Hi all,

Hoping someone can suggest how to fix this little problem...

My veteran Rancilio Silvia has started to overheat to the point where it quite often trips the safety thermostat, so I have to keep resetting it. It's brewing fine, and I've recently descaled it, but the problem remains.

Any suggestions as to what's causing it? Or how I can track down the problem? (I have a multimeter and I'm quite happy to strip down as much of the machine as necessary to diagnose/fix the fault)

Paul

Hi Paul and welcome!

Does it trip the thermostat when in brewing mode or steaming mode?

It may be either the thermostat for brewing temp, or the one for steaming that needs to be changed. The safety thermostat that resets may also need to be changed. These are all inexpensive parts.

If it is not one of the thermostats, and you are certain scale is not the problem, the only other common causes result from the water level inside the boiler becoming too low. You referred to the Silvia as a veteran, and that leads me to be mostly certain that you use her correctly, but I'll go over the causes of low boiler water just in case.

First, upon startup each morning/afternoon, be sure to activate the coffee delivery switch and pump as much water as you want to out of the group head. This not only gives you fresh water to brew with, but it also ensures the boiler is fully charged.

Next, any time you froth/steam milk, you need to always and immediately recharge the boiler directly afterward by turning off the steam switch and activating the coffee delivery switch. While water is coming out, open the steam valve to clean out the inside of the wand pipe.

Also, in rare cases, if the Silvia is left on and idle for too long (many), the water level may drop if steam escapes from the OPV (pump Over Pressure Valve) back into the water tank during each heating cycle.

Hi Joshua,

Thanks - I'm not 100% sure, but think that it's tripping in steaming mode. Mostly, at least.

By the sound of it the best thing would probably be to change all three thermostats... if they're cheap bits it would address the likely causes, and if the problem recurs then I'll know it's something else.

Paul

The brew thermostat goes most often because it opens and closes most often.
But tripping the overheat means that the stream thermostat is a problem as well since it is in the circuit all the time. The steam switch just bypasses the brew thermostat.
But, another problem could be scale build up inside the boiler or poor thermal conductivity between the thermostats and the boiler. They need to have thermal paste between the thermostat and the boiler's surface.

Thanks Randy, I'll take care to get some thermal paste in there when I reassemble things - I'll also try an especially thorough descale. The water here in London is pretty hard and I'm a bit hit and miss about using filtered water...

If the OP is still debugging this problem, another failure mode could be simply that the safety thermostat is defective and opening at too low a temp, potentially at any time. He sounded vague about exactly when it was happening, so this seems plausible. In other words, not really overheating, but appearing to do so. When this thermostat trips at the correct temp, you should have a pretty insane head of steam! In any case, each of the 3 thermostats can be had for US$12-15, so it might make sense to keep spares on hand. I've had a Silvia since 2003, and I've only had one (brew) thermostat failure, about 3 years ago.

Hi Genovese,

thanks for the info... I'm just returning to this thread as, having replaced the brew and steam thermostats I find that the problem hasn't quite gone away. It's only tripped a couple of times in 4 days, and as before (small sample size notwithstanding) i can't really say exactly what is triggering it, so a defective safety thermostat certainly sounds plausible to me. Now if only I'd replaced it with the others, I might not have given myself that electric shock earlier today poking around inside to reset the 'trip nipple' again...

Silvia Overheating - I've replaced both thermostats and still a problem. The lights never change or go off and the overheat protection never kicks in. It just get super heated quickly. Steam comes out of brewhead after a few minutes. I've used thermal paste on new parts but no help. Any chance to save this one?