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[arkgac5]

Hello,

I am posting in the general forum, because my questions can apply across many brands. Move it to the Shaver Forum if needed.

I removed all of the exterior metal siding from my Shaver 165 wood boiler last week. I have had it in service 10 years. I decided I needed to check for leaks, insulation condition, and water tank rust. I did not find any leaks, but did find rust. It has been about 3-4 years since I took off the roof sheet metal to inspect the interior of the water tank, thus resealing with RTV sealant. (And I will testify this is the only way to make sure the RTV is completely sealing the plate!)

After peeling off the insulation, I discovered the top metal of the water tank was rusted severely. I removed the rust scale with a prybar fork as best as I could. No holes as I can see. I then treated the water tank exterior with Ospho, which chemically kills the rust, turning it black. I think it was caused by the leaking RTV seal on the cover plate, which allowed the insulation to get and stay wet.

I have an old farmhouse built in 1917, which has had about all of the upgrades that can be made to make it more energy efficient. i.e. R32 attic insulation, drop ceilings to 8' from 10', R-19 in floors, storm windows, blower door test / replaced leaky forced air duct work, weather calking everywhere imaginable. Total living space around 1800 sq. ft.

I live in North Arkansas where the average winter hi/low temperature is between 26 and 50 degrees. I average burning 7 - 8 cords per year. To compare, I averaged 800-1000 gallons of propane the last 2 years I exclusively used it. I mostly buy my wood. We like our house around 76 degrees F in the winter. I fire my boiler at 150 max, but will raise it to 160 in below freezing temps.

I made the fan damper and drywell Ranco thermostat modifications the second year in service. Absolutely a necessity. Last week I took the burn chamber / ash doors to a machine shop to weld a 3/4" track around the perimeters so I can install a rope gasket on each. I tried using a rope gasket before, but it would not stay in place after a few weeks of use. The track will give more surface for the adhesive to hold it in place.

I also just re plumbed the hot water coil to split the cold water supply on the hot water heater, forcing the cold water to circulate through the boiler coil before entering the hot water tank's cold water pipe. The setup has ball valves to allow the loop to be closed off when the boiler is not fired. I may need a mixing valve here to prevent scalding. I have not used the water coil the last two years, as my Armstrong circulating pump quit working.

My main question is for replacing insulation. I see pictures on the web of various brands with what appears to be 8-10" of batts surrounding the water tank. The Shaver had maybe 2", with the reflective radiant foil on one side. The bottom was not insulated. There were 6" fiberglass un-faced batts on the top, with the radiant foil overlaid on top of the fiberglass.

Would I save fire wood by adding 2" x 2" stringers on top of the skin frame, and insulating with 6" of fiberglass batts on the side walls? Or would Polyisocyanurate Rigid Foam Insulation Board work better? Will the 180 degree water melt it? Is the foil radiant barrier on top give much help in retaining heat? Any other suggestions on better efficiency?

Sorry about the rambling on before getting to my question.

Thanks
Jerry

[hoardac]

After my old wood doctor sprung a small leak in a poorly welded corner I just bought a couple of bags of unfaced pink stuff and covered it completely with new I did not try and use the bare minimum like the factory. It worked well you could feel the difference from how it was. I do not think any stringers would make a difference but I am not a insulation expert. As far a foam insulation I would just have to say if it ever caught fire that stuff burns hot. From what I have read it is better to run you stove at 180 degrees to prevent interior moisture in the fire box.

[E Yoder]

 
I agree on the temps and using the thickest batts you can use without compressing. Definitely don't use anything flammable.

[arkgac5]

I agree on the temps and using the thickest batts you can use without compressing. Definitely don't use anything flammable.

Thanks for the advice. My reason for adding the stringers is to increase the space for insulation. There is already 1" to 1-1/2" of space between the frame and the water tank. Add the 1.5" square tube frame plus another 1.5" stringer adds up to around 4.5". I think an R-19 fiberglass batt is 6" thick. An R-13 is around 3.5". I will fill the top area with as much as it will hold. I will do full wraps around the tank, that way I don't have to use any fasteners to keep the insulation snug under the bottom. I will just staple it to a wood stringer.

Which would be better door insulation: firebrick, or ceramic batt? I read somewhere on the shaver forum that someone put firebrick behind the metal fire shield on the firebox door.

Thanks

[E Yoder]

Makes sense on the stringers.
I would really try to wrap it without gaps, air leakage is easy not to notice.
Any insulation that can tolerate up to 1500℉ should do fine in a firebox door.. Whatever is easier to mount securely. A blanket would need steel or preferably stainless covering it, firebrick not so much but brick could crack more easily if slammed.
Some kind of baffle in the exhaust to encourage heat transfer could help efficiency. Can't do too much without clogging but I've heard of guys using an auger suspended in the exhaust below the water line to force the exhaust to impact the walls can really help.

[arkgac5]

What is the value of the radiant barrier Silvercote insulation? It is a fiberglass core with the foil laminate. I have enough left over from my install to cover the top only. Cost for a 4' x 102' roll is about $130 plus shipping.

I can get the radiant barrier with a plastic bubble core locally in much smaller rolls for much less. Any issues in using this instead? Not so much worried about the plastic core melting as having the radiant function. I assume the best place to put the radiant barrier is on the outside of the un-faced fiberglass batts. Since the max temp for the water tank would be around 180 degrees, I shouldn't have an issue with the heat. I will use the remaining Silvercoat I have to cover the top where the chimney stack comes out of the top of the boiler.

Thanks for all your recommendations and advice.

[mlappin]

If you can get your hands on some, use rock wool for insulation. It’s like fiberglass but the fibers are actually spun from molten slag from the steel mills. It has two distinct advantages over fiberglass, supposedly water beads up and runs off it instead of soaking in like fiberglass and secondly rodents avoid it.

[E Yoder]

A radiant barrier helps if there's an air space to reflect back into. Also if it is on the outer layer the emissivity is low so it slows the radiant loss too. Either way reflective needs an airspace to work.
My concern with anything flammable is although the water jacket is normally 180℉ , if you ever boiled low in water it could get a lot hotter. If the insulation ignites it gets a lot messier.  probably the bubble stuff wouldn't be enough to do much tho.

[arkgac5]

Thanks to all for your help.
Jerry

[arkgac5]

After waiting two weeks for my welder to add rope gasket channel to my Shaver boiler doors, I decided to install the 3/4" rope gasket with out the benefit of a channel. I impregnated the fiberglass rope with high temp RTV gasket maker, then put a generous bead to bed it in. After curing for a day, I fired up the boiler. For the first time, my Shaver boiler doesn't draft when the fan is off.

Then I found a leak on the bottom after running the cleaning chemical cycle. Turned out to be a hole about the diameter of a dime. It was just seeping until I scraped around on it with my putty knife. Then a 2" square piece of rust fell off revealing the hole.

I plugged the hole with wire mesh and quick cure JB Weld, but decided not to trust the JB Weld long term. Welder coming Wednesday. I still have all of the outer skin and insulation removed, so it will be an easy fix. In the mean time I can fire it up and have heat tonight. The family not happy waking up to 55 degree house.

I did add the 2" x 2" wood stringers to the outer square tube frame to double the insulation. Will insulate with r-13 batts and put the r-10 double foil fiberglass core radiant barrier over the r-13. Will add extra layer of r-13 to top area.

Maybe I can reduce my wood consumption a cord or two.

[mlappin]

Something else that works in pinch for a water jacket leak not exposed to fire is that epoxy radiator repair, smear some on, spread the fiberglass mesh, then smear the rest on over that, easily withstands the temps a OWB gets to. Best part is that stuff cures in like 10 minutes or less.