Hi guys,
I'm new to HX and trying to dial in my shots. I've ready everything I've found on flushing times and temperature but I'm still confused about the temperature profile I should be shooting for.

• Machine pressure set to 1.25 bar
• long idle temp is 208.5.
• RedBird espresso; 18g in 34g out in 34 seconds
• group head temperature peaks at 214.5 during flush,
  stop the flush at 209
• 203 - 202 during shot.

I took a video that I'd love you guys to critique. Thanks for the help!
Jim

How's the taste? Is it bitter?

You are on the upper range of extraction temperature.
Although this should be adjusted according to taste.

Range is about 90*c to 96*c (194-205F). That 214 peak is quite high. 205 starting temp is also probably high.

Based on the 20 second flush you perform in the video, it seems you need to lower your boiler pressure. I'd lower it by 0.1 increments and see how it affects your flush lengths and extraction temps.

Other than that, the extraction looks pretty good. You could loosen the grind a bit and see how a different 25ish second extraction taste.
Eventually, you can try playing around with preinfusion too.

Cheers!

Thanks for the response. Shot was a little on the bitter side perhaps. I'll lower the boiler pressure to 1.15 and try starting the shot closer to 202 rather than 205. Thanks again

Folks with E61/HX may chime in on boiler pressure / flush and brewing temp at some point but it's seems like it's been a little quieter lately on here. Understandably.

If you're still flushing an big amount of water in order do get your group to your desired brewing temperature, I would keep lowering the pstat. A friend of mine has his Cellini pstat set to 0.7-0.9. Steam is obviously not as strong but it all depends on the user preferences.
You have the advantage of having a 2.2L boiler which holds plenty of steam!

This is posted here somewhere. I don't know if you've seen it but it's a great chart for simple espresso dialing:


Cheers!

I flushed more water and started the shot at an indicated 203 on the group head thermometer. Temp dropped to 200 - 199 over the shot.
Reading Eric's thermometer guide I think that should be about 196 - 197 at the puck. Tasted ok not great but the flow was also a little fast. I'm opening up the machine tonight to drop the pressure .1 bar.

I don't think you should have to drop the pressure.. There is a recent video on WLL that says for Vibe pumps you set the pressure at about 10 bar on your front dial to get 9 bar throughout.. I've lowered mine to 8-8.5 bar.. but likely you don't need to go less than that..

On my HX, the temp I start at is about the temp of the brew water at the puck.. So if I start at 200, it spikes up to 206-207 (puck doesn't see the spike as the E61 thermal mass sucks up the peak), and levels off at to 205 about 15 seconds in and 203-202 at the end. The puck sees about 200.. The thermometer is about 5F high at 15 seconds and about 3F high at 30 seconds. (verified by SCACE on my Pro500HXPID; the scace also verified the initial spike is not seen by the puck).

If flow is fast, grind finer, don't lower the pressure as you'll be adjusting pressure for every different bean. Setting the boiler steam to 0.7-0.9 will likely give pretty weak steam as once the steam want is full opened the steam will drop to under 0.5 bar..

I would not lower the pressure below 1.1bar. But a med-dark espresso likely does better at 198f than 202f.. So you might need a good flush before you start the shot. I'd flush for 3-5 seconds and you should find that the group temp drops over 2-3 min. then rises again.(Clive recommends a 7 second flush on the Pro500 HX.. but I don't do that long a flush) Pull when it rises and hits 197-198. You might need to flush longer on your machine.. they are all unique. HXs are a bit notorious for wasting water. Since I only drink about 2 espressos a day, I turn on my machine 30 min before I want my drink. At this time, my group is about 195 & rising.. at which time I prep and pull shot. When you do multiple shots, the first shot will cool the water and so you likely won't need to flush between the multiple shots. If you are getting 203-202 during shot.. your puck is likely seeing 198-200.

I've come to the conclusion that the HX design was really for commercial use when shots were being made one after the other and so the group didn't super-over-heat from sitting and they were plumbed in so flushing wasn't a concern. Newer PID HX designs have attempted to reduce flushing.. but I am not sure they are entirely successful. I've actually found that making my coffee as the machine is heating up is one of my best strategies for getting the right brew water temp without wasting a bunch of reservoir water.. I keep the steam pressure up because I like milk-based drinks in the morning and the higher steam pressure allows better micro-foam.

Edit: just watched your video.. You are using a "flush n go" technique. I use the "flush n wait" .. When I said the group thermometer was 3-5F higher than the puck, this was for a 'flush n wait'.. You can read about 'flush n go' but I'd recommend using a 'flush n wait technique'.. flush for 7-10 seconds and see what the group does.. I should dip then rise (may take up to 3 minutes).. Get shot ready in this time.. Pull shot when group is rising and hits 197 and see what your temp is during 15-30 seconds of the extraction. Puck will see about 3-5F lower. Unless you have a SCACE to calibrate your 'flush n go' technique, your group thermometer reading may not conform to the "3-5F" higher theory. Sort of confusing and weird.. and I don't understand it fully, but there are lots of posts on it at HB.

Bluenoser wrote:I don't think you should have to drop the pressure.. There is a recent video on WLL that says for Vibe pumps you set the pressure at about 10 bar on your front dial to get 9 bar throughout.. I've lowered mine to 8-8.5 bar.. but likely you don't need to go less than that..

On my HX, the temp I start at is about the temp of the brew water at the puck.. So if I start at 200, it spikes up to 206-207 (puck doesn't see the spike as the E61 thermal mass sucks up the peak), and levels off at to 205 about 15 seconds in and 203-202 at the end. The puck sees about 200.. The thermometer is about 5F high at 15 seconds and about 3F high at 30 seconds. (verified by SCACE on my Pro500HXPID; the scace also verified the initial spike is not seen by the puck).

If flow is fast, grind finer, don't lower the pressure as you'll be adjusting pressure for every different bean. Setting the boiler steam to 0.7-0.9 will likely give pretty weak steam as once the steam want is full opened the steam will drop to under 0.5 bar..

I would not lower the pressure below 1.1bar. But a med-dark espresso likely does better at 198f than 202f.. So you might need a good flush before you start the shot. I'd flush for 3-5 seconds and you should find that the group temp drops over 2-3 min. then rises again.(Clive recommends a 7 second flush on the Pro500 HX.. but I don't do that long a flush) Pull when it rises and hits 197-198. You might need to flush longer on your machine.. they are all unique. HXs are a bit notorious for wasting water. Since I only drink about 2 espressos a day, I turn on my machine 30 min before I want my drink. At this time, my group is about 195 & rising.. at which time I prep and pull shot. When you do multiple shots, the first shot will cool the water and so you likely won't need to flush between the multiple shots. If you are getting 203-202 during shot.. your puck is likely seeing 198-200.

Adjusting the pump output through the OPV was never suggested. Unless I misunderstood and you are suggesting to do so?

The reasoning for lowering the pstat is quite evident when watching the video the OP posted. A 20 second flush, to go from 208 at idle, down to 205 when pulling the shot (on the digital thermometer) is a bit ridiculous.

Out of my head, I can only think of two quick fixes for this:
1. Lower the pstat until the flush is whiten an "acceptable range" and live with the lower steam power.
2. Install a flow restrictor in the hot pipe of the thermosiphon and enjoy shorter flushes and better steaming performances at the expense of a longer warm up time.

LObin wrote:Adjusting the pump output through the OPV was never suggested. Unless I misunderstood and you are suggesting to do so?

The reasoning for lowering the pstat is quite evident when watching the video the OP posted. A 20 second flush, to go from 208 at idle, down to 205 when pulling the shot (on the digital thermometer) is a bit ridiculous.

no not suggesting that.. but thought that is what was happening.. I agree lower the pstat to reduce temp in steam boiler, but I am wondering if that is necessary.. I'd try to keep 1.25 in steam just to get good micro-foam.. if possible.

hmm.. I wonder if this is a characteristic of the newer designed TS with a restrictor.. I can check mine tomorrow when I make another shot.. But I'm wondering if the flush doesn't drop the temp as fast because of the TS restrictor slowing flow. When I flush my Pro500PID, I don't worry about flushing down to a any temp.(I don't think my temp dives down in the 190s when I flush) I just flush for about 5 seconds and wait.. The temp drops over 2 minutes and bottoms out .. If it doesn't go low enough.. (I haven't finished cooking the eggs and so want it even lower so it doesn't heat back up too fast), I flush again.

Yeah.. you don't need a 20 second flush.. Try a 10 second flush, but watch the thermometer over 3 minutes to see what it does.. bet it will drop at least 5 degrees then start to reheat.. (might drop 7). So if you are idling at 205, this might drop you to 200.. then do a 3 second flush and wait and it might drop you to 197 .. pull then as it starts to reheat.. Don't worry about the initial spike in the first 10 seconds.. your shot won't see that.

So my suggestion was to change to a 'flush n wait' workflow to see if that helps.

Just a guess.. but that's how mine works..

I'm assuming the ECM M slim has a restrictor in the TS.. will look up parts list to see if that is true..

yeah.. it has a 2.5mm restrictor in it.. so maybe it behaves differently than the older HX designs where you could flush and the temp dove immediately down into 190s.. again.. I am talking above my experience level.. Hope I haven't fully confused OP.

Hey guys,
Thanks for the great advice. I was referring to lowering the pstat a bit, as I do think the 20 second flush is a lot. I'll see how much it effects the micro foam production and rebound.
Bluenoser - Are you sure there is a thermosyphon restrictor? I read in a UK forum that..." ECM hx machines do run cool because of the way they put plastic tubes inside the heat exchanger - they don't run thermosyphon restrictors." https://coffeeforums.co.uk/topic/43095- ... iler-temp/
I looked at the parts diagram but I don't see a thermosyphon restrictor or a "plastic tube in the HX but I might be missing it.
https://www.1st-line.com/wp-content/upl ... iagram.pdf