Single boiler single use safety after mod (ECM Puristika)

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
Eiern

#1: Post by Eiern »

I am planning to plumb in my ECM Puristika, using an external rotary pump in place of the internal vibe pump, ditching the external water tank.

As the brew boiler doesn't do steam and doesn't hold much air that could compress it doesn't seems to have a safety valve (at least not on top of the boiler) it doesn't have a vacuum breaker or solenoid valves that I can see.

As it has a heating element that potentially could overheat the boiler the OPV is probably a safety for this as it would return high pressure water to the water tank?

Should I install a safety valve if I remove the OPV, or keep the OPV and set it to say 10 bars and route the output from the OPV out from the machine (seems wrong and messy?) or would any excess pressure go through the rotary pump in reverse and into the water line and it's no issue?

Thanks for any input!

Jonk

#2: Post by Jonk »

Eiern wrote:As it has a heating element that potentially could overheat the boiler the OPV is probably a safety for this as it would return high pressure water to the water tank?
There's a safety thermostat intended to protect against overheating the boiler, with a cut-off around 145C or 3.2 bars. This setup is normal on a lot of single boiler machines.

There's still a reason to keep the OPV though: Rotary Pump: OPV vs. Retention Valve

Eiern (original poster)

#3: Post by Eiern (original poster) »

Thanks, I actually see two of those rated at 145C in the parts diagram.

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HB
Admin

#4: Post by HB »

Eiern wrote:As it has a heating element that potentially could overheat the boiler the OPV is probably a safety for this as it would return high pressure water to the water tank?

Should I install a safety valve if I remove the OPV, or keep the OPV and set it to say 10 bars and route the output from the OPV out from the machine (seems wrong and messy?) or would any excess pressure go through the rotary pump in reverse and into the water line and it's no issue?
Water expands as it heats; the expansion valve / OPV allows a few drops of water to escape the closed system so the pressure doesn't exceed the limits of the hydraulics. If you convert to plumbed in, the boiler will still need an expansion valve. Typically these vent into the driptray. With the caveat that I'm not a certified plumber, I believe it is a plumbing code violation to allow water to flow out of an appliance into the water system; there must be some type of check valve or normally-closed solenoid to prevent backflow.
Dan Kehn
★ Helpful

JRising
Team HB

#5: Post by JRising »

When connecting a formerly vibe-pump machine to a plumbed-in, under-counter rotary pump, there is plenty of space for a good quality check valve where the vibe pump used to be. The Puristika has a check valve installed after the braided "Pump outlet hose" before where the T fitting splits the flow between boiler inlet and OPV inlet, so for this machine you wouldn't really need an additional check valve.

JRising
Team HB

#6: Post by JRising »

Eiern wrote: As it has a heating element that potentially could overheat the boiler the OPV is probably a safety for this as it would return high pressure water to the water tank?
Correct. Because the OPV in this machine is intended to always be relieving while the machine is brewing, it is likely that the OPV will NOT seize in a closed position. It is Teed off between the check valve and boiler inlet pipe. Thus it will always be preventing the boiler pressure from exceeding the pressure to which it was set.

Eiern (original poster)

#7: Post by Eiern (original poster) »

Thanks all!

I'll bring it up with the tech and the plumber so we don't forget about it. I can see that check-valve in the parts diagram.

I obviously don't want to set the OPV on the outside of the machine to 12 bar and then being turned down by my kids or a guest so that I have a leaking machine, so something like disconnecting that stock OPV and mounting a 12 bar one (or an adjustable one set to 12 bar) is a better choice. I have seen a fixed 12 bar one for La Marzocco machines.

JRising
Team HB

#8: Post by JRising replying to Eiern »

If you don't mind wasting water, just route it to drain, it's got to go somewhere if you're eliminating the reservoir. The inlet pressure from your mains isn't going to exceed 5 bar. It won't open the OPV. The OPV will only be relieving during brewing (and a few drops when the boiler is heating). You can just remove the knob if you want to make sure nobody adjusts it.

Eiern (original poster)

#9: Post by Eiern (original poster) »

Ah yes, that won't trip the OPV as the lowest pressure I could set it to was 7.5 or so bars and our building restrict pressure to just over 5 bars at main inlet.