Hello.

I am considering an upgrade to the La Cimbali Junior DT1. My previous machine was a tank machine, so water hookup will be a new feature.

I have a water softener to our entire water system, then I have an under-sink reverse osmosis filter. But, the pressure coming out of the RO filter is very low. Takes 30 secs to fill a tall glass of water.

Would low water pressure matter for the DT1, or should I by-pass the RO filter and use an in-line filter?

Thx.

You need an accumulator tank for the RO system if you're going to use it for this purpose, and you'll still have the issue that RO'd water likely will not work properly due to the low conductivity not tripping the boiler's "I'm full" sensor.

Rotary pumps pulling against a vacuum are not a good thing and I'd bet on it being damaged.

I'd be inclined not to do that and instead put a traditional filter inline from the cold supply, since you already have a whole-house softener.

this is a really good question!

What kind of pressure is typical for home water pressure after an inline carbon filter?

What does a machine with a rotary pump (oh, say an Elektra Sixties A3) require in terms of incoming water pressure?

I used RO water in my old 3 story house in Massachusetts (for fish). I'd moved my RO unit out from California, where it ran fine from the city water pressure, but I wasn't getting enough pressure to get any real volume from my RO system, until I had a plumber hook up an inline electric pump designed to increase water pressure. I think the whole deal was about 500.00. It was a really old house on top of a tall hill, so we had everything possible against us water-pressure wise.

Now I'm thinking that something like an RO unit requires a lot more pressure than an inline carbon filter - but I know a flojet (one of those pumps you stick in a 5 gallon bottle) creates about 30 psi.

Does anyone have any experience with this here?


Ann

You just need enough to keep the pump from cavitating. Pumps like this are likely positive-displacement and can't run "dry", or are impeller-based and cannot self-prime (and also are destroyed by running dry.) Bubbles in the incoming water flow (which occur when you pull a vacuum or close to it) cause erosion in the pump and/or damage to the seals.

For output pressure stability you probably also want a regulated input pressure......

Genesis wrote:You need an accumulator tank for the RO system if you're going to use it for this purpose, and you'll still have the issue that RO'd water likely will not work properly due to the low conductivity not tripping the boiler's "I'm full" sensor.

Rotary pumps pulling against a vacuum are not a good thing and I'd bet on it being damaged.

I'd be inclined not to do that and instead put a traditional filter inline from the cold supply, since you already have a whole-house softener.

I can say with certainty that even distilled water with TDS of 2 or 3 parts per million (RO normally gives from 10-40ppm TDS), allowed espresso machines autofill to operate correctly. I tried this out on a number of test machines, but have no reason to believe it won't work on the majority of them as the probe technology is the same.

It definitely works on: all prosumer Expobars, Izzo Vivi, Izzo Alex, Andreja Premium and another I can't remember the name of (in fact Expobar even recommend using distilled water in their own userguide!).

The rotary pumps usually need a pressure not exceeding around 3 bar and normally pressure is regulated below this on commercial machines. If you consider a machine like the Izzo Alex, which uses a rotary pump to draw water from a tank, this runs with very little if any positive pressure. The main thing is that the pump can "draw" what it needs from the tank. The pressure from the average small 3-4 gallon RO "accumulator tank" should not really pose a problem (even though it will only be around (0.5-0.75 bar). The main thing to be concerned about is the flow rate e.g. can the flow from the tank keep up with demand from the pump. Again in all likelihood this will not be a problem.

I would be seriously inclined to try it, by purchasing a small RO "accumulator vessel" and plumbing directly into that. The worst that can happen is your pump dies (unlikely) and they are not expensive (I think an Alex rotary is only £40). I only use RO water in my Alex and it's very nice not having to worry about scale and other varnishes etc.. contaminants in water affecting my machine...or the taste of my coffee.

You will read that coffee doesn't taste as good using RO water vs tapwater, but our water is so crap with so many additives (fluoride, chlorine etc..) that it smells like ditchwater, so really the taste of my coffee has improved immeasurably..