Savings in fitting timeswitch to undersink heaters

buzz11

At work we have 4 undersink water heaters each one is 10litre size and 2.2kw power, the are left on 24/7 and are located in bathrooms so the hot water is only drawn off when people use the hot taps for hand washing.

Is it worth fitting a timeswitch to each one to save on electricity?

Fitting is very easy, just swap the on/off switch for a timeguard immersion timer such as this one;
https://www.timeguard.com/products/time/immersion-and-general-purpose-timeswitches/ntt03-24-hour-7-day-compact-electronic-immersion-heater-timeswitch

The number of hours the heater is turned on would reduce from 168 hours per week to 40 hours so a 76% reduction but how much power does a water heater use when nobody is drawing off the water?

aido79

buzz11 wrote: »

At work we have 4 undersink water heaters each one is 10litre size and 2.2kw power, the are left on 24/7 and are located in bathrooms so the hot water is only drawn off when people use the hot taps for hand washing.

Is it worth fitting a timeswitch to each one to save on electricity?

Fitting is very easy, just swap the on/off switch for a timeguard immersion timer such as this one;
https://www.timeguard.com/products/time/immersion-and-general-purpose-timeswitches/ntt03-24-hour-7-day-compact-electronic-immersion-heater-timeswitch

The number of hours the heater is turned on would reduce from 168 hours per week to 40 hours so a 76% reduction but how much power does a water heater use when nobody is drawing off the water?

Are they plugged in?

Would it be possible to use something like this to monitor the power usage for a day/week to see if it's worth putting them on timers?
https://purchase.ie/product/all-products/electricity-monitoring-socket

They may use less electricity than you think as they won't be drawing the full 2.2kw all the time. They'll probably use very little once the water has been heated to the required temperature.

autumnalcore

Some manufacturers specify the heatloss per 24 hours e.g.

https://www.heatingsparesltd.com/download/boiler_manuals/Ariston/Water_Heaters_5_to_30_Litres.pdf

Taking 0.7kw as a ballpark you would think you would save 76% x 0.7kw = 0.53kw per day per heater.

But when you factor in that you continue to lose heat while the heater is powered off (albeit at a diminishing rate as the temperature drops) the heat lost while the heater is powered off is put back in when you power on the next day. The savings will probably be tiny.

Retro.

You can't swop the electronic controller with the isolator

You can add it in