Abe Carmeli wrote:Greg,

Since you already have a flow adjusting valve on it, adding a pressure gauge would have been nice. Perhaps for your next upgrade?

It's a good idea at first blush and one that I've tried out. The problem is that the internal volume of the plumbing gets so large that the espresso machine dumps a bunch of water out into the thermofilter on startup, which doesn't reflect what's going on when brewing. So until I can get the internal volume down it's gonna be a temperature only device. It's worth my looking at because the measured pressure reflects the pressure when pulling shots, rather than the pressure against a blind filter. On my Linea, the difference is around 1 bar, which surprised me.

-Greg

Part 2

The TTD was received with a chopped portafilter (happily) but not the one shown on the Espressoparts.com website. There, one sees a rubber-handled, original La Marzocco portafilter, but the one shipped with the TTD is an after-market portafilter with a plastic handle. The shipped pf is a very tight fit on an Andreja Premium due to the 8mm group head gasket that comes standard with the machine. This pf would be a better fit on a machine with a 6 or 7mm head gasket. While these are minor points and have nothing to do with bench testing the TTD, I feel they are appropriate in a review of a complete product, as received.

Also, there was no documentation of any kind with the TTD. I would recommend that an information sheet with some basics specs and a guide for less experienced users, be included.

The Espressoparts.com web page (http://www.espressoparts.com/product/EPTF) has an adequate description of the device so there's no need to dwell on that here, other than to mention that the TTD (sans pf) consists of a standard 58mm basket containing three major components, as seen in the photos: 1) a thermocouple probe placed across the outlet: 2) a grey, epoxy-like insert or cake: 3) a 1/4" pipe and an end cap with a tiny orifice and brass-colored metal "filter material" inserted in the pipe, all of which acts as a flow restrictor/controller. These components are designed to simulate the temperature and pressure found in actual brewing conditions. All this was based on observation. If I've misspoken about any of this, I would hope that Greg will jump in and correct me.

The TTD gives the impression of a very solid, well-designed device utilizing high-quality components, including a Teflon-jacketed, strain relieved, type T thermocouple cable connected to a standard mini-plug. All that's needed in addition to the supplied device, is a digital thermometer that can handle type T thermocouples (and an espresso machine, of course!).

In the next installment I will describe how I measured temperatures and used the measurements to set up my espresso machine to produce a consistent temperature profile shot after shot. I will include charts.

BobY

I started with my testing today. First problem I see on my unit is flow rate. It is exactly 2 oz, or 60 ml. Lower than what I understand it should be. (around 75 ml in 25 sec. ?). Documentation could help there.

Flow rate is important in brew temp measurements. It affects not only the measured average brew temp, but also the variation of temperature within a shot. A 55 ml flow rate will have a slightly lower brew temp, but it will also cut the brew temp variation within the shot by half. Oh, the glory of ristrettos.

Bob, what exactly is your flow rate in 25 sec?

HB wrote:Isn't the flow rate dependent on the pressure with a restrictor? I am guessing that Bob's brew pressure setting is higher than yours and that explains the higher flow rate.

Sure thing Dan. My point is that fixing flow rate, as Greg has done here, may not be a good idea for that very same reason. Different shops use different flow rates for their extraction, and different pressure. Without an adjustable flow rate valve, this is becoming a problem. That is of course if you want to be precise within a tenth of a degree.

Abe Carmeli wrote:I started with my testing today. First problem I see on my unit is flow rate. It is exactly 2 oz, or 60 ml. Lower than what I understand it should be. (around 75 ml in 25 sec. ?). Documentation could help there.

Flow rate is important in brew temp measurements. It affects not only the measured average brew temp, but also the variation of temperature within a shot. A 55 ml flow rate will have a slightly lower brew temp, but it will also cut the brew temp variation within the shot by half. Oh, the glory of ristrettos.

Bob, what exactly is your flow rate in 25 sec?

That's interesting. I've been checking all of the flow rates before sending them out. They are all being run at 9 bars and should produce around 75 mls in 30 secs. The WBC standard and Italian standard is for 30 secs extraction and the tolerance is +- 5 I believe. Could be that your brewing pressure is too low.

-Greg

Abe Carmeli wrote:I started with my testing today. First problem I see on my unit is flow rate. It is exactly 2 oz, or 60 ml. Lower than what I understand it should be. (around 75 ml in 25 sec. ?). Documentation could help there.

Flow rate is important in brew temp measurements. It affects not only the measured average brew temp, but also the variation of temperature within a shot. A 55 ml flow rate will have a slightly lower brew temp, but it will also cut the brew temp variation within the shot by half. Oh, the glory of ristrettos.

Bob, what exactly is your flow rate in 25 sec?

I'll note this in my review, but the flow rate begins at about 2.25 to 2.5 oz in 25 seconds. But strange...as the sessions progress the flow rate goes down. For example, yesterday I think it was at about 1.25 oz after a few hours of pulling shots. That could be a function of my machine rather than the TTD but it needs more investigation.

HB wrote:Isn't the flow rate dependent on the pressure with a restrictor? I am guessing that Bob's brew pressure setting is higher than yours and that explains the higher flow rate.

This will appear in the next installment when I begin to discuss the actual testing, but for the record, my machine is set so that while pulling a shot with the TTD in place, the pressure reads exactly 9.0 bar with a brewstat setting at 1.0 ± 0.05 bar.

BobY wrote:I'll note this in my review, but the flow rate begins at about 2.25 to 2.5 oz in 25 seconds. But strange...as the sessions progress the flow rate goes down. For example, yesterday I think it was at about 1.25 oz after a few hours of pulling shots. That could be a function of my machine rather than the TTD but it needs more investigation.

It could also be coffee clogging the exit hole. Greg, how do you clean it and release a clog?