Hello!

When the machine just starts to heat up, the safety valve starts to hiss and releases all the pressure as it builds up. Percussive maintenance with a wooden spoon fixes it. However, this behavior has become the norm.

It all started all of a sudden a couple of weeks ago.

I replaced the safety valve using this kit - no use.

I disassembled and cleaned the whole thing, including the internal nut, just in case - did not help. Admittedly, I did not clean it too thoroughly - just wiping parts, brushing them a bit, and going to town with cotton swabs. However, I am fairly certain that if a wooden spoon fixes it, the issue is not in the nuts and bolts, but in the valve itself.

Any ideas what could be causing it?

I'm assuming you have a p-stat machine. This is often caused by a small piece of dirt lodged between the two gaskets, or between the outer gasket and boiler sealing face. It can be very annoying. These are 2 tips that have helped me:

1. Do not fill the boiler more than 2/3 to 3/4 of the sight glass. I have found that filling to the top of the sight glass often causes the issue, with boiling water transferring small pieces of debris from the tank to the valve. This debris sometimes causes the anti-vacuum valve to stay open, and tapping the valve assembly with a spoon dislodges it back into the tank. Debris often comes from dislodged scale, common after descaling.

2. Make sure the mating surface on the boiler (the part that mates to the outer valve gasket) is clean and smooth. Sometimes chrome plating wearing off causes a pitted uneven surface that traps particles. (Use a super fine grit emery cloth to clean this up if it feels rough. Lay the boiler on its side when doing this, and put a cloth inside the boiler under the area you are working on, to trap debris. Make sue you rinse the boiler off well afterwards, as you may have introduced more microscopic debris.)

It goes without saying to make sure your valve nut is screwed in tight and you are using the right spring.