Hello,
Our hot water heating system was installed nearly 30 years ago – a few days ago, we experienced a heating failure due to a complete loss of pressure. I then inspected the boiler room... behind a slip-on thermometer, I found a "hole" where water had leaked out. Apparently, there used to be a drain screw there:
This concerned the heating circuit that was practically never in use, meaning the heating water (protected with Korofin) had been “standing” there without regular circulation. On another heating circuit, where the drain screw is still in place, it currently looks like this:
I was able to isolate the affected heating circuit and restart the heating system. Still, I am worried that the same problem might occur soon in the other heating circuits...
Question: what should be done? That is,
Lonerider
Our hot water heating system was installed nearly 30 years ago – a few days ago, we experienced a heating failure due to a complete loss of pressure. I then inspected the boiler room... behind a slip-on thermometer, I found a "hole" where water had leaked out. Apparently, there used to be a drain screw there:
This concerned the heating circuit that was practically never in use, meaning the heating water (protected with Korofin) had been “standing” there without regular circulation. On another heating circuit, where the drain screw is still in place, it currently looks like this:
I was able to isolate the affected heating circuit and restart the heating system. Still, I am worried that the same problem might occur soon in the other heating circuits...
Question: what should be done? That is,
- Can this type of drain screw be obtained somewhere?
- If yes – how do you install it there, when the large union nut screwed onto the pump above partially covers the hole (it screws downward – over the drain screw...)?
- Or does the whole shut-off valve assembly need to be replaced?
- And: where did the old drain screw go in the first place...?
Lonerider
L
Lonerider23 Apr 2026 09:06So... I removed the part and tried to get a replacement from the wholesale supplier. Two problems:
1.) SHT didn’t have the same part (and doubts it’s still available...) — I only got a different one, which is a few millimeters shorter. The seller said I shouldn’t screw the fittings together so tightly because that would compensate for the length... Unfortunately, it doesn’t work out :-(.
2.) The original part was designed for installation with the flow going "downwards" — the new one is meant to be installed with the heating circuit flowing "upwards." If you install it "downwards," the pump presses against the gravity brake... I had to remove the gravity brake.
Since I can’t get the right installation length — question: can you help me find such a part in the correct length (95 mm (3.7 inches), with gravity brake for installation with flow going downwards)? Or can you give me a tip where I should inquire? Or should I call a plumber to modify the pipes so the new part fits(?)...
Thanks
1.) SHT didn’t have the same part (and doubts it’s still available...) — I only got a different one, which is a few millimeters shorter. The seller said I shouldn’t screw the fittings together so tightly because that would compensate for the length... Unfortunately, it doesn’t work out :-(.
2.) The original part was designed for installation with the flow going "downwards" — the new one is meant to be installed with the heating circuit flowing "upwards." If you install it "downwards," the pump presses against the gravity brake... I had to remove the gravity brake.
Since I can’t get the right installation length — question: can you help me find such a part in the correct length (95 mm (3.7 inches), with gravity brake for installation with flow going downwards)? Or can you give me a tip where I should inquire? Or should I call a plumber to modify the pipes so the new part fits(?)...
Thanks
