I initially thought of a dual boiler mod but since I actually don’t really want to go up this path and only want my grouphead to be a bit more stable at a lower temperature and if possible even be able to control it, I came up with this idea.
The change is to add a zoning valve between the boiler and the E-61 group with a bypass. The valve needs to close when the grouphead reaches the desired temperature and the bypass should be the right size to keep it at the desired temperature.
Actually my attempt is going to be much coarser as I want to use a Normally Closed valve and to get it to close below the desired temperature and let the bypass heat the grouphead a bit higher then my desired temperature. In this way I want to reduce a 6+ oz of flush to 1-2 oz flush and to slow down the heat back.
As a starter I will only install a manual valve and keep my machine on 24*7 so I can measure the grouphead temp. In this way I should be able to reach some balance between the grouphead temp and the valve setting.
Did anyone every try this plot or has any comments?
I need information on what valves I can use and on how to measure the grouphead temp.
This is the schematics of the HX espresso machine with the change I want to try out -
Posted Sun Feb 12, 2006, 6:38pm Subject: Re: Stabilizing an HX machine’s grouphead
If you are finding the amount of flushing required is massive and the rebound is too fast, then you can get a flow restrictor placed in the E-61 thermosyphon loop to reduce the overheating to a more manageble level. A friend with an Expobar Lever got his supplier to do this for him and it reduced his flush requirements greatly and increased the stability of the group temp as well.
Posted Tue Feb 14, 2006, 7:45pm Subject: Re: Stabilizing an HX machine’s grouphead
I think your idea is a sound one for reducing the temp of the group.
Trouble is, the group temp is only part of the picture. The water in the HX in the boiler quickly reaches the same temp as the rest of the boiler - too darn hot. Pulling a shot will send that superheated water straight to the filter basket.
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