Hi,
I bought a Conti Comocafe from EBay:
http://cgi.ebay.com/ws/eBayISAPI....=1&item=4461320633

Contrary to the auction text, the "pump" does not work.

There is a one-way valve in the cylinder that draws water from the kettle. The problem is that it returns water as well. I am having a difficult time fixing it. I tried to draw an image of it in a drawing tool but gave up, so I will describe it (but I imagine it is a common design).

At the bottom of the cylinder there is a channel drilled to the kettle. Above this lies a disc with 8 holes around the center (which seals around the circumference with an O-ring). It screws in with a special sort of screw that has a slot in the head for the sealing washer. The center of the washer is raised so that the outside of the washer lies flat with the disc. The washer also has 8 bumps that fit into the 8 holes in the disc. (FWIW, the bumps are much smaller than it looks in the photo below. I'd guess they're 0.1-0.2 mm tall.)

The O-ring was easy to replace, but I tried replacing the special raised washer with 8 bumps with a regular washer, and it didn't quite work. I tried putting the washer inside the slot in the head as well as below it.

Any advice? I could somehow put a one-way valve on the kettle side of the channel, but I'm not sure where I would find a small one (or how to build one).

Bottom of disc:

Top of disc, bottom of washer and screw:


The old washer doesn't even look that bad to me, but it is not doing its job.

Thanks,
-Paul

Ahhhh. We wondered where that machine went Saw it on ebay also... You need Timo--------Timooo, are you out there??? I bet you can help out the Como owner!

I'm thinking maybe of ordering a generic check valve--the other end of the channel comes into the kettle through a metal tube with about a 1/4" diameter. The only problem is that the only NSF-rated check valve from McMaster is huge ...

mogogear wrote:Ahhhh. We wondered where that machine went Saw it on ebay also... You need Timo--------Timooo, are you out there??? I bet you can help out the Como owner!

I took a Tylenol PM for a headache and my lids are drooping. In my drowsiness I'm having a hard time following Paul's description of how things fit together. I need to see how the washer is fastened to the metal disc. Paul, if you could provide a picture of the washer + disk assembled and oriented in their actual direction, and also a picture of everything taken apart, so that the screw is not in the washer. Like an exploded parts diagram. I need to see the diameter of the screw head and how it holds the washer in place against the disk.

Also, is the kettle above the disk? Where is the piston cylinder in relation to the bottom of the kettle? Directly below it?

Also, if the washer cracks when you flex it between thumb and fingers it has lost its pliability and won't work. The one-way washers must be able to cleave to the portholes to seal them when the piston advances, and be able to pull away from the portholes when the piston retreats. Also, make sure there's no lubricant on the flat surface of the head of the piston. Wipe the piston head clean.

Regards
Timo

timo888 wrote:I took a Tylenol PM for a headache and my lids are drooping. In my drowsiness I'm having a hard time following Paul's description of how things fit together.

No need for excuses My technical writing ain't the best.

timo888 wrote:I need to see how the washer is fastened to the metal disc. Paul, if you could provide a picture of the washer + disk assembled and oriented in their actual direction, and also a picture of everything taken apart, so that the screw is not in the washer. Like an exploded parts diagram. I need to see the diameter of the screw head and how it holds the washer in place against the disk.

I hope that helps. (I need a new digital camera, too.)

Ascii art?

--- <- head of screw
| <- gap for washer
--- <- disc that holds washer from below (part of screw--not separate)
|
| <- threads
|


The point is that the washer is not screwed into the disc directly. It is held in place only by the gap in the head of the screw.

timo888 wrote:Also, is the kettle above the disk? Where is the piston cylinder in relation to the bottom of the kettle? Directly below it?

The kettle is above the disk and the cylinder. The entire cylinder is below the bottom of the kettle. (and about 1" behind.)

timo888 wrote:Also, if the washer cracks when you flex it between thumb and fingers it has lost its pliability and won't work. The one-way washers must be able to cleave to the portholes to seal them when the piston advances, and be able to pull away from the portholes when the piston retreats. Also, make sure there's no lubricant on the flat surface of the head of the piston. Wipe the piston head clean.

The washer doesn't crack. It is not cleaving to the portholes, though.

Also--I think perhaps you are misunderstanding something--the piston head doesn't touch the disc at all. The disc remains stationary. It fastens to the bottom of the cylinder. When the lever is pulled, the piston is raised, drawing water through this check valve. Then when the lever is released, this check valve is supposed to seal, and the water goes out through another channel to the group. (and another valve which seems to work so far.)

There was some scale on the disc that deformed the washer slightly. I removed the scale and sanded the surface of the disc. *shrug*

I greatly appreciate the help, and I hope this post makes the situation more clear.

After last night's headache and Tylenol PM, I'm not as bright eyed and bushy-tailed as I ought to be
I am still confused about which way is up.

The solution depends upon the orientation of the piston.

Peppina's piston is base-mounted so that the piston's downstroke is actually advancing towards the ceiling. It looked to me as if the Conti had a similar base-mounted piston, but I've never seen one opened up. If the Conti's piston were base-mounted, then the one-way valve assembly ought to be flipped over so that the washer is below the disk with the flat side of the disk facing down.

So we need to confirm the orientation of the piston. I'm fairly confident that it should be like this if the piston is base-mounted (but would feel more confident if I were looking at the machine opened up)

CEILING
.
.
.
RAISED NIPPLE OF METAL DISK
FLAT SIDE OF METAL DISK with portholes and center tap
Washer
collar on screw to press washer tightly against the flat surface of metal disk
screw head

V PISTON ^
V PISTON ^
V PISTON ^
.
.
.
.
BASE

COUNTERTOP

I think the washer fits between flat face of the disk and the collar of the screw. But I'd need to see a closeup.


In a base-mounted piston with a one-way valve assembly between the piston and a kettle above, when the piston retracts (with the downstroke of the lever) the piston head is moving away from the one-way washer and the suction would pull the pliable washer down away from the portholes, allowing water to flow into the piston chamber. When the piston advances, the washer would be pressed back against the portholes, sealing them, forcing the water to exit under pressure by some other port to the group.


Regards
Timo

timo888 wrote:The solution depends upon the orientation of the piston.

So actually the piston is mounted to the top of the machine.

So, timo, everything is exactly upside-down from your description.

ceiling

piston

port to group

washer

disc

port to kettle

bottom of cylinder


The piston initially is very nearly touching the washer. When you pull the lever, the piston is raised, drawing water into the cylinder. When the lever is relesed, the piston lowers, forcing water out the port to the group.

When I remove the valve and look at it closely, it looks like there is a slight gap between the washer and the disc, i.e., it is open. I thought perhaps it funcitoned like a vacuum breaker (and could be open at 0 pressure). But perhaps that's further confirmation it's broken.

I concluded that the piston cylinder ran from the base of the machine up to just below the kettle, offset back from it by about an inch, based on your earlier statement:

PaulTheRoaster wrote:The kettle is above the disk and the cylinder. The entire cylinder is below the bottom of the kettle. (and about 1" behind.)

PaulTheRoaster wrote:So actually the piston is mounted to the top of the machine.

So, timo, everything is exactly upside-down from your description

If the entire cylinder is below the bottom of the kettle, how can the piston be top-mounted and be above the kettle

Paul, have you been feeding me disinformation intentionally Have you been sent here by the HX contingent to mess with my mind?

Where is the piston head in its fully extended position? Just above the washer?

If your latest word-diagram is accurate

PaulTheRoaster wrote:ceiling

piston

port to group

washer

disc

port to kettle

bottom of cylinder

water is being sucked up from the kettle and we'd have to remove the Conti from the list of gravity-fed machines.

Pictures of the machine taken apart, so the piston is visible, would be helpful.

Regards
Timo

timo888 wrote:I concluded that the piston cylinder ran from the base of the machine up to just below the kettle, offset back from it by about an inch, based on your earlier statement:

That's right.

The kettle is above everything.

There is a channel at the bottom of the cylinder that goes to the kettle.

timo888 wrote:f the entire cylinder is below the bottom of the kettle, how can the piston be top-mounted and be above the kettle Confused

Paul, have you been feeding me disinformation intentionally Question Have you been sent here by the HX contingent to mess with my mind? Smile

Where is the piston head in its fully extended position? Just above the washer?

Heh, I have not been sent here by the HX disinformation team

So ... the entire cylinder, piston, and check valve are below the kettle, but oriented upside down from the peppina.

In the fully extended position, the piston is just above the washer.

When you pull the lever, the piston is retracted.

timo888 wrote:water is being sucked up from the kettle and we'd have to remove the Conti from the list of gravity-fed machines.

Pictures of the machine taken apart, so the piston is visible, would be helpful.

The water is sucked down .... since the entire cylinder is below the kettle.

I will take some pictures later.

Mathias has some nice pictures: http://lm.steen.free.fr/html/photo_gallery-1.html but not of the piston and cylinder.

It looks as though the gravity-water-pressure from the kettle above fills the piston chamber, assisted by the hydraulic suction of the upwardly retreating piston-head. Then, with the chamber full of water, the piston advances downward, and water exits through the group port. If this is the case, then the one-way valve assembly should be positioned like this:


Screw head
collar
washer
flat side of disk with holes
nipple side of disk with holes

Is that how you have it?

When you say it doesn't work, what are the symptoms?

No water or feeble water stream at the dispersion screen?
An airy whooshing sound as the piston retracts?
A airy whooshing sound as the piston advances?

Is there a one-way valve to prevent backflow from the puck? If so, and it is not functioning, when the piston retracts, air would be sucked into the piston chamber through the port to the group; this would reduce the upward suction upon the one-way washer between piston chamber and kettle, and so tend to prevent water from being pulled up into the chamber.


Regards
Timo