RapidCoffee wrote:Rich claimed general agreement on "a preferred intrashot temperature profile for a given mix/roast", and I disagreed.

Again, I apologize for any lack of clarity. What I meant was that we could come to agreement on some "preferred intrashot temperature profile," or even a best "intrashot temperature profile" which might eventually be determined.

I]d intentionally avoided the term "best" because its an absolute. And only use it hesitantly here, because words begin to fail me. I similarly stayed away from the term "ideal" because of its absolute nature and Platonic associations. Please, let's not do Plato. Or Boethius. Please.

This goes to several of the reasons leading to the suspicion LM has not yet designed the beau ideal of a coffee maker, no matter how far the GS3 advances the SOTA. Inter alia, 1) The search for the "best" profile still demands a certain amount of hit or miss on the part of the user; and 2) The GS3 does not, that I am aware of, allow much control over the intrashot profile -- rather its tendency is towards the flat. There are those who are unconvinced that a flat profile is the best profile for every possible blend/roast. Personally, I don't know enough to consider having an opinion, much less stating here. However, whatever the best shape is, an ideal machine should allow the user to determine, then lock it in.

Rich

My GS3 has developed a fault and I will ring the technician on Monday.

Hot water is flowing back into the water reservoir situated under the machine.

The first thing we noticed this morning (Sunday) was the pump cycling every 90 secs or so for about 2 secs. So after making 2 cups each so we could face the day we took the sides off to have a look. There was no water visible anywhere inside the machine. We could see air bubbles in the PVC pipe between the pump and the water reservoir moving towards the reservoir. The water in the reservoir is very hot and has obviously returned from one of the boilers. The reservoir has continued to slowly fill with the machine off.

Would anyone know the most likely place for a valve failure? Does the pump prevent the back flow from the boilers or is there a valve associated with each of the boilers?

Rosemary

I know this might be somewhat late, but how the heck was that hole even possible?

My family has been engineers and craftsmen for many generations now, and looking at that hole and knowing it exists on a 3000 € machine tears at the very core of my being. I would have scraped the whole frame after making such a mistake, or if not, at least plugged the hole with a piece of steel welded in place. And even then that mistake would have haunted me for weeks. I mean, even the hole on teme's machine makes me wanna cry.'

My advice, tear those evil men (I'm referring to the ****s****rs that haven't sent you 2 new machines already) apart! If you don't do it, I will!

I am hoping a new machine may arrive before the end of the month but I haven't heard anything more from Allpress. But obviously I don't want to be without a machine until then as it unusable as it is. The reservoir tank overflows and the PVC pipe kinks with the hot water flowing back through it.

Finland is far closer to Italy than I am. Please feel free to drop into Florence for a "little discussion". The tally is now 2 major faults on top of the poor workmanship (holes).

Rosemary

Rosemary wrote:My GS3 has developed a fault and I will ring the technician on Monday.
Hot water is flowing back into the water reservoir situated under the machine.

<snip>

Would anyone know the most likely place for a valve failure?

It has been two years since I looked inside a GS3...but isn't there an adjustable expansion valve for the brew boiler at the front of the machine on the lower right? Sounds like it needs tightening; the valve normally shouldn't pass water until the boiler pressure reaches about 12 bar on the front gauge. If your right hand gauge doesn't creep up around 12 bar between shots, it's probably this valve out of adjustment.

Hi I don't think it is to do with the expansion valve as the water is flowing backwards from a boiler through the pump and on through the PVC pipe back into the reservoir (not into the drip tray). This PVC pipe normally feeds cold water from the reservoir through to the pump.

Thanks Rosemary

Rosemary wrote:Hi I don't think it is to do with the expansion valve as the water is flowing backwards from a boiler through the pump and on through the PVC pipe back into the reservoir (not into the drip tray). This PVC pipe normally feeds cold water from the reservoir through to the pump.

Oh, sorry for the dumb suggestion I made.

It sounds like there is a malfunctioning check valve ("one way valve") that is failing to prevent water from flowing backwards through the pump and into the reservoir.

Hi Andy

Any idea where the check valve may be? I presume there is one for each boiler? Is there also one with the pump?

Thanks Rosemary

There may be a check valve mounted right on the rotary pump, it may be a little tricky to get to on this machine.

Thanks. I'll be phoning Allpress tomorrow morning. It's always good to have an idea of what it may be when talking to them.

Rosemary