I've replaced the expansion valve but am unable to get it back in. I don't have a digital camera available to show pictures but the valve goes into a brass housing and a spring then goes in and a nipple housing then screws in. There is a 12mm hexagonal nut on the nipple housing but I'm not strong enough to push against the spring and turn the nipple housing and screw it in. I've removed some electric coupling, tried using a 12mm open wrench, 12 mm deep socket etc but I'm a weakling. Has any anyone does this before?

Marvin

There is (hopefully) something you are doing wrong. Here is what it should look like:

There is an o-ring on the adjusting "nut" (bottom fitting in the pic) that should be lubricated with food-safe grease, e.g. Dow-Corning 111 or equivalent. Looking from the bottom up, the adjusting nut is turned clock-wise.

When you get it back together, TEMPORARILY adjust the pump to produce a pressure of 12 bar and, at that pressure, there should be a small dribble from this OPV. Reset the pump to 9.0 bar with a blind filter and you are "good to go".

The adjusting nut has no separate O-ring. I am unable to push the adjusting nut apparatus into the upper body in your photo due to the pressure of the spring. I haven't removed the upper body from the rest of the boiler apparatus, if I did I think I might be able to swing it. I'm was afraid to disassemble any more as I am not at all familiar with this machine, have no real manual or instructions and this is the first I've opened it up to do anything. My fingers are all big left toes. Thanks for the help.

Marvin

Well, I assure you that the adjusting section of this OPV has an o-ring. You can give me a call up until about 12:00 tonight - 301-587-5033.