Isomac Tea losing steam pressure

[Ivarl]

Hi,

I have an Isomac Tea and recently there seems to be a leak somewhere. The machine warms up fine, builds pressure just fine to 1.2 and the green light comes on. Then the pressure drops slowly and the green light comes off, red light comes on and the pressure builds to 1.2 and the green lights comes on again. This keeps on going on a cycle of apprx. 10-15 seconds.

I have changed the pressurestat, boiler safety valve and the anti vacuum valve. The behaviour is still the same.

There is no visible water leaking anywhere and I have tried to listen for steam pressure leakage, but haven't been able to locate it.

Any suggestion for the next step?

Thanks!

[CSME9]

Sounds like bad relay gieger box. Easy to replace but a bit pricey, forum number JP Boyt enterprises can replace or rebuild yours for decent price.

[HB]

...the pressure builds to 1.2 and the green lights comes on again. This keeps on going on a cycle of apprx. 10-15 seconds.

What's the deadband? If it's really tight, say 0.1 bar, then it will cycle more often. Most pressurestats have a ~0.2 bar deadband and cycle around once a minute. If it's not the pressurestat deadband, then heat/pressure is escaping somewhere. As an aside, when you're not using the machine, wrapping the grouphead in a towel will greatly reduce its heat loss and subsequently the pressurestat cycling.

Sounds like bad relay gieger box.

I haven't looked at Isomac in a long time, but IIRC, the control box manages the steam boiler level, not the pressurestat cycles. But you raise an interesting possibility: Maybe the steam boiler level is really, really low. That would cause the pressurestat to cycle more often since saturated steam doesn't hold heat nearly as well as water.

[JRising]

I'm believing it's a tiny steam-leak.

If you have eyeglasses with glass lenses and plastic frames, hold them near every fitting and valve (Away from your face) and look through them as if they're a magnifying glass through which you're examining the fittings... When they fog up, the fog pattern will be pointing at the steam leak.
I know you've already done the vacuum breaker, but I'd still look at it, first... Leaking a bit is what vacuum breakers do best.

Please don't do it with metal-framed glasses unless you unplug the machine.