How much electricity does my boiler use?

amie1234

Hi everyone,

We have a Heatrae Sadia boiler and a box with 'Aztec' written on it which is fixed to the wall. On the boiler spec it says that it is 3kwh but i was wondering if this means that the boiler should use 3 units of electricity per hour to run it?

Also, would the 'Aztec' unit use electricity on top of the 3kwh used by the boiler?

Thank you for your help,

Amie

Cardew

Are you sure that it has 3kWh written? I suspect it states 3kW.

A 3kW heater will as you suggest use 3kWh in 1 hour(i.e. 3 units) if the element was heating all the time.

However it will have a thermostat which will switch off the power when the water has reached the desired temperature, so it is not possible to give a figure of how much electricity it will use in practice.

amie1234

Hi Cardew,

Youre right- it says 3kW!

So that would mean that usage would fluctuate but the maximum amount of electric used at any one time would be 3 units?

Would you have any idea what the Aztec box is? and how much electricity it is likely to consume per hour (there arent any clues on the unit!).

Thank you for your help,

Amie

Cardew

I suspect it is just a control box that uses virtually nothing.

macman

There's no 'sliding scale.' When the 'stat calls for heat, the unit will switch on and draw 3kW. When the 'stat registers that it has reached the set temp, it will switch off and draw nothing (maybe just a few watts in standby).

amie1234

Thank you both for your responses.

I've just found that the Aztec unit uses 12kw. This is a link to what we have http://www.heatandplumb.com/acatalog/Trianco_Aztec_Classic_Electric_Boiler_-_12kW.html

I'm trying to work out what each piece of the kit does. Would I be right in thinking that the Aztec bit is the actual boiler which heats the water which is then passed into the Heatrae sadia tank? Sorry- I'm really not good at this sort of stuff!

The reason I'm asking is because our electricity meter has a fit each time we turn our heating on! We had it on for 3 hours on Sunday and it used 22 units (at 18 degrees). So i'm trying to work out why the system is so hungry!

We may be using the system in the wrong way though, i'm not sure? We have a control unit where you can set a timer for the heating and hot water. Rather than set it we have just been flicking the switch for 15 minutes when we want a shower and then turning the heating on as and when we need it. We thought that this would be the most economical way to do it- so that we werent wasting heat/electricity when we didnt need it.

Any ideas??!!

Amie

Thanks again,

Amie

macman

You have an electric boiler which has an output of 12kW, this passes hot water to your CH circuit and hot water tank. If you start it from cold and it's running full bore throughout then it will use around 36 kWh in 3 hours-so 22 kWh's in 3 hours is perfectly reasonable.
If you had gas CH before, remember that standard rate electricity is going to cost you about 3 times more per kWh. You are using it efficiently, but perhaps not in the most convenient way.

amie1234

Thanks macman,

This is the first time I've lived away from parents- and the first time I've had to worry about bills! Now I know why my mum was always moaning at me to turn lights off etc...!

So, its going to use 15 units max per hour (tank plus boiler)- thats expensive!! Think we might have to get a portable gas fire!

Could you suggest a better way that we could use our heating system to keep costs down?

Thanks,

Amie

amie1234

Also, im struggling to work out why there is a heating element in the heatrae sadia tank and also one in the Aztec boiler. I cant see the point in having two?!

Which one should we be using for the heating and how do we isolate one from the other?

Thanks!

Amie

Cardew

amie1234 wrote: »

Also, im struggling to work out why there is a heating element in the heatrae sadia tank and also one in the Aztec boiler. I cant see the point in having two?!

Which one should we be using for the heating and how do we isolate one from the other?

Thanks!

Amie

Presumably in the summer you won't want heating and so will only use the 3kW Sadia tank for hot water.

Switching off the Aztec boiler shouldn't affect the Sadia.

amie1234

Ok, thanks Cardew. I'll try turning the boiler off tonight.

Thank you for your advice.

Amie