Here is the scoop. I filled my boiler to the top of the sight glass so I would have plenty of water. Powered it up and let it heat. After it hit the top of the first heating cycle, I purged about 8 seconds of steam to get rid of the false pressure, then left it alone for 10 min.

During that time, I used the very scientific measurement process of holding a type K thermocouple against the side of the boiler (about two inches from the base). At the end of 10 min I had a steady surface temp of 217. The boiler was cycling from about .7 to .85.

I quickly put the probe in the opening of the single spout (it is preheated and stabilized at this point) killed the power and raised the lever. After about 6 oz of trickling water the temp had hit 211F. It remained there through another 5 oz of water for a total discharge of 11oz. I held the TC, suspending in the spout so I would not get a false reading from the PF spout metal. Obviously, 211 is way to hot for espresso (it is probably several degrees hotter at the shower screen), hence the burnt shots and my desire to lower the boiler temp.

If I surf the temp in the .5 bar range the shots improve. If I pull a shot within moments of the first boiler heating cycle it is not too bad either, but far from a gosh shot. I still get bitterness. The same bean ground in the same grinder pulls a much better shot in my E61 machine. I get lots of crema and pull at the proper pressure and get extraction times that are pretty much on the mark with the lever, it is just to hot.

I believe a PID may be in my future, any suggestions?

Do you have a variac that you could try first?

I had thought about a variable voltage adjustment device, but this machine is in my office at work. A big old variac sitting on my work table would not look to good. Being the head IT guy, my office is full of flat panels and computers, sleek black cases and high tech gizmos. A big old variac would clash, bad, but a digital display PID controller would not even be noticed.

I also have to watch what I do. I had to get permission from the corporate office risk management just to have the machine in my office (exposed pressurized boiler presents a burn and explosion hazard ). Down side, PID is expensive.

cannonfodder wrote: Down side, PID is expensive.

Have I got a deal for you. Love controls makes a "digital temperature switch," i.e. the Brewtus style controller, for $65. These include 16 amp contact outputs, so no ssr required.

Since the boiler is so decoupled from the final temperature, a PID seems like overkill in any case.

Here's one of many models on sale for fishtanks (the water FAQ was useful in a number of ways)
http://www.automatedaquariums.com/lv_ts13010.htm

Edit:

They're available with TC input for $45 from the maker (Dwyer)

http://www.dwyer-inst.com/htdocs/temper ... SPrice.cfm

Whoa!

How can it be possible with virtually same machines(as i recall you had the Gaggia Pavoni clone) to get so different results?

Even though my grouphead is way colder than yours i experimented and actually benefitted from the wet-towel cooling, just wrapped a cold wet towel around the grouphead like 30seconds before i pulled the shot - huge difference!

These ARE hot machines and obviously we both(all) have issues with heat.


I think there could be some degrees knocked of the grouphead by adding a cork&rubber gasket between the boiler & grouphead?
That way the boiler would not be in direct contact with the grouphead and therefore not transferring as much heat.

I will give it a try a soon as i can.

j7on wrote:
I think there could be some degrees knocked of the grouphead by adding a cork&rubber gasket between the boiler & grouphead?
That way the boiler would not be in direct contact with the grouphead and therefore not transferring as much heat.

I will give it a try a soon as i can.

A couple of weeks ago I was thinking the same thing! I never got around to it because I decided to upgrade to a Cremina. I'm definitely interesting in the results you get. It makes sense - this mostly decouples the group from the actual boiler, reducing the heat transferred from the boiler to the group.

While that would give a small amount of boiler/grouphead isolation, IMHO, the problem is not the groupheads contact with the boiler, but the fact the machine essentially runs in the steam mode, not brew mode. Regardless of how well the GH is insulated/isolated, the water feeding it is still 217F. the only way to change that is to reduce the boiler pressure. If you were an espresso purest, and never steamed milk, a quick Pstat adjustment and the issue is solved.

I believe the thermocouple temp switch Jim points out would fit me need perfectly. I have a couple of Omega Lock 1/8 rigid probe fittings in a bag. I can tap and mount that under the boiler in the base to hide it. Then mount the control unit in a nice stainless box and put it beside the machine.

I could set the temp at 205 (assuming that would provide enough boiler pressure to operate and a couple degrees of temp loss through the GH) and off I go. Then kick it up to 250 for steaming, and then back down. I wonder if I could leave it on all day, just set the temp at 190 to keep it warm. Then a quick heat to brew temp and back down again to standby.

A quick question to Jim. I see they have the TC input units, and then under them, there is a configuration key unit. Do I need both parts ($49.99x2)?

cannonfodder wrote:A quick question to Jim. I see they have the TC input units, and then under them, there is a configuration key unit. Do I need both parts ($49.99x2)?

As far as I can read it, without the key, you cannot change from the type you ordered to another (say K to J). With the key you can. It sounds to me like the key is for plants where lots are used, and they want to store spares usable all over.

See the other thread I posted on this to let everyone know about it (I think this gadget is too bang for the buck to hide). Turns out Barry is using a few for odd and end jobs, so you can shoot him an email for nitty-gritty questions. He likes the unit, even as low cost display, but cautions it's not quite 1/32 din but an odd size. Sean says Dwyer is a good ompany, and he's the real uber-controls maven among us. I have one on order, and will use it on the Peppi and report soon.

I just put in my order.

My temp controller arrived yesterday so I spent the day running around picking up parts today.

I removed the base off the boiler, drilled/taped and mounted my K TC. I have the unit bench rigged on the machine right now and running. I think I am going to like this.

The unit is wired with the NC (normally closed) side of the relay for heating. I can change my boiler temp at will which is very nice. I can set the controller for 170F and leave it there all day, then a quick bump up to brew temp, another quick bump to steam then back down to standby. There is a 1 degree deadband. I set it for 200f, it heats to 201 and shuts off, and there is some carry over after the element shuts down but you can adjust for that. It cools to 199, click, heat again, 201, click, and it is off.

I can tell all of you that 205F does not provide enough pressure to operate the machine. There is just enough pressure to make the gauge twitch and the steam wand gurgle. 225 gives me .5 bar and sufficient pressure to work the machine. Before the controller, I would try to temp surf with the power switch to hold .5 bar, and boy was it a hassle.

I have to mount the controller in a project box, I have already cut the box for the unit. I have the TC wired and the element wired. I need to wire the controller to the power switch on the machine, this is very important and I will go into that later. I am going to drill a hole in the rear center of the base, put in a grommet, run my wires in some split loom tubing into the back of the project box. I am thinking about attaching the controller box to the base of the machine for ease of transport. That way I do not have a controller flopping in the breeze when I move the machine around.

I did take some photos and would gladly post them, but I have exceeded my bandwidth allotment from photobucket for the month. With all my HB postings and blog traffic it went quick this month.

I will probably do some more work on it tomorrow but Thanksgiving cooking is going to take most of my time. Have a nice Thanksgiving everyone.