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| Thread ID: 140665 | 2015-11-23 01:29:00 | Hot water cylinders. | Richard (739) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 1411777 | 2015-11-23 01:29:00 | Has anybody had experience with replacing a water cylinder with pressure controlled by a Nefa/Ajax valve, with a mains pressure system? What are the pitfalls or problems to be encountered? Does all tapware need to be replaced? As far as I am aware at this stage, all hot water piping is copper, so increased pressure in piping should not be a problem. All experiences welcomed. | Richard (739) | ||
| 1411778 | 2015-11-23 03:04:00 | I thought a Nefa/Ajax valve was for a low pressure cylinder?? (ie reduces mains pressure to about 7m head We've got a cylinder of each sort. The mains pressure cylinder is a heat exchanger - the hot pipe goes through a static jacket of water heated by the element, as I understand it. I'm not sure what pressure the jacket operates at. It might have a pressure reducing valve?? but I can't see it. All I know is we're supposed to to operate the jacket's relief valve every 6mo or so but I've only done it once in 10 years and feel guilty The low pressure cylinder is upstairs and has a short vent pipe through the roof, allowing a head of only 3m or so. About 5 years ago we needed to replace the cylinder and the plumber put a relief valve at the top of the vent pipe. The valve increases the effective head to 7m or so. 7m is the rating of the cylinder. The so-called relief valve made a huge difference to shower performance |
BBCmicro (15761) | ||
| 1411779 | 2015-11-23 03:56:00 | Did it about two months ago. Old low pressure one was inside new mains pressure one is outside. The only downside is that the hot water now has to travel about 3 times further than it did with old tank.. No new pipe or plumbing work involved.. | paulw (1826) | ||
| 1411780 | 2015-11-23 03:59:00 | I probably was a bit unclear. I want to replace a low pressure cylinder, which uses the Nefa valve to reduce the mains pressure, with a proper mains pressure cylinder. The head of water you mention balances against the mains pressure in the reducing valve, allowing you to wind open the valve a bit. Too much and you will burst the tank, which is NOT a pressure vessel, the flood could be horrific. As it would be too if you don't check the operation of your relief valve. DO IT TOMORROW! | Richard (739) | ||
| 1411781 | 2015-11-23 07:19:00 | We replaced an old electric low-pressure cylinder a few years back with a mains-pressure gas infinity heater. We did replace the shower nozzle and mixer but otherwise every tap and pipe stayed the same. The main reason for doing so was that the hot-water pressure was pathetic. We now have excellent pressure, a never-ending supply of hot-water and have gained a new cupboard. (where the cylinder used to be.) |
decibel (11645) | ||
| 1411782 | 2015-11-23 07:45:00 | if you don't check the operation of your relief valve. DO IT TOMORROW! all right ALL RIGHT I did it just now to keep you happy :) No problems. I noticed that in addition to the relief valve it has a relief "button". The instructions say to check this is not leaking (I've been putting off operating the lever in case it doesn't re-seal properly and leaks water in which case I should probably not do it on a weekend. And probably not on a Monday because plumbers will be busy after the weekend. Perhaps I'll leave it until a plumber is doing something else around the house... and that's how 10 years goes by) |
BBCmicro (15761) | ||
| 1411783 | 2015-11-23 18:30:00 | Has anybody had experience with replacing a water cylinder with pressure controlled by a Nefa/Ajax valve, with a mains pressure system? What are the pitfalls or problems to be encountered? Does all tapware need to be replaced? HUsband has done heaps. No taps don't have to be changed. Using mains (high) pressure mixers on a low pressure system is a problem, the other way round, no. It's not complicated, just more expensive for the mains cylinder....usually because they are bigger for one thing. |
pctek (84) | ||
| 1411784 | 2015-11-23 21:09:00 | Thanks for all the helpful replies. Sounds like the way to go now. Well done BBCmicro. I shall stop worrying about you now. I know exactly what you mean about trying to get a plumber on a Monday morning. Murphy's Law must dictate that floods always happen on weekends! | Richard (739) | ||
| 1411785 | 2015-11-26 18:19:00 | Yeah, you may need to tutu with the flow adjusters in each shower mixer, otherwise there's a heightened risk of scalding with so much more hot flowing through. I live within a stones throw of the local water treatment plant, and the issue I have is that the supply pressure to the house (and tank) is at times higher than the relief valve (and tank) is rated for. This has necessitated turning the adjuster up on the valve to get more pressure on the spring that keeps the valve shut - not ideal, but seem to have got away with it. With such a low margin of difference between supply pressure and valve seat pressure it means that whenever I periodically test the valve it can be reluctant to seat again properly. It also gets fouled up with deposits from the water which also impairs the valve seat. I've found it best in my case to just leave the damned valve alone once it is firm enough to seat and stay seated. The cylinder is in the garage, so if it gives way there's nothing precious getting wet. It is soooo much nicer having a shower with decent pressure, even though I now keep a flow restrictor on the shower head to cut the flow by about 60%. |
Paul.Cov (425) | ||
| 1411786 | 2015-11-26 20:10:00 | Thanks Paul. That's all good stuff to watch for. BTW Is your name Coventry? My great-great-great-great grandfather was William Coventry, born in Rangeworthy, Gloucestershire in 1720. | Richard (739) | ||
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