Water heater booster v Economy 7

Enigmaman

I regularly go away from home for three-night weekends.

I started out switching off the overnight water heater and using the (Rate 1) booster switch for a minimum of an hour on my return, before reverting to the overnight heater for the remainder of my stay at home. My only fuel is electricity and I am on the BG Standard Variable tariff.

However, my bills have been very nigh - e.g £137 from 3 January - 5 February - and I was probably only there for 20 nights. Even allowing for that being a winter month, we are looking at £2000+ p.a.  

I heard heard booster switches on electric boilers can use 10Kwh.  So more recently I have started leaving the overnight heater on while I am away as the rate 2 price is far lower.

I am wondering which is the cheaper option...three nights of Rate 2 vs one hour of Rate 1?  

QrizB

To answer this, we'll have to know the tariff details.

What do you pay for eack kWh on Rate 1 and Rate 2?

Robin9

If you boost the immersion heater for an hour you will use 3 not 10 kWh

Swipe

And an immersion heater tank is not to be confused with an electric boiler

amanda1024

Have you got a smart meter? Otherwise, you could try reading the meters just before you leave and again as soon as you return and see what the actual usage is

dunstonh

My gut feeling is that turning off a well lagged tank and then boosting it using peak rates would cost more.

e.g. 8p off peak is 42p peak.   So, 5 hours on during off peak equates to 1 hour peak.

Heating a well lagged cylinder that hasn't had any draw may only take 10-20 minutes.  Whereas heating one that has completely cooled over 3 days would take much longer.    So, you are comparing short bursts using off peak rate vs a longer session with peak rates. 

Swipe

dunstonh said:

My gut feeling is that turning off a well lagged tank and then boosting it using peak rates would cost more.

e.g. 8p off peak is 42p peak.   So, 5 hours on during off peak equates to 1 hour peak.

Heating a well lagged cylinder that hasn't had any draw may only take 10-20 minutes.  Whereas heating one that has completely cooled over 3 days would take much longer.    So, you are comparing short bursts using off peak rate vs a longer session with peak rates. 

I agree, but probably not the best example quoting your own fixed eastern region rates that won't apply to anyone here

Robin9

@Enigimaman

A winter bill of £137 a month is not expensive for an electrically heated flat.

  I am assuming you have panel heaters for your source of heating - if so these will be cause of your high bills rather than your immersion heater. Make sure these are off when you are away and reduce the settings - timer/thermostat - when you are at home.

Swipe

Robin9 said:

@Enigimaman

A winter bill of £137 a month is not expensive for an electrically heated flat.

  I am assuming you have panel heaters for your source of heating - if so these will be cause of your high bills rather than your immersion heater. Make sure these are off when you are away and reduce the settings - timer/thermostat - when you are at home.

The OP said they have rate 1 and 2 so will be on economy 7, so doubtful they'll be using panel heaters

Robin9

Than you @Swipe missed that

Enigmaman

Rate 1: 37.61p and Rate 2: 15.32p.

Interesring to know it may only take 20 mins or so to neat up Rate 2 tank where there's been no draw. This is what I was wondering. 

I think the simple answer is I am indeed better off leaving g Rate 2 on and avoiding the booster.

To answer other questions, I have a very new storage heater and do set it to Holiday mode while I'm away, only kicking in if the temp drops to 10 degrees. I have been gradually tweaking the settings to be on less and less.

The £137 O quoted for 33 days' use is a bit misleading as I was only there about 20 days...equating to £212 if I'd been there every day. Is thst still high for a winter month?