I spent a lot of time reading over the various forum on how to tackle this mod. I've attempted most of the Mods available to the Gagga Classic ( PID, brass plate shower screen,IMS baskets etc) with varying degrees of success however I found the results a bit underwhelming when compared to the amount of time / money put in vs the other two machines i've had over the past 12 months as stock ( Delonghi Dedica and Sage Duo Tempo).
I've lost count of the amount of money i've spaffed against the wall on mods in the pursuit of better coffee.
Installing a PID was supposed to be a game changer but I still found most of my shots sour and couldn't get my head around it. Using the WDT technique made a difference, as did using a hammer tamper but still sub optimal.
After reading a bit more on temp stability and intrashot temps / i put my problems down to the small boiler and the fact that cold water is being fed into the boiler as each shot is drawn. Or at least, that's how i understand it.
Anyway, suffice it to say - thanks mainly to this thread, I attempted this mod and am pleased with the results. I just thought i'd add my two cents to anyone else who's attempting to try this...
You 100% need a second OPV ( appreciate this is touched on in this thread) but it's pointless tackling this mod without one. As others have mentioned, the hot water in the copper pipe will just flush back into the tank. I tried it with the original and got a 4 deg drop or more evetime.
I found having two OPVs in the machine too hard to adjust. Easiest way to get around this is cap off the original one that is connected to the boiler.
Remove the spring, get a bit of copper pipe, put it where the spring was and then put everything back on.
My machine is I a pre 2010 model with only a hole for the water inlet so you'll need to drill a small hole for the OPV water to exit on the platform inside the case where the pump sits.
Bending the copper pipe around the boiler is a no. Instead, i used a small glass tumbler and made a coil first. I had to move the solenoid valve 90 degrees to accommodate it which then made me wonder if i should have used smaller pipe. So far no problems but time will tell.
If i was attempting this again, I would probably use 6mm copper pipe instead of 8mm but that's all they had in B&Q. As the pipe is 8mm i have a big hole where the gauge used to be which I'm still trying to get my head around sorting
M10 x 1.00 is the only tap that will work. I tried with the kit I got from amazon with a m10 x 1.25 and 1.50 but no luck. Don't attempt to thread the compression fittings with anything else.
Thats about it, I think. My temps drop about 2 degrees over a 35 sec pull but pretty much stay there -the most important bit, the coffee taste much better.
Happy to answer any questions for people attempting this mod. It wasn't a 5 minute job - it took me about 2 weeks in all as i had to get parts from various places but give yourself a good day to do it.
last but not lest - I have electrocuted myself ( at least) three times on this machine, so be careful.