Bezzera Strega Top Plumb In Issue

[mrgnomer]

Want to share this TOP plumb in experience in case it helps. Sorry if it's been shared already.

I am new to serious spring lever extraction. Liking the Strega a lot. Got it at a good shipping damage discount. Nothing seemingly more than aesthetic damage.

After a couple weeks of running tank only I just plumbed it in. Needed to transition from the braided line to a 3/8" OD pvc line. Looks like the braided line end is 3/8" NPT Female. Is that right?

NPT male to 3/8" OD compression works as an adapter. Did all of the transition steps and connected the line. No leaks, steady 22 psi flow regulated line pressure...all looked good.

This morning on the flush the vibe pump was overly loud. Sounded like a dry running pump. A bit of steaming water came out, dried up then no water. Lever went back up with no water. Weird.

Pulled a shot: seemingly no preinfusion pressure build up. Released the lever and no resistance until almost to the top. Double pulled to get more volume. The shot was surprisingly ok.

Tried another shot. Same no preinfusion, limited grouphead fill.

Anyone have this problem after plumbing the Strega Top in?

Reluctantly I got the tools ready to take the supply line/machine apart and find out what the problem was. Line pressure good, pump engaging, boiler filling...why is the HX line seemingly full while idling but the pump running dry with little water going through the HX during a pull. Is the line plugged? Is the solenoid valve stuck. What.

Before taking the machine apart I thought to give the flush one more chance. After all, line pressure should be going through the HX and if you pull the lever down to open the grouphead feed a steady flow of line pressure water should come out.

With the power off, at first a bit of water flowed out of the head then nothing as I guess the HX line drained out. Kept the lever down and finally a steady flow. Ok, maybe I don't have to take everything apart.

On goes the machine and heat up to boiler pressure max. Boiling water on the flush, brief pause and now steady soft water flow. Release lever and now a normal release of water.

Pulled a shot and preinfusion is back. Release lever on first extraction drip and there's a slow extraction and steady lever rise. Back to normal. Yeah.

I am thinking it might have been a careless mistake to attach the braided line to the machine first and then the supply. By not fully flushing the supply line and kind of priming it before attaching it to the Strega, air in the line got locked and a long flush was needed to get it out and prime the line. Does that sound like what happened? My Strega looks mechanically sound but it is a shipping damage sale. Could something mechanical inside the machine have caused a plumbed in water flow problem?

[DanoM]

I have a Top model too, but haven't ever plumbed it in... BUT you need to disconnect the pump when you plumb in the system. Also put the tank water level bypass wire in place.
(I stand corrected. The pump is also used for line pressure boosting. I dug up my instructions and they don't mention disconnecting the pump for line water feed.)

[mrgnomer (original poster)]

Low tank level bypass I understand. Why do you need to disconnect the pump?

[DanoM]

The pump is only used for tank water as I understand it.
(I stand corrected. The pump is also used for line pressure boosting. I dug up my instructions and they don't mention disconnecting the pump for line water feed.)

[truemagellen]

Also the stainless braided line is BSP not NPT, this is the case on almost all European machines. You can shove a plastic John guest fitting on there with Teflon tape but it's not ideal. McMaster Carr sells adapters and all the coffee sites do too for you to connect to North American fittings.

[mrgnomer (original poster)]

Maybe the female end attaching to the machine is BSPP but the water supply end attached without leaks to a MNPT. The machine end female could also be BSPT but a repair guy told me and I read that British standard parallel pipe is commonly used for espresso machines.
Since I have no leaks with the MNPT I'm assuming that's the thread. I just wanted to know if anyone knew for sure.

[mrgnomer (original poster)]

The pump is only used for tank water as I understand it.

On a machine like Profitec 800 I think that's the case. I'm pretty sure the Strega uses the vibe pump to fill the brew group and pressure the preinfusion up to 11bar. Even when plumbed-in my machine pump goes on when the lever switch triggers it. I believe it's filling the brew group and building the preinfusion pressure.
Some don't like the noise of the pump or would rather preinfuse with line pressure . The pump can be disconnected for that.

[mrgnomer (original poster)]

As a follow up the water flow through my Strega's grouphead remains normal. Looks like it probably was the air in the plumb in line that needed a long flush to bleed out. The 3/8" MNPT thread in the female end of the braided hose from the machine is showing no signs of leaking. That makes sense for a machine to at least use a supply line with a thread common to the market it's in.