I've run a Nuova Simonelli Oscar for 6 years. It has been in the repair shop twice (both times for a blown gasket somewhere around the boiler that resulted in a water leak). Now I suspect it has a bad pressurestat (turns off as if it has no water a second or two after you switch it on).

I'm wondering if I should continue to throw money at this machine, or should I be looking at 'upgrading' to something more industrial strength, that won't break as frequently? Apart from repair costs, my time spent figuring out what's wrong with it, calling a repair tech, shipping it to their shop and back, etc etc, is pretty valuable to me. So a unit that 'just works' for a few years would be worth some extra $$.

Also any recommendations on what to upgrade to would be handy. At present I don't have 20A power or plumbed-in water but both wouldn't be hard to add. The primary consideration is counter space. Anything significantly larger (say 1.5 times as wide) than the Oscar would be too large.

Thanks.

Depending on usage and the particular model, pressurestats that switch full current fail every few years due to carbon buildup/arcing. As you can judge from this forum and others like CoffeeGeek, many owners do their own minor repairs, saving on downtime and cost. Upgrading to a more robust model may reduce failures in the years ahead, but based on my forum readings over the years, I have the impression the Oscar is a reasonably reliable machine. Unless I was unsatisfied with the Oscar's performance, I would be inclined to repair it since gasket replacement/pressurestat replacement very couple years isn't uncommon for any espresso machine, especially if it's run 24/7.

Thanks. Followup question: is pressurestat replacement a job that I can safely attempt myself ?
(I'm an electrical engineer and competent with plumbing but I'm slightly unnerved at the notion of replacing a safety device in equipment that can explode if said safety device is not working).

dboreham wrote:Followup question: is pressurestat replacement a job that I can safely attempt myself ?

Sorry, I don't know you. After you've reviewed the site's terms of service, you could unplug the machine, remove the cover, and judge for yourself. Note the pressurestat isn't a safety device. In fact, they occasionally fail stuck in the on position, leading to the pressure release valve opening for the purpose of preventing the explosion you mentioned (see sticky pressurestat for various reports).

Ah, ok thanks. All I need to know is that it isn't a critical safety device. That was the worrying part..

By the way: sound advice to unplug first, but not required in my case : when I was 5 or 6 my Dad (also an electrical engineer) sat me down and told me to always be sure that I can see the entire cord from an appliance including the plug, at all times when working on the unit. The concern being that you unplug, start working then someone else waltzes along thinking 'why is this cord unplugged...' and plugs it back in. He also said that it wouldn't look good to see the headline "Electrical Engineer's Son Killed by Electrocution" in the newspaper. Probably not so diplomatic, but it stuck for life

And that was 240v too, back in the old country..

Thanks for the humorous story, I'll have to share that with my sons. Unplugging the machine is especially important because the power switch may interrupt the neutral lead, not the hot lead as one would expect. Please don't ask me how I know. Bottom line: Before removing the cover, always unplug the machine!

dboreham wrote: The concern being that you unplug, start working then someone else waltzes along thinking 'why is this cord unplugged...' and plugs it back in. He also said that it wouldn't look good to see the headline "Electrical Engineer's Son Killed by Electrocution" in the newspaper. Probably not so diplomatic, but it stuck for life

^^Listen to this man
It's not a fairytale. I know someone who had this happen to him. Apparently, 380v 3 phase hurts like hell.

HB wrote:Thanks for the humorous story, I'll have to share that with my sons. Unplugging the machine is especially important because the power switch may interrupt the neutral lead, not the hot lead as one would expect.

Oh indeed. I've heard stories from house inspectors who said that every building they check has at least one outlet with neutral and live reversed.

So, this story has taken an amusing twist:

I removed the cover and after 20 min head scratching and consulting the wiring diagram I become convinced that the problem was not with the pressurestat (my machine, it turns out, already has the newer industrial grade 'stat, and it tested ok with ohm meter).

Therefore I set to thinking what could make the machine believe that it has no water. This of course led to the water sensor thing under the tank. So I removed it, thinking it must be some cunning pressure or hall effect type thing, and perhaps was defective.

Imagine my surprise when I find that the screw terminals end in...well.. screws. Oh yes! They are detecting water by measuring its resistance. But every schoolboy knows for sure that pure water is an insulator. Could they be that dumb ?? After some more Google searching I have the answer : yes !

Then the penny drops. The problem was in fact caused by our cats. Read on:

Normally I feed the machine prime Costco 'drinking water' (with minerals added for taste, the small print says). However, for a recent trip away from home my wife had bought a number of large 'drinking water' bottles, to be used by the house-sitter to refill the cats' water dishes (well pump was turned off while we're away as an anti-pipe-freezing precaution). Now, upon our return the cats had not drunk all the water (cats drink puddles, snowmelt, whatever nasty liquid they happen to find on the garage floor, rather than the water you give them..). Therefore I was awarded the large gallon water bottles to be used in the Oscar. After a week or so, it stopped working. This water in fact is reverse osmosis processed, with no added secret sauce, and therefore is a good electrical insulator.

It turns out the Oscar water sensor is a tricky beast. It was unimpressed with tap (well) water. Also not moved by adding some ion concentration to the water (salt). It took the return to prime grade Costco water to persuade it to work again. You also can not trick it by shorting the terminals together (at least I couldn't).