I am very new to home espresso, having jumped from a pourover Chemex straight into a plumbed-in ECM Synchronika this year, so bear with me and my ignorance.

I have a BWT filtration system hooked up with an inline regulator which has been set to 2 bars (30 psi) of pressure with the machine off and pump lever disengaged. However, when I engage the pump lever while the machine is still off, it reduces the inline pressure to about 1.5 bars (~22 psi).

First off, is this normal? I would have thought from my limited knowledge that the inline pressure indicated on the regulator would stay constant.

Secondly, when I turn the machine on and it's heating up while idle, the pressure reading rises again, to about 35 psi.

I am concerned because the Synchronika manual mentions that operating pressure should not exceed 2 bars, but mine is sitting idle at around 35 psi while the machine is on, and then drops to around 25 psi when I put the lever to the 45 degree position.

I have tried using the regulator to reduce the inline pressure, but then it seems like not enough water is going to the machine to refill the boilers as they are depleted, because the pressure drops to 0 when the brew lever is engaged, and then slowly comes back up to ~1.5 bars when the lever is disengaged.

Any thoughts?

I very much appreciate any help in advance.

N1trogen wrote:...when I engage the pump lever while the machine is still off, it reduces the inline pressure to about 1.5 bars (~22 psi). First off, is this normal? I would have thought from my limited knowledge that the inline pressure indicated on the regulator would stay constant.

Sounds normal. If water is flowing, the filters themselves provide resistance, lowering the (measured) pressure downstream.

N1trogen wrote:I am concerned because the Synchronika manual mentions that operating pressure should not exceed 2 bars, but mine is sitting idle at around 35 psi while the machine is on, and then drops to around 25 psi when I put the lever to the 45 degree position.

Sounds normal. The increase is likely due to thermal expansion. From the FAQ: What is normal pump pressure at idle? They are recommending lower pressure to reduce the risk of a closed solenoid letting water slip by. A reading of 25 versus 35 PSI wouldn't concern me, especially since the higher reading is due to (temporary) thermal expansion that would immediately fall with the release of a few drops of water.

N1trogen wrote:I have tried using the regulator to reduce the inline pressure, but then it seems like not enough water is going to the machine to refill the boilers as they are depleted, because the pressure drops to 0 when the brew lever is engaged, and then slowly comes back up to ~1.5 bars when the lever is disengaged.

Water filters reduce the flow rate by offering resistance. If the (filtered) flow rate is too low, you'll need to add an accumulator after the filters. An accumulator is simply a small tank with a pressurized bladder that acts as a buffer between the water supply and filters to even out the flow rate when there's a momentary demand faster than the water filter will allow. The order would be something like water supply -> filter -> check valve -> accumulator -> pressure regulator -> espresso machine.

Jeff wrote:There are frictional losses with flow

Friction's a minor concern. The limiting factor on volume flow per time in a clean, open line is cross sectional area at the narrowest point in the supply line, because area determines maximum volume flow per second - and no amount of pressure can increase that physical maximum. But 1/4" line should be more than adequate for a Synch unless it's really long (like 30 feet long) and/or convoluted enough to cause really turbulent flow. Flow gets more complicated when you look at viscosity, wall characteristics, etc - but no other factor really matters here unless your water's viscous

My Technika does fine on a 1/4" line with the regulator at 1.5 bar, as did Oscar before it. And it behaves exactly as you describe. The line pressure will be lower when flowing into an open circuit than when static in a closed one. It rises with temperature sitting in the supply line and brew path, as it should because that water is incompressible and in a closed space when the brew lever is down.

You need a diagnosis before you can treat. Measure the volume flow from your group head (without PF) with the lever in the PI position and again with the pump on. The latter should be at least 200ml in 30 seconds. I don't know and can't find any numbers for minimum acceptable flow rate into the machine, but someone here probably knows. If your water deficit is normal, I'd leave the regulator at 1.5+ and not worry about it. There is no 3 way solenoid in our classic e61 machines - the valve that does that is in the group and is mechanical. It's what you open when you lift the brew lever for PI.

If your water flow is too low, follow its path to find the narrowing. Have you checked your filter? It may simply be full. There may be debris in one of the orifices, in your plumbing, or even scale in your gigcleur or other part of the internal brew path. I change the softener and filter cartridges at each change of seasons when I also clean the HVAC filters. You don't mention a softener. If you have one and it's before the filter (where it should be), some of the active gunk can get into the filter and clog it. If the softener is after the filter (where it should not be), the gunk can get into and clog your regulator and/or any region of your brew path. And be sure to flush new cartridges with at least 2 gallons of water before connecting the outlet to your machine's water feed.

Jeff wrote:What diameter piping and how long is the run from the regulator to the machine?

(There are frictional losses with flow)

I am using 3/8" on everything, and the regulator is reducing pressure before water goes into the filter, then the line from the filter system to the machine is two 3 ft lines fitted together (6ft total).

HB wrote:Water filters reduce the flow rate by offering resistance. If the (filtered) flow rate is too low, you'll need to add an accumulator after the filters. An accumulator is simply a small tank with a pressurized bladder that acts as a buffer between the water supply and filters to even out the flow rate when there's a momentary demand faster than the water filter will allow. The order would be something like water supply -> filter -> check valve -> accumulator -> pressure regulator -> espresso machine.

Thank you for your reply! My house's inline water pressure is too high for the BWT filter, so I installed the regulator before the filter, so it looks like water supply -> check valve -> regulator -> filter -> machine. Is there anything wrong with doing it this way instead of the way you mentioned?

N1trogen wrote:I am using 3/8" on everything, and the regulator is reducing pressure before water goes into the filter, then the line from the filter system to the machine is two 3 ft lines fitted together (6ft total).

The BWT Bestmax is a great system. With 3/8 all the way, your Synch should be getting far more water than it could ever need even with the regulator set at 1 bar, unless there's a clog or kink somewhere. I can't imagine any reason for you to need an accumulator. Most of us put the regulator after the filter/softener cartridges, but I can't see why putting it before would cause any problems with volume flow except that water line debris that would have been caught by the filter could partially clog the regulator. I assume you bled each hose after connecting it to its supply end and before hooking it up to the next connector in the chain, starting with the hose that connects the line to the regulator and working your way out to the machine.

I strongly suggest that you measure the water flow from the grouphead in ml per 30 seconds. If it's too low and your house line pressure is anywhere over 3 bar, something's partially clogging your water path somewhere between the line feed and the grouphead. If you're getting 200+ at 2 bar, do it with the regulator set to 1.5 bar and then 1 bar. A significant partial clog somewhere could compromise flow just enough to cut volume dramatically below a certain pressure. This is quite unlikely, but it's possible.

If flow is lower than 200ml/30 sec, also check the fitting that connects your two 3' hoses together. The integral gasket rings in modern SS compression hose ends can bulge into the orifice if overtightened or damaged. I assume that whatever inline junction you used is as high quality as the rest of your system. But male-male unions can have surprisingly tiny channels in them, and even a mm or two of narrow channel will cut flow despite having 3/8 hose on both sides of it.

bluesman wrote:I strongly suggest that you measure the water flow from the grouphead in ml per 30 seconds. If it's too low and your house line pressure is anywhere over 3 bar, something's partially clogging your water path somewhere between the line feed and the grouphead. If you're getting 200+ at 2 bar, do it with the regulator set to 1.5 bar and then 1 bar. A significant partial clog somewhere could compromise flow just enough to cut volume dramatically below a certain pressure. This is quite unlikely, but it's possible.

Thanks for your reply! I tested the 2bar flow rate this morning with the machine on and pump on, and it came out to 330ml in 30sec. I reduced it a bit to 1.75bar, and the flow rate was around the same, at 300ml in 30sec. Is there an optimal flow rate I should be targetting, or is keeping it at 1.75bar okay?

I did notice when I pull the lever to the 45 degree position with no pump, the pressure went from 1.75bar to ~1bar. Then when I activated the pump, it shot it straight up to 9bar. Is that normal?

Also, my pressure rises straight from ~1.75bar to 9bar when I'm pulling a shot of espresso. There is no gradual climb, which I heard is what I should be aiming for, but maybe you could provide some clarity there as well.

That's all quite normal. If your machine puts out well over 200 ml in 30 seconds, you're fine - more is neither better nor worse, it's just more. You should have no problem at all running at 1.75 bar.

When the lever is down, the water path from supply line to group is closed and there's no flow - so you'll show line pressure. When you open the valve in the group by lifting the lever, water starts to flow with no resistance other than that of the fluid path itself (which is very little) - so your pressure will drop a bit. If you were to put a pressure gauge on a T in your faucet line, you'd see the same thing. Turn on the water and the pressure will drop a bit. The major resistance to flow is the puck, and it takes ~9 bar to move the right amount of water through it to extract what we want in our cups. That 9 bar figure is not invariant - there are many who like their shots made with lower pressure, and some machines (especially levers, I think) work very well as low as 6 bar.

If you have other devices with pumps and pressurized water systems on the same line as your espresso machine (e.g. dishwasher), you'll notice some fluctuation in line pressure. This is also normal and of no concern.

One of the claimed "disadvantages" of a rotary pump is that it ramps up to full pressure more quickly than a vibe pump does. I've seen this described as "slamming" the puck. I don't think this makes any difference at all with my traditional medium roast espresso blends, especially with PI. But this is part of what drives people to use "pressure profiling", which means adjusting the pressure throughout the brew cycle for best results. You can start the brew cycle at 3 bar for 5 seconds, then ramp it up to 9, then back to 5 or 6 to finish the shot. I'm not a light roast fan and I don't want fruit, flowers, or fantasies in my cup - so I have no experience at all with profiling. But many whose judgment I trust say it makes a big difference with some coffees.

Wow, thank you so much bluesman, I greatly appreciate how informative you have been. I think I will go ahead and keep pressure at around 1.5-2.0 bar so that I'm well above hitting 0 bar when I pull the level to 45 degrees. When I had it closer to 1.0-1.5 bar idle, the tank would seemingly run out of water when in the 45 degree position, because it would make an awful noise and show 0 bar pressure.