Boiler insulation

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robert mayrand
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#1: Post by robert mayrand »

I was wondering if any of you tried to insulate your boiler with Zotefoam evasote that are sold in outdoor store as sleeping mat in different thickness. This is not those blue mat, it's a higher quality product often yellow. The specifications of the manufacturer mention that this foam can be installed internally at 150f I guess that the outside temperature of the boiler and the temperature inside the casing might be just under this rating. Another alternative would be closed cell foam called minicel (really dense gray foam) again sold in outdoor store for fitting kayak, this foam is available in thickness from 1/4 inch to 4 inches and is rated by the manufacturer up to 220F.It would be a nice alternative and both are product that offer really good insulation, are easy to work with with no toxic fiber, and readily available. Price for 1/2 inch evasote come to about 5$ square feet and about the same for the minicell. I'm working in the outdoor industry and work with those product all day, so I think I'll give it a try and keep you posted.


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Robert
Rob
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HB
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#2: Post by HB »

I'm not familiar with the products you mentioned, but keep in mind that a steam boiler's surface is hotter than 220F, though the ambient temperature in the casing should be a lot lower (IIRC, most are around 140F).

You may also be interested in this thread; it outlines a number of insulation options. There are a few other discussions I found by searching on boiler insulation.
Dan Kehn

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robert mayrand (original poster)
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#3: Post by robert mayrand (original poster) »

Already read the post you mention, but thanks for the link. I don't understand why you say that the tank would be hotter then the water inside?
I'll do some testing probably with the minicel and keep you posted. The product is so easy to work with and so resistant that it looks a lot more promising that all the other I've seen in the post above.

Robert
Rob
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HB
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#4: Post by HB »

robert mayrand wrote:I don't understand why you say that the tank would be hotter then the water inside?
Er, I said the steam boiler surface would be hotter than the 220F you noted. Specifically, you said "this foam is available in thickness from 1/4 inch to 4 inches and is rated by the manufacturer up to 220F." At 1.1 bar, the steam boiler's internal temperature is 251F, so it's safe to say its external temperature will tax the upper limits of the insulation material you propose.
Dan Kehn

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robert mayrand (original poster)
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#5: Post by robert mayrand (original poster) »

Sorry, beginner's mistake. I thought that the boiler should be at around 205F.

Robert
Rob
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HB
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#6: Post by HB »

No problem, glad we cleared up the confusion.

For the sake of completeness, even dedicated boilers idle higher than brew temperature because of radiant heat losses. For example, the single boiler Quickmill Alexia boiler temperature of ~221F corresponds to a brew temperature of ~201F, a spread of around 20 degrees. The boiler-to-brew temperature spread is even larger for the ever-popular PID'd Rancilio Silvia.
Dan Kehn

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robert mayrand (original poster)
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#7: Post by robert mayrand (original poster) »

Hi Dan,
Is it the same with lever machine or is it only concerning HX?

Robert
Rob
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HB
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#8: Post by HB »

Yes, it's basically the same. Most levers discussed on this forum, including your Cremina, use steam boiler pressure to fill the chamber below the piston. Their steam boiler pressure is usually around 1.0 bar / 248F. This would not apply to open kettle (unpressurized boiler) lever machines like La Peppina.
Dan Kehn