male thread sizes. Both have the same internal diameter for the sensing bulb.
Attachments
Aquastat_Temp_Switch.jpg
Temp_Well_in_Tee.jpg
Temp_Well_in_El.jpg
Last edited by Yanche on Tue. Oct. 16, 2007 11:14 am, edited 1 time in total.
Yanche
Alternate Heating Systems S-130
Stoker Boiler burning Anthracite Pea Coal

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beatle78
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Post Tue. Oct. 16, 2007 11:06 am

ohhh, I get it.

So for example:

I may put a 1" T inline with my system with some 1"-3/4" reducers so the water will flow from the stove into a 1" T around the well finger and then back into the 3/4" pipe. This way the volume of water will not be restricted by a well finger sticking into the middle of the pipe!

Man, you guys are awesome! This project would have been a disaster without this forum!!!

Sat is the big day to tackle the majority of this project :)

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beatle78
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Post Tue. Oct. 16, 2007 11:12 am

thanks Yanche!

Ok, so another important point is to make sure that some portion of the well finger is in the flow path of the water.

hmmm.... Do you think 1" is big enough or would I need to go bigger based on your experience?

Thanks!

Jeremy

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coaledsweat
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Post Tue. Oct. 16, 2007 11:18 am

1" should do it if the well is 1/2", if its 3/4, I would go 1 1/4".
The increase in flow is exponential to the pipes increased dia.

You should be able to get the well at a plumbing/heating supply house, Graingers may have them too.
Last edited by coaledsweat on Tue. Oct. 16, 2007 11:22 am, edited 2 times in total.


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Yanche
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Post Tue. Oct. 16, 2007 11:20 am

1 inch will be large enough. I've got 1-1/2 pipe sizes because I'm potentially moving the entire 130K BTU's of my boiler's output. You have much less capability in your heating coil.
Yanche
Alternate Heating Systems S-130
Stoker Boiler burning Anthracite Pea Coal

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beatle78
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Post Tue. Oct. 16, 2007 11:27 am

just to clarify, when you say 3/4" well and 1/2" well. Are we talking depth of the well or the diameter of the fitting?

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coaledsweat
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Post Tue. Oct. 16, 2007 12:10 pm

beatle78 wrote:just to clarify, when you say 3/4" well and 1/2" well. Are we talking depth of the well or the diameter of the fitting?


The NPT thread size of the well.

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beatle78
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Post Tue. Oct. 16, 2007 12:56 pm

coaledsweat wrote:
beatle78 wrote:just to clarify, when you say 3/4" well and 1/2" well. Are we talking depth of the well or the diameter of the fitting?


The NPT thread size of the well.
Bare with me here. Why would the NPT size of the thread cause me to need a larger diameter pipe? 1" -> 1-1/4"

Is the 1\2" well also shallower than the 3/4" Well?

Also, can I use either a 1/2" or 3/4" well or is that determined by the size of the probe?

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coaledsweat
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Post Tue. Oct. 16, 2007 3:01 pm

The well will stick into whatever you put it in about 4-5". If you have run 3/4" pipe and put a 1/2" well in it, it will cut your flow by about 75% of the original flow. It may work fine as is, I would go larger. It may be me, just anal retentive engineering that's all.
To visualize, take a quarter (3/4" pipe) and place a penny (1/2" pipe) on it. Now the only path your water has is the silver that shows, you won't be moving much water through it after the well goes in.

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coaledsweat
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Post Tue. Oct. 16, 2007 3:05 pm

beatle78 wrote:Also, can I use either a 1/2" or 3/4" well or is that determined by the size of the probe?
The well size is determined by your probe, it must fit snug. Also you should get some kind of gook with the well, it helps the heat transfer. It isn't critical but it makes it more accurate and responds quicker as the heat transfer is optimized.

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Post Tue. Oct. 16, 2007 3:28 pm

I think once you get a well in hand, and thread together a tee and a reducer/adapter for the well, you will see what coaledsweat is pointing out. As long as the well isn't choking off the flow, it should do fine, a little extra room for the water to flow may be better. Just don't restrict it to less than an unobstructed pipe.

I don't have any of the 'gook' :) for any of my aquastat probes and wells. Is there a high temp heat conductive product available,, could I just use some other product? I have taken many apart, and have never found the heat conductive grease or gook. Any ideas?

Greg L
Burning Pea/Buckwheat through an antique stoker [semi retired SSboiler],
Running an Axeman-Anderson 260M boiler burning Pea, About 150-250#per day
Farming, Fixing, Fabricating and Flying: 'spare time' what's that?


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