Does heating water via oil tank use more oil than just heating?

savvysocks

I live in a three bedroom semi detached house with oil fired heating. I’ve lived here for four years, and in all that time have used the immersion heater to heat my hot water, in the hope that it would save on precious, expensive heating oil! But now I’ve been told that if I set my hot water to come on at the same time as my central heating, it won’t use any extra oil. Is this the case?

Cardew

Welcome to the forum.



No it is not the case! You don't get 'ought for nowt'!



Indeed unless you have an Economy 7 electricity tariff, it is cheaper to use oil to heat water rather than an immersion heater..

dogshome

As Cardew has posted, unless you have an ECO7 meter useing an Electric Immersion Heater costs more than Oil Fired hot water.


However your Oil boiler has a fixed maximum output, and useing it to produce both Heating and Hot Water at the same time means that it runs longer to bring each of these up to an acceptable temperature.


If you have a programmer that allows you to set separate timings for Heat & Hot water, set the water only to come on for two hours at 4am, with the heating only at say 7am - Depending when the family get up

s_glover

I'm reading this thread with interest , having moved into a house with oil fired heating for the first time last week.
At the moment we don't have the ability to time the HW and CH separately but when we install a new boiler and upgrade the system, we will be able to in the future. Presumably timing the HW and CH for separate times would cost more than together, assuming you say have both on for 2 hours in the morning?

Cardew

s_glover wrote: »

I'm reading this thread with interest , having moved into a house with oil fired heating for the first time last week.
At the moment we don't have the ability to time the HW and CH separately but when we install a new boiler and upgrade the system, we will be able to in the future. Presumably timing the HW and CH for separate times would cost more than together, assuming you say have both on for 2 hours in the morning?

No it won't cost more to have HW and CH at separate times.


The point 'dogshome' was making is that you won't need CH at 4am to 6am so it makes sense to heat the hot water over that period. Then when you require CH later in the morning the whole output of the boiler can be applied to the CH without it having to cope with both CH and HW together; and thus the house will heat quicker.


The cost(oil consumption) of running the boiler depends on the kWh required to heat the HW and heat the radiators. If the HW requires, say, 10kWh and the radiators 15kWh for the period you require CH, the boiler will output 25kWh regardless of when you program HW.

s_glover

Thank you Cardew