DMH Yes. Most likely. I would assume that the old springs have lost a bit of their kick over the years and the news springs, which are still readily available, would be consistent with the original design.
DMH On PID systems is it normal to measure the liquid or steam temperature in the boiler and is there a difference? I already have a spare port which can be used to measure liquid temperature but would need probably need to drill and tap a new opening in the end plate to measure steam temperature.
Koffee_Kosmo This is the theory At our altitude water becomes steam at 100 degrees Celsius So a boiler must reach that temp to make steam and steam collects in the upper section of the boiler This is then released by the pressure to the steam wand Water cools down as it goes through the pipe work to the group head for brewing duties This temp is hopefully at 89 to 92 deg Celsius when actually brewing coffee KK
DMH Thanks KK. All true. My thoughts are that a pressurestat controls by boiler pressure and the temperature of saturated steam varies according to this pressure. At 1 bar 100C and approx 107C at 1.3 bar. So after thinking about it a bit more both the liquid and steam should be at the same temperature. So it doesn't really matter if the PID measures liquid or steam temperature. I may just measure both temps and see how it goes.
DMH More cleaning and the polishing is required but I thought I'd temporarily install the boiler and check the available room for the electrics and controls. I think I am now almost committed to a PID/SSR relay with a sirai as an overpressure shutoff so I drilled an tapped a new 1/4'BSP hole in the boiler end plate and direct mounted the sirai. Whilst its in a good and easily accessible position it may get a bit hot so fit a hex nipple and a socket to give me a bit of air space from the boiler. The old 1/4" opening on the opposite site is now available for a thermocouple so I'll get one made up with a 1/4"BSP compression fitting. There is a ton on room under the boiler and I assume that this is for gas fired models. Also the front plate of the machine has a few openings which I assume are for the inspection of the frame. I don't have the controller or the front plate back yet but I'm thinking that I may be able to discretely mount the PID controller and SSR under the boiler so that the display is visible through the existing opening. I'm also thinking of a power light and an element on light also and I'll either drill a hole through the front plate for these or mount these behind the opening also. The machine didn't come equipped with an ON/OFF switch and I need to find a good position for this. I don't want a simple toggle but would much prefer the old fashioned Bremas rotary cam with a black faceplate. [attachimg=1]
DMH It turns out that my chromed items are ready three weeks earlier than expected so its time to finish off a few loose ends and start assembling the machine. I'm still not sure on the best way to control the machine. I have read on many times that it is common practice to replace the mercury with with a Sirai pressurestat yet I can't understand why. The mercury switch is simply and consistently switches with a deadband of 0.1 bar which is about half of that of my new sirai. To complicate matters I also have also purchased a temperature controller with a SSR. As a complete novice in the field of coffee machines I am asking and would like opinions on which is the best way to go. Option 1 - Mercury Switch Option 2 - Sirai Pressurestat Option 3 - Temperature controller and SSR All items are in stock and ready to go. Also looking at insulating the boiler. I was thinking of using HT Armaflex and planned on picking up a role from their Melbourne office. It turns out they won't sell to non account customers and were a pain to deal with. If anyone has a source of this material it would be greatly appreciated. If not I'll use ceramic fibre which I have ready access to.
Koffee_Kosmo Option 3 Temperature controller and SSR, is my preferred choice if it can be easily be incorporated into the rebuild from the start KK
DMH Been a long time since I last posted. The progress on the Gaggia has stalled. The machine is virtually assembled with a Sirai pressure stat and a new old stock Bremas rotary cam on/off switch. A day or so with the wiring followed by the installation of the piston seals and the machine will be ready to go. The main thing holding me up is the size of the machine and the fact that I have nowhere to put it. Also I don't really like the hotel group and would prefer a proper 2 or 3 group lever machine. Playing around on ebay I just picked a 2 group pump machine of the same vintage. For a couple of hundred dollars it was worth a try. Not sure of the model but it is similar to the Gaggia ELE of which there are a few on the German forums. Unlike the German machines which use a Sirai and the more modern round flanged heating element mine is very similar to the Tell and uses Tell type heating elements and a mercury switch. Unfortunately one of the bulbs was broken. This machine is also equipped with a standard 10amp plug. Thinking of replacing my single 3 group 1750w element with the two 2 group elements for a faster heat up on a 10 amp supply. Another thought is turn the 2 group pump machine into a 2 group lever machine. This would involve another go of sandblasting/painting plus the cut and reweld of the stainless steel 3 group front.
DMH Turns out one of elements in the 2 group is shot. Easiest thing to do now is finish the 3 group and then restore the 2 group boiler and casing and convert to lever later on. The two group boiler is significantly smaller than the three group and makes a lot more sense in a domestic situation. By the way if anyone needs the Gaggia pump groups yell out as I have no intention of using them. [attachimg=1][attachimg=2][attachimg=3][attachimg=4]
Koffee_Kosmo Levers are wonderful to use - best of shots to you when you start using this unique machine KK
DMH This is what the two group looked like. It is now almost stripped. Turns out that the family likes the hotel group so I may as we'll finish the 3 group as is. I'll use a few bits and pieces from the two group and put the rest in storage for spares for when I eventually find and rebuild a 1 group Gaggia America. For the short term the machine can stay in my office. The new paint finish is French Blue so possible final locations are around the pool or at the beach shack. Only problems are that the pool house doesn't have a roof and the beach stack is just about the same size as the machine.
