Stuggi wrote:Sorry for resurrecting this thread, but Dave, could you give a bit more details about your setup? Are you using any kind of commercially available timer or?

To the OP, how exactly did you wire in this switch?

On my Elektra T1, I used a Potter & Brumfield Delay Relay, which I mentioned here (and IIRC I did this based on Dave's idea). You have to power the pump via a dedicated power feed, and then you use the normal power signal to the pump as the relay's input, and make the relay switch the dedicated power feed to the pump. I imagine there are more clever ways to do this as well, but that's the basic idea. Real simple.

shadowfax wrote:You have to power the pump via a dedicated power feed, and then you use the normal power signal to the pump as the relay's input, and make the relay switch the dedicated power feed to the pump. I imagine there are more clever ways to do this as well, but that's the basic idea. Real simple.

So, I'm guessing that I'd be working with 220V input? If I have a two group, I'd have two delay relays? I'm gonna have to get a schematic. Something tells me that the soft touch programmed semi-auto pads aren't switching 220V, and that I can somehow trick them into some sort of pre-infusion with a low voltage delay...
hmmmm....

Psyd wrote:So, I'm guessing that I'd be working with 220V input? If I have a two group, I'd have two delay relays?

I am having trouble gauging if you're being sarcastic or not... but just in case, you really only need one delay relay per pump, not per group. You don't need to intercept the keypad button presses with your relay or know what type of signal they are; it's just as simple to tee power off the main power to the machine, send it straight to the pump, and switch it with a 240VAC x 240VAC relay, using the pump's original power signal as the input to the delay relay. This abstracts the complexity of re-working the system's existing wiring, and lets you just augment it, which is considerably easier and more easily reversible.

But the problem still persists, how do you do a pump delay preinfusion on a 2 grouper if you want to run both groups at the same time (or more exactly start an extraction after the first is already under way)?


The touch buttons on the keypad are in 99% of cases low voltage DC, mainly because switching it is cheaper and you can put logic circuits behind it to get what you want done fast and efficient. These mods here are more old world with higher voltages, hefty relays that does the switching etc. Still, the benefit is that working with main voltages is that since everything is more dangerous and things need to take a lot more abuse, that part of these machines are usually much more simple and easier to tap into, everything's done with wire instead of circuit boards etc.

If going with a timer I think this one http://www.auberins.com/index.php?main_ ... cts_id=115 might be worth considering as it would double as a shot timer.

Stuggi wrote:But the problem still persists, how do you do a pump delay preinfusion on a 2 grouper if you want to run both groups at the same time (or more exactly start an extraction after the first is already under way)?

To preinfuse on a multigroup machine with one pump you have to do something similar to what Slayer does (off -> needle valved inlet -> regular inlet). LM paddle groups (non-Strada) do something similar, physically moving jets into the water path.

Synesso Hydras avoid this by having multiple pumps. Synesso actually sells timers for their Hydras so you can program an automatic preinfusion period before the pump kicks on.

Either system works.

+1 on Ben's comment, with the addition that LM-USA is now advertising individual pumps a la Synesso Hydra as an option on any of their multigroup espresso machines, along with a great list of other factory mods that look pretty awesome (individual boilers, which is a prereq for individual pumps, as well as an option for a separate inlet for your steam boiler).

Having played with the paddle group on a La Marzocco, the machine lets you preinfuse at line pressure when no other groups are on, and the needle valve in the grouphead that's actuated by the paddle can modulate line pressure. Then when the pump acitvates on one group, the other paddles modulate pump pressure. You can still preinfuse this way, but it acts very different, pressure-wise. It struck me as odd that LM didn't have the pump turn on as soon as ANY paddle opens even slightly, which would let you preinfuse a lot more consistently when varying between working with only one group or multiple groups simultaneously. Still, it's not that big a deal, and it's good to see you can get separate pumps now if you want to pay extra for the more consistent behavior.

Hmm, maybe I should get that valve after all, might be nice to have around if I decide I would might wanna modify anything in the future.

shadowfax wrote:I am having trouble gauging if you're being sarcastic or not...

Totally serious. When I'm considering a similar project, it's always nice to hear the thinking process of someone who has already summited that peak, yeah?

One other question; if I'm interrupting the power to the pump, what happens when the auto boiler re-fill kicks in? I will still research sending the low-voltage signal through the delay, (I'm never going to 'need' to use both groups simultaneously) and dealing with the pre-infusion that way, but it's nice to know that there is an easy back-up plan.

Psyd wrote:Totally serious. When I'm considering a similar project, it's always nice to hear the thinking process of someone who has already summited that peak, yeah?

Fair enough, I was just thinking you probably knew a lot more about it than you let on, based on other comments you've made about wiring/electrical power.

One other question; if I'm interrupting the power to the pump, what happens when the auto boiler re-fill kicks in? I will still research sending the low-voltage signal through the delay, (I'm never going to 'need' to use both groups simultaneously) and dealing with the pre-infusion that way, but it's nice to know that there is an easy back-up plan.

This depends how fancy you wanna get. The easy thing to do is tap the pump power supply signal and put the delay relay there: this will result in you always having the programmed delay, whether brewing or boiler-filling. That's not a problem on a machine that's plumbed in, really, because you get water flow to the group either way (and, why would you do this on a machine that wasn't plumbed in, since you won't get any preinfusion anyway?).

If you wanna 'get clever,' you could totally do things differently and leave the pump's power almost completely intact. You get 2 relays (a delay relay and a normal mechanical/solid-state relay), and some wire. Isolate and cut the hot wire going to the pump, and augment each end with 2 wires. This way, you can wire in the 2 relays in parallel, so that either or both can activate the pump. Then, connect the input on the delay relay in serial to the power signal for the 3-way group solenoid. Connect the normal relay's input in serial into the power line for the 2-way boiler fill solenoid. This way, the pump will come on immediately in a boiler fill, but will run the delay program when a brewing program is initiated. Make sense? I may have botched the explanation.