Immersion cylinder replacement help pls!

Discussion in 'Plumbers' Talk' started by Shellie90, Jan 14, 2021.

  1. Shellie90

    Shellie90 New Member

    Hello, just looking for some advice as I live in an all electric home and have been having an immersion heater crisis since 2019! I have a very very old immersion heater (the ones with a square outer jacket) and what happened was the tank worked fine for the first 4 years of being in my flat and one day the immersion switch fuse blew. I assumed it was the thermostat, got that replaced, worked for a while and again blew. I then got the actual immersion element changed, again worked for a couple days and blew as I switched it off. I was due a rewiring so assumed it could be an electrical fault so have now got the whole flat rewired. It was working fine for a while and then blew again as I switched it off recently. I think it’s worth replacing the whole cylinder as it really has aged over 30 years and could be leaking heat or have a wiring fault within the actual system. It’s really causing me mental distress now lol (who knew immersion heaters could be so stressful!).

    My Questions to you pro’s are:
    1) I was wondering if anyone knew of any alternative water heating systems besides an immersion heater?

    2) Do they sell single element immersion tanks? (I think my electrician cut the economy 7 switch accidently so I only have one socket powering the top part of the element on a standard tariff) I live alone so wouldn’t mind a smaller tank to switch on only before using.

    3) If I were to get the whole cylinder replaced what sort of price am I expecting to pay

    4) Are there any good companies out there you would you recommend for the job?

    5) I have considered a combi boiler but I don’t really get how they work, do I need to get a whole new system installed throughout the flat or can it just be used to heat my hot water?

    Apologies for all the questions, I’m really a rookie and don’t know anyone in the plumbing industry to ask. Thanks!
  2. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    1. Asides from a gas boiler, no

    2. Yup, or you can get a dual element cylinder and leave the cap on the second port

    3/4. No idea I'm afraid, but not a lot. Beware though, a cylinder is worth a few quid as scrap, don't let them just take it away without giving you money off your bill

    5. A combi boiler takes mains cold water from the street supply and heats it when required using mains gas. You just need a single pipe between the boiler and somewhere with a hot tap (existing pipes can be reused, might just need some jigging!

    What do you currently have for central heating?

    Edit: just spotted that you're an all-electric home so some of the above is irrelevant unless you can get a gas supply installed. If you can't, you'll definitely want to get the economy 7 connected up and use that
    Shellie90 likes this.
  3. Shellie90

    Shellie90 New Member

    This is really helpful thank you so much for your response, will look probably look into installing a new tank and connect economy 7 supply. Last question, do you know if economy 7 needs to be wired on a separate fuse board, I believe my standard electric tarif is cheaper in the evenings as opposed to actual eco 7.

    Thanks again!
  4. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    An Economy 7 meter will have two cables coming into your house/flat. One will be live the whole time for all of your normal circuits (sockets, lights, shower, cooker etc), the other (usually to a second fuse board/consumer unit) will only be switched on by the meter at off-peak times and will supply your hot water cylinder (lower immersion heater if it has two) and storage heaters if you have them

    Normally the second immersion heater (the top one) will be fed from you 24/7 supply and will only be to give you a quick boost of hot water when you decide you need it.
    Shellie90 likes this.
  5. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    Got a photo of your cylinder?
  6. RolandK

    RolandK Screwfix Select

    I would agree that a replacement tank with immersion heaters is probably your best bet. There are other options if you don't have gas like heat pumps or using solar etc. but installation costs are high. As you already have an immersion heater/ tank the basic plumbing should already be there to hook up a new tank to. Definately reinstate an economy 7 or equivalent off peak tariff. Heating water with electric is already 3 to 4 times more expensive than gas so need to drive down the cost as much as possible.
    I'd suggest that you get an electrician to check out the wiring in preparation for the new install especially with the problems you are having. Could well have some gremlins there!
    I had a new cylinder and heaters installed last year and it was about £700 all in but that was a rather large cylinder.
    Yes, economy 7 goes on it's own circuit. The new tank should be more efficient than your old one with far better insulation so cheaper to run.
    Good luck
    Shellie90 likes this.
  7. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    Where are you based Shellie?

    Maybe someone on here can do the job or recommend someone
  8. Shellie90

    Shellie90 New Member

    Thank you, yes
    Thank you so much, yes have attached (its a horrible looking thing!)
  9. Shellie90

    Shellie90 New Member

    Thank you so much for your help really useful info, think that’s my best bet. I have an electrician coming to fix something on the weekend so will be sure to ask :)
  10. Shellie90

    Shellie90 New Member

    Based in East London
  11. RolandK

    RolandK Screwfix Select

    You're very welcome. Let us know how you get on.
    Shellie90 likes this.
  12. andy48

    andy48 Screwfix Select

    1. As requested above, a photograph of your hot water cylinder would be useful.
    2. I'm not just being picky, but what you have is a hot water cylinder (HWC), directly heated by an immersion heater.
    3. If you have the old square type, it is highly likely that your cold water storage cistern (CWSC) is located immediately above the HWC, and may well share the same supporting frame.
    4. If that is the case you will probably have to replace the whole thing.
    5. The immersion heater is a long insulated heating element, usually between 11 and 27 inches long. The heating element (same as an electric fire) is enclosed in special insulating material, which in turn is enclosed in a metal sheath. Down the side of the element is a thin metal tube, and inside the tube is a thermostat. When you turn the immersion heater on, electricity passes through the element and heats it up. This in turn heats the water around it. When the water reaches a set temperature, the thermostat turns off the electricity, otherwise the water would boil. When the temperature drops a bit, the thermostat turns the element back on. You can turn a knob on the end of the thermostat to alter the desired water temperature. Modern thermostats also have a second thermostat within them, which cuts the element off completely if a certain temperature is exceeded. These are called overheat thermostats, have have to be manually reset.
    6. An immersion heater can trip the electric (MCB or fuse) in a number of ways. The main ones are:
    6a. The heater develops a fault and the insulation breaks down. The electricity short circuits and blows the fuse.
    6b. If the wires to the head of the immersion heater are not tight, the cables may not make good contact and an electric arc develops. This can damage the insulation of the cables, and again lead to the fuse blowing.
    7. A significant cause of immersion heaters becoming faulty is a build up of limescale in the cylinder. This thermally insulates the element from the water, and causes it to overheat locally. It is of course a particular nuisance in hard water areas.
    8. Depending on the construction of the cylinder, it is often possible to isolate the incoming water, slacken the immersion heater, drain the cylinder, remove the immersion heater and clean out the limescale via the hole left by the immersion heater. Usually cheaper than a new cylinder, and no disturbance of pipework.
  13. Shellie90

    Shellie90 New Member

    Thank you very thoroughly explained, I did recently get the immersion element replaced to a brand new one so chances are the limescale has either effected the tank as it is very very old, (The water temp has been turned down to 55 degrees and the water would still be super hot despite this so could be!), also I do live in a hard-water area so is possible, the wiring from the element is also very aged so that could also be a possibility. I think best bet is to replace the whole thing as it has become a nuisance and age is playing a major factor I think.

    Thanks :)

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice