Insulating The Boiler On An Izzo Alex (MK I)

Insulating the Boiler on the Alex MK I

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Well a subject that's strangely appropriate to the time of year as we shall see!

I have been searching for some time to find a low cost and suitable material for boiler insulation. Many of the products on the market are for kilns (expensive), or are what I consider unsuitable such as glass fibre (rockwool), or metallised/foil backed plastic.

The boiler runs at around 128C in an HX machine, so you need a product that will withstand that temperature. This in reality means a product stable at least to 180C or better. The product also needs to be flame retardant and use man made fibres (as natural fibres are likely to degrade over time, e.g. damp, rot, heat), but be food safe!

I have finally selected a product, which meets all the main criteria I originally set myself for boiler insulation. This is no joke by the way, perfectly serious.

The product is called The original Buffalo Snow Tree Skirt

OK down to details, the product states (on the packaging) that it melts at 232C, it's 100% Polyester and is flame retardant. Now the 232C is no guarantee of stability at a continuous temperature of 112-128C when surrounding a coffee machine boiler, but it's a reasonable bet that it's going to be OK and not harden or disintegrate with use.

I have yet to fit this stuff but when I do, I will avoid one area of the boiler, the ends of the heating element (Only because I suppose it's possible that those terminals could actually become hotter than the water and the boiler itself). I intend to fold it double or triple and only insulate the boiler, but NOT cover electronic components or valves such as the vac breaker or pressure release etc..

To attach it to the boiler, I used cable ties and very thick cotton based string

This stuff was bought at my local Focus (do it all) DIY store, but it (and similar products) can probably be bought in a wide range of places. The cost was £2.99 and there is enough to insulate at least 2 boilers.

Well here it is, "I'm dreaming of a white Christmas" with my " Buffalo Snow Tree skirt


I had 3 reasons for doing it:

1. The beast is hot and I think my Gicar box and other components may last longer. Also I don't burn my fingers on the cup tray any more!

2. I can run the machine as low as 0.6 bar (although about 1.0 bar is the best all round compromise), much less heat energy, cooler group, smaller flush, steaming not as effective but with insulation, heating element can easily "catch up". Boiler now at 112C instead of 122C. Although the machine can be run at lower pressure, running at 0.9 to 1.1 bar does give better steaming performance, which is desirable when offset against doing a slightly larger cooling flush.

3. Less stress on the pressurstat microswitch and heating element

The differences in element timings are marked

On for 10 seconds, off for 2 minutes (previously on for 15 seconds off for 50 seconds). I also do have a tiny tiny steam leak from near the autofill (very small leak), and sometimes vac breaker doesn't seal perfectly, so it may be cycling a little more than it should. All in all a success so far, but will know for sure when I check the material in 2 weeks time and then a months time. I think it will be OK tho, and the string, no problem, in fact I think it might last a lot longer that the plastic cable ties!! It's very thick and robust and doesn't burn on meat in the oven!!

Note: 19th June 2007…I have been using RO water for a long time now, and the slight leak from the vac breaker seems to have gone away completely. Boiler heater Timings since insulation are on for 14 seconds….off for 2m 45 seconds. I'm very pleased about that.

Update 1 March 2008

I have had the insulation in for a year now and an inspection of the machines internals has shown no deterioration of the insulation product, no hardening and no melting. The insulation works as well now as it did when I installed it.