How long to have immersion tank on for?

[dllive]

Hi guys,

Ive recently moved into a house. It has an antiquated immersion cylinder. I have it heat itself for about 30 minutes each morning - I only need it to do a bit of washing up each morning before work.

However, recently the water has been coming out only luke warm. Yesterday I tried having the element on for 1 hour, and this seems to heat the water sufficiently.

I thought maybe the element or the thermostat was faulty, but then maybe 30 minutes just isnt enough time. I just thought Id canvas opinion here: should I have the immersion on all the time (even though I only use it in the morning to do washing up), or maybe have it on for an hour each morning? I want to have a bath soon (normally I shower - which is electric so doesnt use the immersion cylinder's water) - what would be the normal time to have an immersion on for that?

These may seem like stupid questions, but Ive never had an immersion cylinder before so I dont know what the norm is.

Thanks.

 

[Charnwood]

Was 30 minutes enough previously?
It is winter. Could cold ambient temperature be a factor.
Is the cylinder adequately lagged/insulated?

The element could have become scaled up.
You will practically have to heat the whole cylinder full of water, even though you only want a bowl full of hot water. Although, if adequately lagged there should be some residual heat from the previous heating session, if not all used up.

A kettle might be a better option for a bit of washing up.

 

[JohnD]

Does the cylinder have insulation? What colour is it? Do you have ekectric storage heaters?

Do you have a boiler?

 

[dllive]

Hi JohnD,
Ive uploaded a couple of photos: //www.diynot.com/network/dllive/albums/15757

As you can see, its an old tank - no integrated insulation jacket. I have put quite a bit of insulation jackets around it.

I do have electric storage rads and I dont have a boiler.

Ive added a photograph showing that there is only about 28cm above the thermostat. Is this going to be an issue getting the old element out? (if the element does need replacing).[/img]

 

[JohnD]

as you have electric storage heaters you ought to be on a cheap overnight tariff for your electricity. In which case you should heat the cylinder overnight at your cheap rate using a timer.

the stat is turned to max which is scalding. Set it between 50 and 60. It will turn itself off (and stop using electricity) when it is hot enough.

the stat is fairly modern so the element probably does not need changing. When it does you will remove some of those slats and it will lift out through the airing cupboard.

 

[Bosswhite]

What is the Storage heater tariff like, could you fit a timer to the Immersion heater switch and heat the water overnight,

It does sound as if the suggestion of heating a kettle for hot water is the cheapest alternative though.

 

[dllive]

Thanks guys - very useful comments.

In which case you should heat the cylinder overnight at your cheap rate using a timer.

I do have a timer. At the moment I have it come on at 5.30am (at the cheaper tariff). My current routine is to have just enough hot water for a bit of washing up in the morning. Im out at work all day. I dont need hot water in the evenings (other than a shower which doesnt use water from the tank). So Id like to avoid having the immersion on longer than I need. Maybe Im being too conservative! Ive never had an immersion before so I dont know how long I should have it on for - say - a bath.

the stat is turned to max which is scalding. Set it between 50 and 60.

I read somewhere that cooler than 70 degrees is dangerous because bacteria can grow. Is that wrong/bad advice?

the stat is fairly modern so the element probably does not need changing.

Thats good to know. Ive no idea what a newish stat looks like compared to an old stat!

you will remove some of those slats and it will lift out through the airing cupboard.

hah! that hadnt occurred to me - thanks!

 

[JohnD]

legionella is the most worrying infection, and grows between 24C and 45C. Above that temperature it does not multiply

it is killed at 55C, but is killed more quickly as the temperature increases.

http://www.hse.gov.uk/healthservices/legionella.htm

 

[Agile]

You should insulate the tank well and set the stat for about 60 C.

If heated by off peak thats cheap so Ideal to use as required.

But for just washing up an on peak kettle is going to be cheaper!

Tony

 

[dllive]

Thanks guys - great advice as always!