Hi All,

Today I was changing the gaskets on the steam valve and since this conversion is totally reversible I decided to go back to the vibrating pump mode to compare the flow of one pump vs the other. Here the results. Please comment at to what you see, either good or bad.
And Finally the shot I pulled on the rotary pump after done with the fun game of comparing these two.
A few things that I learned:

1) The vibe pump can not be used with the check valve. The OPV will not build up pressure hence the pressure will keep climbing.
2) The rotary pump need the check valve in place. The hot water will back flush through the line possibly reaching pump and filter. Also the line pressure will sky rocket and not sure if is good to your filter system at least.

neydor wrote:Hi All,

Today I was changing the gaskets on the steam valve and since this conversion is totally reversible I decided to go back to the vibrating pump mode to compare the flow of one pump vs the other. Here the results. Please comment at to what you see, either good or bad.

And Finally the shot I pulled on the rotary pump after done with the fun game of comparing these two.

A few things that I learned:

1) The vibe pump can not be used with the check valve. The OPV will not build up pressure hence the pressure will keep climbing.
2) The rotary pump need the check valve in place. The hot water will back flush through the line possibly reaching pump and filter. Also the line pressure will sky rocket and not sure if is good to your filter system at least.

Looked like your flow with the rotary was a little on the fast side. Too fast to keep the "raindrops" from coagulating. The vibe was slow enough to make "raindrop pron".

As for the check valve with the rotary... (should get a check valve, no excuses) BUT

1) I found that I did not get any (or enough to detect) back flow towards the pump... unless... I turned on the soft water spigot. I have a Y after the softener where one side goes to the pump and the other side goes to a filter water faucet on the kitchen sink, that the wife uses to fill her Keurig so it too doesn't scale up. If she or I turns on that faucet, it will also draw water from the BDB without the check valve in place. It is then that you will feel heat in the tubing all the way back to the pump. But unless you draw water from that spigot, there is no or negligible back flow of hot boiler water

2) A check valve will of course protect the downstream elements like the filter, from extraction pressures. This alone makes it a good idea.

-Peter

You are correct, and that got me thinking whether the IMS screen is contributing to that or not. So I switched the screen to the original one and flow is more even now. Still I wonder what consequences does it have on my shot and how can I control it?

You probably aren't looking to spend more money about now... But I discovered by accident, that when I stacked two IMS screens one on top of the other and installed them (then I went away for three months and forgot I had done it), It holds the pretty raindrop pattern for higher flow rates. This has become my standard setup now. But I already had two IMS screens.

You might try putting your IMS on top of your stock screen and see what you get.

There is apparently quite a community of folks out there (not just in the BDB world) who play around with all kinds of shower screen distribution mods.

-Peter

I applaud you team for such an amazing work and detailed explanation

My wife is going to hate you soon, until she has her cup of coffee...

I'll start buying the bits and pieces while we are getting ready to relocate, and go Slay-Rota once we move in to the new house and find (beg for) my coffee corner..

I have a sneaky suspicion that it would cost a little more here in New Zealand !

pcrussell50 wrote:You probably aren't looking to spend more money about now... But I discovered by accident, that when I stacked two IMS screens one on top of the other and installed them (then I went away for three months and forgot I had done it), It holds the pretty raindrop pattern for higher flow rates. This has become my standard setup now. But I already had two IMS screens.

You might try putting your IMS on top of your stock screen and see what you get.

There is apparently quite a community of folks out there (not just in the BDB world) who play around with all kinds of shower screen distribution mods.

-Peter

Man, never in my life I would come up with that Idea. Thanks for the tip... I put my IMS on top of the stock like you suggested and its definitely better, but I don't know if I still prefers the flow of the stock screen by itself.

neydor wrote:Man, never in my life I would come up with that Idea. Thanks for the tip... I put my IMS on top of the stock like you suggested and its definitely better, but I don't know if I still prefers the flow of the stock screen by itself.

LOL. I take no credit as it was an accidental discovery. I was farting around one night securing the machine to be off for a couple of months, and for no good reason at all, never intending to actually use it that way, just the kind of farting around that people with ADD do, I stacked the two together... And then forgot about it until I got back home to use my machine again.

-Peter

And Vulcanization was discovered when Charles Goodyear accidentally spilled raw rubber(latex) on his wood burning stove.

Hmmm...

For those of us who are interested in plumbing in our DBD, please do exactly what Peter did which is to connect the rotary pump to its own power source and switch to turn it on/off. Do not connect it to the power source provided by the machine (which the Ulka pump is currently connected to), doing so will cause the T435T-600 triac on the controller board which controls the brew pump to stop functioning and your pump will keep on running. I learned this last night after using a multimeter to measure the resistance of this particular triac.

You could possibly do it by way of a relay to handle the current required to drive a rotary.

BUT

I had another very specific reason why I have my rotary pump on a separate switch. And it has to do with operational flexibility, and how I pull shots. Lately, I've been doing a high pressure pre infusion, using the pump like Londinium machines. Which means I bump the pump ON to hit 4 or 5 bar, then turn it off. As the pressure drops below that, I do a quick bump again with my on/off switch, to get it back to 5 bar, then off again. Leaving the pump off most of the time during pre infusion, until I'm ready to do the actual extraction, when I turn the pump back on again. My pump control switch is in my right hand. Then my left hand is used to turn the solenoid on and off, and run the needle valve for flow control. Think like a jet pilot (which is what I and fact do for a living), with both hands occupied by throttle and stick. I do espresso with my right hand on the pump control and left hand on the solenoid and flow control.

Also, my pump is under my kitchen sink, wrapped loosely in bubble wrap, and inside a cardboard Amazon box for extra quietness. It's nearly silent now except for a slight hum.

-Peter