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Discuss Immersion heater/constant or timed? in the Central Heating Forum area at UKPlumbersForums.co.uk.

  1. Husk24

    Husk24 Member

    Hi All

    I have a 200 litre water cylinder which I heats up the water using my gas boiler.
    This was already in my house when I moved in it 3 years ago.

    Until recently I have had the timer on from 6am- 9pm every day with temp of around 60 degrees. As I have had my new boiler installed and nest thermostat I wanted to experiment with setting times for the water. It appears the water starts getting cold after 3-4 hours of very light usage, it doesn’t seem to retain the heat.

    1. Could there be an issue with the tank? Does it need servicing? / replacing anode rod?

    2. Is it cheaper to have it timed or like previous all all during the day/evening?

    Thanks in advance
  2. Husk24

    Husk24 Member

  3. YorkshireDave

    YorkshireDave Plumber Top Contributor!!

    How are you heating the water? Electricity or via central htg boiler?
  4. Husk24

    Husk24 Member

    Gas boiler as mentioned above, I would never use electric- definitely know that’s more expensive.
  5. YorkshireDave

    YorkshireDave Plumber Top Contributor!!

    Missed it :eek:
    You'll need to work out the recovery time. If its old it will be higly scaled so much slower. If you need more hot water, consider using an anti stratification pump. That will give you a complete tank full of same temp water.
    Def cheaper to heat as needed. 24/7 was a myth.
  6. chris watkins

    chris watkins Plumber

    When you say the water starts to get cold do you mean at the taps or in the cylinder so that it would re-heat if the boiler was on?

    Alway more economic to have the boiler heat the cylinder for a hour max then not again until hot water has almost / run out.

    Un-vented hot water cylinders do require servicing just like the boilers. Have you checked for water at the tun-dish??
  7. Husk24

    Husk24 Member

    I haven’t checked anything, I have water discharge sometimes from the tun dish, what exactly im I suppose to look out for?

    The water starts to get cold at the taps. It was installed 8 years looking at the label on it.
  8. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    Not the best unvented cylinder IMO , sorry . If you are seeing any water at the tundish you need a G3 / unvented engineer to have a look .
  9. chris watkins

    chris watkins Plumber

    If there is water discharge from the tun-dish it needs a service you need to call in a Part G / unvented certificated plumber, by Law you are required to hold this to work on them.
    If hot water is discharging this could be why you are running out so quickly.
  10. Husk24

    Husk24 Member

    I noticed it a week ago but nothing today, nothing is leaking today.
  11. YorkshireDave

    YorkshireDave Plumber Top Contributor!!

    Apologies for my, frankly daft, posts earlier. o_O

    There are two issues here.
    1 - heating times.
    2 - possible problems.

    1. The time it takes to heat your water depends on a number of things. At 8 years old it is possible the internal heating coil is quite scaled. That will inhibit transfer of heat into the water and slow it down. I do not know how our system is configured, but if you are trying to heat your home AND your water at the same time that will be a slow process. Better, far better, to heat your water when your heating isn't being called for. Our for example, runs from 04:00-06:00 and then we 'top up' 12:00-13:00.

    Only by testing how long it takes for your cylinder to be 'satisfied' will you be able to work out when and how long to have your hot water on for.

    You need to check your cylinder stat. It should be set for 55degs C where it is. That will give you 65 deg water at the top of the cylinder. Water in a cylinder is stratified. It has different temps at different levels. Hottest at the top coldest at the bottom. As a consequence as you use the water, the cool mixes with the warm and you get delivered luke warm water quite quickly. If you want a full tank of water at the same temp, then you have installed an anti stratification pump. This circulates the water INSIDE the cylinder so it's ALL the same temp.

    So, some work and investigation to do.

    Moving on to possible problems. Your cylinder needs annual maintenance. This maintenance must be carried out by a G3 registered plumber. At the very least, they will ensure your cylinder is operating as best it can under its installation circumstances. It may well be that one or more of the safety valves are letting by and slowly releasing hot water to drain. To me, of much more importance is that the sacrificial anode is regularly maintained to minimise internal corrosion in your cylinder so that is lasts as long as it can. Regardless, to NOT maintain it means you risk it becoming a very serious safety issue in your home. I kid you not.

    Get an experienced G3 engineer round and they will advise as to your options.:)
    • Like Like x 1
  12. Husk24

    Husk24 Member

    Hi YorkshireDave

    Thanks for the comprehensive reply.
    I have spoken to my usual boiler man, he’s planning to have a look, but he did ask me about the temp of water, and he doesn’t think I’ve set it to 60, the problem is I gof this ancient dial and just guessing, the water that comes through the tap after its been heated is warm and not too hot, I can easily put my hands on the running tap. I am wondering whether this is the case, im thinking its 60 degrees but infact it probably is 40! I guess i need to measure the temp. Anybody know what temp would the max temp be? This is my dial on the cylinder.

  13. chris watkins

    chris watkins Plumber

    70 deg C, so turn it to max then back a touch, hot water should be stored at 60-65degC.

    Don't forget this will increase the amount of expansion so the safety valve will open again - you still need that service!!!
  14. YorkshireDave

    YorkshireDave Plumber Top Contributor!!

    Looking at your image, the stat is def set far too low. Water at 65 deg C would not be tolerable for your hand. Ergo, turn it up!

    I would estimate, based on just about every other stat of its era, yours would do 45-75 degs. So, to start, I'd set it 3/4 way round (not that far from Chris' advice). What you will find is that its too hot or cold. Turn it then a 'smidge' one way or the other every 48 hrs till it's as you wish it to be. ;)
  15. Husk24

    Husk24 Member

    Great thks, I shall try that.

    Im not sure it is a coincidence I had problems with my boiler valve sticking few weeks back and that’s when i noticed the drip in tun dish, but it hasn’t happened since, the valve has been replaced.
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