I will ask, just in case, is it pumping water? I know my Fluid-O-Tech gets real noisy when the supply line is turned off (as in forgetting to turn the valve back on after doing some sort of maintenance which requires closing the supply valve).

Mitch -

Exactly what pump did you order/install? The EP website - http://www.espressoparts.com/cgi-bin/ep.pl shows a Hydropure pump rated at 140 gallons/hour (gph) and the Hydropure website shows pumps going down to 16 gph.

140 gph = ~147.2 milliliters/sec ; 16 gph = ~ 16.8 milliliters/sec. The AVERAGE flowrate during espresso production is ~ 3.0 milliliters/second. Yes, sometimes you need to fill the steam boiler - hopefully not during the event. Lots of water is being bypassed during normal operation = a good source of noise. I do believe you would have been better off with the "baby" pump.

edit - this is the pump manufacturer that Hydropure uses - http://www.nuert.com/espresso-machine-pumps.php

In the event you do not know this, Hydropure is your next door neighbor - http://www.adernet.com/hydropure/index.html - well, maybe . He SEEMS like a real nice gentleman of Italian descent and may very well be a faster route than going back to EPNW. Maybe refer him to this thread and mention that you "talked" to me.