Thanks Randy - that's a good idea - I'll try swapping them too.

tekomino wrote:Yep, definitely check pressure. High pressure will make "sharp" tastin espresso with aftertaste. My palate is for some reason very sensitive to this and I taste it without fail...

Just to make sure I got this right....

Am I increasing or decreasing the pressure?

Does increasing the pressure also increase the temperature?

THanks Danny

The temperature is controlled by the thermostats. The pressure relief valve sets the maximum pressure that can be developed in the boiler, and thus in the entire brew path. A change in OPV setting will have little effect on brew temperature in that machine. If the taste is harsh, biting, sort of "rude," and as tekmino said, sharp, then lower then pressure a little. You may have to do that a few times to find the best setting. Another guideline is that if you have to grind finer with the machine that is delivering poor espresso, then the pressure is too high.

I keep forgetting that single boiler machines don't have p-stats. I've been an HX guy for so long, you see.

Still, the problem might be brew pressure related or might not.

In any case, it's always a good idea to check on brew temps, because it's such an easy, and consequence free thing to check. For another, boiler pressure and brew temperature are interrelated. PV = nRT and all that.

If, as I infer, the brew from the problematic machine is too bitter, your temp is probably too high. Instead of waiting 30 seconds after the light's gone out try 1 min, 15 sec; then try 2 minutes. See if a cooler temp doesn't get you closer to the sweet spot. If not, you can adjust the pressure with nothing lost but a little time.

BDL

Hi guys,

I owe you all a huge thank you - especially Randy!!!

I just swapped over the brew thermostats - and that was the difference.

As soon as I swapped them over the good machine started making yucky coffee. and instead of switching off after 55 seconds, went down to 45 seconds.

The bad machine started making good coffee - went to 55 seconds before switching off - and i could increase the amount of coffee in the basket from 13 grams to 14 grams.

On Monday, I'm going to buy a new thermostat!!!

Once again - thank you so much for the helpful advice - I was at my wits end with the machine!!!

Danny

on a side note...

I was looking at this article - to find out how to change the thermostat.

http://www.wholelattelove.com/articles/ ... cement.cfm

In it, they say that the thermosat on the left is for the brewer. until the new one arrives, I thought I'd change the dud one accross from the brewer position, and put the other good one in the brewer position. It works - but still didn't come up to a proper temp - and switched off after 45 seconds. Oh well - I guess I'll have to wait till the new one comes.

I'm glad you figured out the problem!

You know, you COULD just PID the machine..

Randy G. wrote:1 - The Silvia does not have a pressurestat.
2 - Try swapping the brew thermostats and see if you can get the good machine to perform poorly that way.
3 - Adjust the pressure relief valve.

I was going to say it could have something to do with the thermal dead band differing between the machines due to differences in the thermostats (if that is possible).

It is a hassle, but try porting the grinder and coffee between the machines, along with the water sourced from the good machine. The more variables you can keep the same when testing will make it easier to make changes which could help ID the source of your problem.