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Post by cameron999 on Jan 19, 2021 18:11:56 GMT
So we all know that if you've got to change a valve on an open vented system you can bung the tank in the loft and you should be good to go
But what about sealed systems? A lad at my work has told me that if you isolate the flow and return at the boiler and something like shut one side of every rad then you'll get a few litres of water but then it will ''hydraulic lock'' and no more water will come out. How true is this? It was a bit ago but I never attempted it, i tend to just drain down if I've got a trv to change or something (i only ever work on small systems like 2-3 bed houses, so it only takes 10 min to drain down then 5 to fill up).
So is this something that works/is a thing/is kinda true but there's more steps to it? How do you guys do it?
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Post by dickpuller on Jan 19, 2021 19:29:10 GMT
So Cameron, good Jock name👍👍👍
You indeed can ‘crank’ a sealed system, again all you’re doing is creating a vacuum.
I’d hesitate to shut off Combi Boiler F&R ISO valves. Any Combi more than 4-5 years old, these valves will piss out when turned On again!
But feat not!! Open up the Combi, make sure the wee cap on the AAV is closed(stick a bit like of Bluetack on it if it’s missing).
There will be a short blast of pressure & then all will be good.
Two Golden Rules;
No air in, no water out
Only one open end at a time.
HTH👍
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Post by endfeed on Jan 19, 2021 20:43:57 GMT
Would it be too risky to cut into the 22mm flow or return with this method?
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Post by tomplum on Jan 19, 2021 21:01:58 GMT
hello cameron, welcome to the brewcabin, yes it is true, you can ' airlock' the system by using bungs, or take the pressure off a sealed system by ' taking the pressure off, and its ideal for a seasoned campaigner to do this because, there are dangers, There will be water in the pipes and it will want to get out, So you have to have the experience to manage the flow, I would not attempt it on a white carpet or a cheap wood effect floor, For a diyer I would not recommend it, because if things go wrong, as they often do, a diyer would not know in which direction to run, you would run in one direction for a towel , you can't find one, so you go a different way for a hose pipe, none there, so you go back and see the room covered 2 inches deep in dark coloured water and its a bad feeling Like most plumbers, I've been there  |
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Post by woodbine66 on Jan 19, 2021 22:06:06 GMT
Would it be too risky to cut into the 22mm flow or return with this method?
Could be because you've got two ends of the pipe open. Also, unlike whipping off a rad valve which can easily be put back on if there's a tsunami, once cut - the pipe stays cut.
Could be -
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Post by dickpuller on Jan 20, 2021 6:21:47 GMT
Would it be too risky to cut into the 22mm flow or return with this method? If you can isolate all radiators for example, LS Valves, don’t trust TRV’s to close fully!! Modern 10Bar LS Valves rarely leak. It needs planning & careful thought. REMEMBER the golden rules, ONE open end. Which is just simple Physics for the hard of thinking👍👍 As Tom has said, it’s easy to get it wrong. Even for an Artisan like my good self, hard to believe I know!! |
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