The check valve is a long way from the brewhead; My worry would be that a little bit of expansion in the hose (or elsewhere along the line) would let some pressure relief draw back a little bit of coffee water come back into the line. You don't really even need reverse flow, just an open link and no flow, I would think. Ultimately the best thing is probably tuning the expansion valve and adding a leak detector. That's on my to do list...

Good point Nicholas. I didn't really contemplate the fact the hose itself could expand and absorb the pressure. I was more thinking that the pressure would more easily absorb into the boiler/OPV than into the hose itself. Either way, this was all good info to share!

Well, in case you've never seen one, here's what a pump check valve looks like.



Man, orders from Stefano via USPS get here fast as heck. He sent this on Thursday afternoon, and it's here--from Oregon to Houston--on Saturday. UPS would have charged the price of the check valve to do it this fast...

So that's all working. Other than the mount that I need to finish, I am pretty happy with the setup under the counter. By the way tom, there's only one door on the counter, and the hinges have these little levers that you can pull to disengage them, and it's like there's no door at all!

The other part of my order was a new 3 way solenoid pilot. I don't recall if I mentioned it, but outboarding the pump made me realize that the irritating buzzing I was hearing was actually the stupid solenoid valve. When I checked the coil, it was more or less fine, indicating that the pilot was having trouble opening all the way during brewing. It was rather intermittent, which also seemed to point towards some physical trouble opening the valve properly. Strange that it didn't leak in spite of the noises, but alas. The new pilot is nice and quiet during operation.

Dave's handles came in earlier this week; I don't think he understated how great they look.







They're just great in the hand, and the increased size of the handles fits my hands better. The figuring is just exquisite in person; photos can't do it justice.

Thanks, Dave!

Hi Nicholas,

I understand you removed the Pstat completely, so that now the boiler heater is only controlled via the TC+PID? At first I wanted to do the same thing, but my recent machine problems made me think again. Let's say you switch from the pstat to a TC+PID+SSR combo and it works well keeping the proper boiler pressure with minimum deadband. Now let's assume the autofill function fails badly and doesn't want to stop pumping water into the boiler. New fresh cold water entering the boiler of course means that the temperature will start falling. PID will see this and activate the heating element as it has to maintain the setpoint, so now you have pressure rising due to autofill function failure as well as the heater running at full power heating up the water building even more pressure. The same thing might happen when you have a broken boiler fill solenoid and you engage the pump when pulling a shot. Water will not flow through the coffee, but instead it will go straight into the boiler (less resistance), building up the pressure. PID will also do it's work turning the heater on and again you have the same problem.

I thought it might be a good idea to leave the pstat inside the machine and use the pressure gauge connection on the boiler to install the TC. Next you set the pstat to 2-2.5bar and connect it's relay cables to the main power supply on the machine. This means that as long as the machine is below 2-2.5bar it will have power and the boiler pressure will be controlled via the PID+TC+SSR, but if something goes wrong and the pressure rises to 2-2.5bar the pstat will switch it's relay as well as the whole machine off.

Or am I missing something obvious?

I'm still thinking of using a pressure transducer to control the pressure, but it might be a bit easier to do it with the TC (fitting straight on the boiler and I don't have to move anything around).

Regards,
dsc.

Tom, you're correct. If you can mount the pressurestat (you just need more fittings, really), it can be used as a very effective safety device. you would need to set it lower (~1.5 bars, I think), as I think the boiler safety valve will open up before 2-2.5 bar.

Another, probably significantly better safety measure is to get yourself a water-shutoff system with a water sensor under the machine, so it will shutoff the water supply and power to the machine in the event that a leak springs. This will catch a LOT more problems than a dodgy autofill or broken solenoid... e.g., small leaks, a fitting shears and starts to flood your house... that kind of thing. I'd say a leak is a much more likely problem than a dodgy autofill, too.

Let me know what you end up doing. I believe there's a thread around here about a nice safety system worth looking into... I'll probably go that route eventually. If you figure out a good way to incorporate TC and pressurestat, I'd love to know.

Hi Nicholas,

if I choose to use the TC I will probably mount it on the boiler using the pressure gauge input hole and leave the pstat as it is (with a slightly higher setting). If I have a PID which shows temperature and that relates to pressure I don't really need the boiler pressure gauge and I'm planning to get rid of the double gauge anyway (I will try to install a normal single gauge for group measurements).

Of course the pressure transducer still sounds like an interesting option, but to install it I will have to remove the pstat and try to mount the transducer in it's place. Another option would be to mount the transducer on a flex hose and attach it to the boiler using the existing pressure gauge input hole. This unfortunately calls for additional fittings as the transducer is 1/4" BSP male and the hose has a 3/8" male thread at it's end, although I might have another one with a 1/4" female tucked in a box somewhere.

Regards,
dsc.

Tom: Build something I can easily copy. I've one of the thermocouples too and was reluctant to totally trust a PID controller.

Mark

mhoy wrote:Tom: Build something I can easily copy. I've one of the thermocouples too and was reluctant to totally trust a PID controller.

Am I the only one who finds it somewhat amusing that you two have trusted those Sirai pressurestats all this time, but you won't trust a PID? If you're serious about safety mechanisms for your espresso machine, you ought to consider something along these lines...

Well the original Sirai pressurestat in mine fused shut from the looks of one of the contacts, so yes, it's certainly another point of failure...and there is a pressure relief valve so I guess it's not critical. And yes, water is much more likely to leak but worry is part of human nature.

BUT I might try writing the PID control s/w myself and I've written software for long enough to know there are and will be bugs...

Mark

Hi guys,

I trust the PID, it's the situation I described before that would worry me (and yes there's the safety valve which goes off at 2-2.5bar, but with a full boiler it makes a huge mess). On the other hand I'm near the machine 90% of the time, so if anything goes wrong (like autofill failure) I would probably notice it.

I wouldn't worry about the machine leaking inside, the only weak point I can think of is the water connection (of course a bit more dangerous in the case of out-boarded pumps), the rest of the pipes and compression fittings should be fine.

In my case it's all down to the length of the TC or the length of the threaded 3/8" to 1/4" adapter I've got. If the TC is too short to mount straight in the pressure gauge connection hole I will be forced to mount it where the pstat is connected, thus disconnecting the pstat. If I can mount the 3/8" to 1/4" adapter where the pstat is (it has to go through a hole in the the thick steel base and still have enough thread visible to screw in the compression fitting from the bottom) I will be able to mount the pressure transducer in it and get proper direct pressure readouts. Today I will dry fit the TC and disassemble the pstat to see if any of the two is possible.

Regards,
dsc.

Ben Z. wrote:Your setup looks pretty good, but I have to ask why go through the trouble of the compression fitting in the group head and everything when you could just route a fine gauge tc between the two pieces of the group and run it through the inside of the machine? It's just as accurate, invisible, and cheaper. I pretty much followed the method Bob Barraza proposed and it worked fine. I disconnected the honeywell controller I was using to monitor the temps because it looked silly and I had my flush regimen figured out. The TC is still in place, but not connected to anything.

I think I owe Ben an apology for defending my TC setup. I got the opportunity to borrow a Scace device from a local roaster for the last week or so, and I realized that the 1/16" TC + fitting may not be the best. Compared to the Scace device, my TC install was reading rather high, but oddly enough, not remotely consistently in terms of offset. As a result, I got a 36 ga. TC and installed it:



I've liked it pretty well so far, and I find it tends to read about 0.5-1.0F higher than the Scace device where I have it, which is right inside one of the 4 holes in the group bell. Originally, I had it right behind the shower screen, but I found that it read out quite inaccurately (very low) there. I assume this is due to the TC's resistance to registering large, fast changes in environment temperatures. It idles much closer to brew temp where it is now, and as a result seems to read very consistently off-set from the Scace during brewing.



Finally, I wanted to comment on the group jet idea that Dave had that Tom and I tried out. I tried it well before Tom, and I was initially impressed with how much easier it was to flush, but it really did take a long time. Tom really didn't find that he liked it, and when he finally tried it and hated it I thought about it for awhile and tried going back to the regular group jet. It was really nice to get back to the fast flushes, oddly enough. Call it a solution searching for a problem, but I also decided to try line preinfusion as well, since I already have my machine set up for it quite well. I bought a Potter & Brumfield Delay Relay that goes from 0-10s:



So far, it's a fun little toy. I am looking forward to trying it out more (just installed it Friday).

Hi Nicholas,

good to hear everything is well on the Elektra front and that you decided to switch to a thin wire TC. I think it's a bit faster although you have to be careful when installing it, I crushed the cables on one TC I tried to use and it was giving me some strange readouts.

I'm curious what you think of the delay relay, I use my DIYed version with 3s preinfusion and it seems to work well, maybe a bit easier to get even pours than before. I think it also works a bit better with the original jet in place, the new one slows down the flow too much and you end up with too little water entering the group.

Anyway I got my stepper motor now and will start working on that pressure profiling system when I get back to the UK. Should be fun.

Regards,
dsc.

shadowfax wrote:I think I owe Ben an apology for defending my TC setup. I got the opportunity to borrow a Scace device from a local roaster for the last week or so, and I realized that the 1/16" TC + fitting may not be the best. Compared to the Scace device, my TC install was reading rather high, but oddly enough, not remotely consistently in terms of offset. As a result, I got a 36 ga. TC and installed it:

Hey, no fair, I haven't even had time to install the group head TC that I got from you. At least I've still got the TC in the bell. You must polish things up before the pictures, as your pictures always look good.
=-=-
Mark

Yeah, Mark, I'm sorry; I feel bad for leading you "astray" on the adaptor. It looked cool while it lasted, though... Maybe you can sell the TC to someone who wants to use it on their E61? Anyway, I'd be glad to send you one of my 36 gauge TC's as a small compensation if you want, but it sounds like you're covered on TCs.

shadowfax wrote:Yeah, Mark, I'm sorry; I feel bad for leading you "astray" on the adaptor. It looked cool while it lasted, though... Maybe you can sell the TC to someone who wants to use it on their E61? Anyway, I'd be glad to send you one of my 36 gauge TC's as a small compensation if you want, but it sounds like you're covered on TCs.

Nicholas: Don't worry about it, I actually like the adapter since it's a lot sturdier than the one in the bell. I was thinking of drilling couple of holes in the bell to help retain the TC as it kind of wanders about when I put it back together, but never bothered since I don't take things apart when I don't have to. You and Tom are forging ahead with numerous mods, I'm just happy pulling shot after shot of what I think is good/great espresso. My wife is very happy with the looks, size and sound level of my Baratza Vario. It has also improved thing another notch and I've little to complain about. Life is good.

It's interesting seeing how many T1/A3 and now D1's are being refurbished and put into a re-newed life. Got to love this forum, thanks Dan.
=-=-
Mark

Nicholas, do you still have the delay relay in your setup? Did you find any improvement in the cup with this style of preinfusion?

I do still use it. I think it helps a bit, but the improvement is marginal at best. I don't think it's nearly as good as the ramp-up on an E61 or another machine with a preinfusion chamber that is downstream of the gicleur--the flow rate is still so high that I think the preinfusion is just a sharp jump to line pressure and then another sharp jump to pump pressure.

I am not sure that I'd recommend it. It is pretty easy to install if you're handy with wiring, and you can't argue with the cost, but it's definitely not something that's revolutionized my espresso or anything approaching that. Of course, I also haven't played around with extra-long preinfusion, either--I've stuck with 3-4s and haven't gotten the inclination to try longer times with all the other stuff I've had going on. I think Tom played around with his preinfusion setup and ultimately decided to build his own pressure profiling valve, if that tells you anything...

When I did this on my two group, I had the delay set to allow a full puck infusion before the pump kicked in. I dont recall the time. I would turn the delay way up, hit the brew button and stopwatch. After x many seconds I would stop the infusion, remove the potafilter and gently knockout the puck and break it in half. I kept increasing the time interval until I had a fully infused puck but no drops coming from the basket yet. Then I set my timer for that and did not mess with it any more. It made an improvement on that old Faema but I had extraction issues with it, probably an issue on the portafilter side of the machine. I have not been so inclined on the Elektra. As long as I pay attention to the dose all is good. If I dont, she reminds me by spraying me with some channeling jets, usually just before work while waring a white shirt.