The Super Strega: Modifying preinfusion pressures and other functional improvements - Page 2

#11: Post by **kmills** » February 25th, 2014, 9:18 am

Ok thanks, that makes sense. As I read it over a few times its not clear (to me) which leg Tom is tapping onto, maybe its because I don't know the specifics of the strega. I will try this on my Silvano by wiring it in on the hot leg in series between the brew switch and the pump. I'll document and do a writeup when I get around to the instal.

February 25th, 2014, 10:29 pm

I switched up the wiring to the hot side and tested everything. I took multiple shots with the machine torn almost completely apart for better visibility for these photos. I will edit the first post with the steps to avoid wiring in to the neutral side.

I've also added several small steps to cut down on the noise the vibe pump makes, and even now, at its loudest, is a fair bit quieter than it ever has been, and that's without adjusting the pStat which gives temporary relief from high noise.

I have a few other ideas I'm working on, but it's been a busy day and I'm done for now. I'll update the first post with more photos and extra stuff later on.

February 26th, 2014, 12:54 am

I'm waiting for someone (other than me) to replace the stock gauge with a dual gauge; and then post the how-to. I'm thinking if I could see the pressure ramp up, no dimmer would be needed; since the pump could be cut at the desired p/i pressure.

On the other hand, I'm not really the go-to guy when t comes to clever ways of modding machines.

#14: Post by **erik82** » February 26th, 2014, 1:31 am

I've been thinking about doing a double gauge. The problem is the single gauge of the Strega which has a diameter of 40mm and the smallest double gauge is 52mm but you would like to have around 60mm for a nice double gauge. Making the whole of the standard gauge bigger will be a real pain in the ass with the frontpanel mounted. Taking the frontpanel out means tearing down the whole machine. Laser cutting would be the best option but then you really need to take the frontpanel out.

I've been thinking about the design [anonymized] did with his Rocket by building in and extra magnetic valve and OPV but for what I want (minimum 3,5,7,9,11 bar) I would need 4 extra magnetic valves and 4 extra OPV's. This would be very expensive to build and cost a lot in maintenance over the years.

Other option I thought about where an easily adjustable OPV but they don't like to be messed around a lot. I looked at pressure regulators for food industry with a build in display and buttons for adjusting the pressure. These are nice but expensive and the display with buttons needs to be mounted outside the machine and the pipes go in the back and underside of it so that's no option.

Still figuring it out. My Strega is only one month old so my warranty will be a problem when making these kind of alerations to a machine. Maybe I'll just tear the Strega apart and make the hole in the frontpanel larger to arond 60mm. That's the best and easiest option I can think of building in a dual gauge like the one on the BZ10. Maybe someone else has a better idea for mounting a dual gauge or separate manometer?

http://users.rcn.com/erics/ · #15: Post by **erics** » February 26th, 2014, 2:07 am

Maybe I'll just tear the Strega apart and make the hole in the front panel larger to around 60mm.

It is relatively easy to disassemble the Strega to the point where you can see that a larger gauge will/will not fit. If I remember correctly, this is, unfortunately, NOT attainable with this chassis.

The ideal situation would be to have a gauge like the BZ10 reading the pressure in the line feeding the group (like the BZ10) BUT, it won't fit . . . it has been a few years since I looked into this as this mod was something I considered.

#16: Post by **erik82** » February 26th, 2014, 2:18 am

Do you mean the inside of the machines doesn't have the room to fit the double gauge and pipes needed to build in the extra manometer or simply that the hole of the current gauge is too small? The first is a real problem where the last can be solved by making the current hole bigger.

Another option would be to swap the boiler pressure gauge for a PI pressure gauge. You would lose the ability to see the boiler pressure which isn't really neccesary unless there is a problem with the machine. When something goes wrong you really want to see the boiler pressure. This withstands me from just swapping it out. I just need to have a look if it can be done with the room we have in the case.

There are many options but I need to find out which one is the best. As an alternative option we still have the option of building a manometer portafilter and just adding the dimmer.

February 26th, 2014, 2:53 am

another_jim wrote:I'm waiting for someone (other than me) to replace the stock gauge with a dual gauge; and then post the how-to. I'm thinking if I could see the pressure ramp up, no dimmer would be needed; since the pump could be cut at the desired p/i pressure.

On the other hand, I'm not really the go-to guy when t comes to clever ways of modding machines.

Since the gauge is just tapped into the boiler, showing boiler pressure, wouldn't it be better to just go thru the work of disassembling the whole damn thing to get to the faceplate, take it to a machine shop and have them cut another hole somewhere in the faceplate where there is (?) room for a separate gauge? (if there is any actual room for another one, I'd have to do a lot of homework to see).

Could a coiled thin copper gauge line like the one that's on there already be fed to a tee that shows the output side of the pump before it hits the OPV? And then, wouldn't that give us real time pre-infusion pressures? I'm only scratching in the sand here. I don't know if it's even possible.

First post updated to show the OE vacuum relief valve, and to show the steps of adding a Romex strain relief plug. More to come tomorrow where I'll edit out the wiring for the hot-side wiring in it's place.

#18: Post by **Oskuk** » February 26th, 2014, 4:41 am

My vote goes too to another gauge on another place. The recent situation is no good for reading and is prone to break a glass on steam. Still I'd leave it there, so you have not to plug it.

Btw What is the reason for "Vacuum Relief Valve Drain Line Modification"?

#19: Post by **JohnB.** » February 26th, 2014, 7:52 am

If you remove the case & look at the back of the stock gauge you will see that going larger isn't going to work as it's too close to the boiler. Even a similar sized gauge with dual attachment points would be hard to install as there is very little room between the boiler & chassis in that area.

There are are already other gauge holes cut through the chassis as it's evidently used on a number of their machines. One likely candidate that I was thinking of using is on the right side (facing) of the group in a nice eye level location. Of course you will have to cut a hole in the face plate without making a mess of things. Currently my Strega sits on my roasting table so I like having the gauge up on top in a stand where I can see it.

#20: Post by **JohnB.** » February 26th, 2014, 8:00 am

another_jim wrote: I'm thinking if I could see the pressure ramp up, no dimmer would be needed; since the pump could be cut at the desired p/i pressure.

The dimmer allows you to fully pressurize the group at any pressure. I was surprised to see that I can set the vibe pump to put out a steady 1 bar. Trying to get low P/I pressures by lifting the lever & cutting the pump after a few seconds won't put much water in the group so your spring will be engaging way up near the top.