Bit of a long post, but stick with it ... :-)
So, today, I finally got the time to go to our burger joint to fit the pressure reduction valve that I bought a couple of weeks back, to stop the 6 bar pressure relief valve ahead of the unvented water heater, from lifting off its seat all the time. For those who haven't seen the valve in my earlier posts, here it is :
It has a 22 mm through bore, and comes complete with custom 22 to 15 mm reducing olives, as well as standard 22 mm olives, if you are going to fit it direct to 22 mm pipe. So far, so good. Off goes the water, on go the taps. All drained down, and three inches whipped out of the 15 mm pipe where it's going, in no time. I then fitted the compression nuts over the pipes, and then put the two sections of the reducing olives over the pipe ends, after carefully studying the supplied diagram to make sure that they were going in right. The diagram is quite clear, and the assembly order is exactly as you would expect. Basically, the 'inner' part of the olive comprises a 'straight' section about 5 mm long that fits into the body of the valve. Behind this, there is a 'flare' at about 45 deg that matches a correspondingly angled 'seat' in the valve body. Behind that is a 'conical' section of again about 45 deg, tapering down the opposite way to a 15 mm hole to accommodate the 15 mm pipe. This is the piece of the adaptor, that is going to grip down onto the 15 mm pipe. There is then a completely separate piece that is a brass ring about 5 mm deep, that has a corresponding conical seat inside its front face, and a square rear face to go against the inside face of the compression nut. Unfortunately, the online instruction sheet doesn't show this, so I've had to try and describe it.
What should happen, is that as you pull up the compression nut, the conical seat of the outer ring, presses on the conical taper of the inner part of the adaptor, crushing it onto the 15 mm pipe. At the same time, the 45 deg flare a little further in, should be pulling up against the corresponding seat in the valve body, to form a seal.
Except it didn't. Both sides dripped like a good 'un. The low pressure side was actually worse than the high. And from here on in, the day just got worse. I had been careful not to pull the nuts up more than about a quarter turn beyond where the adaptor had obviously gripped the pipe, as I am fully aware that over-tightening a compression fitting can distort it and prevent it sealing. So I carefully pulled it up a bit tighter. Not a jot of difference. Water off again. Disassembled. Inner part of adaptor seemed to be tightly pinched onto the pipe. I carefully examined the flare and the seat in the valve, but both looked ok and undamaged. However, as that was about the only place that I could see that water could be getting past, I put a good wodge of PTFE tape around the flare, and bolted back up. And still it leaked ...
Thinking that perhaps I was wrong then about where the water was getting out, I then nipped to B&Q and bought a couple of end-feed 22 to 15 mm reducers, that had nice long straight bits at the 22 mm end. As a safety net, I also bought a pair of 15 mm straight couplers. Glad I did ...
With the valve back off, I fitted the supplied 22 mm traditional olives over the reducers, and inserted them into the valve body. Nice fit, and the olive is butting up to the seat in the valve nicely. Out with the cutter again, and a bit more pipe removed to accommodate the new length of the valve with it's reducer 'tails' fitted, and to allow the original reducing olives to be removed, as of course, these are now firmly clamped to the pipe, never to come off ...
Valve back in place, compression nuts pinched up, olives appear to be clamped firmly to the 22 mm sides of the new reducers. Other ends of the reducers soldered to incoming and outgoing 15 mm pipes. Water back on.
AND THE BASTARD LEAKED. BOTH EFFIN' SIDES !!!!!
No amount of additional tightening, PTFE'ing, swearing at it or kicking of the cat that wandered past the back door, would improve it. So, with time marching on towards opening, I gave up, and fitted a piece of 15 mm pipe back into the gap, using those two couplers that I had fortuitously purchased ...
As both (very different) ways that I've tried to mount this thing have failed to work in the same way, and the fact that the low pressure side is actually worse than the high, the only conclusion that I can come to, is that the example that I have has been machined badly at the olive seats, or else the product overall, is a piece of shit. During over 40 years of DIY plumbing, I think I've seen most general problems of this type, and I don't ever remember one defeating me before. I'm not an expert by any means, but compression joints and adaptors, are hardly rocket science. I'm not sure what to do now. I was thinking that I might be able to get an O ring in between the olive and the seat, but I'm not sure that would be successful. Anyone got any suggestions, or can think of anything that I'm doing wrong, or missing. Incidentally, when it was in place, with the pressure gauge fitted, it did at least seem to be working, with a steady 3 bar output.
Arfa