Quick Mill Verona (Quick Mill Vetrano Dual Boiler in the US)
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There have been reports of US users experiencing pump noise when using this machine, this takes the form of a momentary cavitation sound, it's usually a less than 1 second harshness in the sound. This cavitation should not cause a problem in long term use, but can be annoying. I understand that no UK users are experiencing this and can only attribute that to the shipping constraints (shipping with empty boilers), or perhaps the boilers not being completely full at the factory. There are difference in the US and UK variants, but these are simply the voltage, portafilters supplied, LED lights and a few other features, the basic plumbing and operation of the machine is the same for both countries.
I need to stress here that this procedure is for the UK Verona, should any users be experiencing problems, US users using this procedure, do so at their own risk and should ideally contact their reseller before doing this, as their warranty may be affected. I also must stress that this has not been discussed with or authorised by Quickmill themselves. Any damage a user may cause to their machine (in whatever country they are in, is their problem). So that's the disclaimers out of the way, on to what I believe is the cause of the problem.
I was not getting this fault with either of the 2 Verona machines I had (pre and post production models). I attribute that down to the fact that these machines were built specifically to send to me and individually freighted with no delays or special procedures after the factory tests and boiler fills. After reading on the Coffeegeek forums about this problem, I could not understand what was so different, that they would get the problem and I didn't. Then I remembered some issues with other dual boiler machines from La Spaziale and Izzo, where this problem also sometimes occurred, but only under specific situations. These were specifically:
- Air in the boiler - Duetto after changing heating element
- Priming against a hot boiler (La Spaziale Vivaldi S1) - I must stress the La Spaz was not designed to operate off a bottle on the counter top, probably for this reason
In both cases, this particular pump cavitation could be heard and it's slightly different to the one where the pump sucks air, then water. If the brew boiler gets an air space inside, this can cause this particular cavitation problem as the pump forms voids in trying to pump/prime. In a boiler without air, there might be some static Hydraulic pressure in the boiler caused by the expansion of water. This may initially climb to 11.5 bar or whatever the expansion valve is set to, then as the valve lets water out, this pressure slowly drops and will usually settle at about 0.5 or 1 bar. This happens because on a full boiler the pressure is a static hydraulic pressure and even if a few drops are let out, this pressure drops to nothing. When you have an air space the situation is different, it's like a spring (it's compressible) and a few drops of water will not reduce this pressure at all. See http://en.wikipedia.org/wiki/Hydrostatic_test for more information if you are interested. When you lift the lever, if their is air in the boiler, the pump is working against compressible medium under pressure and for various reasons it's this which causes the noise as voids are formed within the pumps chamber. I am not going to go into any more details than this, but there is lots of manufacturers documentation and information on the web, which you can seek out to understand the phenomenon better.
I induced the condition so that it was happening almost all the time in my machine, by repeatedly, lifting and lowering the hose into my water tank while the pump was running to introduce air into the brew circuit (lots of it) and I suddenly had the Grr noise every shot (after a short break)…I had plenty of air. You might wonder why doesn't it happen in the steam boiler, plenty of airspace in that….well the airspace is much larger and only under 1.5 bar pressure.
This is the important bit, if you got this noise what should you do. here there are 2 solutions depending on how bad it is.
- If it's infrequent and very brief, you might just want to do nothing and in a few months any air will have been absorbed and the sound will go away. You might want to think about why it happened in the first place and ensure your float never sticks and that you use good quality water.
- If it's really happening a lot and just annoying the hell out of you, then carry out the procedure below at your own risk.
Equipment you will need
- Screwdriver for opening up machine
- 11mm open ended spanner (everyone's got one somewhere)
- Syringe and needle thingy or small tube, those things you use for filling print cartridges are ideal (or go to the local pharmacy, convince them your not a drug addict and ask for one)
- Cup of water
- Paper Towel
Unplug the machine
Remove the top cup tray (it just lifts out) and remove water tank. Remove the 2 screws that hold the water tank carrier in place (they're at the top front of the machine). Then at the top of the back panel, you will see 2 more screws, remove those. Reach your hand down the left side and near the bottom of the panel form a fist and press against the back panel as you make the fist, it will pop free of the lower retaining pin, move to the right hand side and repeat. If your fist is small, bulk it out with a tea towel. Lastly remove the screw in the middle which holds the water tank carrier in the machine
Lastly remove the screw in the middle which holds the water tank carrier in the machine
Now don't disconnect the water tank carrier, just move it out of the way, because you need it connected.
Find the brew boiler and the small capillary pipe and nut that is on the top of the brew boiler, leading to the pressure gauge. Use the images below to help you. Each image can be clicked to see a larger version and each one has been annotated.
Essentially, you undo the brass nut sealing the capillary tube flange to the brew boiler with the spanner. When the nut is undone don't let it slide down the capillary tube, it will be a ball-ache to get to it and pull it back up. very very gently, lift that little sealing flange things on the end of the capillary tube away and to one side (try to move it as little as possible). Grab your handy dandy syringe, fill it with water and inject it in said hole until its full. Lift the group lever and wait 1 minute, then lower the group lever and refill. You should do this a couple of times more for 15 seconds each time. The reason for this is the water level will go down as water drains through the top brew valve in the group (it's why you need to refill) and it's my way of getting any trapped air pockets. it's probably unnecessary, but do it anyway.
carefully ease flange back onto pipe, lower nut onto thread and with fingers tighten as far as possible. Now tighten the brass nut with the spanner…be gentle, this only needs nipping up, DO NOT BE HAM FISTED..BE GENTLE. Mop up any water from top of boiler with paper towel.
OK you are done, just a quick check that it's not leaking, put water into water tank, stand carrier up as best you can and place tank in it so the float detector is working. before you place tube to pump in tank, hold upright,take syringe and ensure it's full. We don't want to get any air back in there do we.. This bit, be careful and at your own risk. Plug machine in, switch on, place a blind filter in the group and with lift brew lever. Use a Torch to check that the nut you tightened at top of boiler isn't leaking. Lower brew lever.
That's it, your done. The machine might make 1 or 2 Grr noises, probably because it's angry you fixed it, mine made noise one time, but after that it's been fine.