Posted Mon Apr 5, 2004, 10:11am Subject: Is it really safe to leave a HX on 24/7?
I've been reading various posts about leaving HX machines on 24/7 but there doesn't seem to be much of a consensus on whether or not it is or is not a good idea. My primary issues are:
Is it a fire hazard leaving a machine with a 1400 watt heating element on while no one is home?
Will the heat promote bacterial growth in the water reservoir?
Which puts on more wear on the machine - leaving it on or turning it off and on 2-3 times a day?
Fire hazard - I would say no, but grew up learning anything that gets hot should be supervised (irons, ovens).
Bacterial growth - germs like warm places.
Wear - Ted sums it up well:
marrone Said:
Mean time between failures (MTBF) doesn't mean much in some circumstances. Computer hard drives use/used ball bearings with very consistent MTBF levels having to do with metal fatigue after >10,000 hours. If the computer is on 24/7 the 10k hour mark will simply come along sooner. More pointed example is the cheesy fans that predictably go bad very quickly on a computer that's always on, and rarely malfunction on grandpa's Dell.
I guess my point above is that the benefits of running equipment 24/7 need to be weighed against the negatives. On the Isomac, the pressurestat contacts probably have a finite life based on the number of cycles (+/- 1400 / 24hr. of operation), as do the boiler and other pressurized components. Cutting the number of cycles on the boiler pressure adds cycles to the pressurestat and hours to the heat on the natural rubber o-rings and plastic Y's. Help one thing, hurt another.
We're making the same bet, just on different components.
Terry of espressoParts.com presents another point of view:
terryz Said:
In my experience , 110 volt machnes operated with a timer are more prone to control unit failures. There are a variety of reasons for this occurance.
The other reason for a 24/7 operation is that scale forms at the juncture of warm and cold. Thus when you shut the machine off daily, you are building scale deposits quicker than a machine left on all the time.
I'd be interested in hearing non-anecdotal evidence that confirms or refutes the assertion that 24/7 uptime affects MTBF rates. For what it's worth, in the perenial debate among computer hardware engineers, the majority leans toward "turn it off at the end of the day" and they deride those who say otherwise as recounting data from the early 1970s. As I recall the details of one story, IBM once issued a warning to owners of a certain 3270 display model ("green screen" as shown below), telling them that daily on/off cycles would dramatically affect the MTBF rate. Customers diligently followed IBM's advice, and screen burn-in was born -- and spawned an entire micro-industry of "screen savers" years later. Ironically, IBM manufacturing quickly corrected the fault in the 3270 line. More than two decades later, many customers and engineers insist the displays must be left on.
Hence why this discussion provokes such a strong sense of déjà-vu in me. I've read similar discussions on cars ("Should I leave my car running for 15 minutes while I wait for my wife, or restart it?"). But I digress.
tobake Senior Member Joined: 8 Sep 2004 Posts: 88 Location: Sweden Expertise: I live coffee
Espresso: Unico Splendor Grinder: Rancilio Rocky DS Vac Pot: Bodum Santos Drip: No Drip, but Eva Solo Coffee Roaster: IMEX Caffe Rosto
Posted Mon Sep 10, 2007, 6:19am Subject: Re: Is it really safe to leave a HX on 24/7?
Fire Hazard - YES!!
Came home saturday night and felt the smell of electric fire in my flat. Instantly understood that it came from my Unico Splendor. Opened the baby up and saw that all whats left of the solenoid was pure charcoal. Just pure luck that it stopped there as my machine is fitted on a wooden counter.
From now on I am not going to leave it on 24/7, that´s for sure!
Posted Mon Sep 10, 2007, 2:59pm Subject: Re: Is it really safe to leave a HX on 24/7?
Fire hazard? quite possible.
Very costly mess hazard - definitely.
Doesn't have to be on - just plugged in.
Apparently these machines ($1000-$2000), which have an SSR (solid state relay), are wired in such a way that the SSR can gate the boiler ON, even when the machine switch is OFF - it only has to be plugged in. The engineers that designed it assumed that the triac in the SSR would never fail. All electronics fail eventually.
If the SSR becomes "flakey", or fails to "ON", there is nothing to stop the boiler from running away other than the temperature-fuse or the resetable fuse. Hopefully the emergency relief valve on top of the boiler will open so the boiler doesn't blow, but then, the contents of the boiler will steam up through that valve and condense all over the inside of your machine, possibly shorting out something, likely ruining your expensive controller, possibly burning out the heater element.
This has nothing to do with whether the machine happens to be turned on at the time of the SSR failure.
SSR failure does happen.
I just had one. Fortunately I was there, and also fortunately it failed to "mostly off", though later as I was playing with it, it failed to full on.
I now have the machine plugged to an intermediate highly visible power strip with a light on it, and I shut the strip off when I'm not using the machine, and definitely when I'm not there.
This is a thread that I camped on to after it happened to me: "X1 Explosion."
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