hot water problem - airlock - PRIMATIC tank

14 Nov 2006
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United Kingdom
Primatic cylinder..has worked almost flawlessly for almost 30 years (for a rather flawed idea imo).

Old stone cottage/long-house ..single storey with long pipe runs in loft to bathroom at other end of cottage from the cylinder. Plastic cold water storage tank raised on platform (before my time) to give adequate "head". It's enough most of the time. Over the years have had just a few airlocks in the long pipe run and have always been able to get rid by using mains pressure cold water ..running it back up the hot pipe via shower take off fitting on bath mixer tap (not ideal I know)...or using a VAX in suck mode. Anyway it has always worked (but not this time).
The other issue (only 2 or 3 times over the years has been ( leaks as far as I can see) air in the cold feed pipe from the cold water storage tank down to the Primatic. Symptom is that we have only have HW in the kitchen (where the cylinder is) but the push force from the cold storage tank is compromised by any air so that HW flow from the cylinder up and along the loft pipe run to the bathroom is affected just enough.
So a few years back I fitted a connector above the gate valve in the cylinder's cold feed down-pipe (just over 1 metre above the cylinder entry fitting) so I can (briefly) drive mains pressure water back up into the cw storage tank clearing any air. The three times I have had to do it it's worked a treat.

The other day the pressure dropped at the bathroom taps (not sure why?..first time in 2 years) but we still had some flow. I decided that I'd first ensure the cold feed pipe from the storage tank in the loft was totally air free so connected a hose-pipe fed from the mains to my fitting having shut the gate valve below first to ensure the force of water was sent upward to the storage tank. There was a little air in the feed pipe from the cw tank I think (just from listening). Anyway I closed the valve to the fitting & removed the hose pipe..then re-opened the 28mm gate valve on the vertical feed pipe to the cylinder.

Absolutely nothing at the bathroom end and (I think) slightly reduced flow in the kitchen. Have tried everything I have ever done before to get flow back to the bathroom..left it overnight..nothing. A bit baffled to be honest as I thought I knew all the wrinkles in this old place. last idea..can I run the mains pressure cold water through my cold-feed pipe fitting directly down into the Primatic. By turning off the gate valve at the bottom of the cold storage tank my ("injected") mains water will be diverted directly downward from the fitting & into the cylinder and hopefully up and out to the loft pipe run and down through to one of the bathroom taps that would be left open. I have never done this..hence this (rather long) post.

What I don't want to do on any account is to mess up the air bubble in the Primatic up..I know in theory it's on "the other side" ..but if there's any risk at all of affecting it I'll leave it for now til the weather warms up a bit. The Primatic is fed HW on the other side by a wood-stove which we need running at the moment.

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