[Solved] Unscrewing Anode Plug in GALMET SGW(S) Boiler: Accessing Hidden Nut without Damaging Insulation

Hello,

Will anyone suggest a patent for unscrewing the anode fixing nut in the Galmet SGW(S) boiler at home? the nut is hidden in the insulation by about 2 cm, therefore it is impossible to reach the Swede unless I destroy the styrofoam and I would like to avoid that. In addition, the size of this plastic nut as in the picture is quite strange, quite different from the mounting of the anode or heater itself. The anode and heater are screwed with a 5/4 wrench, while the plastic plug on the outside of the wall is 75mm and 35mm inside. It's hard with such keys in the supermarket

tubular wrench. Is it exactly 75mm or 3”?

I measured yesterday evening quickly, but from what I remember it came out on a 75mm caliper, maybe a little more than 3 inches, it's probably still far away

I know that larger wrenches are in inches and you can buy 3 of them.

Some tubular could even fit inside. Some have a fairly well-pressed hexagon on the outside. Depending on the thickness of the wall, maybe a 30mm tubular one will fit there. This is easier to get.

I was just thinking about looking inside. Thanks for your help, I'll look for a tubular one today. If it's a little bigger, you can always tighten it I'll let you know when I unscrew it

Maybe you can find an M24 screw somewhere, it has a hex size of 36 mm.

Unscrew the cable and measure the current between the anode and the housing, because maybe you don't have to unscrew it, if the current is above 1 mA, it's ok, if 0.5-1, it's better to check if below 0.5, the anode needs to be replaced or has become scaled.

Thanks for the info, but I had to unscrew the top plug anyway because I was still installing the heater and I wouldn't drain the water. I did not get the key, which was the reason for mobilization and making my own Surprisingly, after 7-8 years, the anode is like new (wow) there is not much stone inside, it did not even cover the bottom. I have one more question because I'm not a plumber; p does an air cushion have to be left in the standing boiler? When I installed the heater, I flooded the boiler almost to the tap, leaving about 5-10 cm of slack, screwed the top cap and added water again, then the pressure was created and everything is OK, but I'm concerned if it's supposed to look like this? it turns out that the boiler is 100% filled with water

What about a pillow? It is a billiard and it is supposed to have and air will come out when using hot water and there should be an air vent on the heating, i.e. the coil.

There should be no air, because it is always an environment for corrosion. In such tanks, there will always be some air collected from the degassing of the water, or that somehow got into the installation.
I still have a note about the installation of the heating module. For proper operation, the module should always be mounted with the cable downwards, due to the location of the thermocouple in relation to the heating element.

OK, I'll tighten it up tighter. Thank you for your help

OK, I'll tighten it up tighter. Thank you for your help

Added after 1 [minutes]:

Socket made of own design + Swedish wrench. Unfortunately, supermarkets do not have such large wrenches and the prices at auctions are such that it is not worth making a purchase several times.