hi!
i have a new NS oscar and sometimes it behaves weird.
after brewing the coffee, i turn on the steamer. a bit of steam and water come out and then it stops completely and i have to wait for the machine to re-heat.
does anyone know about this problem?

usually though, it performs great and with the steamer in full power.

thanks!
omri

Sounds like false pressure. Either the vacuum breaker is stuck, or there isn't one (according to what I've read, older models of the Oscar did not have one). If so, you will need to release false pressure once the boiler heats up.

The Oscar still comes without a vacuum breaker as a standard part, which is unfortunate. As Dan indicated, open the steam valve to release false pressure after the boiler heats up. Nuova Simonelli places a label on the top of the machine indicating that you should turn on the unit with the steam valve in the open position, but that requires that someone be near the machine to hear when steam starts coming out.

These posts re the Oscar steam problem are helpful to me as my Oscar was purchased new from a reputable Toronto dealer in September and produced good steam for approx 4-5 weeks and then I noticed that the steam pressure appeared to be declining to the point where it would not produce any froth, just hot milk. Tried cleaning jets, etc, but no improvement. Dealer had a look at it and advised opening steam valve after switching machine on and leaving open (as per recent factory advice, also noted in this thread). Dealer agreed with my observation that steam pressure appeared to be slightly below normal and may require a new thermostat which they would gladly replace under warranty if opening valve at start-up did not resolve to my satisfaction./ Tried it at home. Same problem. Will return to dealer for thermostat replacement. Meantime I can fire-up my old faithful Rossi POD machine. Comments would be welcome.

cricketer76 wrote:...I noticed that the steam pressure appeared to be declining to the point where it would not produce any froth, just hot milk.

Is the steam really wet? If so, the water sensor could be coated with scale, resulting in an ever-increasing water level as scale acts as an insulator. Otherwise the pressurestat (not thermostat) is the only cause I can think of.

Thanks Dan for the correction and question. Yes. I would say that the steam is quite wet. Is it likely that scale on the water sensor would appear after only 7-8 weeks since new? I brew approx. 2-3 daily and flush briefly after use. Is there a recommended scale remover/method for the Oscar?
Thanks.

cricketer76 wrote:Is it likely that scale on the water sensor would appear after only 7-8 weeks since new?

Depends on how hard your water is. In this area, no way. In parts of Europe, easily. No need to speculate if you're handy; remove the probe and you'll know whether or not this is the cause. You can double-check the boiler level by using a wooden skewer as a dipstick through one of the fittings atop the boiler.

Use citric acid to descale; search on 'descale' or 'citric acid' in the unabridged FAQs and Favorites for instructions.

Excellent advice. Thanks!