Coal to Gas Burner Conversion?

Harry_6

Howdy, recently a customer asked about replacing the conversion kit that changed their 1910 boiler from coal to gas. The gas burner and associated parts date from probably the 50s and are pretty decrepit and troublesome. They don't want to spend money on a new boiler, since the original still works fine. It's the replacement burner that's in bad shape. The question is: does anyone still make a coal to gas conversion kit?

leonz

Is the boiler a one pipe steam boiler or a gravity hot water boiler?

The only way you will find out is if you go to a very large plumbing
supply house to find if a replacement gas burner for the one they
have is available.

mattmia2

Someone that knows what they are doing can put a gas power burner on it. Whether that is worth what it would cost to do it is sort of doubtful.

Big Ed_4

You first need to build a chamber . Either build it with brick or prefab . I would build it with brick .You need to learn the proper BTU needed to the size chamber . Shape of chamber I would recommend a "Pear" A gas burner Carlin or Riello ... Figure it out before you start

pecmsg

Just replace it for a properly sized boiler. 

EdTheHeaterMan

You can't afford NOT to replace the boiler. The coal boiler with a modern power burner will make that boiler a little more efficient, but not much. The amount of heat that is being wasted by that behemoth of a water tank. The off cycle losses are enormous and getting a little package boiler will cut down on that loss. If it is hot water, and you have a large amount of water in the cast iron radiators, then a modulating condensing boiler will cut that gas bill in half easily.

If it is a steam boiler, then a much smaller water content cast iron boiler will end up with a lower operating cost.

Just run the numbers for them. If they took out a second mortgage at 7% for 15 years, I’ll bet the payments for that mortgage would be less than the amount of $$$ the gas bill savings would be.

This has been my experience over the years of my working on HVAC systems of all kinds. If you get a boiler with a more efficient flame inside it, and you reduce your gas bill by $50.00 per month. Then that $50.00 per month more than pays for the $40.00 per month loan payment. And guess what… Your loan payment will never go up but your gas bill will, so as the gas rates increase, your savings will increase also. In 10 years the price of the gas you are not using may be over $75.00 per month and you are still only paying $40.00 per month for that 10 year old NEW boiler. And there is a warranty on it and everything.

Do you really want to depend on a 65+ year old boiler to protect your most valuable possession from freezing up this winter? Unless you want to shovel coal like in the days of old, you really need to get rid of that thing.

bburd

Installing a new burner on a boiler so far past its normal service life is false economy.

Big Ed_4

Is the system steam or water ? Steam would have a glass site glass on side of the boiler...If it is water is there circulator ?

EdTheHeaterMan

I wonder if Harry ran away because he didn't like the answer he got here. This is one of many. https://www.amazon.com/Carlin-Combustion-000-275-Conversion-Burner/dp/B08H5JQPPC

Big Ed_4

Friday Night , I remember

Harry_6

Thanks for all your wisdom. I am not the actual contractor, so all I can do is offer them my opinion. That's why they called me. It is hot water, and so it is even easier to sell the efficiency savings for a new boiler. This is probably moot, since their original description of the problem made it sound like the burner was junk. Then, after the second HCAV guy looked at it, he's saying it might be the thermocouple! Why didn't the first guy look at that first? I will offer them my opinion that they should bite the bullet and get a new boiler, but who knows what their situation is.

Big Ed_4

Let the tech fix it ..

sopcopotoptop

Big_Ed_4, please elaborate on building a combustion chamber. Aside from removing the coal shaker grate assembly and taking off the clean-out door and building a plate to mount the burner assembly to and seal up the ash clean-out opening what interior changes, especially in the below grate area are needed? The boiler is an ARCO 4-28 hot water boiler from the 1910’s to 20’s. Thanks.

EdTheHeaterMan

Regarding coal conversions, I did not do many of them in my rookie years, but I did remove old oil burners from coal conversions in order to build a new combustion chamber out of fire brick and install new oil burners like the Carlin CRD100 in the 1970s.

The first step is to remove the grates that hold the solid fuel (coal/wood) which was already done when I "modernized" the boilers I worked on. Next thing is to build the combustion chamber floor with insulated fire brick. After that you would build the rear wall and side walls as you might build a wall by staggering the bricks so all the vertical lines were not lined up. At the corner you would also stagger the bricks until you were at the front of the chamber where you would use a piece of 4" vent pipe to leave an opening for the burner's fire tube. Once that was in place you would finish the chamber walls so the chamber was just above the lowest part of the water jacket of the boiler. That part of the boiler was called the mud legs.

With the chamber wall slightly above the mud legs of the boiler you then take vermiculite to backfill the hollow space between the chamber and the boiler base. This is where you find that sealing up the front clean out doors and ash pit openings are important. the vermiculite would insulate the fire chamber from the exterior walls of the boiler base. It would also add a little support for the chamber so it would not fall apart after the fire cured the mortar between the fire bricks. A well built chamber was like an archway where the pressure from the backfill would hold the bricks from collapsing out and wedging the bricks together would keep the chamber from collapsing inward. Some mechanics were better at this than others. Once the fire chamber was completed and the backfill was pressed into place, you would cap off the chamber's backfill insulation with some high temperature retort cement. That would cover the loose insulation at the top of the backfill with a seal between the top of the fire brick and the side wall of the boiler's wet jacket, high enough above the mud leg to protect the mud legs from the intense heat of the burner flame.

Here is a video of how one might build a round combustion chamber by hand https://www.youtube.com/shorts/Ny5q23aXy_U

With today's precast ceramic fiber combustion chamber kits, you can cut the time from 2 days to 2 hours to build a combustion chamber in an old coal conversion.

EBEBRATT-Ed

@EdTheHeaterMan

Don't know about the Vermiculite. That stuff used to have asbestos. I would use mineral wool block insulation. Also we were taught to build the walls first using brick and refractory cement and then the floor after and the floor was laid dry.

Probably doesn't matter in residential because the chambers are small and expansion and contraction is not an issue in that size.

The first tech didn't replace the thermocouple because the boiler is old. In this day and age everyone is taught to replace not repair.