Added a fitting to my wood-fired boiler

ayelvington · Oct 24, 2011

I've been vexed up until now because my wood-fired boiler regulated poorly and wasted wood. There was an temperature/pressure gauge installed in the water jacket next to the high-temp aquastat, but the working temperature aquastat was outside of the jacket in the water loop. This made for the boiler getting too hot, forcing circulation, and then shutting down the blower.

FYI: There was a solid state temperature controller on the boiler when we bought the house. The controller was dead because of all the power spike we get, so I opted to go with tried-and-true Honeywell aquastats that last forever.

I got a weldable tank fitting from McMaster-Carr and jumped in today to move the working temperature aquastat into the water jacket on top of the boiler.

Speed-bump 1: My hole saw caught, bent the pilot bit, and tore up the saw a bit. I was using a 1/2" drill and the kick was pretty scary. Had to take a trip into town for replacement pilot bits and a new 1-1/8" hole saw...

Speed-bump 2: Hole drilled and prepped. I'm decked out with helmet and leather. No gas. How did THAT happen? Back to town for a full bottle.

Speed-bumps 3-5: The welds leaked under pressure. Just a pinhole, but enough to drive me to distraction. I finally located the pinhole and simply covered it in metal. no mo leaky...

End of story: I'm pretty confident that my nights of over-temps and wasted wood are over! Winter is coming, and I'm a happy camper.

Here is a link to photos:
Boiler modification | Facebook

yomax4 · Oct 24, 2011

ayelvington said:
I've been vexed up until now because my wood-fired boiler regulated poorly and wasted wood. There was an temperature/pressure gauge installed in the water jacket next to the high-temp aquastat, but the working temperature aquastat was outside of the jacket in the water loop. This made for the boiler getting too hot, forcing circulation, and then shutting down the blower.

FYI: There was a solid state temperature controller on the boiler when we bought the house. The controller was dead because of all the power spike we get, so I opted to go with tried-and-true Honeywell aquastats that last forever.

I got a weldable tank fitting from McMaster-Carr and jumped in today to move the working temperature aquastat into the water jacket on top of the boiler.

Speed-bump 1: My hole saw caught, bent the pilot bit, and tore up the saw a bit. I was using a 1/2" drill and the kick was pretty scary. Had to take a trip into town for replacement pilot bits and a new 1-1/8" hole saw...

Speed-bump 2: Hole drilled and prepped. I'm decked out with helmet and leather. No gas. How did THAT happen? Back to town for a full bottle.

Speed-bumps 3-5: The welds leaked under pressure. Just a pinhole, but enough to drive me to distraction. I finally located the pinhole and simply covered it in metal. no mo leaky...

End of story: I'm pretty confident that my nights of over-temps and wasted wood are over! Winter is coming, and I'm a happy camper.

Here is a link to photos:
Boiler modification | Facebook

I have built a few and enjoy the one I have.. Heats 7000 sq ft and hot water too. There are a lot of cool mods to do to the inefficient outdoor stoves. I have quite a plumb job on mine. 4 pumps, 4 aqua stats and a modified blower fan..

ayelvington · Oct 24, 2011

yomax4 said:
You have an outdoor wood boiler that holds pressure? Must be an Aqua-Therm? Most have no pressure. I have built a few and enjoy the one I have. Holds no pressure though. Heats 7000 sq ft and hot water too. There are a lot of cool mods to do to the inefficient outdoor stoves. I have quite a plumb job on mine. 4 pumps, 4 aqua stats and a modified blower fan..

INDOOR boiler with rocker grates, so probably a coal boiler that I burn wood in. Working pressure is 10 psi, and test pressure is 30 psi. If you look at the pictures, you can see that I have a flapper valve on the air feed to the blower. The power to both is controlled by the set-temperature aquastat that's now in the middle. I have a 10-degree set back on the aquastat, so it turns the blower on if below 150, and off at 160.

Over-temp is at 190 to give a little elbow room. Overtemp forces heat to the garage (large blower unit) and the living room (large space, and why waste the heat?).

yomax4 · Oct 24, 2011

Cool stuff. Sorry I didn't open the pics before I replied. Nice set up. I use a Ranco digital stat that looks like an aquastat but is easily programed. I use 180 as the high and 160 as the low. I have it installed in a well I made on the 1" return Pex line. I have enough water in mine (600gln) so I can recover from a 20 degree drop most of the time. In MN. In January, I have to tighten up the variables a little. I still burn many tons of wood. per winter.

ayelvington · Oct 24, 2011

I would have liked to have gone digital, but the power around here just eats stuff up...

I went with the Honeywell stuff since they are rock simple and bullet proof!

I'm in NW PA and go through a lot of wood too. I have about 2 months worth in the racks now, and we'll be out in the woods cutting as soon as the ground gets hard enough for our tractors and RTVs. Did I mention that there's a lot of mud here?

Stay warm and enjoy MPR for me! I used to work for one of their affiliates in the UP of Michigan...

Jeepnford · Oct 27, 2011

I built a non-pressurized wood boiler last year,I got done with it so late in the year I just barely got it going to heat the house. So this year I poured concrete under it,plumbed pex into the shop,built a box with a heat exchanger and a simple box fan for a blower,and put the aquastat in the house so I can look at it without going outside. Mine will also blow excess heat into the shop. This is one thing I've built in which my wife is happier about it than I am.

yomax4 · Oct 27, 2011

Jeepnford said:
I built a non-pressurized wood boiler last year,I got done with it so late in the year I just barely got it going to heat the house. So this year I poured concrete under it,plumbed pex into the shop,built a box with a heat exchanger and a simple box fan for a blower,and put the aquastat in the house so I can look at it without going outside. Mine will also blow excess heat into the shop. This is one thing I've built in which my wife is happier about it than I am.

Is your boiler indoors or out? The above post has a nice indoor set up. Mine is one of the outdoor types. I had every trouble you could have the first year or so but got it under control and have not used a drop of Propane for 3 years.