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Date: 26 Feb 2007 15:48:51
From:
Subject: LM pressure/temperature variations
The pressure gauge on my 2gp AV Linea is showing variability - at
times 15bars+ and lately just at 4bars (all idle times, brewing
pressure is 9bars). This is reflecting on the PID readout - low temps
at low pressure and on the right temperature at higher pressures. (PID
is set at 96C which gives 92.5C Scace reading). What I've done in
attempt to fix the problem:

- check the expansion valve (which didn't help - the pressure still
goes up and down)
- check PID (all ok)
- check element connections (all ok)
- boiler probe is new

Seems there's a lot of turbulence in the pipes...a lot of cold and hot
water mixing perhaps. Shall I see to the check valve? ...Any advice
appreciated.

Cheers
HD





 
Date: 13 Mar 2007 05:19:09
From: gscace
Subject: Re: LM pressure/temperature variations
On 12, 9:53 pm, gob...@hotmail.com wrote:
> Thank y'all so much for the help. Update:
>
> The check valve's in good nick.
> The element is new.
> Brew solenoids ok.
> Thermal cutoff switch ok.
> PID connections ok.
> Main power supply ok.
>
> After so much taking apart things, checking, and putting them back
> together again, not to mention the endless prodding with multimeter
> leads, the culprit was an ailing solid state relay.
>
> The side of the SSR that I couldn't see turned out to be warped by the
> heat coming from the steam boiler which was only an inch away. Inside
> the SSR was black dust everywhere and caked up contacts.
>
> Just replaced the SSR this morning and the machine's been on for the
> last 3 hours and so far very promising:
>
> - PID at constant 96C
> - SSR clicks are full and resolute (I'd forgotten how clicky it is)
> - pressure gauge languors between 10-12bars
>
> ...pulling espressos...priceless.
>
> PS. Since I've realised how delicate the SSR can get, especially at
> such scary proximity to the steam boiler, does anyone have great ideas
> on how I can protect the SSR? (wires can't extend long enough for the
> SSR to be anywhere else)
>
> Hazel

My recommendation would be to look at Paul Pratt's website and see how
he mounted all of that stuff because it is extremely clean. Then I'd
get the wire necessary to duplicate his setup.

-Greg



  
Date: 13 Mar 2007 08:30:04
From: notbob
Subject: Re: LM pressure/temperature variations
On 2007-03-13, gscace <gregory.scace@nist.gov > wrote:

> My recommendation would be to look at Paul Pratt's website and see how
> he mounted all of that stuff because it is extremely clean. Then I'd

howzabout a URL.

nb


 
Date: 13 Mar 2007 03:20:36
From: Paul Pratt
Subject: Re: LM pressure/temperature variations
On 13, 10:53 am, gob...@hotmail.com wrote:
> Thank y'all so much for the help. Update:
>
> The check valve's in good nick.
> The element is new.
> Brew solenoids ok.
> Thermal cutoff switch ok.
> PID connections ok.
> Main power supply ok.
>
> After so much taking apart things, checking, and putting them back
> together again, not to mention the endless prodding with multimeter
> leads, the culprit was an ailing solid state relay.
>
> The side of the SSR that I couldn't see turned out to be warped by the
> heat coming from the steam boiler which was only an inch away. Inside
> the SSR was black dust everywhere and caked up contacts.
>
> Just replaced the SSR this morning and the machine's been on for the
> last 3 hours and so far very promising:
>
> - PID at constant 96C
> - SSR clicks are full and resolute (I'd forgotten how clicky it is)
> - pressure gauge languors between 10-12bars
>
> ...pulling espressos...priceless.
>
> PS. Since I've realised how delicate the SSR can get, especially at
> such scary proximity to the steam boiler, does anyone have great ideas
> on how I can protect the SSR? (wires can't extend long enough for the
> SSR to be anywhere else)
>
> Hazel

Pictures pictures!

Glad you got it working. I'd really be interested in seeing where the
SSR is mounted. Also my PID's are silent, no clicks...(relay
output???)

Paul



 
Date: 12 Mar 2007 19:53:41
From:
Subject: Re: LM pressure/temperature variations
Thank y'all so much for the help. Update:

The check valve's in good nick.
The element is new.
Brew solenoids ok.
Thermal cutoff switch ok.
PID connections ok.
Main power supply ok.

After so much taking apart things, checking, and putting them back
together again, not to mention the endless prodding with multimeter
leads, the culprit was an ailing solid state relay.

The side of the SSR that I couldn't see turned out to be warped by the
heat coming from the steam boiler which was only an inch away. Inside
the SSR was black dust everywhere and caked up contacts.

Just replaced the SSR this morning and the machine's been on for the
last 3 hours and so far very promising:

- PID at constant 96C
- SSR clicks are full and resolute (I'd forgotten how clicky it is)
- pressure gauge languors between 10-12bars

...pulling espressos...priceless.

PS. Since I've realised how delicate the SSR can get, especially at
such scary proximity to the steam boiler, does anyone have great ideas
on how I can protect the SSR? (wires can't extend long enough for the
SSR to be anywhere else)

Hazel



  
Date: 13 Mar 2007 01:15:53
From: Andy Schecter
Subject: Re: LM pressure/temperature variations
gobann@hotmail.com wrote:
> The side of the SSR that I couldn't see turned out to be warped by the
> heat coming from the steam boiler which was only an inch away. Inside
> the SSR was black dust everywhere and caked up contacts.
>
> Just replaced the SSR this morning and the machine's been on for the
> last 3 hours and so far very promising:
>
> - PID at constant 96C
> - SSR clicks are full and resolute (I'd forgotten how clicky it is)
> - pressure gauge languors between 10-12bars
>
> ...pulling espressos...priceless.
>
> PS. Since I've realised how delicate the SSR can get, especially at
> such scary proximity to the steam boiler, does anyone have great ideas
> on how I can protect the SSR? (wires can't extend long enough for the
> SSR to be anywhere else)


G'day, mate, glad to hear you're up and running.

Your SSR clicks? Sounds like it's not an SSR (Solid State Relay), but a
mechanical relay instead.

You could slip some insulation between it and the steam boiler, or else extend
the wires so that the relay can move to a cooler neighborhood!


--


-Andy S.

http://www.flickr.com/photos/andy_s/sets/


 
Date: 28 Feb 2007 09:46:05
From: gscace
Subject: Re: LM pressure/temperature variations
On Feb 27, 1:47 am, gob...@hotmail.com wrote:
> Hallo Andy and Paul. Thank you for the replies.
>
> Yes, this intermittent problem is a pain in the proverbial because
> there are times when everything seems to be going well and times when
> it's just confounding. Great leads though - Paul, I'll see to the
> check valve and the group solenoids as it could very well be a leak.
> Andy, I'll pop open the side panel again and check the connections
> from PID to SSR, SSR connections, cut through the heat shrink to the
> element leads again and check the connection there.
>
> Last month I pulled the Linea apart to do a full descale of the brew
> boiler and pipes and fittings. I put it back together and for a month
> everything was fine 'til few days ago. Ya think I might've missed
> something during the pulldown?
>
> ...will give updates... thanks again.
>
> Cheers
> Hazel



Might be as simple as a piece of crud getting stuck on a check valve
seat. It's happened to me before after major dismantling / cleaning
efforts on other machinery.

-Greg



 
Date: 26 Feb 2007 22:47:39
From:
Subject: Re: LM pressure/temperature variations
Hallo Andy and Paul. Thank you for the replies.

Yes, this intermittent problem is a pain in the proverbial because
there are times when everything seems to be going well and times when
it's just confounding. Great leads though - Paul, I'll see to the
check valve and the group solenoids as it could very well be a leak.
Andy, I'll pop open the side panel again and check the connections
from PID to SSR, SSR connections, cut through the heat shrink to the
element leads again and check the connection there.

Last month I pulled the Linea apart to do a full descale of the brew
boiler and pipes and fittings. I put it back together and for a month
everything was fine 'til few days ago. Ya think I might've missed
something during the pulldown?

...will give updates... thanks again.

Cheers
Hazel



 
Date: 26 Feb 2007 21:08:54
From: Andy Schecter
Subject: Re: LM pressure/temperature variations
gobann@hotmail.com wrote:
> The pressure gauge on my 2gp AV Linea is showing variability - at
> times 15bars+ and lately just at 4bars (all idle times, brewing
> pressure is 9bars). This is reflecting on the PID readout - low temps
> at low pressure and on the right temperature at higher pressures. (PID
> is set at 96C which gives 92.5C Scace reading). What I've done in
> attempt to fix the problem:
>
> - check the expansion valve (which didn't help - the pressure still
> goes up and down)
> - check PID (all ok)
> - check element connections (all ok)
> - boiler probe is new

Hi Hazel:

It really sounds like your PID is OK, but when it calls for heat, the element
sometimes doesn't produce any. When this happens the temperature drifts down,
the water contracts a bit, and the boiler pressure gauge reads lower.

Intermittent problems are the hardest to diagnose. It could a bunch of things
in the chain:
1. output stage of PID is busted (hopefully not)
2. connections from PID output to solid state relay input are bad
3. solid state relay is bad
4. power connections to and from solid state relay are loose (but you say
you've checked that).
5. element itself has intermittent problems.

It would be nice to get a meter in there and take some readings while
carefully jiggling the wires...which is a job only for someone experienced
with electricity.




--


-Andy S.

http://www.flickr.com/photos/andy_s/sets/


 
Date: 26 Feb 2007 18:04:25
From: Paul Pratt
Subject: Re: LM pressure/temperature variations
On Feb 27, 8:20 am, gob...@hotmail.com wrote:
> On Feb 27, 11:09 am, "Paul Pratt" <p...@just-java.com> wrote:
>
> > On Feb 27, 7:48 am, gob...@hotmail.com wrote:
>
> > It's normal. The only thing I would do is adjust the exp. valve so it
> > drips around 11-12 bar.
>
> I've done that - adjusted the exp valve to drip around 12bar...it's
> just that now the pressure's at 4 bars (can't tighten the valve
> anymore) and the temp reading's been at 77C for the last 30 minutes
> (the element light has been on all this time too).
>
> HD

So the pressures not fluctuating but stuck at 4 when idle? Brew boiler
check valve could be faulty. Beneath the drain the pipe that leads
from water distribution block and to the brew boiler should be fairly
cold up to the check valve. If it's hot the valve is not working. You
can take it apart and clean it or buy a new one. They are simple and
easy to clean though. There's an o-ring in there that may have
perished.

Be careful removing that valve though and make sure the brew boiler is
at zero pressure before undoing any fittings. Turn off water supply
and then bleed off pressure by undoing the expansion valve slowly
until it goes to zero. Better stiill on a cold machine.

Check also that no water is leaking from the group solenoids into the
drain and releasing pressure.

For a short term remedy you could use the check-valve from the pump
and then put that back when you have repaired the old one or new one
has arrived.




 
Date: 26 Feb 2007 16:20:34
From:
Subject: Re: LM pressure/temperature variations
On Feb 27, 11:09 am, "Paul Pratt" <p...@just-java.com > wrote:
> On Feb 27, 7:48 am, gob...@hotmail.com wrote:
>
> It's normal. The only thing I would do is adjust the exp. valve so it
> drips around 11-12 bar.

I've done that - adjusted the exp valve to drip around 12bar...it's
just that now the pressure's at 4 bars (can't tighten the valve
anymore) and the temp reading's been at 77C for the last 30 minutes
(the element light has been on all this time too).

HD



 
Date: 26 Feb 2007 16:09:16
From: Paul Pratt
Subject: Re: LM pressure/temperature variations
On Feb 27, 7:48 am, gob...@hotmail.com wrote:
> The pressure gauge on my 2gp AV Linea is showing variability - at
> times 15bars+ and lately just at 4bars (all idle times, brewing
> pressure is 9bars). This is reflecting on the PID readout - low temps
> at low pressure and on the right temperature at higher pressures. (PID
> is set at 96C which gives 92.5C Scace reading). What I've done in
> attempt to fix the problem:
>
> - check the expansion valve (which didn't help - the pressure still
> goes up and down)
> - check PID (all ok)
> - check element connections (all ok)
> - boiler probe is new
>
> Seems there's a lot of turbulence in the pipes...a lot of cold and hot
> water mixing perhaps. Shall I see to the check valve? ...Any advice
> appreciated.
>
> Cheers
> HD

It's normal. The only thing I would do is adjust the exp. valve so it
drips around 11-12 bar.