Gaggia Classic - technical questions
- dsc
- Posts: 1166
- Joined: 17 years ago
Gents,
a few months ago I've bought a very cheap, used Gaggia Classic from ebay, something for my missus and her love of cappas. Of course this turned into a massive rebuild project, which included handpolishing the frame, pulling everything to bits, fixing design flaws etc. I finally managed to get it up and running and before I progress any further with more mods I've got two questions:
- the Classic has two thermostats, one brew thermostat on the bottom of the boiler and one steam thermostat mounted on the top. My plan is to get rid of both and use a PID + TC combo to control the temps and make it more precise. The PID I have is an Omron E5CN, which offers multiple setpoint operation, so I should be able to change setpoints on the PID itself with a flick of a switch, the only question remaining is where to stick the thermocouple. Does anyone know the reason behind the original design of two thermostats, one on the bottom and one on the top? why didn't they stick both stats on the bottom of the boiler? a rough guess is that the top one measures steam temps, so it's high up and the bottom one is for below100degC, so the lowest point is needed. If so, can I get away with a single thermocouple where the original brew thermostat is, or would I have to drill / tap and put and sheated TC inside the boiler?
- steam valve is leaking steam and dripping, which is mighty annoying. I've cut of the end of the valve which was blocking the movable part from unscrewing completely from the valve and polished the head of the valve stem, but the damn thing still leaks slightly. The whole thing is made from brass, which should be soft enough to seal properly against the base of the valve, but something doesn't fit as it should. Any ideas on how to make the thing leak-free?
I know toy-like machines are not hugely popular on these boards, but maybe someone can shed some light on the above. Any input is appreciated.
Regards,
dsc.
a few months ago I've bought a very cheap, used Gaggia Classic from ebay, something for my missus and her love of cappas. Of course this turned into a massive rebuild project, which included handpolishing the frame, pulling everything to bits, fixing design flaws etc. I finally managed to get it up and running and before I progress any further with more mods I've got two questions:
- the Classic has two thermostats, one brew thermostat on the bottom of the boiler and one steam thermostat mounted on the top. My plan is to get rid of both and use a PID + TC combo to control the temps and make it more precise. The PID I have is an Omron E5CN, which offers multiple setpoint operation, so I should be able to change setpoints on the PID itself with a flick of a switch, the only question remaining is where to stick the thermocouple. Does anyone know the reason behind the original design of two thermostats, one on the bottom and one on the top? why didn't they stick both stats on the bottom of the boiler? a rough guess is that the top one measures steam temps, so it's high up and the bottom one is for below100degC, so the lowest point is needed. If so, can I get away with a single thermocouple where the original brew thermostat is, or would I have to drill / tap and put and sheated TC inside the boiler?
- steam valve is leaking steam and dripping, which is mighty annoying. I've cut of the end of the valve which was blocking the movable part from unscrewing completely from the valve and polished the head of the valve stem, but the damn thing still leaks slightly. The whole thing is made from brass, which should be soft enough to seal properly against the base of the valve, but something doesn't fit as it should. Any ideas on how to make the thing leak-free?
I know toy-like machines are not hugely popular on these boards, but maybe someone can shed some light on the above. Any input is appreciated.
Regards,
dsc.
- mariobarba
- Posts: 403
- Joined: 13 years ago
You'd probably be better off over at the gaggia owner's group on yahoo.
Good luck
Good luck
- MVendi81
- Posts: 59
- Joined: 13 years ago
You're correct in your assumption of why the original thermostats are located where they are--the one on the side is used when the machine is in 'normal' brewing mode, while the top one is used when you press the steam switch.
I have several years' experience with a Gaggia Coffee (essentially the same as the Classic, but uses one of those cheap, spring-type brew valves for the group, whereas yours uses a 3-way solenoid and also comes standard with an OPV), which I PID'd. I used an RTD instead of a thermocouple, attached to a small screw, which is placed in the same location where the original brew thermostat was. Obviously drilling and tapping to get measurements directly from inside the boiler would be optimal, but I'm not sure it'd be worth it for such a machine.
As far as the steam valve, you might want to visit partsguru.com and order a replacement (part #EF0045-01-A). I did the same thing as you when mine started leaking, and they are very difficult to get back into proper working order. A small bit of advice though: when you descale, make sure you run some solution through the steam valve assembly to get the gunk off the tip of the valve stem. Once scale (or other debris) begins accumulating it deforms the part of the valve that's supposed to create the seal, which is why they're notorious for leaking.
I have several years' experience with a Gaggia Coffee (essentially the same as the Classic, but uses one of those cheap, spring-type brew valves for the group, whereas yours uses a 3-way solenoid and also comes standard with an OPV), which I PID'd. I used an RTD instead of a thermocouple, attached to a small screw, which is placed in the same location where the original brew thermostat was. Obviously drilling and tapping to get measurements directly from inside the boiler would be optimal, but I'm not sure it'd be worth it for such a machine.
As far as the steam valve, you might want to visit partsguru.com and order a replacement (part #EF0045-01-A). I did the same thing as you when mine started leaking, and they are very difficult to get back into proper working order. A small bit of advice though: when you descale, make sure you run some solution through the steam valve assembly to get the gunk off the tip of the valve stem. Once scale (or other debris) begins accumulating it deforms the part of the valve that's supposed to create the seal, which is why they're notorious for leaking.
- PacMan
- Posts: 127
- Joined: 13 years ago
I use to have a PID classic and liked it a lot. I wouldn't really call it a toy-like espresso machine, quite capable entry machine.
I think a single temp probe in the original brew thermostat (side of boiler) thermowell is sufficient. Keep in mind that here you measuring the temperature of the outside of the boiler. What I did was set the PID to a varying range of temps and then measured the temp of the water that came out of the group. This gave me a reproducible offset that I could use whenever I needed to change temps. It also gave me a good starting point when I would come on here and read that "espresso X works best at temp Z." Keep in mind that even if you had a probe measuring the temperature of the water inside the boiler it wouldn't be the same temp as what is coming out of the group head.
For steaming I think the Classic also works very well once you've upgraded the steam wand. I usually just flipped the steam switch (bypasses pid, resulting in the reading being merely a thermostat) and watched the display temp. I would start steaming ~10 degrees before the the heaters would click off. This gave me great steaming for a small amount of milk, enough for a 5oz Capp.
Also, my steam wand leaked too. I just kept a cup under it.
I think a single temp probe in the original brew thermostat (side of boiler) thermowell is sufficient. Keep in mind that here you measuring the temperature of the outside of the boiler. What I did was set the PID to a varying range of temps and then measured the temp of the water that came out of the group. This gave me a reproducible offset that I could use whenever I needed to change temps. It also gave me a good starting point when I would come on here and read that "espresso X works best at temp Z." Keep in mind that even if you had a probe measuring the temperature of the water inside the boiler it wouldn't be the same temp as what is coming out of the group head.
For steaming I think the Classic also works very well once you've upgraded the steam wand. I usually just flipped the steam switch (bypasses pid, resulting in the reading being merely a thermostat) and watched the display temp. I would start steaming ~10 degrees before the the heaters would click off. This gave me great steaming for a small amount of milk, enough for a 5oz Capp.
Also, my steam wand leaked too. I just kept a cup under it.
- dsc (original poster)
- Posts: 1166
- Joined: 17 years ago
Gents,
Thanks for the replies. The only reason I called it a toy-like machine is because I have an Elektra T1 tucked away, packed and ready for sale, a machine that I've played around with for around 3 years. The Classic is really going back to basics:)
The reason why I want the steam to be controlled by the PID is simply because I don't want any thermostats left over in the machine, if I have a PID, might as well use it for brew and steam. I understand there's going to be an offset if I measure on the outside, but as long as it's the same at a range of temp, I'm not worried.
As for the steam valve it's really annoying, I'm actually surprised the valve doesn't use any gaskets, just a sharpened valve stem and a flat valve head. I actually had the whole valve in pieces, descaled and cleaned, so I'm surprised it still leaks, guess I have to put a bit more work into it.
As for the steam wand, I've done the Silvia change-over mod and it works like a charm, perfect milk everytime, almost no effort.
Overall the Classic is a nice and simple machine, too bad it's a bit too small (moves around the counter when you lock the PF for example), both dimension-wise and boiler-size-wise, but it's perfect if you just want a quick espresso, without having to wait ages for the whole thing to warm up.
Regards,
dsc.
Thanks for the replies. The only reason I called it a toy-like machine is because I have an Elektra T1 tucked away, packed and ready for sale, a machine that I've played around with for around 3 years. The Classic is really going back to basics:)
The reason why I want the steam to be controlled by the PID is simply because I don't want any thermostats left over in the machine, if I have a PID, might as well use it for brew and steam. I understand there's going to be an offset if I measure on the outside, but as long as it's the same at a range of temp, I'm not worried.
As for the steam valve it's really annoying, I'm actually surprised the valve doesn't use any gaskets, just a sharpened valve stem and a flat valve head. I actually had the whole valve in pieces, descaled and cleaned, so I'm surprised it still leaks, guess I have to put a bit more work into it.
As for the steam wand, I've done the Silvia change-over mod and it works like a charm, perfect milk everytime, almost no effort.
Overall the Classic is a nice and simple machine, too bad it's a bit too small (moves around the counter when you lock the PF for example), both dimension-wise and boiler-size-wise, but it's perfect if you just want a quick espresso, without having to wait ages for the whole thing to warm up.
Regards,
dsc.