# Replacing bulb thermostat with bimetallic one. Advice pls



## mexier (Aug 21, 2014)

Good morning, a few days ago, the espresso machine of a friend of mine stopped heating.

With a multimeter, we diagnosed the problem in the three-phase bulb safety thermostat.

It's a 220v machine but wiht three fase safety thermostat

The current path is: main switch -> thermostat > sirai pressurestat and then heating element

I have an extra bimetallic safety thermostat and I asked if it was possible to use that one by placing it downstream, between the live cable going from the pressurestat to the resistance.

The safety system would be like this: main switch-> sirai -> bimetallic safety thermostat -> heating element .

I saw this in other machines and I was wondering if there is something that escapes me or if it's okay.


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## DavecUK (Aug 6, 2013)

To do that on an Isomac machine in a busy commercial setting might not be a great idea.


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## mexier (Aug 21, 2014)

Machine is la san marco 95 practical, is this unsafe?

sorry for the poor pic, I can't rotate it.

how can i interpose the bimetallic with 3phase cable (even if @220v)) incoming and going to the sirai?


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## DavecUK (Aug 6, 2013)

Ah a San Marco, even a photo.............................. there are some considerations

Is it a machine able to run on 3 phase and reduced power single phase?

Is it in a commercial environment, there may be insurance and liability considerations from altering the specification? This is a safety thermostat after all and just because you saw something working, I would guess you didn't see it actually protecting the system during a problem. This is the problem with safety stuff, it might allow use of the machine, but you only know if it's working correctly after the event! I think with only that photo to go on and a complete lack of relevant information, you will find it very difficult to get a useful answer.

Below is a link to an on-line manual with electric diagrams etc.., As your machine might be one of 12 different model variants (you don't way which)...it might be of benefit for you to go through some of this, especially the diagrams.

https://www.manualslib.com/manual/924725/La-San-Marco-95-Series.html?page=4#manual

One key thing that jumps out at me and please don't take this the wrong way, I'm trying to save you from yourself. As you had absolutely no idea of the sort of minimal information you need to provide to get an answer (even after hints from me), I suspect you may well lack the knowledge to do this safely, especially if you have a larger commercial machine with a big boiler.

http://www.dailymail.co.uk/news/article-1311946/Sainsburys-coffee-explosion-injures-7-caf.html


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## mexier (Aug 21, 2014)

Instead just because I understand that it is an essential security system that I posed the problem. Otherwise I could have completely removed the thermostat and it would have been much easier, do not you think? if you bypass the switch, the machine will start working again

What I'm looking for are answers and suggestions maybe providing more necessary information and your irony is simply ridiculous. Honestly, I think you did not understand much of my original post and the positioning of the thermostat. If additional informations are needed (as it can be obvious) just ask to figure out which way to go, instead of giving minimal or arrogant answers.

I appreciate your wanting to save me from myself but if you can not be collaborative simply abstain.

Responding to threads is not mandatory and can be done in MANY ways, even if you feel like an espresso guru. Nothing personal, just keep your shitty ways for yourself, especially if you did not understand the original point


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## Jollybean (May 19, 2013)

Dave actually is an espresso guru. Take his advice or not. It is up to you.


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## ajohn (Sep 23, 2017)

I'm no espresso engineer but I don't think I would do what you are suggesting. I'd assume it's not a case of it doing what it is supposed to do and it has failed open and wont reset if that is possible.

Why not look for a replacement eg this one may fit

https://www.partsfps.co.uk/safety-thermostat-switch-off-temp-169c-3-pole-for-la-san-marco-part-108463

Actually I suspect @DavecUK could comment on the likely hood of that or similar fitting.

John

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## El carajillo (Mar 16, 2013)

As above Dave is highly knowledgeable on coffee machines. Sometimes his responses can seem a little sharp / blunt.

I think he is trying to save you from yourself. There can be several levels of safety measures on electrical equipment / coffee machines which work depending on the severity of the fault / problem. By bypassing the bulb fuse you could be removing a level of protection and causing a more serious problem further along.

Contact the manufacturer and ask their opinion , I think it will probably follow Dave's suggestion.


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## DavecUK (Aug 6, 2013)

mexier said:


> Instead just because I understand that it is an essential security system that I posed the problem. Otherwise I could have completely removed the thermostat and it would have been much easier, do not you think? if you bypass the switch, the machine will start working again
> 
> What I'm looking for are answers and suggestions maybe providing more necessary information and your irony is simply ridiculous. Honestly, I think you did not understand much of my original post and the positioning of the thermostat. If additional informations are needed (as it can be obvious) just ask to figure out which way to go, instead of giving minimal or arrogant answers.
> 
> ...


Wow...way to go to get help. I thought I was actually being very helpful and polite. If I wasn't I would have said........

"You clearly have no idea what you are doing but can't even be arsed to provide the minimal information needed such as what bloody machine it is, exact model (12 to choose from), is it being used commercially, or even annotate the photo. To attempt to modify or bypass a safety system in these circumstances would be stupid and irresponsible. Why not just use the proper parts or get a local espresso machine engineer in."

However, I didn't. I tried to help...as far as I am concerned, you are on your own now and I don't think anyone on the forum would be foolish enough to help you bypassing a safety system and injure yourself or your customers (if it's a commercial machine). Perhaps it would do your manners some good if it did explode, without hurting anyone of course.


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## ashcroc (Oct 28, 2016)

mexier said:


> Instead just because I understand that it is an essential security system that I posed the problem. Otherwise I could have completely removed the thermostat and it would have been much easier, do not you think? if you bypass the switch, the machine will start working again
> 
> What I'm looking for are answers and suggestions maybe providing more necessary information and your irony is simply ridiculous. Honestly, I think you did not understand much of my original post and the positioning of the thermostat. If additional informations are needed (as it can be obvious) just ask to figure out which way to go, instead of giving minimal or arrogant answers.
> 
> ...


Have you considered replacing the three-phase bulb safety thermostat with a three-phase bulb safety thermostat in exactly the same place? I think you're really trying to overthink things just to get away with not having to go to the bother of sourcing the correct part.


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## mexier (Aug 21, 2014)

I thought that the question asked was less complex but speaking of a security system I understand that I did not provide enough information for appropriate suggestions. That said, I agree that it is crazy to remove the thermostat and in fact my intention was to move it further downstream but on the same power line where it is originally placed. At least in this I thought I was clear. Unfortunately in the manuals is not provided an electric diagram but only hydraulic and at the moment I can't take other pictures.

It is not a matter of laziness in finding the original part. The thermostat stopped working suddenly, no overheating or lack or decrease of the water level in the boiler. This wanted to be a starting point to understand how to replace a part that seems to be not very effective. A three-phase thermostat in a single-phase machine whose resistance is fed at 220v and the machine is born single-phase. Thank you (almost) everyone for the replies


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