I'm a fairly new Expobar Lever owner and definitely want one of these restrictors! So what is the contact info for the supplier? Has anyone found any generic Home Depot/Lowes type washers that work for this? Would really appreciate help here, I think the Water Department is going to fine me for wasting H20 with all these cooling flushes!

Updating this thread, since I got an office a few weeks ago, and installed a restrictor last night.

First, it was REALLY hard to undo the nuts, to install the restrictor.

Second, Whole Latte Love carries the restrictor, the part number is EX-50020020, I think it was a couple bucks.

I used a 21mm flare wrench to get the group head nut loose. I had a 24mm for the boiler side, but it didn't fit, but I was able to use an adjustable wrench for this end, and got it off OK.
You do need a 21 mm fixed wrench on the group head, not sure if I really needed a flare, but it was $20 shipped for a flare set from ebay, so I just bought the set, I though I needed a 24 too, turned out I didn't.

Tried it this morning, and my cooling flush was reduced by about 1/3 over what it was before this. I need to play with it some more, and I think I am going to reduce my boiler pressure from its current setting of 1.2bar max.

Randy

Thanks all for such an informative thread. My restrictor arrived from WLL earlier this week and I plan to install it this weekend. First, excuse my stupidity as I have zero experience with plumbing hardware. My opened up Office Lever is shown in the pic. As I understand it, I just need to remove the tube nuts on the boiler and group head ends of the top HX pipe, remove the pipe, put the restrictor into the grouphead, and put it back together, right? Also, just curious, but what is the purpose of that steel box with magnets in it that's covering the boiler-end joint of the HX (with the zip tie on it in the pic)?



Thanks,
Alex

Just don't skimp on the correct wrenches or you will spend $ on knuckle bandaids. The correct size and type of wrench to use is a 21 mm tubing wrench.

You may be able to use those magnets as a "magnetizer" for your collection of screwdrivers. No other machine, from any manufacturer, in any category, has been fitted with these to the best of my knowledge.

Woohoo! Thanks very much to everyone who gave advice on installing this little $2.50 wonder. Finally got all the tools and got the restrictor installed. I took a video that I'll post, though I'm still doing a little tweaking with my routine so I'll see how it goes. Summary of my experience:

1. Machine is an Expobar Office Lever and the grouphead would idle around 210-212 on Eric's thermometer adapter.
2. Like Randy and Jon, getting off the pipe fittings on the upper thermosiphon was a big PITA. The nut on the grouphead end was easy enough to get off with the 21mm flare wrench. On the boiler side, though, like Randy said the 24mm wrench was too small (I believe the correct size is 25mm, which I didn't have), so I also had to use an adjustable wrench. It was really difficult to get leverage since the boiler is essentially freestanding, but I finally got it off using a 21mm socket wrench over the top of the joint so I could have something to push against (i.e. was pushing up with the adjustable wrench while pulling down with the socket wrench).
3. After I got everything installed the grouphead now idles at ... drumroll please ... 201.

Did some tests and my cooling flush was cut to about 1/3 - essentially just past the end of the water dance and go. Pulled a shot and it was super easy - the thermometer registered 203 when I got the first drips and 202 when it was done

HOWEVER, the downside of this is that it now takes much longer for the grouphead to rebound to brew temperature. For example, I pulled one shot and then rinsed off the portafilter, and 15 mins later the thermometer was down at 182, and it wasn't going up. It was almost as if the thermosiphon flow had 'failed' - I did some quick pulls and shortly thereafter the temp started going up again. I think the main issue is I'll have to learn how to adjust my routine for the way the machine now works (i.e. no more rinsing the portafilter).

So, while I'm super happy with this mod, all of this futzing with temperature has made me arrive at a somewhat controversial conclusion: For 95% of home users, the "PID single boiler + thermoblock machines" (e.g. QuickMill Silvano) are much better choices than HX machines. The reasons:

1. Temperature control is much easier.
2. No cooling flush
3. The PID single boiler machines are much cheaper.
4. Can still steam and brew at the same time (or at least steam immediately after brewing).

While one could argue that the issues I've hit are Expobar-specific, all HXes require the cooling flush, and without Eric's adapter you're still "flying blind" with respect to temp. Also, the other HXes are hundreds more than the Expobar, making the value prop that much worse (QM Anita is 60% more than the Silvano, for example).

Just found this article by Randy Glass explaining thermosyphon stall. I definitely think that's what happened to me previously when I mentioned I thought my thermosyphon flow failed. My theory is that, with the thermosyphon restrictor installed, a stall may be a little more likely because when the pump is turned on you should get more flow coming from the bottom of the thermosyphon than the top (as there is no restrictor on the bottom connection with the grouphead), so clearing out any steam bubbles may take more time.

Now that I know the cause, though, this should be very easy to prevent, and I now I know I have a quick remedy if I see that the temp isn't bouncing back.