Couldn't help myself

Lacehim

Nice job D. So next coffee social at your place then?

derrilex

Very possibly Lacehim, might wait for the weather to warm up so the pool can be used :thumb: Gary, yep, too good to walk past OG, kitchen needs a rework to accommodate this and other projects. Cheap deals if you get in good with Chris 😃 Doubles are great C-Man. OPV is adjusted now so we shall see how the next one pours

derrilex

Ok, so I had the covers off the Mitica adjusting the OPV and I noticed how quickly the machine was cycling. It was on for 7 seconds and off for 27 seconds on average. I pulled the 99 out and fired it up and it is on for 9 seconds and off for 1 min 47 seconds. Hmmmmm. I looked for leaks and found nothing, as one would expect. The machine does sit in front of an enormous servery window and there was a breeze blowing through but still.... Anyway, I went to Bumrings and picked up a roll of R 2 Earthwool. It's non combustible and can be delaminated for thinner sections and at $ 25 for a huge roll it made sense. There is heaps of room in the Mitica so install is easy. It's not pretty but very effective. All back together and the figures are now on for 7 seconds and off for 2 mins 15 secs on average. Result ! Here is the stuff I used http://www.bunnings.com.au/products_product_earthwool-r20-90-x-430mm-glasswool-insulation-roll_P810890.aspx?search=insulation&searchType=any&searchSubType=products&page=3

Lacehim

I really don't understand why this isn't done standard on all espresso machines to improve efficiency. Typical manufactures that don't worry about in the inside, they just worry about the bling on the outside.

derrilex

If I ever pull the boiler out I'll make it look a lot neater but as it is the insulation completely encases the boiler, keeps the wires off the hot bits and gives the brain heaps of protection. I guess cost is the factor but really, there is no excuse. It could be done so neatly and easily at the point of assembly in the factory but the 50 cents worth of insulation is obviously not manufacturer (all of them) priority. The shiny bits sell

Brett_H

Great result there and quite a BAAH... gain :rofl: Seriously now has this effected your machines thermal stability and subsequent shot temperatures/cooling flush times?? I did this on my old HX and had to adjust the pressure-stat down further to stop the burnt coffee tastes.

derrilex

I do have to flush a bit longer now Brett. Although the splutter is quite subtle compared to the 99 so one has to listen carefully. Mind you, I'll take that any day over a over keen cycling boiler. I've knocked the Pstat down a touch to just over 1.1

Brett_H

derrilex wrote:

I do have to flush a bit longer now Brett. Although the splutter is quite subtle compared to the 99 so one has to listen carefully. Mind you, I'll take that any day over a over keen cycling boiler. I've knocked the Pstat down a touch to just over 1.1

Absolutely agree and any Bezzera owner will tell you that even at a mere 1 bar it's still enough steam to coat your ceiling in milk!!

derrilex

Yes it is 😉. The Mitica textures milk so effortlessly too. Note that I'm giving credit to the machine not the nut behind the wheel 😃

UNM

Interesting. I would have thought shot temperature would drop slightly not rise with the insulation Edit: Did you fully insulate lines from heat exchanger to group head?

Brett_H

UNM wrote:

Interesting. I would have thought shot temperature would drop slightly not rise with the insulation Edit: Did you fully insulate lines from heat exchanger to group head?

Yep, me too! Mine got noticeably hotter at the group head. I think insulating the copper pipes to the GH would really mess up the manufacturer's thermal design for the machine wouldn't it??

derrilex

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

UNM

derrilex wrote:

Not on purpose. I just carefully stuffed the cavities with insulation. Why would shot temps decrease ? that makes no sense. 😃 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

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

Does the Bezzera Mitica have an electric heated head ?

conikal

Koffee Kosmo wrote:

Does the Bezzera Mitica have an electric heated head ?

No, its the E61 group with thermosyphon heating.

derrilex wrote:

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

UNM

derrilex wrote:

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

UNM wrote:

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

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

Insulate it and be even happier C-man 😃

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