yokusan wrote:that is exactly what I did in the second video. The water is then flowing through the OPV and air is coming out with the water in the brew line.
first of all - remember that the pressure in HX line is way higher than in your boiler (10 bar vs. 1) so if there is any leak, it will happen the other direction. is your OPV set right?
yokusan wrote:In addition, the heating element is constantly on as signaled by the glowing lamp. This is equivalent with a constant pressure drop detected by the pressurestat.
no, that just means you're cooling down boiler - depending on crossflow design and OPV placement it could be well just a cooling effect of heat exchange. pressostat doesn't sense dynamic changes of pressure (drop), sorry.
yokusan wrote:How would air get through a leaking boiler fill valve into the brew line? Isn't the filling hose of the boiler at the bottom in water?
yea, common misconception. if your HX is broken, then nothing is really getting in - it rather leaks out (if your OPV is set right). I suspect that the air you see there is not from boiler.
you can do real test to determine of your HX is broken (with cold machine):
1) disconnect heating element
2) disconnect boiler fill solenoid (remove the coil or wires)
3) remove the connection between boiler and fill valve
depending on it's position in machine, the boiler might drain (good!)
4) find lowest cap/connection/whatever on boiler that you could unscrew to let the remaining water out, drain boiler and keep it open
5) fire up the machine
what is going to happen:
machine sees low water level in boiler
it starts filling (runs pump and opens fill valve)
3 way valve is closed, fill valve is disabled (step 2), so the HX system will reach the maximum pressure allowed by OPV (should be at least 9 bar)
- if there is water coming out of fill valve-boiler connection, replace this valve
- if there is water coming out of the open port on boiler (step 4), HX might be shot and you should disconnect the boiler for proper inspection
- if there is water coming out of OPV and nothing else happen, check the OPV pressure. if it's fine (9+ bar), you're fine as well as your HX and the problem is elsewhere