Barksdale 0.05bar pressurestat 1st look - Page 7

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Genesis

#61: Post by Genesis »

The easiest solution to the contact problem is a SSR - they're not expensive, under $50, and eliminate that issue permanently.

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timo888

#62: Post by timo888 » replying to Genesis »

Yes, the SSR solves the contact problem. Unfortunately, I wouldn't know where to begin retrofitting my vintage machine with an SSR. If there's a tutorial on this, I would be happy to study it. Nothing I hate more than the fog of my own ignorance.

Regards
Timo

Genesis

#63: Post by Genesis »

Its very simple.

Remove the wires from the pressure stat and connect them to the power (contact) side of the SSR.

Determine which is the "hot" side (you can do this with a VOM or by tracing the wires in the unit) and connect that to one pressure stat terminal. The other goes to the "trigger" side of the SSR, and the other side of the SSR trigger connection goes back to neutral (white wire on the inlet cord.)

When the pressurestat closes it applies 110V to the "trigger" side of the SSR, which closes the connection on the power side and energizes the heater.

The exact connection points depend on the particular machine, but this is typically about a 15 minute deal. The biggest issue is figuring out where to stick the SSR where it can't get wet and won't short out, yet will dissipate the heat required (the frame of the machne makes a suitable heat sink, but you need to deal with finding a place where you can mount it and it won't get wet from spit off the vacuum breaker, etc)

This is one of the reasons I like the Quickmill machines - they did this right up front. This is the sort of thoughtfulness that's in the REST of the machine, and I like it a lot. If I had a machine that had direct connection from the pressurestat to the heater it would be the very first thing I'd do with it before I used it, because those heaters draw a LOT of current and there's no reason to run that through a set of mechanical contacts with SSRs being $20-25!

Use a 25A SSR so you have some margin (a 20A is technically ok for most machines but I like to upsize so as to gain more margin with thermal derating, especially in applications like this)

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Compass Coffee (original poster)
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#64: Post by Compass Coffee (original poster) »

FWIW some machines that don't drive the heater from the pstat don't use an SSR but rather heavy duty mechanical relay so the relay not necessarily pstat is the noisy click. (Barksdale pstat is very quiet but not about to drive the Bricoletta's heater directly from a 15A max pstat contact.) One of these days I'll replace the mechanical relay on my Bric' with a SSR, but not high on my financial needs list. The placement of the current mechanical relay will likely work well for a SSR being mounted on horizonal surface next to side "ribbed" skin up off the botton an inch or so but below the boiler. The ribbed skin design allows natural cooling flow with cooler air entering the bottom while heat leaves the top. Measured temps internally towards the bottom barely above ambient while top keeps cups nice and toasty.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com

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timo888

#65: Post by timo888 »

What if there's a thermostat in the mix, which cuts power to the heating element if the boiler should overheat?

Regards
Timo

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Compass Coffee (original poster)
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#66: Post by Compass Coffee (original poster) » replying to timo888 »

Would of course depend on how wired. Are you referring to a regular boiler tstat (either brew or steam) or high temp safey tstat? Though it just dawned on me maybe using a steam tstat in series with a pstat could add an additional level of safety should the pstat fail/stick contacts closed. It's never happened to me but understand that's the most common pstat failure mode.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com

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timo888

#67: Post by timo888 »

Compass Coffee wrote:Would of course depend on how wired. Are you referring to a regular boiler tstat (either brew or steam) or high temp safey tstat? Though it just dawned on me maybe using a steam tstat in series with a pstat could add an additional level of safety should the pstat fail/stick contacts closed. It's never happened to me but understand that's the most common pstat failure mode.
High-temp safety tstat.

Regards
Timo

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Compass Coffee (original poster)
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#68: Post by Compass Coffee (original poster) »

Barksdale died, put original Mater back in this AM. Deadband had been creeping wider, suddenly way wider 2+bar before off. Tried fiddling with it dialing up and down and trying again, no go remained way wide full bar+ on to off. Maybe my cooling loop wasn't adequate, or maybe just luck of the draw. No matter, I won't be replacing with another Barksdale, just order another Mater or Jager to have as spare.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com

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another_jim
Team HB

#69: Post by another_jim »

Three years isn't a bad run
Jim Schulman

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Compass Coffee (original poster)
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#70: Post by Compass Coffee (original poster) » replying to another_jim »

Don't get me wrong, I wasn't complaining. If I could pop on a website and order a Barksdale I'd probably do it. But the benefits are really insignificant, if really any at all, for the hassle of making multiple phone calls to order a pstat. I mean, does .05bar versus .1bar deadband on an E61 HX machine boiler pstat really make squat of a difference in the shot when you know how to surf well? I think not.
Mike McGinness, Head Bean (Owner/Roast Master)
http://www.CompassCoffeeRoasting.com