Success with Old Tarm MB-55

[Sherwood M]

Over a year ago I was given an old Tarm MB-55, 1970s vintage, 140,000 BTU wood boiler. I cleaned it up, pressure tested it, set it aside, and spent the winter picking brains, searching forums for information and trying to figure out where in our small house I could find a suitable place for it. In the Spring I went to see the people at Tarm USA with a plan to fit it into a very small room which I would construct in the corner of our garage. I expected they would tell me my plan made no sense and naturally they would try to sell me a new state of the art boiler. Instead they said they liked my plan and assured me that with heat storage my old boiler would work just fine. The room is in the only area of the garage that made sense and is just big enough to fit the old boiler beside a 700 gallon storage tank which my cousin fabricated from 12 guage steel. The room shares a common wall with the house so I was able to install ductwork for a forced air circulation path through the house to take advantage of heat that escapes from the furnace and the tank. I continuously pump 90 degree air from the boiler room into the kitchen with a return through the basement. The tank is painted on the outside and on the inside only above the water line and hopefully will pass the test of time. For the heat exchanger I coppied the STS system using two parallel 150 ft coils of 3/4" L copper tubing carefully wound using a 55 gallon plastic barrel as a form. The copper is completely isolated from any steel in the tank and is supported in place with a framework I made from old 1/2" copper pipe. The tank is insulated with foam, 4" sides, ends, and bottom and 6" on the top. The good people at Tarm USA gave me excellent diagrams for piping and electrical for using the wood boiler in conjunction with an existing oil fired hydronic heating system. I followed their plans to the T! Cost for the entire project (I did all the carpentry, plumbing, and Electrical) was about $3500, with most of that being for the Metalbesbtos chimney and copper for the coils. I went into the project doing my best and hoping it would work out, but realizing my new room could end up as an expensive "out house" Thanks to the people at Tarm, lots of friends with good ideas, and a lot of beginner's luck our new heating system works like a dream. I am sure the old boiler takes some more wood than a new gassifier but I think it is more forgiving to operate. Using a Termovar mixing valve, boiler temperature seldom strays far from 180 degrees and stack temperature is consitently at about 300. I haven't seen any sign of creosote in the chimney and there is extremely low build up on the sides of the fire box. In the morning the fire is always completely out and only light fluffy ash remains. There are never any chunks of charcoal as I always had in my wood stove. At about 5:00 I fill the fire box with wood and forget the system for the night. By morning my 180 degree water is usually down to about 140, high enough to heat the domestic hot water tank. The folks over at Lyme helped me to solve two or three glitches we had in the beginning. They were always professional, quick to answer the phone and always had the solution I needed. The house has been at about 70 degrees for the last month and we haven't burned a drop of oil. There are lots of old wood boilers around and I expect by using heat storage many would work very well. If anyone is in the neighborhood and wants to see this creation I am always happy to show it off.

 

[pybyr]

Hi Sherwood- Trevor here- glad you have glad tidings. I am still working on my install, but seeing yours "under way" was part of what inspired me

 

[Sherwood M]

Hi Trevor,
Between reading a few of your posts and spending some time with your good neighbor up the road who has filled me in about your system I understand you are doing very well. Sounds like you will have a real Cadillac which I look forward to seeing. I couldn't resist doing this post partly to brag a bit but also to give credit where due and to give folks who are on tight budgets some Encouragement. Hope your "bolting of the tank" is going well. Keep up the good work, Sherwood