heating time for immersion shower?

Hi there,

We have an immersion to heat water for our shower and hot water for the taps. There's a timer in the hot press and outside we have on/off and sink/bath. we were told when we moved in that heating it for half an hour should do for a 20 min shower. We chose the sink option as it seemed to take less time to heat.

That has worked so far in the ensuite which is a power shower. We had low pressure in the main bathroom as it was gravity fed so hadn't been using it until the landlord recently put in a pump.

Since we've started using the pump so for the main bathroom- I know the water probaby wouldn't last as long but when i heated the water for 40mins I barely got 10 mins of hot water in the shower. We usually have the heating on for a least an hour most days aswell but we haven't had it on the last couple of days-that may have made a difference.

Got advice to heat water on bath for at least an hour and then I will get only 7 mins of hot water.Seems like hardly any time.

Any ideas? how long is best to heat for?

thanks

An immersion heater will not keep up with a power shower. Immersions are normally either 2.5kW or 3kW. You can get larger ones, but they cost a lot to run and normally burn out frequently. Your electricity bill must be quite high running on immersion heating. It is the equivalent of boiling the kettle continously and that's the most expensive way of heating water. Immersion 3kW = Kettle 3kW!

Depending on the size of the pump, a power shower could be delivering anywhere from 9 litres to 15 litres per minute. So say it's 10 litres per minute, that would be 10 litres x your 20 minute shower = 200 litres. Approx 40% of this will have come from your cold, so you will have used approx 120 litres of hot water. You will have emptied a standard 30 gallon copper cylinder before you finish your shower.

Your only option is to heat the whole of the cylinder with your primary heating, i.e. oil or gas boiler and/or install a bigger cylinder. That way you are heating the whole of the tank. It will heat much quicker than an immersion heater. Cheaper too.

Also take shorter showers!