coffee-forum.net
Promoting coffee discussion.

Main
Date: 13 Jun 2007 05:06:23
From:
Subject: HELP! Rancilio Silvia overheating issue
My Silvia is a bit of a rebuild. It was previously poorly maintained,
so I acquired her, replaced the boiler, and took everything apart and
cleaned it. Reassembled everything. Plug her in, she begins to heat
up, she keeps heating up keeps heating up, and eventually trips the
overheat. I figured I must have a bad brew thermostat, so I replaced
the brew thermostat. No dice--same exact problem. Then I figured I
must have wired something incorrectly, overriding the heating element
"shut-off mechanism." I went over and over and over the wiring
diagram. I am nearly 100% certain that the wiring is right. I wanted
to PID the machine anyway, and I thought for sure this would solve the
issue. I purchased the PID, installed it all according to
instructions. I expected that the PID would solve the issue of the
heating element not kicking off. It did not. She still continues to
climb indefinitely. I have gone over the wiring, and I am nearly
certain that everything is in its proper place. All of the functions
of the unit work properly with the single exception of the fact that
the heating element never kicks off while the machine is plugged in
and turned on--that is until it reaches the way-too-hot point and
shuts off automatically. Any thoughts?





 
Date: 14 Jun 2007 17:21:32
From: megatec45
Subject: Re: HELP! Rancilio Silvia overheating issue
On Jun 12, 10:06 pm, espressosm...@gmail.com wrote:
> My Silvia is a bit of a rebuild. It was previously poorly maintained,
> so I acquired her, replaced the boiler, and took everything apart and
> cleaned it. Reassembled everything. Plug her in, she begins to heat
> up, she keeps heating up keeps heating up, and eventually trips the
> overheat. I figured I must have a bad brew thermostat, so I replaced
> the brew thermostat. No dice--same exact problem. Then I figured I
> must have wired something incorrectly, overriding the heating element
> "shut-off mechanism." I went over and over and over the wiring
> diagram. I am nearly 100% certain that the wiring is right. I wanted
> to PID the machine anyway, and I thought for sure this would solve the
> issue. I purchased the PID, installed it all according to
> instructions. I expected that the PID would solve the issue of the
> heating element not kicking off. It did not. She still continues to
> climb indefinitely. I have gone over the wiring, and I am nearly
> certain that everything is in its proper place. All of the functions
> of the unit work properly with the single exception of the fact that
> the heating element never kicks off while the machine is plugged in
> and turned on--that is until it reaches the way-too-hot point and
> shuts off automatically. Any thoughts?

Make sure to check that all the wire nuts don't have a strand of wire
hanging out. there can also be a pinched wire that might hve been
caught near a screw, or crushed under the boiler, could also be broken
insulation, touching metal that might be causing the short.



 
Date: 13 Jun 2007 09:59:25
From: daveb
Subject: Re: HELP! Rancilio Silvia overheating issue
This represents a very serious shock / electrocution hazard.

when replacing the boiler again -- for which you should complain about its
short life to your supplier --

BE very certain that the 3 way valve is NOT leaking.
If it is, it will permit the boiler to drain dry, by gravity alone, causing
the boiler to FAIL again!

dave
www.hitechespresso.com





 
Date: 13 Jun 2007 13:57:39
From:
Subject: Re: HELP! Rancilio Silvia overheating issue
I'll run the continuity check. Thanks so much.



 
Date: 13 Jun 2007 13:19:57
From:
Subject: Re: HELP! Rancilio Silvia overheating issue
You are a genius! I couldn't figure out why it was tripping my GFI,
but working in my other outlets. A sign I probably should not have
ignored. Ok, so I understand the problem, but the jargon at the
beginning was a bit over my head....can I solve it, and if so, how?
Sorry to be the ignorant among thousands of techies. Thanks so much
for the reply.
PRS



  
Date: 15 Jun 2007 00:26:09
From: seastl
Subject: Re: HELP! Rancilio Silvia overheating issue
On Wed, 13 Jun 2007 13:19:57 -0000, espressosmith@gmail.com wrote:

>You are a genius! I couldn't figure out why it was tripping my GFI,
>but working in my other outlets. A sign I probably should not have
>ignored. Ok, so I understand the problem, but the jargon at the
>beginning was a bit over my head....can I solve it, and if so, how?
>Sorry to be the ignorant among thousands of techies. Thanks so much
>for the reply.
>PRS

I saw this late, but wanted to add this to Jim's spot-on advice:

If you have submerged the boiler (either old one or new one) in water
(boiling or otherwise) as part of your cleaning/descaling process, you
may just need to bake it in order to remove the moisture which is
shorting the resistance element to the element housing. Baking at 250
degrees for several hours will do it. The water ingress is typically
around the ceramic insulators by the terminals.

You should also restore the red insulating varnish on the two ceramic
posts in order to minimize moisture intrusion in the future. Make sure
it extends beyond both ends of the ceramic post. Also ensure that the
moisture is removed first. The element should show a minimum of about
3 megohms of resistance to ground (housing) from either terminal. If
it's below a few hundred kilohms, you'll possibly start seeing
problems with GFCIs tripping, etc. There would only be a safety issue
in that case if the boiler became ungrounded for some reason. Then it
would stop heating until you grabbed it and provided the circuit
completion ;-).

Brad


  
Date: 13 Jun 2007 09:43:37
From: jggall01
Subject: Re: HELP! Rancilio Silvia overheating issue
On Wed, 13 Jun 2007 13:19:57 -0000, espressosmith@gmail.com wrote:

Just noticed that you already replaced the boiler? Before you put in
another one, do the continuity check I suggested.

Jim


  
Date: 13 Jun 2007 09:38:38
From: jggall01
Subject: Re: HELP! Rancilio Silvia overheating issue
On Wed, 13 Jun 2007 13:19:57 -0000, espressosmith@gmail.com wrote:

>....can I solve it, and if so, how?

Usually, this means a new boiler (the top half, above the big flange
with the bolts). On newer Silvia's the heating element is brazed to
the boiler shell and cannot be replaced. I understand that older
models had a separate heater that was replaceable, but the seals
around the terminals leaked.

I've never done this repair, so I'm not the right one to advise you on
difficulty. If you check online you should be able to find a few
vendors that sell the integrated boiler/heater, probably for around
$100.

Jim



 
Date: 13 Jun 2007 08:57:01
From: jggall01
Subject: Re: HELP! Rancilio Silvia overheating issue
On Wed, 13 Jun 2007 05:06:23 -0000, espressosmith@gmail.com wrote:

>...Plug her in, she begins to heat
>up, she keeps heating up keeps heating up, and eventually trips the
>overheat. I figured I must have a bad brew thermostat, so I replaced
>the brew thermostat. No dice--same exact problem...

A Silvia is wired so that the brew and steam tstat's are on the low
side of the heater circuit. The heating coil is at mains (120VAC or
220VAC) voltage all the time. But no current flows until the circuit
is completed as long as everything is operating correctly.

Unfortunately, this means that if the heater shorts to the grounded
brass boiler, it will behave as you describe. A fault current will
keep the heater going non-stop because it bypasses the thermostats.

The overheat switch is on the high side of the coil, BTW. So when it
trips the heater is de-energized regardless of any ground faults.

Plug the Silvia in to a GFI. It should trip if your problem is a
fault current. I'd also do continuity checks between the heater
terminals and the surface of the boiler (unit unplugged). There
should be no measurable continuity between either terminal and the
boiler.

One more thing - if my speculation is correct, then it is very
dangerous since all of the metal on the machine could be parked at
something like 120V/220V. Anything that provides a good path to
ground will get a nasty shock.

JGG