build up on tubing

[shorton]

Hi guys,

I have my home built system up and running but it doesn't make nearly enough heat so will require some re-working, right now my big problem is build up of heavy soot and junk on the heat tubes within the firebox. The fire brick and side walls stay really clean due to hi temps but the black iron pipe with water flowing in it can't get hot enough to burn clean.
Any thoughts on how to clean this pipe or how to keep it cleaner. When the buildup gets thick I go from 20 degrees increase on one pass through to 2 degrees!

Thanks
Shane

 

[Willman]

Do you have return temperature protection? Post some pics of your set up maybe a diagram also.

Will

 

[afblue]

Do you have any pics?

 

[shorton]

OK I will try to take a few pics tomorrow along with a diagram and flow chart.

Does anyone know the price or cost of boiler tubing? I think I will change out the pipe coil I am using in favor of a jacketed tube stack, I will get vastly more surface area for heat transfer. What material is best for tubing and end plates? Carbon steel, stainless steel, ??

 

[afblue]

Whatever plate steel boilers are made from. I though I have read that stainless has issues with some wood gases being acidic, not to mention its rediculously $$$$$!

 

[shorton]

OK, I don't know if this will work but here goes,

the pic showing the silver tank and the brown tank, the silver is heat storage and the brown is the chip fired boiler. There is twenty feet of one inch black iron coiled inside and 24 feet of 1" copper under the brown cover. The storage tank is well insulated, about 300 gallons.

the pic showing the pipe coil with buildup on it. When clean I can get about a 20 degree jump on each pass.

the pic showing some of the pumps and piping. Hot water goes to a manifold and to heat exchangers one and two, also into the tank.
Return water goes into another manifold that goes into the tank and cold side of the coil.

I only lose about 6 degree on a full round trip to heat X one and nothing to Heat X two.

The problem is that with the coil dirty I only get a couple of degrees increase per pass.

I think I am going to take out the coils and put in a large tube and shell setup so I need boiler tubing and end plates. This way I can get around 125 feet of 2" tubing with way way more surface area to transfer heat.

I need to know where I can buy tubing and what type is best for use in a wood boiler. Should it be set into the end plates with a tube expander or welded? The end plates will have to be welded to the sides of the can.

My chip feed system is in it's second generation now and will need more tweeking.

Shane

 

[shorton]

Will, what do you mean return temperature protection?

 

[Willman]

There should be a valve that provides 140* water min. on the return to your boiler. My guess is the build up on the tubes is due to water temps too cool. Lots of pics on here of some boiler designs with the same issue (search seton boiler). The valve is called a danfoss or a 3 way. Plenty of posts on this. Beings as your burning chips I figure that a lot of heat is lost to drying the chips. It takes a lot of heat to drive off the moisture.

Will