Digsy Posted October 23, 2017 Share Posted October 23, 2017 I’ll soon be doing some fairly major plumbing inside my airing cupboard which will be much simpler if the copper cylinder is removed. Question is, do I stump up £150 and just replace it while I am on the job? My first copper cylinder lasted less than 5 years before splitting around the base. This one has been in for about 15 years, and I know most of them only come with a 2 year guarantee. I live in a very hard water area and the tank that split after 5 years was full of limescale when it came out so god knows what this one is like. Also, are the fitting locations for cylinders standardised? I.e. if I buy another 900x450 cylinder with 22mm compression fittings, will it be plug & play when I install it, or will I have to cut the existing connections about? Looking at the cylinder that is in now, I am fairly certain that did not require any changes to the plumbing as the pipes have been painted almost right up to the unions and the is no evidence of this being disturbed from when I had the cylinder replaced the first time. Was also considering replacing with a stainless steel cylinder, but from what I have read they can be something like 30% less efficient due to stainless steel being a much poorer conductor of heat, so even if they need to be replaced more frequently, a copper cylinder will pay for itself in the long run. I am happy to do the plumbing myself, just trying to weigh up the potential size of the job. Quote Link to comment Share on other sites More sharing options...
Ark Posted October 23, 2017 Share Posted October 23, 2017 I'm only an amateur DIY plumber but I'd say for £150 and an easier job, yes do it. Maybe even swap out your circulating pump and control valves while it's all drained. Bitter experience has taught me that direct replacement plumbing parts are never quite plug 'n play, so always expect some buggering about. However, if you use push fit tank connectors (like these) you can join back to your existing copper pipes with a bit of plastic pipe - doddle. I'm sure real plumbers would throw their hands up in horror but hey, it works. And my entire plumbing systems appears to have been professionally installed on a 'hey, it works' basis. Quote Link to comment Share on other sites More sharing options...
Digsy Posted October 23, 2017 Author Share Posted October 23, 2017 Thanks for the feedback. Yeah, that's pretty much what I was thinking. This is part of a complete bathroom refit so in terms of extra cost it's peanuts. My circulating pump is on service valves already, but good call on swapping the motor valve - I will certainly do that too. I have been pointed towards push-fit stuff by several people, including by one professional. I'll give it a go eventually, but not sure about using it on a hot water tank for my first try! Actually, flexible hoses would be ideal for connecting a tank up with minimal hassle but I guess maybe they can't handle the temperatures / pressure? Even though, mine is a vented system, so the only pressure would be from the head of water in the loft tanks... *EDIT* Just Googled and found out that (obviously) the internal bore on flexible hoses is far too small to use on cylinder connections. Quote Link to comment Share on other sites More sharing options...
Ark Posted October 23, 2017 Share Posted October 23, 2017 A brita filter kitchen tap I bought used plastic pipe and push-fit fixings to handle mains pressure water - never dripped once, unlike the brass compression isolation valve it connected to. As with all things, buy quality fittings for peace of mind, and remember to use the inserts so the ends of the plastic pipe don't collapse in the joints. Oh, and with the price of copper you can save a small fortune by using plastic pipes for the whole bathroom. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted October 23, 2017 Share Posted October 23, 2017 It is unusual for any 2 cylinders to have tappings in the same place, and depending on the size of the cylinder and the area you live in (really) they can be male or female threads, or even 22mm or 28mm compression fittings. Also check to see if your existimg cylinder has a coil (some even have 2), immersion heater bosses etc. Most immersion heaters now have a thermostat built in, but some have a separate 'stat. I would, however, change the tank. Usually by the time you acrually realise you need a new one, the existing one has rotted through entirely. Dont use flexi's, use copper tube. You can use plastic pushfit, but i wouldnt on visible areas like an airing cupboard. I believe it is good practice to use sweeping bends rather than elbows where needed on the cylinder connections of gravity systems. Quote Link to comment Share on other sites More sharing options...
Digsy Posted October 23, 2017 Author Share Posted October 23, 2017 It is unusual for any 2 cylinders to have tappings in the same place, and depending on the size of the cylinder and the area you live in (really) they can be male or female threads, or even 22mm or 28mm compression fittings. Well that's a colossal pain in the butt I will have to have a closer look, measure up and compare to some new ones. For info its a single coil with an immersion heater boss and a single take-off. cold in and hot out are both 22mm and the coil connections look like 28mm. I need to add a second take off and gravity loop to feed a booster pump, hence the reason for the surgery. Quote Link to comment Share on other sites More sharing options...
formatzero Posted October 23, 2017 Share Posted October 23, 2017 I replaced my Economy 7 tank about a year ago.I contacted a supplier by phone with the tank dimensions and location of the tappings,and hey ho a perfect fit ,simple job. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 30, 2017 Share Posted October 30, 2017 Was also considering replacing with a stainless steel cylinder, but from what I have read they can be something like 30% less efficient due to stainless steel being a much poorer conductor of heat, so even if they need to be replaced more frequently, a copper cylinder will pay for itself in the long run. I meant to reply ages ago and got distracted, why would you want a drum that contains hot water to conduct heat away faster than one made of a less conductive material? Most modern copper cylinders are jacketed with foam insulation to retain the expensively created heat.... I would think the most heat insulating material possible that is structurally suitable would be the best! Quote Link to comment Share on other sites More sharing options...
Digsy Posted October 30, 2017 Author Share Posted October 30, 2017 I meant to reply ages ago and got distracted, why would you want a drum that contains hot water to conduct heat away faster than one made of a less conductive material? Most modern copper cylinders are jacketed with foam insulation to retain the expensively created heat.... I would think the most heat insulating material possible that is structurally suitable would be the best! Not sure Chris. Maybe I got the wrong end of the stick. I just saw that stainless steel cylinders were available for about the same cost as copper and thought it was such a no-brainer that I did a quick Google and found the information that stainless was less efficient than copper. I admit I didn't research it thoroughly. Maybe the coil is made from stainless as well, so it doesn't transfer the heat into the cylinder as effectively? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 30, 2017 Share Posted October 30, 2017 Yes if the heating coil was less thermally conductive that would make sense! I think that must be it, but can't see why a stainless cylinder couldn't have a copper coil unless electrolysis was the issue, but then there must be an interface of dissimilar metals in the fittings somewhere... hmmm Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted October 30, 2017 Share Posted October 30, 2017 Yes if the heating coil was less thermally conductive that would make sense! I think that must be it, but can't see why a stainless cylinder couldn't have a copper coil unless electrolysis was the issue, but then there must be an interface of dissimilar metals in the fittings somewhere... hmmm This is a particular issue with copper. Thry used to fit sacrificial annodes to copper cylinders, but they found that the annode would actually cause the destruction of the tank in many cases, as the annode would do its job, but the local corrosion would first destroy the wire suspensing the annode, which caused it to fall to the bottom of the cylinder, which would then rot through very quickly. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 30, 2017 Share Posted October 30, 2017 This is a particular issue with copper. Thry used to fit sacrificial annodes to copper cylinders, but they found that the annode would actually cause the destruction of the tank in many cases, as the annode would do its job, but the local corrosion would first destroy the wire suspensing the annode, which caused it to fall to the bottom of the cylinder, which would then rot through very quickly. How aNNoying https://www.merriam-webster.com/dictionary/anode You are going to tell me that's a Yorkshire way of spelling it, aren't you? Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted October 30, 2017 Share Posted October 30, 2017 Nothing to do with Yorkshire, just my inability to spell words with more than two letters Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 30, 2017 Share Posted October 30, 2017 I won't mention Yorkshire fittings then Positive (anodic) vibes to you Quote Link to comment Share on other sites More sharing options...
Digsy Posted October 31, 2017 Author Share Posted October 31, 2017 If you want a cure for insomnia, here is the full report on the "stainless versus copper" cylinders study: https://www.mcdonald-engineers.com/sites/mcdonald/files/copper_v_stainless_research_report_-_small.pdf Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted October 31, 2017 Share Posted October 31, 2017 A quick skim through suggests the inefficiency of stainless versus copper is down to the material of the heat exchanger coil itself as above. We can sleep soundly now, thanks Quote Link to comment Share on other sites More sharing options...
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