No you are not imagining things, changing top limit of pstat by 0.1 bar will make a big difference in the amount of water you need to flush. Since you don't have a thermometer and you flushed the same way as you did before, what you did was pulled a shot say instead of 202F which may be partially burning the coffee at the hump a bit and you may have lowered it to say 198F.

In my machine the pstat range change translates very clearly into the cup.

It all depends on what type of machine you have and your routine on pulling the shot. If i had to buy again, i would still be ok with my pro 500, but maybe would do the pro 500 pid as it has a restrictor installed.

oh wow!!! you made me feel good about having an HX specifically for the reason that it does not flow through the boiler!!!! hahahah, and since I am not using hot water nor steam, the same water is still in the boiler, right???
so let me understand whether it's good or bad for my heating element and also calcification....:

1.the same water in the boiler means that it's already decalcified and is not bringing any more minerals into the boiler and heating element resulting in less mineral build up --- GOOD!

2. the same water in the boiler and around heating element for weeks...what effect it can have? GOOD or BAD?? should I flush it from time to time, for some specific reason??
i don't plan to use the hot water out of it, and I don't really plan to do any steaming unless some visit will ask for cappuccino

3. I really do like the idea of fresh water for coffee flowing through the pipe only instead of the one that is trapped in a boiler!!! but i said that more less in the first point.


BASED ON THAT FOR ME IT'S A WINNING FOR HX MACHINE DESIGN OVER DUAL BOILERS WHERE WATER STAYS IN THE BOILER AND IN DIRECT CONTACT TO THE HEATING ELEMENTS BRINGING UNEVITABLE MINERALISATION AND OTHER THINGS WITH IT...

NICE, UNTILL SOMEONE WILL MAKE ME LOSE MY EXCITEMENT WITH SOME UNAWARE CONS ABOUT THIS "ALWAYS FRESH WATER" DESIGN, I THINK THIS IS AN ADDED BENEFIT TO THE HX DESGN, AT LEAST FOR ME!

I ALSO PLAN TO HAVE SOME EXTERNAL DOSE OF GLASS TOO THAT WILL SERVE AS A TANK WITH PIPE ATTACHED TO THAT, AND WILL LEAVE SOME WATER IN THE TANK WITH THOSE UGLY IRON PLATES THAT MEASURE THE AMOUNT OF WATER IN THE TANK....

You've got it about right. If you steam, the minerals in the boiler gradually increase, as you are taking what is essentially distilled water out and leaving minerals behind. If you don't steam, then the mineral content stays more or less the same. If you use hot water from the hot water wand, AND steam, then the minerals don't build up, as fresh reservoir water comes in to make up for the hot water coming out. In your case, since you don't steam, you could fill the boiler with 'perfect' water and not have to worry about minerals. Perfect water in the boiler would be distilled water (not RO as the PH would be wrong. Then, the only place you might get deposits would be in the HX tube, which could be dealt with chemically. All this is conjecture on my part...anyone out there with views? Jump in!