Hm. This is a puzzle, and I do like puzzles.

Do you get vigorous boiling water from the group head (aside from the readings), or does it just pour out?

Aside from the likely inaccurate thermometer, assuming that it is giving relative readings, the group temperature should not be a lot cooler than the boiler water when first run with an unflushed HX.

I was pondering how this could be, and I finally found a diagram for this machine (well, the BZ99, but the BZ99 and the Livia 90 are the same, according to many searches). Refer to
http://bezzera.it/pdf/BZ99_GB.pdf

Page 11 has the boiler on it.

The HX is a cup shape, with fresh cool water entering from the top (via part #4, 5) and hot water leaving from the bottom through a dipper tube (part #2).

What if this dipper tube had corroded off, or developed a hole, or failed in some other way - you would have cold water entering at the top and leaving at the top.

Have you looked inside the HX?

I just verified that the thermometer is accurate by boiling water on the stove, I got 210-211F.

Comparing my Livia to the diagram, it does look like the hot water to the grouphead comes from the dip tube. I have not opened the HX since re-assembly since it requires replacement crush washers that I don't have more of.

On a cooling flush, I got 195-200F water (hard to measure since there is some steam and it's coming from the group), but it fairly quickly comes down to 165-170.

My bad, the diagram on pg 11 is up to 2006, after 2006 they moved the dipper tube to the output.

I would suggest that either the water isn't vigorously boiling at 205 when it comes from the boiler, or something else is going on. Unless your atmosphere is mighty thin, you ain't gonna get boiling water at 205 degrees.
Either that or your thermometer doesn't react very quickly, or your methodology for measuring a stream of water is flawed.

There's a difference between measuring a pot of water and a stream of water. It isn't so easy - are you using a bead thermocouple which will get you instant response, or something with a bit more thermal mass?

Something doesn't add up.

I am using a thermapen. It's not perfect, but it is fast and accurate. Even assuming the boiler water is at ~212, isn't that 40deg lower than it should be? And the grouphead water is definitely dropping to 170 within a few ounces.

Yes, but if you get vigorously boiling water spouting from the boiler, then SOMETHING must be driving it out, not the pump - and it wouldn't be boiling if it were < 212 degrees (give or take a little). Hence my statement that something doesn't add up.

If you do get vigorously boiling water shooting from the water tap, then I assert that:
#1 - there must be steam pressure in the boiler
#2 - the water must be > 212 degrees or so.

I don't think this has been covered, but is the vacuum breaker working properly? If not, then you'll read high pressure, but low temps. Try the following - purge some steam from the steaming wand. If you get air hissing out, followed by steam, and the boiler pressure on the gauge drops rapidly, close the wand and wait for the pressure to come back up again. Then measure the water temps. If they're up to where you expect they should be, then you likely have a stuck vacuum breaker and a boiler full of compressed moist air, not steam (until you purge it out the steaming wand).

allon wrote:Yes, but if you get vigorously boiling water spouting from the boiler, then SOMETHING must be driving it out, not the pump - and it wouldn't be boiling if it were < 212 degrees (give or take a little). Hence my statement that something doesn't add up.

I would think it would still be driven out at ~205, no?

I've verified that the vacuum breaker works.

I'm going to try to attach a different pressure gauge this week.