Insulating a propane powered boiler

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bm_cricket
Posts: 203
Joined: 11 years ago

#1: Post by bm_cricket »

Hi all,
I'm planning to insulate my 2-group lever Astoria that uses propane (and electric). I want to find an insulation that can be wrapped around the top, sides, and each end of my boiler, but naturally not the bottom. So far, I'm considering something like the R rated Roxul from Lowes http://www.lowes.com/ProductDisplay?par ... &cId=PDIO1.

My needs are a little strange because it's going to be a couple of inches away from open flame, and the boiler body itself gets to about 400f. That's in excess of temperature ratings shown on any of the foam pads I've come across. Has anyone else insulated a propane powered machine? Any tips? There are tons of places around Home-Barista discussing insulation and honestly, if I wasn't dealing with open flame I would just go with malamene foam. It sounds great!
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bm_cricket (original poster)
Posts: 203
Joined: 11 years ago

#2: Post by bm_cricket (original poster) »

As a follow up, I think my boiler is losing 940 BTU, but if I insulate it with 15R R-Value insulation then my boiler heat loss could go as low as 62 BTU. Did I do something wrong? Has anybody else done this math and had such a drastic improvement?
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TomC
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#3: Post by TomC »

You're extremely lucky, both by posting the request and by location.

I bought this stuff here from a guy in Oakland, who still has a big roll of it he's looking to sell. It's rated way higher than what you'd need and is quite thick. You might be able to wheel and deal the price down a tad, what he has it listed at is per foot. And the listing has been up constantly since JANUARY, so clearly its not in high demand.

I bought some to insulate my Conti Empress case, but went with a different type that is thinner. As it is right now, I have no use for the section I bought, and if it's long enough, I'll sell it to you even cheaper, and save you the longer drive across the bay. I only mentioned his link so you'd see the temp ratings and description, and expecting your boiler to be much larger than my 5 or 6 liter boiler. I did buy more than I figured I'd need though, so if you want I can measure it and let you know. I'm sure I have close to 24" in length.
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bm_cricket (original poster)
Posts: 203
Joined: 11 years ago

#4: Post by bm_cricket (original poster) »

I just checked it out and you have me sold. I'll PM you! Thanks!
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OldNuc
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#5: Post by OldNuc »

Take the reciprocal of the R value and that is the heat flow rate.

bm_cricket (original poster)
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#6: Post by bm_cricket (original poster) »

It looks like I got my math right. I plotted a few numbers up and I really think I need to insulate. I never realized how much heat loss I'm looking at with this machine!

Please take a look at let me know what you think. Does anybody think I made a mistake?
Life is short, enjoy every sip.

bm_cricket (original poster)
Posts: 203
Joined: 11 years ago

#7: Post by bm_cricket (original poster) »

BTW, I put this into terms of Watts, and in terms of percent watts from a 2,600 Watt element. Naturally, these numbers are super idealized but I'm reasonably sure my math is right. If you want to check my math (I encourage it!) then PM me and I'll email the excel file to you.




My numbers are really, really, really ideal. I'm not even sure if they are right, does anybody care to check them?
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Chert
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#8: Post by Chert »

Thanks for the link and idea, guys. I used the material that cloth stores sell to cover ironing boards with some spare pieces of malamene foam inside that, but a professional insulation job would be a great idea. Probably would work better too. :wink: I sewed mine in part and wrapped the boiler. Since you will leave the flame-boiler interface area insulation free, Bill, how do you envision adhering the material to the boiler? and will you make a cover or flap to go over the flame-boiler interface when you are going electric?
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OldNuc
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#9: Post by OldNuc »

That looks good and if you use the foil backed blanket or wrap the bare wool with thin sheet SS shim stock and hold in place with ss tie wraps or wire you will really cut your heat losses. A thin SS jacket looks very good when you show off the guts.

bm_cricket (original poster)
Posts: 203
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#10: Post by bm_cricket (original poster) »

I'm only going to cover about 2/3 of the boiler circumference. It will start at the edge of the heat-shield on the back of the boiler and wrap up and around to the front of the boiler. I plan to attach the insulation pad to a piece of thin metal, maybe thicker than tin foil, but still thin enough to cut and bend easily. I'll attach them together with spray glue so I can work with them more easily. I'll use the same template cutting tricks that Bob Barraza shows off in his walkthrough on Insulating the Elektra A3's boiler. I'll attach it with some stainless steel tie wire. The bottom will just be bare, exposed boiler. The ends are going to be tricky because one end has a heating element, and the other end isn't actually flat! I plan to try the same method with the metal coated insulation and hopefully it will just work.

BTW, has anyone checked my numbers? Does anybody know about "real world" heat loss from boilers? All my numbers were calculated as if my boiler exists in a physics text book. ;-)
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