I'm wondering about pro's and con's to leaving my machine on overnight.  I was taught (possibly old school) to leave it on overnight, but now Im wondering if this is necessary.  It seems like a lot of wasted energy and money. 

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We leave ours on all night. Simply because we are open from 6a-11p every day. Turning our machine off for a few hours isn't worth it because of the heat loss. Although, I'm sure it won't go stone cold in 6 hours, it is nice to have a hot machine ready to do work. I guess it depends on the difference in your close-to-open time.

Just my $.02

I was advised a few years ago about leaving the machine on overnight. The reason given to me was that a constant change in temperature on all of the seals in the grouphead, boiler, and other seams would wear down faster from the expansion/contraction of the metals around them.

What type of machine are you referring too?

What you were taught is good advice for several reasons.  In not particular order:

1) It can take many hours for a cold machine to reach thermal stability, and if you are concerned about shot-to-shot consistency, having to re-heat your machine each day does not lend itself to this.  

2) As Evan said, the constant change of temperature can fatigue joints, and threads, as well as wear out seals, but in my opinion, if you are on a consistent Preventative Maintenance Schedule, this should never really be and issue.

3) The biggest issue is what happens to all the dissolved and suspended solids and minerals in the water.  Solubility goes up with heat, so that hot water in your boiler(s) and lines hold more dissolved solids when hot.  As the water cools and solubility decreases, guess what precipitates out? You got it.  Then, before you know it, you have scale in you boiler, lines, valves...performance is affected and the life of the most expensive piece of equipment on the bar is dramatically shortened. 

Keith

www.VeniaCoffee.com

Traditional? Leave it on unless you won't be using it for a couple of days. Superauto? Turn it off.

When you aren't using it your heating elements duty cycle, so the machine only really draws power for the 10 or so seconds every few minutes that it takes to keep the boiler hot. Compare that to the 10+ minutes of constant power draw that it takes to bring the cold water and brass up to temp from cold and it isn't nearly the difference you'd expect.

Also keep in mind that, depending on your machine, it may take an hour for everything to come fully up to temp.

I advise my customers to leave their machines on.

Theoretically water consumes the most energy at physical change state, i.e. when it's turned into steam.  Though not a feature I am aware of on any current machine, it would be ideal to turn the steam boiler temp down to just below boiling overnight.  No need for long heat soak in the morning (like when starting a cold machine) and probably far less cycling through the night.  You could also insulate the boilers, like old Lineas were, and it would improve shot-to-shot consistency.  Even more so if you have a copper boiler, they loose the most heat.  

I wouldn't recommend shutting a machine off for the same reasons mentioned above.  Though I would add if your dissolved hardness is that high, you really need to do something about it regardless.  Aside from the wear on the machine, hard water takes more energy to heat. 

 

if your dissolved hardness is that high, you really need to do something about it regardless.

The main concern is in the steam boiler of 2 boiler machines, or the main boiler on heat exchange machines.  When steam is made, it leaves all the minerals and dissolved solids behind in the boiler water.  As steam is used, more water is added to replace the water lost in steam, adding more minerals in the process.  Over time, TDS in the steam boiler becomes quite high, even if you have ideal 150 TDS water at your tap (this is why making americanos from the tea/hot water port is a bad idea...can really taste off and impart bad flavors to your otherwise perfect shot). 

Keith

www.VeniaCoffee.com

I'm speaking to hardness of feed water alone.  If your water hardness is not over 4 grains (and I think that's high) and you purge the steam boiler daily, you shouldn't see a huge problem.  But if that 150 TDS on incoming water is all hardness, that's 9 grains of hardness.  That'll void the warranty on most commercial machines.  And it will build up in the brew boiler as well.  In an ideal world, you would feed 10 TDS RO water to the steam boiler and 150 TDS (or whatever mythical ideal number you want) to the brew boiler in a dual setup or the boiler and heat exchangers. 

And I agree, the economizer/hot water taps are wrong for making drinks with.  

La Marzocco Linea

Chad Kimm said:

What type of machine are you referring too?

Thanks a lot everyone..... I will keep it on!  Great info.. have a wonderful day.

Technically, if the steam is not released then the heat of transition is not lost. Because of the pressure, the boiling point is raised and the water boils only when pressure is released. The reduction of energy used if turned down would be related to a lower heat gradient only. Good theory though.

Guys, this is fascinating stuff. I'm breaking it out into a separate sidebar discussion here. Please continue down this line over there. Thanks.

Jeremiah said:

Technically, if the steam is not released then the heat of transition is not lost. Because of the pressure, the boiling point is raised and the water boils only when pressure is released. The reduction of energy used if turned down would be related to a lower heat gradient only. Good theory though.

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