Can anyone figure this out?

I have a new Rocket Cellini Evoluzione. It can take water from its built-in tank or be plumbed. I just plumbed it with a waterstop and a descaling filter. Now the machine is making a strange noise when the boiler is autofilling. It didnt do this when it took water from the tank. (It works okay however)
But its quite annoying since one of my reasons for choosing this machine is that it has its quiet rotary pump

My own suspicion is that maybe the water from the plumbing has too big a pressure. Could this be it?

And if so:
I guess in this case the solution would be some kind of water pressure regulator?
Does anyone know a good, cheap suitable device that can be bought online?
Does anyone know if the Rocket DVD that I asked about in one of the previous topics is addressing this kind of problem?

Could it be something else? the noise only comes when the boiler is autofilling - not when im brewing.

Fortunately it makes such a great coffee that i have been a happy guy since the day I got it though

eeffoc wrote:Could it be something else? the noise only comes when the boiler is autofilling - not when im brewing.

It sounds like the pump is cavitating. That happens when the pump attempts to draw water faster than the inlet pipe's flow rate (think of sucking on a very small diameter straw). Insufficient pipe diameter, a pressure regulator set too low, or filters can add drag and prevent the pump from drawing water fast enough. It happened to the Elektra A3 that I installed long ago; increasing the pipe diameter from 1/4" OD to 3/8" OD fixed it.

Hi Dan thx for the answer.

The water into the machine has to go through a 1/8 knob - is that what its called? to get into the machine. So maybe your right. I cant change this though!

When I was testing the water piping going to the machine it seems like its running fast as hell thats why i thought myself that it was the opposite problem?

If you can't increase the diameter of the inlet, you can always add an accumulator between the machine and its hookup. An accumulator is basically a tank with an inflated rubber bladder. When the pump calls for water faster than the inlet source can supply, water is pulled from the accumulator. Another name for the same thing is a water expansion tank, commonly used for water heaters and reverse-osmosis water filter systems.

I had what seems to be the same problem on mine when I hooked it up to line - a brief 'buzz' at the start of a brew cycle, and a constant 'buzz' when the tank was filling. The 'buzz' sounds a bit like a kazoo playing something like a middle-C note. Probably not great for the pump. The addition of a small accumulator on the machine side of my espresso filter cured the problem (as HB has already suggested).

Thx
Can you tell me what its called the device you put on. Brand, model? And do you know where to buy it online?

I am out of town right now, so can't provide you with any specifics. I had a professional plumber put it in and he called it an accumulator (aka water expansion tank, as HB said). Dan provided a link to these devices, so you might start looking around there and learn a bit how they work, and how to hook one up and where to hook it up. All I can say is on mine I did a complete overkill (I think) and put in a 2 gallon model but I think a lot smaller (like maybe 1/4th the size) would probably have worked fine also. They aren't very expensive - the plumber cost a lot more than the tank.

I'll be back in 2-3 weeks and can provide specifics then, if you still need them.

Regards

Martin

"Buzzing" does sound like cavitation. I occasionally hear a bit just after I flip my supply valve from main to tank, but not otherwise. The expansion tank referred to by Aldehyde serves as a accumulator, and is usually labeled "thermal expansion tank," after its use in plumbing: damping the pressure spike caused by expansion of the 40-60 gallons of water in a tank-type water heater when the burner cycles on. Even a smallish one like this 2-gallon model can make a big difference. In my house, before remediation, I was getting pressure swings from 40psi (normal pressure on the low side of my household regulator) to 100psi (pressure in city main). Not only is it hard on pipes and fixtures, but it wreaks havoc with the output of my secondary regulator for the espresso machine. Wanting super-tight control for the sake of the coffee, I installed an otherwise extravagant 5-gallon tank in the cold water line to the water heater, and my regulated house pressure now cycles between 40psi and 43psi - quite an improvement! As essential as these devices are with the tank-type heaters common here, they may not be useful with the "instant" types common in areas of lesser energy -ahem- profligacy, since they do most of their heating only after the tap is opened, which prevents pressure buildup.

To be effective as an supply accumulator for a pump, a tank needs to be between the pump inlet and any upstream restriction. Given the small volume (however great the rate) needed to fill an espresso machine boiler, a 2-gallon accumulator should be glorious overkill. If space is tight, there are much smaller units made by Shurflo, otherwise known for their bottle pumps. You could also locate the tank at a distance and connect via a pipe and a "T" fitting, but the longer the distance, and the narrower the pipe, the less effective it may be.

But before going down that road, I suggest you try to identify what might be so restrictive as to starve your pump. It could be a defective or obstructed valve, perhaps even one that was present before you made your hookup. Your filter could be too restrictive for some reason. Try filling a measured bucket from your supply hose while timing it. Remove/bypass any suspect part and repeat. In my case, I added a 1-micron carbon-block filter, and the flow rate from my supply hose plunged from 3 sec/liter to 20 sec/liter. I was leery, but my rotary pump seems perfectly happy with it.

One term used by the OP has me puzzled: "waterstop." If this means what I think it does, I'd like to throw a flag right now. My local stores sell "flood preventers," which are valves that are supposed to stanch extreme flows by slamming shut. Some are stand-alone, and some are integrated into faucets or supply hoses for washers and fixtures. I don't have enough experience to knock them all, but there are some that perform poorly under normal conditions: they restrict flow hugely (e.g. refill of a toilet: 5 minutes without, 20 minutes with), and if air bubbles enter the pipes due to an outage (or one of my projects), the bubbles trigger the valve, and to reset it you must relieve the inlet pressure to the valve, sometimes repeatedly. Oh, and that one I installed on my toilet, it was off and into the trash the next day.

Waterstop may be a backflow valve. Most cities require them to prevent water from backwashing into the city water supply.

. . . But before going down that road, I suggest you try to identify what might be so restrictive as to starve your pump.

An important point to say the least.

How about some pics of your water path installation? What does your brew pressure gage read after you have pulled a shot?