My new Expobar Office Lever machine arrived this week and I installed the Chris Coffee grouphead thermometer on it.

I let the machine warm up for an hour and the boiler pressure gauge is reading 1.1 bar. However, my group head thermometer will only read between 193 - 198.

Then when I do a "cooling" flush, the temp will rise to a max of around 202-206 and the settle around 200. As soon as I turn off the cooling flush the temp starts dropping back down to around 193-198.

This doesn't seem correct to me. Is this normal?

The idle seems low but I'm not familiar with the thermosyphon design on that machine. Sounds like you don't need a cooling flush. It is normal for temp to drop back down like that after a shot.

Sounds like the machine may come with a restrictor installed.

After i put in a restrictor i idle around 197-198 after 60-90min warm up, i do a 4-5 sec flush before i pull my shot. My temp starts around 198-200, peaks at 203-204 and ends at around 198-200.

Hopefully some owners will chime in to give you suggestions/opinions.

However, my group head thermometer will only read between 193 - 198.

That is very unusual for the group temp to vary that much. Normally, the group temp varies in a cycle similar to the boiler pressure/temperature cycle but greatly attenuated.

Is your portafilter in or out of the group and what is your room temp?

It sounds like a normal HX with a restrictor to me. The group temperature at idle is not meaningful; this will vary with ambient temperature, drafts and so on. The important temperature is what you get after a flush (in this case not a cooling flush, but a warming one like on some DB machines). A stable 200 (93 C) is about on the money, as you will have about a 3 degree drop between the group and the puck (more or less).

If you would rather your HX worked a bit more like a dragon, then it should be fairly easy to slightly drill out your restrictor (caveat I don't have your machine and I personally don't have a restrictor). An alternative is to tweak your presurestat (or PID) up a bit. This should increase your boiler pressure, giving you a stronger thermosyphon flow, group idle temperature and higher brew temperature, which can be brought back down to where you want it with a flush. It will also increase your steam. You could do a little surfing here on the HB pages and you'll find a tonne of info on restrictors and their use.

That's the little I know. Perhaps those who have messed about with restrictors will jump in.

Radio.YYZ wrote:Sounds like the machine may come with a restrictor installed.

After i put in a restrictor i idle around 197-198 after 60-90min warm up, i do a 4-5 sec flush before i pull my shot. My temp starts around 198-200, peaks at 203-204 and ends at around 198-200.

Hopefully some owners will chime in to give you suggestions/opinions.

On a Profitec Pro 500 PID (HX), using Erics Thermometer, I have set the PID to get an idle of about 199 after 60 minute warm up. No flush and it will rise to 207 about 10 seconds into extraction and settle back to about 202. Portafilter is in with the warm up. After one shot, my idle decreases to about 195. But that next pull will go up to 202 and finish about 198.. (less of a swing). I've got to be careful at this point, because after the 2nd shot, my idle will be down to about 190. I need to wait a bit to get up to 195 to pull that 3rd shot or it will be sour. This takes about 5 minutes, maybe more.. still learning.. on mine.

I'm assuming the big E61 will even out the temps as the brew water exits.. so that first shot likely runs a bit hot.. and later ones are pretty close to 200F. I find that I have to leave the portafilter in as much as possible or it will cool off group too much.

erics wrote:That is very unusual for the group temp to vary that much. Normally, the group temp varies in a cycle similar to the boiler pressure/temperature cycle but greatly attenuated.

Is your portafilter in or out of the group and what is your room temp?

The range is because of after 60min heatup and lower for second shot after five minutes.

pre restrictor i was 205-206 after 60 min heatup.
post restrictor i am at 198-199 after 60 min heatup.

Bluenoser wrote:On a Profitec Pro 500 PID (HX), using Erics Thermometer, I have set the PID to get an idle of about 199 after 60 minute warm up. No flush and it will rise to 207 about 10 seconds into extraction and settle back to about 202. Portafilter is in with the warm up. After one shot, my idle decreases to about 195. But that next pull will go up to 202 and finish about 198.. (less of a swing). I've got to be careful at this point, because after the 2nd shot, my idle will be down to about 190. I need to wait a bit to get up to 195 to pull that 3rd shot or it will be sour. This takes about 5 minutes, maybe more.. still learning.. on mine.

I'm assuming the big E61 will even out the temps as the brew water exits.. so that first shot likely runs a bit hot.. and later ones are pretty close to 200F. I find that I have to leave the portafilter in as much as possible or it will cool off group too much.

Very interesting because i had the pro 500pid's restrictor and it is 2.25mm, but the tube (upper e61) is wider that comes from hx tube. So the machine is engineered slightly differently but i have gotten very good results adding a 2.6mm restrictor to my non pid machine (2.25 did not work as well).

One thing i am finding, and i will have to confirm is that if the bump is higher the shot does change the flavour so thats why i do a flush to reduce the hump. My hump is around 203.5-204.5F after a 4-5second flush. I wait five minutes or more for my second and follow up shots and i get consistent results (only a quick 1-2 seconds screen flush).

Try to do a screen flush starting at 5 seconds and reduce it to 4 and 3.. and see how the flavour of the coffee changes, if it doesnt then without flush is good for you but for me i am finding the hump does change the flavour a bit for my coffee.

Radio.YYZ wrote: Try to do a screen flush starting at 5 seconds and reduce it to 4 and 3.. and see how the flavour of the coffee changes, if it doesnt then without flush is good for you but for me i am finding the hump does change the flavour a bit for my coffee.

thanks for the suggestion.. I'll try it to see what happens.

Thanks for the feedback everyone. I appreciate it.

erics wrote:That is very unusual for the group temp to vary that much. Normally, the group temp varies in a cycle similar to the boiler pressure/temperature cycle but greatly attenuated.

Is your portafilter in or out of the group and what is your room temp?

That's similar to my Rocket's behavior. Left to warm up for 40+ minutes, the grouphead thermometer will read 199-200. The. A short flush will see temp spike to 210 and then start to come down. 1st shot temp will start at around 204 I dictated, dipping towards 199-198 indicated.

Grouphead temp will then dip to 193, and sometimes as low as 190 during recovery, after a short screen cleaning flush. It takes a long time for it to creep back up to nearer 200.

Short flush and go on subsequent shots give initial temps in the 203-205 range if flush is really short, or 200 dipping to 198 if a tad longer.

Sounds to me like water in the HX quickly rises in temp to above brewing temp, and that, yet, group tends to idle colder and not recover quickly.