Immersion heater control

[Mike Johnson]

Still have an old clock timer for our immersion, but thinking that using our oil boiler during the summer is possibly going to be more expensive than electric on overnight economy 7, what do you guys recommend,

 

[James]

I suggest that you are probably correct

 

[brianmoooore]

A litre of heating oil contains just over 10kWh of energy, and modern oil boilers run at around 90%+ efficiency, so a litre of oil gives you 9kWh+ of heat.
Taking oil at the 60p/litre it was a short time ago, that works out at about 6.6p/kWh, compared with the 9p or so per kWh that was being paid for off peak electricity, so using electricity for water heating was about 50% or so more expensive than oil.
Oil is currently around £1/litre, so even at that price it's ~11p/kWh, so comparable to what E7 electricity was.. E7 is increasing to around 16p/kWh, so the savings with oil are still there.
Against the above argument is the fact that the electricity to hot water transition is 100% efficient, so all your electricity gets turned into hot water, but this happens in the middle of the night. After that, heat begins to leak away through the insulation of the HW cylinder.
On the other hand, you can use oil to heat the water closer to the time you need it, so cutting cylinder losses, BUT all the energy used to heat the water in the boiler itself and the boiler pipework, will be effectively lost when the boiler shuts down after heating the water. In winter, this lost energy adds to the heating of the house, but in the summer this doesn't apply.
As you can see, oil or electricity is far from a clear cut choice, but ultimately it'll depend exactly where prices settle, not that oil prices ever do.
I've just switched two of my properties temporarily from oil water heating to full price electric water heating, in the hope of eking out the very low oil level in the tanks until the oil price drops substantially. The cost of a oil delivery is currently dropping at about £30 a day, which is much more than the electric water heating is costing me, but at some point that will change.

 

[Mike Johnson]

I find your analysis a bit skewed, none of the boilers, including the latest gas condensing, I have put my gas analyser on have got anywhere near 90% efficiency, the closest is my own oil boiler at 30 years old at 82% efficiency, my overnight tariff is 7p/kWh so the saving with oil has disappeared, my top up for oil coming tomorrow is £0.95 Lt, so still looking for recommendations for a electric overnight E7 timer.

 

[brianmoooore]

Oil boilers are slightly more efficient than gas, and the 90% figure I've used is less than the manufacturer's claim.
No off peak tariff available where I live is anywhere near 7p unit. 12p is about as good as it gets at the moment.

 

[Mike Johnson]

Notwithstanding any of the above does anyone have a recommendation for an electric overnight Economy 7 timer, I had this one in France: Electronic Economy 7 Timer | Secure (ELECTRONIC 7) - https://www.tlc-direct.co.uk/Products/HOELEC7.html and seemed OK, just wondered if anyone knew of anything better?

 

[brianmoooore]

That's the one I have in my own house. There's also a version with a mechanical dial which I think is still available.

 

[Mike Johnson]

There's also a version with a mechanical dial which I think is still available.

How quaint.

 

[pirate]

Following suggestions on this forum i replaced my old-style timeclock for a Sangamo digital one. Previously I left it "on" all day, just letting the stat control the hot water. Yes, hot water all day, but the I restricted it to just 1 hour a day, early morning, which is plenty for normal use, and save at least 30% immediately. I have my morning shower, and a freshen up later in the evening, by which time the water is less hot, obviously, but if I had a bath then I'd struggle to fill it with the hot water available. If I need more hot water, a half hour boost is fine. There's no option to electricity where I live. My energy supplier has announced big increases from 1 April. Off peak is going up from 14p to 20p/kwh, and day rate from 21 to 30p (in round figures) so quite a rise...and the standing charge is doubling, a 100% rise, for no added value that I can see. I'll shop around later in the year, but my off-peak rads are off now, and won't be put back on until October arrives.
Yesterday, a local filling station was offering diesel at the bargain price of 184.79/litre...I think I'll have to take in a couple of those Ukranian ladies I've seen on t'internet to boost my income!

 

[Mike Johnson]

Obviously someone who lives by themselves if 1hr heating of water lasts all day, would not last the morning with my OH, shower, dishwasher and washing machine on every day.

I think doubling of the standing charge is to pay for the upgrade in infrastructure to pay for all the car charging points, that the majority of us don't really need.

 

[pirate]

yes, I do live alone, and in an extremely well-insulated house. Plus I spend a fair amount of time away from home. In a previous life with wife and daughter the fuel bills were huge, and way out of proportion. Lighting was a big cost as we had 44 50W halogen downlights, so when daughter came home from work, hall, landing, bedroom = 22 lights on! Changing to LED saved a fortune.
Yes, doubling the standing charge may be due to the need for upgrades, but nobody in my estate can have an EV charger due to the layout of parking. My motoring habits preclude an all-electric car anyway, but I'd be unable to charge it properly at home anyway. So, all of you who are able to install chargers, remember to say thank you to folks like me who can't but are helping to pay for the supply upgrades!