# PID Temperatures for steam?



## nightslayer (May 29, 2016)

A quick question for all of you who have PIDed the Gaggia - the pressure in the steam boiler should be proportionate to the temperature of the water in the boiler if my understanding of basic physics is correct (pV = nRT). So theoretically bumping the temperature up on the PID by leaving the heating element on should increase steam pressure, since the V, n and R values are constant in the boiler.

My current PID values are set at (edit: ) 148-149C as recommended by Auber (whose PID I am using), which gives me fluctuations between 156C and 146C as the heating element comes on and off, and pressures between 4-8bar according to a pressure gauge I've got on. I've been wondering - how high could we actually set the steam temperature to without burning out the heating element, and would it be worth doing - i.e. would the steam pressure decrease too quickly upon opening the valve anyway?


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## rob177palmer (Feb 14, 2017)

Good thread - following!

Mine set to 140, I recall, as recommended by @MrShades. I recall his instructions were not to top 150, to avoid stressing he system unduly?


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## Samduncombe (Dec 29, 2016)

I have mine at 131, it's bloody powerful enough for at that temp. I have the post 2015 so not sure if that will make a difference. At 150 mine started spluttering and complaining at me. The original thermostats were set to 120 i think, so I'm happy with the extra oomph at 131 personally!


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## destiny (Jun 4, 2015)

There is one thing you are forgetting which is that there is only a limited capacity for steam in this small boiler so you may increase the pressure to start with but will still run out of water/steam fairly quick, most likely with limited benefit and a risk of burning out the element in my opinion (heating air!).

I had seen an older style Classic running ~120°C limit for steam but with the pump being on/off to supply more water to maintain the pressure.


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## nightslayer (May 29, 2016)

destiny said:


> There is one thing you are forgetting which is that there is only a limited capacity for steam in this small boiler so you may increase the pressure to start with but will still run out of water/steam fairly quick, most likely with limited benefit and a risk of burning out the element in my opinion (heating air!).
> 
> I had seen an older style Classic running ~120°C limit for steam but with the pump being on/off to supply more water to maintain the pressure.


The way I understand it there isn't exactly a lot of liquid expelled from the boiler when steaming, seeing as it is that the volume of my (~140ml of) milk increases by maybe 50%, most of which is air and not water being injected into the mixture, which means perhaps 40-50ml of liquid leaving the boiler during steaming at most? The pressure is probably lost from the valve being opened, which, again according to pV = nRT, increases V(olume) and hence decreases p(ressure) (and requires an increase in T(emperature) for a proportionate increase in p(ressure))?


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## greymda (Oct 6, 2016)

on Rancilio, but they are pretty similar. 135C, perfect microfoam.


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## nightslayer (May 29, 2016)

Hmm. I was wondering why my temperatures seem to be set so high relative to everyone else's. Different positioning of the temperature probes perhaps?

Auber's manual reads "The original steam thermostat of the Gaggia is designed to turn off the heater when the temperature reaches 293 F (145C) and on again when temperature drops to below 275 F (135C)", with this thermostat located at the top of the boiler, translating to a reading of 154 and 123 respectively measured at the place they recommend attaching the probe (at the bottom of the boiler closer to the heating element). This doesn't seem to be anywhere near the original of 120 most people seem to think they are set at?


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## Jack-Jones (Mar 23, 2016)

I'm using the recommended settings on one of @MrShades smaller PID's and find 137°C to be perfect. Lots more steam available than a standard Gaggia, initially more pressure available to purge the steam wand and recovers far quicker.


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## JojoS (Oct 1, 2014)

I have the Auber PID installed on my Gaggia Classic and my understanding is that the steam control function is merely the use of the alarm switch of the PID controller. Off at 149C and on at 148C. Also note that the RTD sensor is located where the brew thermostat is usually located and not the location of the no longer used steam thermostat. I think it is normal to have swings in temp display as high as 156C before it swings down. For me too much wet steam is not desirable in milk microfoam so I purge the steam wand quite a bit. I prefer to have not more than 10% steam water by weight to steamed milk for my morning latte.


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## nightslayer (May 29, 2016)

Yup I have the same, but have you ever wondered that 149 seems to be a bit high? Also, I've noticed that my steam pressure actually somehow builds as the steam boiling cycles on and off.. Also, at what point do you decide that the steam is dry enough?


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## AndyZap (Dec 29, 2016)

Jack-Jones said:


> I'm using the recommended settings on one of @MrShades smaller PID's and find 137°C to be perfect. Lots more steam available than a standard Gaggia, initially more pressure available to purge the steam wand and recovers far quicker.


Re MsShades PID - do you use the PID temperature display offset (e.g. recommended -8°C)? Then the steam setting 137°C is translated into 137+8=145°C at the temperature sensor. if the Auber PID does not have this offset, then the optimal temperature settings seems very close.


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## rob177palmer (Feb 14, 2017)

Finally upgraded to the Silvia wand. That and the PID = astonishing steaming capacity from my little Classic!


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## Jack-Jones (Mar 23, 2016)

AndyZap said:


> Re MsShades PID - do you use the PID temperature display offset (e.g. recommended -8°C)? Then the steam setting 137°C is translated into 137+8=145°C at the temperature sensor. if the Auber PID does not have this offset, then the optimal temperature settings seems very close.


 @AndyZap.

Yes, I have the offset set to 'on' which apparently is set to show the actual brew water temp as opposed to the temp of the Boiler wall, so approx' an -8°c difference between the two. I assume, once set, it will also show the same variable between actual steam output and boiler wall, but it will take @MrShades to clarify that, as I'm only going off the figures quoted in the manual, which doesn't quote for steam, only brew water. Hope this helps!


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## MrShades (Jul 29, 2009)

Jack-Jones said:


> @AndyZap.
> 
> Yes, I have the offset set to 'on' which apparently is set to show the actual brew water temp as opposed to the temp of the Boiler wall, so approx' an -8°c difference between the two. I assume, once set, it will also show the same variable between actual steam output and boiler wall, but it will take @MrShades to clarify that, as I'm only going off the figures quoted in the manual, which doesn't quote for steam, only brew water. Hope this helps!


Yup - actual boiler temp minus the offset will be your steam set temp - so with an offset of -8 you'll have 145c at the sensor/boiler. The Classic steam stat is 145c as standard - but this is obviously mounted on top of the boiler rather than at the side.

HTH


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## nightslayer (May 29, 2016)

MrShades said:


> Yup - actual boiler temp minus the offset will be your steam set temp - so with an offset of -8 you'll have 145c at the sensor/boiler. The Classic steam stat is 145c as standard - but this is obviously mounted on top of the boiler rather than at the side.
> 
> HTH


Ah thanks for the clarification! So now we know we are mostly working with temperatures ranging between 145 to 148 or so.

Next thing I was wondering - does anyone temperature surf the steam heating cycle? I know that starting the steaming at different points (i.e. PID temperature readings) produces different steam pressure profiles based on when the thermostat reads the temperature drop and the boiler kicks on; does anyone know when an optimal time to start the steaming would be?

Additionally, how long do people usually wait before steaming milk - the first time when the steam light flicks on (and boiler temperature is >145), or do you give your machine time to 'warm up' to steaming boiler temperature, so to speak, with a couple of on-off steam cycles? I know when I leave my machine with the steam switch on for like 5 minutes the steam is powerful as hell..


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## Jack-Jones (Mar 23, 2016)

I don't need to temperature surf as such. After pulling the shot and flicking the steam switch, by the time I've got the milk out of the fridge and filled the jug (45 seconds or so) the steam temp will be reading slightly in excess of 140°c (I have it set at the recommended 137°c and to kick in again below 136.9°c) I then purge the steam wand (2 to 3 seconds) which sets off cooling and by the time I've knocked out & rinsed the PF the steam temp reading will have reached as low as 132.2°c before it begins to rise rapidly. It's then (around 135°c) that I start to steam the milk.

For me and my PID'd Classic, that works out to be the best solution I've come across for maximum steam with little delay between pulling a shot and steaming milk.

I've noticed, if I start to steam at 140°c (or at its peak) the steam temp readout can go as low as 128°c, where there is a slight drop-off in output and pressure, but it is slight and quickly builds up again. Unlike it was prior to me fitting the PID, where it was difficult to quickly and completely purge the steam wand with the available pressure and it would take an age to build up a decent enough amount of steam just to make milk for one Cap or latte.


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