Dual Thermostats on Water Cylinder

Is there much merit in fitting two thermostats to a large water cylinder in a large property that is often occupied by just two people who use the shower almost exclusively? I envisage mounting them at one quarter and two thirds from the bottom of the tank and switching between the two as required to the programmer.
Mike
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     snipped-for-privacy@btinternet.com writes:

Could do.
Note the bottom one must be above bottom of the heating element or coil, which is usually higher than you suggest. If it's too low, it will sit on the area of the tank which always remains cold, so the tank will heat as though there is no thermostat.
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Andrew Gabriel
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On 12/08/2014 18:38, Andrew Gabriel wrote:

My tank stat for my oil fired boiler, uses a probe which passes through the 2" insulation right at the bottom of the tank by the drain valve.
It is set to about 35C.
The temperature in that area gets to about 40C according to a different thermometer I have there.
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Michael Chare

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On Tue, 12 Aug 2014 17:38:22 +0000 (UTC), snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote:

Thanks Andrew, Good point, I will check the height I was going on the Danfoss instructions for theirATC thermostat to be fitted between one quarter and one third from the bottom.
Mike
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There is very little benifit. The convection currents in the tank cause similar masses of water to be heated. Use of a lower stat means water is slightly warmer than with and upper stat, so no benifit.
This is why some tanks are fitted with twin immersion HEATERS which has the effect you desire. Even then, some heat moves downwards by conduction when the upper heater is used.
I have an instantaneous electric shower fitted in the same cubicle as a conventional shower. This means I can use solar hot water or electic water when not available.
I suggest you get an electric shower if you never use the bath.
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On Wed, 13 Aug 2014 07:37:12 +0100, harryagain wrote:

For once Harry is on the right track. Twin stats would only give benefit if you have some means of only heating the top of the tank. A conventional primary coil will reheat the whole tank.
If there is or can be fitted am immersion heater at the top of the tank it might be cheaper to use that for small amounts of hot water rather than the gas/oil heated primary. But TBH compared to space heating water heating is minimal, another insulating jacket or boxing in the tank and filling the void with insulation could concievably make greater savings.
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Dave.
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On Tue, 12 Aug 2014 18:26:52 +0100, mail-veil wrote:

Yes, so that when only 2 people around just use the top heater, and when the hordes descend switch the other one in as well, so more hot water and gets heated faster between showers/baths.
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