I have a venue without water supply (outdoors service). I’m wondering if it’s possible to rebuild a smaller HX machine (like the Expobar MegaCrem Mini) to vibration pump? The Rancilio Silvia Ulka EP5 maybe?
We first thought of an Isomac Tea or something, but the waiters refused to operate a lever machine (can’t spend 25-30 seconds looking at the brewing).
It is always possible, but no where near feasible. Pump, mounts, deaerator, over pressure, suction solenoid, water pick up, tank, tank mount, tank empty sensor, Check valve, new wiring harness (if the controller supports it) , water lines, a Tee fitting for the relief and deaerator, Vibratory suction fitting, and what ever I have missed or forgotten.
It would be easier to mount a water pressure tank on a cart under it with a low pressure cutout switch to kill the machine with a loss of water. Todays bladder tanks are very good for this. Not only that, but you will still maintain the machines warranty and parts system.
Anyway, machine is out of warranty, so no worries. One guy I know claims he had an Expobar MegaCrem Mini without a pressurized tank. He just immersed the hose in a water tank and adjusted the pressure on the pump head and it worked fine. Would that be the case, or is he remembering wrong? Line pressure here is usually 4 bars, so would adjusting the pump compensate enough?
No, the rotary pump is a vane pump. It is not designed to have a negative pressure on the suction and will fail prematurely from lack of lubrication (water) and seal air leakage. You may be able to find a rotary pump that is designed to pull a vacuum, but I think they are slightly bigger and less efficient. There fore it would need a bigger motor. And it is dangerous to have air in the boiler. The boiler air removal valve only works at no pressure. Allows air and a little steam to vent as the boiler starts to heat, then closes.