Thermostat talk at EPNW- FYI / discussion

[mogogear]

While I was at EPNW today I was asking for a couple of thermostats like Paul had put on one of his Faema's. Wired around the belly of the boiler and wired in place between the PStat and the element.
Bill and I have swapped some notes on the fact that it seemed like a good thing to add to our equipment. So I asked the counter guy at EPNW, he reached around the corner into the warehouse and asked a desk guy( sorry GUY- I was too busy talking to you I forgot your name) and he strongly cautioned against the practice. ( I was confirming temp on the model I was inquiring about)

He said:

If you put one on, and if the Pstat fails and hangs on. the OPV will most likely keep bleeding off steam and defeat the temp rise. That the temp to interrupt would not occur as "I was" planning.

He cautioned that it could give the false sense of security and that the only real way to protect against element overheat( boiler out of water etc) was to install a probe type thermostat that would be close enough to the element to react when indeed the water runs out and the area near the element finally gets upto the 265 degree range. I don't have the number of what he showed me but will add it shortly.

I was very clear , as was he- That he would not do the strap-on( no pun intended ) thermostat and that if I had a machine that was on 24/7 to splurge and upgrade to the probe type.

Food for thought for those of us with machines that have one of a kind elements etc..

So what's the groups thoughts on this.. I am merely sharing this for discussion. I took his advice since he worked at a reputable service parts supplier/ that is a friend of this site/ Big supporter of us all / and did I mention the Promised land for stuff I need?

[PaulTheRoaster]

But a lot of HX machines *do* have safety t-stats that aren't probe type. I get his point, but maybe a safety t-stat that opens at a lower temperature than the opv would be best.

[Paul]

I don't have a firm opinion other than some protection must be better than none . There are some faema elements that have a fitting on their boss to which a safety probe screws into. Such elements are used in bigger commercial fellas. I note that the device used on Paul's faema is from a LM; if it is good enough for LM . . .

[Paul_Pratt]

Yes it's true that before the fuse will pop up, the safety valve should blow. If you are in the same building you will hear that, on a 4 group Marzocco the sound can be quite scary. That said I have had many many occassions over the past several years where the fuse has prevented element burn out from lack of water, in fact just last week on a 1 group Marzocco. In 10 years I've never had an element burn out.

For me the 1.8 bar valve is 1st line of defence for a sticky p-stat or sticky thermostat. The pop fuse is the 2nd line of defence for sticky p-stat/thermostat and low water. (dodgy autofill box, broken solenoid, blocked solenoid etc..).

And it helps you sleep better at night.

Paul

[mogogear]

Hey I am completly in the neutral here. Logic can sway me back and forth. That is why I posted the input I got. I am hoping it spurs some good logical assertions. It helps us all think about what we know..Thanks, both of you are very high up in my book as far as real world experience...

[bill]

Hi Greg,
Since all your replies have been from folks named Paul I thought you should get one from someone different!
The advice you received is interesting. In fact, I had wondered whether the outer shell of the boiler would get that hot if it boiled dry. I'm not sure how to find out for sure unless someone is willing to do a test for us. (not me, that's for sure!) Or maybe someone remembers enough of their college thermo course to calculate it. (again, not me, that's for sure!).
Both of our machines have inline fuses to protect the wiring but I don't think that'll do anything for the element itself. Maybe a probe to sense a low water level and open the circuit would work?
I'm interested in the replies you're going to get.

[mogogear]

You know the most critical point maybe to have the probe or Tstat as near the element as possible. The tstat for example on the Creminas is screwed to a inset on the element base plate. Right in amongst the hot stuff.... Ahhh, well , a lowly thinker like me is going to sit and let you smart ones lead me to the right path...

[peacecup]

The pstat on the Export is right near the element, on the bottom. The Lusso's is on the side I think, also right near the element. They are the same pstat, but I don't remember the name. You might ask grong to check his Lusso, which is easier to access.

PC

[bill]

The pstat on the Export is right near the element, on the bottom. The Lusso's is on the side I think, also right near the element. They are the same pstat, but I don't remember the name. You might ask grong to check his Lusso, which is easier to access.

PC

PC,
I assume you mean tstat and not the pstat? Is the tstat a button type on the outside of the boiler next to where the element is located? I think that's the type my Pavoni used and it actually fit in to a recess in the base plate.

Mo,
Which brings up another possibilty. Would the surface-type tstat work better if it were located in a similar postion on the larger boilers?

[mogogear]

Perhaps, I would assume the closer the better. Also my friend a EPNW also rebutted my statement about the Tstats being resettable-- he corrected me they are resettable only one time...?

[peacecup]

I'm confused - I found a photo I had of the Mater (I thought it was a P stat) :



There is also a thermal cutoff switch, the red reset button of which is hidden under the white wire connectors. I once plugged my Export in without any water in it and flipped the cutoff. I was able to reset it, but Gene at Vanelis cautioned me that it might need to be replaced if tripped again. Both the Mater and the cutoff are probably easy to buy and install, and seem to be adequate for the current makers of the PV Lusso,

PC

[bill]

I'm confused - I found a photo I had of the Mater (I thought it was a P stat) :

image: http://www.home-barista.com/forums/userpix/310_mater_compressed_1.jpg

There is also a thermal cutoff switch, the red reset button of which is hidden under the white wire connectors. PC

Hi Peacecup,
The thermal cutoff switch is what we're interested in. If the Mater pressurestat fails or for some other reason the boiler is low on water that thermal cutoff is all that's left to protect the element (as you found out when you plugged the machine in without water).
It's interesting, too, that you heard the same thing as Mo (the reset only works one time then the thermostat needs to be replaced). That must be true.
Do you know how the thermal cutoff is attached to the base of the boiler? Is it in a recess as I remember the one on the Pavoni?
Bill

[peacecup]

I'll take the base cover off and have a look after I pull my evening espresso. I'm working on some Cafe D'Arte Capri dark roast, which they call southern Italian. I stopped at their shop in Seattle last week, where I got a nice espresso, and had a look at a chrome Elektra spring lever. I was impressed at the weight and solidness of the Elektra. It would be fun to try a different group size, since the PV is the smallest available. I saw a lot of lever machines on this trip, and I have side-grade fever. I got to peek at Mogo's Caravel and Bezerra, but of which I covet. I'd like to have some time with some different types of machines, manual levers, larger groups, etc. But for now the espresso from the PV is still so good that I'm in no hurry.

PC

[peacecup]

Just had the last espresso of the day. The grind was a tad too tight, so the pour was slow and had a slight bitter finish, but it was still very good.

The thermal cutoff on the PV is directly above the Mater in the photo - I was mistaken, you can actually see part of the red reset button. I just removed the bottom cover and had a look - it is mounted flush,and not recessed. The Export is like the Pavoni in that the element is mounted on the bottom and extends up vertically - the club styles are mounted horizontally. Presumably, any time the thermal sensor "feels the heat" of an unsubmerged element it will trip. It may need to be mounted slighty ABOVE the element, so if part of the element is exposed, it feels it.

One of the great things about these little levers is that the worst scenario (short of a melted boiler) is replacing the element, the cutoff, and a few seals.

PC

[bill]

PC,
Thank you for going to the trouble to do that. I really appreciate it!

It would be fun to try a different group size, since the PV is the smallest available. PC

Yes, as you may remember I used to have a La Riviera with the same size group as yours. I did an experiment once and bolted an Elektra group to the Riviera boiler (the bolt holes lined up perfectly). The bigger group really improved the looks of the Riviera. I wasn't happy with it because the spring was very easy to stall, but I think it just needed to be replaced.
I still have the Elektra group and if the bolt holes would line up on your PV you're welcome to borrow it and play around with it. Someday I'll get around to rebuilding the Elektra but not in the near future.

[bill]

Just had the last espresso of the day. The grind was a tad too tight, so the pour was slow and had a slight bitter finish, but it was still very good.

The thermal cutoff on the PV is directly above the Mater in the photo - I was mistaken, you can actually see part of the red reset button. I just removed the bottom cover and had a look - it is mounted flush,and not recessed. The Export is like the Pavoni in that the element is mounted on the bottom and extends up vertically - the club styles are mounted horizontally. Presumably, any time the thermal sensor "feels the heat" of an unsubmerged element it will trip. It may need to be mounted slighty ABOVE the element, so if part of the element is exposed, it feels it.

One of the great things about these little levers is that the worst scenario (short of a melted boiler) is replacing the element, the cutoff, and a few seals.

PC

I can see it and I think you're correct. The element on Mo's Conti and my Gaggia are mounted on the side of the boiler. If the tstat were mounted directly above where the element enters the boiler it should sense any heat buildup quickly.

I'll be interested to see what Mo and the three 'Pauls' think.

[PaulTheRoaster]

I'll be interested to see what Mo and the three 'Pauls' think.

I'm sure the other 2 Pauls have a more informed opinion than me.

It just seemed odd to me that nearly every machine comes with a safety device that gives a false sense of security. Manufacturers aren't known for adding superfluity to machines, at least not at the price level of consumer machines.

It's possible the fellow at the desk meant that a safety t-stat should be mounted on the element flange rather than the boiler. That makes some sense--since if the boiler were dry, the element gasket might insulate the boiler from the element flange plate long enough to render the safety t-stat useless.

[mogogear]

I think to clarify, I told the gentleman who gave me the input that's spawned this topic, that I was interested in strapping the Tstat to the belly of the boiler. ( As I had seen on several other machines)

He was insisting that this was possibly futile.

He recommended the probe type tstat as the best rememedy for machines not having one . Those having them ususally have them placed on or very near the element.

He was asserting that merely clamping one to the boiler may or may not interupt the circuit by sensing the overheat situation, due to no ideal testable proximity.

It most likely is better than nothing, but if your guarding something very valuable, elelments that are hard to impossible to find etc, you might splurge for more than $25.. and / or really be precise in placement and temperature model chosen.

I won't start a sentence with "HE" anymore in this post