Strange pressure regulator behavior

#1: Post by **CoffeeMac** » July 20th, 2021, 3:57 pm

I have a pressure regulator inline between a Shurflo pump/accumulator and my espresso machine. I use this to control preinfusion pressure.

I had the regulator set to 5 bar output this AM and it was working normally. The pump/accumulator is supposed be set at 90 psi (6 bar) per the manufacturer spec sheet.

This afternoon I was surprised to see the gauge reading 8 bar - about 115 psi!

I released some water through the group and the pressure reading on the regulator dropped to about 4.5 bar with water flowing and then settled to about 5.1 bar when I stopped.

Any idea why this is happening? I'm not sure where in the system anything over 6 bar would be produced! I'm thinking it might be back-pressure in the water column between the HX circuit and the regulator, which would slowly heat after my last shot and build pressure.

#2: Post by **stefano65** » July 20th, 2021, 5:07 pm

A one way valve might solve the issue if the pressure is backflow from expansion when machine heating up???
possible but not knowing the machine you have is possibly not true ether.

#3: Post by **BaristaBoy E61** » July 20th, 2021, 9:50 pm

Sounds like it might be a check valve between the water line pressure regulator and the water inlet of the machine.

July 20th, 2021, 10:08 pm

There is a NRV at the primary water inlet of the machine. I'm thinking something got stuck in the valve, preventing it from fully seating. Maybe a bit of PTFE thread tape? If it doesn't clear itself by this weekend then I'll open 'er up and clean 'er out.

#5: Post by **BaristaBoy E61** » July 20th, 2021, 10:25 pm

That might do it and it's a good place to start.