Advice/Information on current boiler setup

[Penumbra]

I am not sure whether this post is appropriate for this forum so if not, please accept my apologies.

I live in a flat which has no central heating and is electricity only and I am looking to optimise my energy usage regarding the boiler.

The boiler is a Megaflo 145DD and the current setup appears to be that the immersion is always switched on (assuming that's what the mains switch next to boiler is). The timer (Grassun) is also fixed on. When I moved in, I vaguely remember someone mentioning that given the type of boiler that this is an efficient set up as once the water gets to a certain temperature in the boiler then it stops heating it. This was in comparison to letting the water cool down and having to heat it all up again.

Can anybody confirm that this is a relatively efficient setup or suggest any improvement?

Thanks.

 

[steadyon]

We'd need to know a little more about the set up before definitively answering the question. In particular, do you have cheap rate (e.g. Economy 7) electricity as well as normal rate electricity. Its likely that you do if you have electric storage heaters.

In general, the amount of electricity you will use is determined by the amount required to bring the cylinder up to temperature, plus the amount of hot water you use, plus the heat loss while the cylinder is hot but no hot water is being drawn. The megaflo's are very well insulated, and heat loss is specified at 1.32Kw per day, so the heat loss is quite low (about 30p / day?).

The cost of heating the water in the first place, and replacing the heat of drawn off water, depends on:

a. How much hot water you use.
b. Whether you have cheap rate electricity. Its normally less than half the price of ordinary rate electricity.

Have a look at your electricity meter. If its a dual rate one, you (probably) have cheap rate electricity, which will come on between about midnight and 5:00 am. You can't change the times.

If you have dual rate, this should be connected to the lower heating element in the Megaflo (which is a directly heated hot water cylinder, not a boiler) so that it heats the whole cylinder.

The top immersion heater should be wired to the normal mains, usually via a "Boost" control of some sort, and can be used to heat up the top third of the tank should you run out of hot water.

 

[Penumbra]

Thanks for the reply. It is economy 9 so I do have dual meters, however, I am looking to move away from it as given the split between the cheap and expensive rates I would be better off on an ordinary tariff.

If I understand correctly, the Grassun timer effectively does nothing? The lower heating element comes on at specific times, out of my control, based on the economy 9 off peak times? If the 'boost' is constantly left on then it won't continually draw the same amount of power based on the temperature of the water it is heating?

I am assuming the current setup is fairly efficient as my total kwh usage is fairly reasonable but would be nice to understand exactly how everything works.