thanks so much for the detailed reply! As you said this is great info so i am glad you left both parts up. I obviously need to work on my spanner technique as I havent seen any others have this issue, its actually quite hard to find the bit of pipe required. As the machine has 2 switches, one for on and the other for steam I presumed that on would still heat the brew boiler. I think following your reply it is safer if I just wait for the brass pipe!
thanks Richard On Thursday, February 13, 2020 at 5:25:47 PM UTC, bmacpiper wrote: > > Well crap—I somehow read “OPV” in your question, instead of "p-stat". So I > wrote up this whole response before realizing that. I’m going to go ahead > and leave it, since the discussion might be helpful to someone else down > the road. But your basic questions are also answered later in the email. > I’m assuming you have a failed p-stat, which means it’s not a big deal if > you damage the old one on the way out. > > Best and talk soon, > bmc > > ----------------------- > > > Hi again Richard, > > A couple of things you’re saying don’t add up, so I want to clarify. In > fairness, I have a B2, so things may have changed. > > On my machine, the OPV (over pressure valve) is not a plastic part. The > p-stat (pressure stat) is a plastic part, however. > > Forgive me if I’m telling you things you already know, but here’s how it > sorts out: > > —The OPV is located behind the drip tray, on the right as you face the > machine, and may have a sticker over its access hole that says “do not > adjust” or similar. The adjustment screw is a large slotted screw, and is > used to adjust the maximum pressure to the brew boiler when pulling a shot > or backflushing. When that pressure is reached, water is shunted back to > the water tank (pour over machines) or into the drip tray (plumbed > machines). Note that this is not a safety mechanism; it’s used only to set > brew pressure to 9 bar or whatever. On top of the brew boiler is an over > pressure device that protects the pressure vessel from exploding, in case > something goes wrong with the OPV and/or logic controller. If this > activates, it will sound like a freight train coming through (loud hiss) > and there will be condensation all over the inside of the machine. A good > time to unplug, dry it all out, and figure out what the hell went wrong. > > —The p-stat is inside the machine, sitting atop a copper tube, and is > typically a black plastic device with 3 wires attached. This is how you > adjust the pressure to the steam boiler (I set this to about 1.45 bar). > Power goes to the steam boiler, and when 1.45 bar is reached, the p-stat is > switched to allow power to the brew boiler instead. When you hear “steam > boiler has priority”, this is the part that controls it. Since it is a > direct open connection into the steam boiler, the threaded interface > between the copper tube and the plastic p-stat must be able to seal against > 1.45 bar or more, and thus will not use grease, etc. to lube the threads. > > —In the case of both the p-stat and the OPV (and all other threaded > connections that have to be sealed), Expobar uses a food-grade sealant on > the threads. It is very thin, and dries almost instantly if the parts are > hot. If you use it to re-assemble things, you have to work very quickly, as > you usually only have a few seconds to get things tight and oriented > correctly. This sealant is very strong, and when removing parts that are > sealed with it, it definitely feels like you’re going to strip threads. > I’ve spent many hours of my life with a wrench in hand, and breaking this > sealant loose always makes me nervous, but I have also never stripped any > threads on the machine due to the sealant. I will say that it is > exceptionally important to use good technique. The best is if you have two > open-end wrenches, one for each side of the joint, that are both very well > fitted to the nuts. Try to have them aligned so that they are as close to > each other as possible, and then offset by maybe 15 degrees, and just > squeeze them together to break the part/nut/etc. loose. If you try to have > one in each hand, you will inevitably smear the corners of the nut/part and > then have a tough job ahead. If you only use a wrench on one side of the > joint, you will almost certainly twist the soft copper pipe and crimp it > shut, beyond repair. > > Be sure to use a brush (brass, for example) to gently clean all the old > sealant off the threads. It will seem almost fragile and tends to flake out > quite easily. I have had success using the sealant from Expobar/WLL, but > have also used yellow teflon tape on many parts (heating elements, p-stat, > OPV) with no leaks. It’s not what Expobar calls for but does work, and much > easier disassembly in the future as needed. > > —As to your question on whether the brew boiler can be used without a > p-stat, the answer is “sort of”. Since the steam boiler has priority, you > would have to jumper power to the brew boiler if you’re not letting the > steam boiler come up to temperature. One workaround when the p-stat sticks > (and never lets the brew boiler heat) is to reverse the power out wires on > the p-stat that go to steam and brew. This basically gives the brew boiler > priority, and since the steam boiler never heats and hits 1.45 bar, power > never switches over to it. The obvious problem with this scenario is that > the brew boiler gets power continuously, until its over-temp sensor on top > activates and cuts power to it. You may have the over pressure device on > top activate before that over-temp sensor activates; I just can’t recall. > If memory serves, the logic board (giemme and/or PID) will also be > monitoring temp in the brew boiler and only sending bursts of power if the > boiler is not up to set point yet, so that’s further protection. Either > way it’s outside of design specs, and not something I’d do as a permanent > fix. > > OK, hope this helps and talk soon. > b > > On Feb 13, 2020, at 01:30, Rich <[email protected] <javascript:>> wrote: > > Hi All, > > apologies for a spate of questions, again I have had a search but cannot > find anything. Has anyone else had the issue of the PStat getting > physically stuck in the brass fittings? I cant remove it so have had to buy > a new pressure pipe which isnt in stock until the end of the month from a > company in France (open to suggestions for UK suppliers?). Do people use > grease or any kind of lubricant to make sure these don't get stuck in the > fittings, it seems a tight fit and quite easy to shred the plastic? My > other question is whether I can use the brew boiler without a PStat, I > guess I can and that its only for the steam boiler but I wanted to check in > case I missed something! > > Thanks again > > Richard > > -- > You received this message because you are subscribed to the Google Groups > "Brewtus" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] <javascript:>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/brewtus/468d7892-12c5-43ad-8506-520fb5d8fdfe%40googlegroups.com > > <https://groups.google.com/d/msgid/brewtus/468d7892-12c5-43ad-8506-520fb5d8fdfe%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- You received this message because you are subscribed to the Google Groups "Brewtus" group. 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