Coal fired boiler piping

Keith_3

I salvaged a sixty-year old Capitol Red Top boiler that had been converted to gas from day one that luckily had all the grates, etc.  I plan to use coal and heat two shops with it.  The first shop is already piped using salvaged 1 1/4" pipe, monoflo tees and cast iron radiators.  The second shop is seventy five feet away and has two levels, one three feet lower than the other with approximately 850 sq ft on each level.  I plan on installing two out and back runs, one for each level, and using salvaged radiators, etc. in this shop also.  At present I come off the boiler with 1 1/2" pipe then branch off to the 1 1/4" runs. 

My questions are: 

1 -  What piping would be best to run underground between shops?  I was thinking about Pex-Aluminum-Pex.  The drawback(s) to this material is 1" maximum size availability and I am concerned about expansion and contraction with this material at each end.     

2 -  If I did use 1" diameter piping between shops could I convert back to 1 1/4" pipe to go between the radiators or would I have heat loss or flow problems? 



I sure would appreciate any and all advice because I have never tried an underground run before.  

                                                                                       Keith

Dan M_6

What size is the boiler?

You might not need as large pipe depending on the BTUs you are putting out.

EX. Maximum flow rates

1" Tubing at 8gpm can move 80,000 BTUs

1 1/4" at 14GPM 140,000 BTUs

1 1/2" at 22GPM 220,000 BTUs



You can reduce size for underground and then go larger inside the building.

You might need a booster pump in each shop depending on the flow and head requirements. Use heavily insulated underground lines and something with an o2 barrier. I know a guy that buried uninsulated outside lines 3' down and there is no snow where they run from the boiler to the house. Lots of heat lost through the ground.

Hope this helps, Dan

Keith_3

Coal fired boiler piping

There are no markings for the output of the boiler.  It has a round firebox.  An educated guess would be 80-90,000 BTU's based on the size of coal fired boiler in my home.  The main reason for using the 1 1/4" is I'm a scrounger.  I got the boiler, piping and monoflo tees all for $100.00.  The radiators have been free to cheap.  What piping will be used between the shops will need to be purchased new and I know that PEX is used a lot around here for outdoor wood stoves. 

Robert_25

Boiler Piping

Hi Keith.  What is the diameter of the grate in your coal boiler?  Also, are you burning anthracite or bituminous coal?  Is the boiler a natural-draft unit?  There are some interesting formulas for calculating the btu output of coal-fired appliances, if you have the grate area and fuel btu content I can give you an educated guess.

Your underground piping diameter will depend on how many btu's the buildings require, and how much radiation you install.  The good news is you're not the first one to do this.  Check out the following posts over at the nepacrossroads forum (you might want to join us over there, we are a friendly group):



[url=http://nepacrossroads.com/about5705.html#p55758]http://nepacrossroads.com/about5705.html#p55758

[url=http://nepacrossroads.com/about7451.html#p74119]http://nepacrossroads.com/about7451.html#p74119

[url=http://nepacrossroads.com/about5996-30.html#p61433]http://nepacrossroads.com/about5996-30.html#p61433



As for the monoflow loop and radiators, it sounds like your system would hold quite a bit of water.  Hand-fed coal boilers really like a steady load. Your boiler will have to be piped so that it doesn't get "shocked" when one of the zones calls for heat.



-Robert

Keith_3

Coal fired boiler piping

Robert,

      Sorry not to reply sooner.  I have been invaded by family from out of town for the last few days.

      Thanks for the links on using PEX, it's very interesting.    We use bituminous coal around here because there are a dozen or mines within a 15 mile radius of my home and the nearest source of anthracite is over 100 miles away and it is expensive, $55 per ton locally versus over $100 per ton for the anthracite.  I don't know what the BTU content of the coal is but I keep my home nice and toasty with it and typically bank the fire for 12 to 14 hours at a time.   

      The inside diameter of the new boiler is 24" or approximately 3.14 sq. ft..  It is a natural draft setup but I have pressurized the furnace room because it helps control smoke from coming out of the firebox door when fixing the fire and ash dust when cleaning out the ashes.  Also, it is great for getting the heat up in the boiler faster.  I have used this pressurized system in my home for years with great success.

I have never heard of a formula for calculating BTU's based on the size of the firebox. 

     I will attempt to attach a couple of photos of my boiler, which does not have its mineral wool wrap or outside cover installed yet along with the only data tag that was ever found. 

     Again thanks for the information.

                                                                                       Keith

Robert_25

boiler size

Hi Keith - Your boiler is actually listed in the Beacon Boiler handbook!  It was rated for 1080 sq. ft of hot water radiation.  1080x150 btu/sqft = 162,000 btus/hr. 



I have a boiler with roughly the same output, but I burn anthracite.  I am very interested in your pressurized boiler room setup, I bet it really helps prevent any soot in the boiler room.



The same forum I posted earlier has a section for bituminous coal, there is a lot of good information on coal quality and burning characteristics from different mines. 

Keith_3

Coal fired boiler piping

Robert,

       Where does the 150 btu/sq ft figure come from?  Is it based on a generic rating of bituminous coal?      

       I'm afraid I can't take the credit for the pressurization idea.  My neighbor worked at the local paper mill and this method was used in several areas of the mill.  He incorporated it into his furnace room and I liked the idea.  He uses a three blade open fan mounted in the side wall.  I have a salvaged fan from a gas fired furnace mounted in the attic and pipe it down through the ceiling.  It works great for keeping the soot in the firebox.  It helps to a degree when shaking down the ashes but not 100%.  I already have this set up in the house and can go from 0 - 130 degrees in fifteen minutes.

       One modification I intend to make is to install a six inch dust collector fan for the coal bin.  Whenever the coal falls it distributes dust around the furnace room.  I plan on installing two pipes, one high and one low. 

                                                                              Thanks,

                                                                              Keith