Immersion question

Jo4

Flyboy152 wrote: »

That's a very long time to heat a standard hot water cylinder.

Mine takes the same length of time, should I be concerned?

macman

Ah, but what about the ongoing heat loss while the tank is heating up?

grahamc2003

Flyboy152 wrote: »

Most immersion heaters don't have thermostats, but they all have thermal cut-outs.

Every standard domestic immersion heater i have seen has a requirement for a thermostat if wired correctly. The thermostat is a separate piec e of kit which slides into a tube in the centre of the immersion so it senses the water temperature between the elements. Not sure what you mean by a thermal cutout, but they are real thermostats, which both disconnect the power at the high threshold, and switch it back in when the temperature cools to the lower threshold, a degree or so below the cut-out temperature.

AFAIAA, there's no requirement for any other form of cotrol - and particularly nothing like a kettle, which has a switch set to turn off when boiling, and a second safety switch which trips when the elements reach a much higher temperature (to protect against dangers of putting the kettle on with no water in.).

I really can't believe there are any doestc immersion heaters desgined to work without a thermostat of some sort, and they would be very dangerous if there were. Boiling water in the hot tank would build up pressure driving that boiling water into the cold tank, which could melt, if plastic, and dump that boiling water above your head.

espresso

Flyboy152 wrote: »

Most immersion heaters don't have thermostats, but they all have thermal cut-outs.

Incorrect.

All domestic immersion heaters manufactured from 1st March 2004 are fitted with a combined thermostat and safety cut-out to provide further protection against boiling if the water thermostat fails. From April 1st 2004, BS EN 60335-2-73 is the only standard applicable for immersion heaters manufactured for sale in the European Union.

The death of a ten-month-old girl who was scalded in her cot could have been avoided had warnings about faulty immersion heaters been passed on.

see here

Flyboy152 wrote: »

No, it's for use during the summer months, when you don't need the gas boiler on.

Incorrect again!

The immersion heater is not for summer use, it is fitted as a backup method. It is cheaper to use a gas boiler all year round if you have one to heat your hot water, rather than use an immersion heater.

.

Pincher

Heat loss during heating? Surely it's the heat loss the rest of the day that you should worry about.

Obviously you should start the shower 15 minutes before the end of the heating period. You rinse off with the last of the warm water. Towel dry, and switch off the immersion. As stated before, you should use one these to avoid forgetting to switch off:

http://www.tlc-direct.co.uk/Main_Index/Water_Heating_Index/Immersion_Heater_Timers_2/index.html

So you start with a lukewarm tank, and end with a warm tank.
Losing heat and money to the environment? Humbug!



Summer use

Assuming you do not pay standing charge, and the supplier does not scalp the Tier 1 units into the winter months, you can potentially save a few pounds by switching off the gas supply. Second DAN misers would shower using electricity once a week. A third DAN miser would simply have cold showers, of course. :rotfl:

Cardew

Pincher wrote: »

So Cardew would have heated the water to 69 (= 20 + 38.8 ) degrees, with 80 litres at the bottom not so hot.

Thanks!

Just one point 20 + 38.8 = ???

macman

And presumably a 4th DAN miser would cut the showers altogether and save on the water bills...

Flyboy152

espresso wrote: »

Incorrect.

All domestic immersion heaters manufactured from 1st March 2004 are fitted with a combined thermostat and safety cut-out to provide further protection against boiling if the water thermostat fails. From April 1st 2004, BS EN 60335-2-73 is the only standard applicable for immersion heaters manufactured for sale in the European Union.

How many immersion heaters were fitted before 2004, against the last seven years?

Incorrect again!

The immersion heater is not for summer use, it is fitted as a backup method. It is cheaper to use a gas boiler all year round if you have one to heat your hot water, rather than use an immersion heater..

It costs me less money to heat a tank of hot water by the immersion heater, than by the gas boiler. But less to run the central heating and heat the water, rather than heating and immersion combined. I have worked it out as about seventy per cent cheaper. It is roughly the same in the properties I let out and all my family's systems as well.

macman

The kwh input to heat the a tank of x litres by y degrees is the same whether using the gas boiler or the immersion heater, but gas is around a third of the cost per kwh. Even given the lower efficiency of a gas boiler, how do you get a figure of 70% cheaper?
And you don't have to switch your CH on to heat the boiler, unless you have an ancient system without the most basic controls?

Cardew

Flyboy152 wrote: »

It costs me less money to heat a tank of hot water by the immersion heater, than by the gas boiler. But less to run the central heating and heat the water, rather than heating and immersion combined. I have worked it out as about seventy per cent cheaper. It is roughly the same in the properties I let out and all my family's systems as well.

Show us how 'you worked it out' please.