« Last post by Murray Glue on May 22, 2013, 01:33:11 PM »
Hi and thanks for your reply. Sorry its taken me a while to get back to you...
The piping from the cylinder down to the wetback is the same as was installed for the 3Kw " Pulse Valve " model I took out. Its 20mm but it is smaller than the tubing ends that stick out of the new 3kw wetback, which are 25mm.
The plumber had to do some squashing ( not a professional plumbing term, but thats what he did ), to get it to where he could weld one to the other. Could this reduction in pipe sizes be the cause of the problem?
I crawled into the roof space to check: the tempering valve is connected between the top of cylinder outlet ( H ) and the cold water supply ( C ) and outputs to the hot water taps in the house. I guess this is to cool the water if it gets too hot at the top of the cylinder. So, no its not in the wetback side of things. My apologies for throwing that one in.
Yes the wetback up-pipe goes to the top of the cylinder where it is open vented through a standpipe on the roof, which is lagged and sleeved, and is about 3 m high. The cold water down to the wetback comes directly out of the cylinder a few inches above the base of the cylinder, which is my experience of where it should come from.
The wierd thing is that when you light the fire from cold, you get gradual heating of the riser side, while the down pipe stays cold, or cool anyway...then after fifteen or twenty minutes there is usually a succession of gurgles and burps, and some rattling of the whole set-up, after which it settles down but both pipes appear to be rising. Eventually there is very little difference between the riser and the down-pipe as far as temperature are concerned, but there is little or no boosting of the water in the cylinder when you go to take a shower.
I would love to get this sorted out....so any input would be gladly received. I have installed a couple of systems before, myself, and they have worked fine. One included a temperature controlled pump to do the circulating as there was a distance of several metres horizontally and with no rise to the cylinder. But this one is a straightforward setup and should work without issues.
Is it possible that I should instal a non return in the downpipe...to replace the pulse valve that was in the existing system before I decided to change the wetback? ( And wish I hadnt!! )...I was told that its bad plumbing practice to instal any kind of restricting valve in a wetback system, in case it fails.