Brew Temperature Adjustment and Stabilization

[Sprintn]

Hi,
I'm new to this site but have been making and studying espresso for a hand-full of years now. It has become if bit of a hobby/obsession which i find a bit strange given that i'm a bit of a gearhead and racing/italian car enthusiast. My machine is an Olympia Cafferex which, after some learning about machines and espresso, i found that I needed to replace the pump on. The replacement pump was great because it was an adjustable one. All i needed to do was feed the water release line into the reservoir for the runover water to empty into when the pump hit it's desired pressure of 9 to 10 bar.
My question is... is there a way to adjust the brew temp. on this machine? Although I tend to get a nice layer of creme, it is a light color as opposed to a brown or reddish brown color.. which would mean to me that my temp is too low or that the temp is not staying stable throughout the 25 - 30 seconds of brew time. The consistency of my pull looks good as the stream hangs fairly straight down as it pours... and it looks as if it is losing its flavor right at about 25 seconds given that the stream starts to look light in color at about that time. So... water brew temp is the only thing I can think of.?.? Also... is there a way to measure this without spending an arm and a leg on some of the equipment i have seen for this?
Thanks in advance for your help

[cannonfodder]

I have not worked on that machine before, but the boiler temperature should be adjustable. There will be a small pressurestat, usually mounted on a small riser tube atop the boiler. If you had a photo of the machine with the shell off I am shure we could point it out. As far as temperature, you could try the thermometer in a Styrofoam cup trick. Take a digital thermometer and push the probe through the side of the cup near the bottom, around a half inch above the bottom of the cup. Pull a water flush into the cup, you should be around 190F. You are not going to set the brew temperature using that but it will give you a rough idea if you are close. The other possibility is coffee that is past its prime. It will go blond quickly.

[Sprintn]

Dave,
Thanks for your reply. As i have had this machine apart quite a bit, i think i know what adjustment you are speaking of. However... Which direction do i turn the adjustment to increase Boiler Temperature/Pressure? Although i know that adjusting the pressurestat on the boiler may help the boiler temp, will this also adjust the temp for the heat exchange that heats the water for brewing? I guess this is one thing about my machine that i am confused about since the brew water and the boiler water are, or seem to be, different? How does the brew water get up to temp so quickly? Is the Boiler temp also the brew temp even though the water is from two different sources?
Thanks

[erics]

This may help you see the "innards" of the boiler:
http://www.olympia-express.ch/ServiceSupport.asp
Usually pstats have a + and - near the adjustment screw to indicate the proper rotation depending on what one is trying to do. Personally I wouldn't do anything until you know where you are at present.

That will cost a few fingers - attach a 0-30 psi pressure gage to your steam wand or jump in and buy the nice adaptor that Richard is manufacturing here: olympia-cremina-boiler-neck-mounted-pressure-gauge-reducing-coupling-t1548.html

The fact that you are in Vail, CO (8200 ft elevation) means that your boiler temperatures (and all other temperatures) are ABOUT 6 F lower than us sea level folks. See this (chart is about half way down):
how-does-high-altitude-affect-brewing-t1494-20.html

A description of your espresso brewing procedure would tell a lot.

[HB]

I guess this is one thing about my machine that i am confused about since the brew water and the boiler water are, or seem to be, different?

This question and more are answered in How I Stopped Worrying and Learned to Love HXs.

[cannonfodder]

I would recommend reading all the threads Eric and Dan pointed out. I would also suggest you not make any boiler pressure changes until you know what it is set at. Blindly adjusting it could be very bad.

Too much pressure and the release valve will open and vent steam everywhere, too low and you will never get a good shot. Most heat exchanger machines run in the 0.9 to 1.2 bar range depending on what you want. Lower pressure gives you a cooler boiler, the heat exchanger heats slower, you time between shots will increase since it will take the machine longer to recover temperature between shots. You steam for milk will also drop, but your cooling flush will be shorter. Increasing the boiler pressure will give you a hotter boiler, the heat exchanger will heat faster and the water in it will get hotter which will require a longer cooling flush. Your recovery time between shots will decrease since the heat exchanger will heat up faster and you will have more steam for milk frothing.

[Sprintn]

Thank you all for all of the great responses and links!!
I'll follow the advice and do some homework.
Cheers

[Sprintn]

This may help you see the "innards" of the boiler:
http://www.olympia-express.ch/ServiceSupport.asp
Usually pstats have a + and - near the adjustment screw to indicate the proper rotation depending on what one is trying to do. Personally I wouldn't do anything until you know where you are at present.

That will cost a few fingers - attach a 0-30 psi pressure gage to your steam wand or jump in and buy the nice adaptor that Richard is manufacturing here: olympia-cremina-boiler-neck-mounted-pressure-gauge-reducing-coupling-t1548.html

The fact that you are in Vail, CO (8200 ft elevation) means that your boiler temperatures (and all other temperatures) are ABOUT 6 F lower than us sea level folks. See this (chart is about half way down):
how-does-high-altitude-affect-brewing-t1494-20.html

A description of your espresso brewing procedure would tell a lot.

Eric,
Be happy to. But... how much detail do you want? Grind, tamping, water type, etc.????

[erics]

But... how much detail do you want? Grind, tamping, water type, etc.????

As none of the respondents have first hand knowledge of your gem, I was curious as to your flushing procedure, if any. For EXAMPLE - say you donate a few fingers and measure your boiler pressure (maximum) to be 1.00 bar, i.e. heating light comes on at, say 0.80 bar and goes off at 1.00 bar. At your altitude, you may very well be able to pull a nice shot with no flushing WHEREAS if your machine were being operated at sea level, the boiler temperature would be ABOUT 9 degrees higher and would necessitate some flushing.

[Sprintn]

Eric,
SOrry... was gone for a bit.
FOrgive my ignorance... but i guess i do not understand what you mean by "Flushing Procedure".?.? I know all about periodic BackFlushing, but this is for cleaning therefor probably not what you are speaking of.
Thanks
Quentin