Hi all,

i, well actually my wife, just descaled the boiler of our Isomac Tea. When she flushed the boiler to get rid of the citric acid left the machine starting pumping water again and she closed the valve. Like 30 minutes later when i checked the machine i noticed that the pressure gauge did not went to its regular "i'm ready" position.

I turned off the machine, waited till it cooled down a little bit and turned it on again... no pumping, not a single sound (sound in terms of pumping or heating).

My best guess is that closing the valve in the wrong moment caused some kind of vacuum somewhere?

I remember i already had a similar problem when i was descaling the boiler some months ago, but after some on/offs and waiting for a day everything worked fine again.

I there anything i'm missing related to descaling the machine? And is there anyway to fix this vacuum (if it is something like this) like by opening all valves before turning the machine on or something?

Thanks, best: Lars

edit: i just removed the green cable from the control box (the one that connects to the boiler). turning the machine on then starts the pump as regular. No idea what is it useful for, but i've read it on some thread here. The security valve does not move (which is regular behaviour i assume?). The vacuum breaker valve seems normal (i can lift it)...

Actually this sounds exactly like my problem, except that mine is directly related to descaling the boiler minutes before it acts like this:

Isomac Tea pump not engaging on startup

That green cable (assuming it is solid green) serves as the "input" to the control board as regards your boiler water level. Disconnecting that cable from the control box will always start the pump and open the boiler fill solenoid and fill/overfill your boiler. You should not have disconnected it, especially since

No idea what is it useful for, but i've read it on some thread here.

If the machine is still heating up, I would let it heat up as normal and then get the excess(?) water out of the boiler via the hot water tap until the pump automatically comes on to refill the boiler. There are lots of useful posts on this forum concerning the Isomac Tea - let the search engine be your friend.

it's not heating up... just tried that again, but it's still cold after 5 minutes. Worst thing is, that the only local shop that also did repairs does not exist anymore, so it's completely up to me to fix it. I assume next check should be the heating element? Anyway i'm still confused since there must be any connection to descaling the machine minutes before it stopped working. Any ideas in that direction?

Also i'm wondering about the fill level of the boiler - any way to check that the easy way? Should the security valve move just like the vacuum breaker or is it fixed and only moves when the boiler is over-filled?

I tried the search before posting of course, but all posts i found did not seem to have any relation to descaling the machine before. I can't believe the heating element or anything outside the water circuit that the citric acid did not touch suddenly broke?

Ok, removed the boiler level sensor, cleaned it, removed most of the water from the boiler, put the sensor back in, switched on the machine: pump is filling the boiler, but when done nothing else happens, no heating. So now i know the sensor seems to be fine (can i assume the control box is also fine then?). What should be the next thing to check?

Most Isomac Teas (I don't believe the most current ones) are equipped with a thermal fuse usually encased in a red vinyl-like sleeve near the heating element. This fuse is one-time use only and I believe yours has died. In the pic below it is just to the right of my glasses.



Disconnect the fuse and check with an ohmmeter. You COULD temporarily bypass the fuse but that is taking a chance that all else is well and will remain so until you replace this fuse (if dead).

Ok, already saw that fuse... btw: i noticed a short "click" sound coming from the control box when i turn on the machine. Hard to tell if it's there always, since i never hear it with the casing attached. Could you give me a short advice on how to check the resistance on that fuse? I never really used my voltmeter...

(broken sentences - I don't enjoy typing)

Machine off and unplugged. Carefully disconnect fuse. Set meter to measure resistance. One probe to one end of the fuse, one probe to other. If resistance is infinite, fuse is dead.

Push, pull, bend... it's doesn't seem to move. Looks like only way to remove it, is breaking it. Also checked my "online dealer" for spare parts and he doesn't seem to have a replacement fuse

You can slide the contacts for the voltmeter under the plastic sleeves that appear to be protecting a crimped connection, or follow the ends of the wire to the other end and you may find an uninsulated terminal. Don't give up, it isn't that hard. As long as it is just wire between the ends, you should have continuity.