No announcement yet.

Isomac Tea - a couple of issues with steam & pressure

  • Filter
  • Time
  • Show
Clear All
new posts

  • Isomac Tea - a couple of issues with steam & pressure

    Hi All

    I have an Isomac Tea that is a couple of years old. Earlier this year it was off for about 3.5 weeks, and since then it has had a couple of issues, that I think are related.

    The first issue is that the boiler heater on / off pressures seem to have changed. When I first turned it back on after 3.5 weeks I noticed that the boiler pressure was going up to almost 2 bar, and the heater was still on. I removed the pressurestat, gave it a blow-out, and re-fitted it. The heater was now turning off around 1.5 bar, and I can adjust this. However what seems wrong is that there is around 0.5 bar difference between heater on & heater off, regardless of where the pressurestat adjustment is set. ie if I set it to turn off at 1.5 bar, it won't turn on again until 1.0 bar. I never really took much notice of what pressure it switched at before, but I'm pretty sure the on / off difference was much lower. I'm assuming that a new pressurestat should solve this.

    The second issue is that the boiler pressure is dropping much faster than I think it should. I've just timed the heater on / off cycle, and the boiler pressure drops from 1.4 bar (where I've currently got the pressurestat set to turn the heater off) to 0.9 bar (where the heater turns on again) in around 3 minutes, while the machine is at idle. I can actually see the pressure guage moving, with the steam and water taps off & the the brew lever closed. If I am pouring a brew the boiler pressure goes down even faster.

    I have removed the fill solenoid to check for obstruction & blow it out. I've also removed the fill sensor & cleaned a lump of scale off the end of it - this slowed the boiler pressure loss from around 1.5 minutes to around 3 minutes. I can't see or hear any steam escaping anywhere, and there doesn't seem to be any flow either back into the water tank or through the overflow into the waste container.

    The machine is still working, and still making nice coffee & milk.

    Any help would be appreciated.

    I'm also after a new pressurestat & a green light from a sponsor. I sent a blanket request a few weeks ago, with only one reply. I emailed the sponsor back asking for pricing but they didn't get back to me. I'm in Adelaide and can't seem to find a local supplier, so I need someone who will ship parts to me.


  • #2
    Coffee parts should have what you need, great service.

    On mine the dead band on the pressure stat is about 0.2 bar from memory.

    Three mins to drop 0.5 bar doesn't seem too bad, loss of heat drops the pressure even if the system is fully hydraulically sealed.



    • #3
      Thanks. I'll change the pressurestat & see how it goes.