Couldn't help myself

derrilex · July 2013

Not on purpose. I just carefully stuffed the cavities with insulation. Why would shot temps decrease ? that makes no sense. :D Temps should either be hotter or more stable but not colder IMHO

UNM · July 2013

on 1373325561:

Not on purpose. I just carefully stuffed the cavities with insulation. Why would shot temps decrease ? that makes no sense. :D Temps should either be hotter or more stable but not colder IMHO

Think about what you are changing. Pstat holds boiler temp steady, no change there. Insulating boiler reduces temperature loss from boiler and duty cycle. Internal temperature in cabinet decreases, therefore increasing heat loss from lines between heat exchanger to group head. More loss in the lines means lower group head temperature. Simples! Except of course, you have both noticed a rise in temperature, so I am clearly wrong. Not so simple! Perhaps the faster heat up of the boiler results in overshoot at the high end, but insulation reduces overshoot at the low end (should be visible on pressure gauge)? Perhaps insulation on part of the heat exchanger lines counteracts the lower case temperature. Perhaps the reduced temperature in the casing increases flow rate through the thermosyphon loop (I am guessing flow rate is primarily determined by temp differential between flow and return lines). Anyone understand the physics at work here and care to explain?

derrilex · July 2013

I reckon you're over thinking it a bit. Insulation = either insulating against heat loss or heat gain, in this case heat loss from anything copper. Therefore, to my way of thinking anyway, the boiler will retain heat better, transfer heat to the HX better, which makes the thermosyphon work better and makes the heat loss from the hx - group pipes less = a hotter or more stable shot. Reducing the energy loss at one point ( boiler, hx & lines) increases the potential energy at another point, in this case the group head. Now I'm over thinking it

Koffee_Kosmo · July 2013

Does the Bezzera Mitica have an electric heated head ?

conikal · July 2013

on 1373331602:

Does the Bezzera Mitica have an electric heated head ?

No, its the E61 group with thermosyphon heating.

on 1372494285:

...... Amongst them was a Mitica, essentially exactly the same internals as a Strega but with a E61 head instead of the lever group......

UNM · July 2013

on 1373328882:

I reckon you're over thinking it a bit. Insulation = either insulating against heat loss or heat gain, in this case heat loss from anything copper. Therefore, to my way of thinking anyway, the boiler will retain heat better, transfer heat to the HX better, which makes the thermosyphon work better and makes the heat loss from the hx - group pipes less = a hotter or more stable shot. Reducing the energy loss at one point ( boiler, hx & lines) increases the potential energy at another point, in this case the group head. Now I'm over thinking it

Thing is you are NOT increasing temperature of the boiler. Just reducing your energy use and environmental impact to maintain it. The heat exchangers are within the boiler and at the same temperature as before. Just common sense (except that I seem to be wrong). Wasn't something I really thought about until you said shot temperature went up. Be interesting to see what happens when I do my boiler. Oh and reasons why manufacturers don't all insulate boilers. Makes servicing harder Costs money Impacts performance of heating tray. Messes up group head temperature. In a commercial environment, the electricity is a tiny portion of running costs and offset by charging for coffees. Different for domestic machines that spend most of their time idle and not generating revenue.

derrilex · July 2013

on 1373334888:

The heat exchangers are within the boiler and at the same temperature as before. Just common sense (except that I seem to be wrong).

Yep I know I'm not increasing the temp of the boiler, and I know the heat exchange unit is inside the boiler. And yes they are both at the same temp as before and yes the unit is now much more efficient to run. The heat LOSS in the boiler ( and therefore the HX unit) is the thing that has been changed. If I were to wait for the boiler to cycle so it's at full temp, before insulating the gauge would drop quickly back to the point where the element would cycle back in ( 27 secs ish). Now it takes over 2 mins to reach the same cut in point. If I pull a shot with NO insulation the boiler is loosing temp quickly (and therefore the HX) until the element kicks back in. With the insulation in place the boiler remains hotter for longer ( and therefore the HX) over the duration of the shot. The thermosphyon / brew pipes are insulated but only as a result of stuffing, nothing deliberate. If the retained heat energy can't escape to atmosphere through the insulation then it's going to present itself at the brew head. My logic anyhow. You can't just loose energy, it's either converted to another form of energy and / or moved from one point to another. Perfect example is my roaster. I insulated it and did a roast. Same bean weight, same beans, same pre heat etc.... 1st crack was at 7.30 instead of 10. If the heat energy can't escape through the sides and bottom of the roaster ( as it was before) then it will present itself elsewhere - in this case, in the beans as a much faster time to 1st crack

C-man · July 2013

I may be wrong but it seems to me small boilers are a weak point on Domestic machines bigger commercial boilers seem to be more stable At first i did not want to wait for a 4lt boiler to heat up, now on my S24 I am very happy with it.

derrilex · July 2013

Insulate it and be even happier C-man :D

C-man · July 2013

on 1373358908:

Insulate it and be even happier C-man :D

If only I could spare some........

derrilex · July 2013

:D. Yep.

conikal · July 2013

on 1373338762:

.... If I pull a shot with NO insulation the boiler is loosing temp quickly (and therefore the HX) until the element kicks back in. With the insulation in place the boiler remains hotter for longer ( and therefore the HX) over the duration of the shot. ......

And,... remember when pulling a shot, the cold water from the pump is injected directly into the HX /TS circuit in order to reduce the brew temp down from boiler temp levels. so ..." the boiler remains hotter for longer ( and therefore the HX)" ... may well influence the shot temp to be hotter. Also, my personal belief is that on most m/c's... ( E61 particularly),.. the actual HX temp is not critical and its the temp of the group which controls the shot temp. So be careful that your insulation doesnt cause the group idle temp to increase significantly.

derrilex · July 2013

I have not measured temp by any means except taste and sound. Taste is great and if left to idle a flush is needed. All good. :thumb:

UNM · July 2013

on 1373425016:

so ..." the boiler remains hotter for longer ( and therefore the HX)" ... may well influence the shot temp to be hotter.

Except that we are agreed the boiler is NOT hotter. The length of time it takes to drop by the approx three degrees from high point to low point (determined by pstat deadband) is extended, so it also remains cooler for longer (the second half of the time that the heater is off) if you look at it that way. Yes, my mind works in mysterious ways. I know I am a tad geeky at times, As derrilex noted, the heat LOSS has changed, but that is evenly balanced by the heat input due to the pstat doing exactly what it is meant to.

on 1373425016:

Also, my personal belief is that on most m/c's... ( E61 particularly),.. the actual HX temp is not critical and its the temp of the group which controls the shot temp. So be careful that your insulation doesnt cause the group idle temp to increase significantly.

And that, I suspect, is a far larger factor than the boiler insulation when it comes to shot temp. I have looked again at the photos posted earlier and it looks like derilex has basically gone around filling every crack he can get to, tradie that he is

. Barely room in that casing for anything except insulation. This has effectively insulated the HX loop (but not the head obviously), hadn't really focused on that first time around. Rereading the cycle times posted I am amazed it manages to get up to the high end of the temp range in seven seconds, that is a pretty responsive element. My Grimac takes 35 seconds on time (1650w) and the Azkoyen took 25-30 seconds (2400w). Even uninsulated, my boiler takes about 1min 45 sec to drop back down. I shall be interested what difference I see with insulation as it will happen soonish. If I get down to 5-6% like derrilex, I'll just leave the machine on and idling a lot more often just in case I need coffee during the day. c-man - commercial machines certainly ought to be stable, the environment they are in demands it. I would have thought that the domestic machines in this price range would also be stable - that big hunk of brass is what provides stability during the on/off cycles of the element, and certainly ought to flatten out small temp variations during the cycle.

derrilex · July 2013

on 1373533345:

Yes, my mind works in mysterious ways. I know I am a tad geeky at times,

I think that Saab is messing with your head :D

derrilex · July 2013

Ok, so with a view to tidy up the insulation around the boiler I ended up going a bit OTT. I've refitted the HX, element and safety valve and the sealant should be properly cured by tomorrow so next up is to cut a nice neat blanket to wrap it all up the refit to the chassis. Very easy to remove I must say.

Brett H · July 2013

Mate, its the diy guys ht are supposed to be over killers... Having said that I love the pics and the cleanliness.

derrilex · July 2013

Not being a "electro fitter tech" or whatever qual one is meant to have to work on these things I guess I can claim DIY status on this one :D

Koffee_Kosmo · July 2013

Just today I was at the place I purchase my insulation I saw a lovely product to suit It is a - 4mm high temp foam with a flexible woven fabric alloy impregnated sheet adhered to it It would be perfect for boiler insulation KK

derrilex · July 2013

And they gave you a big sample roll of it right ? :D

Koffee_Kosmo · July 2013

on 1374526780:

And they gave you a big sample roll of it right ? :D

No sorry Your post came after KK

derrilex · July 2013

Typical

derrilex · July 2013

A bit of wool

Ol Grumpy · July 2013

I'd hate to see what you do when you bring a new car home D? : huh?

Ol Grumpy · July 2013

Spotted D's new car..... Haw Haw Haw!..... Sry... Couldn't help myself..... Bwaaaahaaaaahaaaaa.....

derrilex · July 2013

A couple more just to satisfy UNM's wool fetish :D

derrilex · July 2013

on 1374552141:

Spotted D's new car..... Haw Haw Haw!..... Sry... Couldn't help myself..... Bwaaaahaaaaahaaaaa.....

That's what all the cruisers look like out at Cubby Station :D

UNM · July 2013

Looking good D. Plenty cable ties to keep it neat. All that work with the brasso worth it then?

derrilex · July 2013

Nope :rofl: Just left it with the acid finish this time

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