Very confused - gas vs economy 7 home heating

Stephenf

We recently moved into a new home (mid 60s property). It has a Potterton Suprima 80 boiler and a megaflo tank.

I was surprised ot find out form the previous owner that they used Economy7 to heat up the wter overnight.

Two things -

1. my instinct says this must be more expensive than gas - we have gas CH.

2. we're finding tha the hot water is running out very easily - maybe afer just one bath a day. Ive started adding an hour 'boost' about 7pm via gas to ensure we all get a hot bath!

Any advice appreciated - should I use the gas only for heating and water and get the electricity moved over to a standard tariff?

Thanks
Stephen

Cardew

Welcome to the forum

Probably the biggest drawback from having an Economy 7 tariff is you pay a premium for the 17 hours 'daytime'(peak) rate electricity.

Gas v E7 water heating depends on 3 factors - price of gas, price of off-peak electricity and efficiency of gas boiler. In most cases gas will be cheaper, but not by a huge margin.

You would do well to try and estimate your annual electricity consumption(without considering water heating) with a view to changing to a 'normal' 24/7 tariff. You can go to a comparison website and enter your estimated annual consumption and get a price for a 24/7 tariff. Then enter for E7 with vaying percentages used at cheap rate - 15%, 20% 25% etc.

macman

Typically you'd need to be using a minimum of 33% of your electricity on cheap rate E7 to make it pay.
A lot of people switched over from storage heaters to gas CH in the past and simply failed to change the electricity tariff or metering to suit-this is usually then only picked up on when the property changes ownership.
Even cheap rate E7 is still more per kWh than gas, so as Cardew says, it is down to boiler efficiency.

Pincher

Stephenf wrote: »

I was surprised ot find out form the previous owner that they used Economy7 to heat up the wter overnight.

My mother got talked into Economy 7 30 years ago, even though we had gas central heating. She did the dishwasher and washing overnight, then did the ironing in the morning. Nothing could persuade her she wasn't saving money.

That's where the vampire myth comes from: door to door salemen can't come into the house unless you invite them in. And, once they have their teeth into you, you become their minions.

Stephenf wrote: »

Ive started adding an hour 'boost' about 7pm via gas to ensure we all get a hot bath!

So you have Gas water heating already.

Stephenf wrote: »

Any advice appreciated - should I use the gas only for heating and water and get the electricity moved over to a standard tariff?

Yes.

Don't have to change the meter, so you can always switch back to Economy 7 if you want.

Stephenf

Thanks everyone have moved it across ot gas only.

However, still surprised by how little hot water we're getting.

Now have set for three hours a day but am only getting one bathful of water - and not a lot of hot really due to it being used by the other half and baby.

After that it's cold. is it possible we're only warming half of the megaflo tank?

Cheers
Stephen.

Richie-from-the-Boro

The Cylinder

Megaflow/sadia, modern ones use coil~in~coil, older ones may differ but are designed for gas

E7 cylinders of either type, are electric two stat/element only cylinders, older ones may differ in that they have only one stat/element and are designed for electricery

So I'm confused :

Both the O/P and the previous owner were using a coil [gas] cylinder for electric water heating - I don't think so !
- - or
The new owner is properly using a coil [gas] cylinder for gas water heating and the previous owner was also doing the same, but was confused, and thought he was using E7

In which case it was always gas fired hot water so either :

- the cylinder size is not large enough to store sufficient hot water
- the lagging is so 60's it looses heat almost as fast as it stores it
- or the boiler is not on long enough to make enough hot water
- or the good lady's needs use what's available - so back to the tank size
- or you have an old 'dual-fill' washing machine and a new baby

Stephenf

Hi,

Just bought brand new Miele washer so hopefuly it's not that.

Same hapened again tonight. HW on from 6-8pm. OH and baby bathed at 7pm. Just tried and a little lukewarm water.

Now I'm confused though as the Megflo tank doesn't look to be lagged at all - I found that weird but assumed that's how they work.

Tank looks to have two heating rods, one at the bottom and one about half way up. One at the bottom goes straight to the mains, I assume as an emergency immersion and the one half way up is tied to a timer for the economy7.

Cheers
Stephen.

Cardew

Stephenf wrote: »

Hi,

Just bought brand new Miele washer so hopefuly it's not that.

Same hapened again tonight. HW on from 6-8pm. OH and baby bathed at 7pm. Just tried and a little lukewarm water.

Now I'm confused though as the Megflo tank doesn't look to be lagged at all - I found that weird but assumed that's how they work.

Tank looks to have two heating rods, one at the bottom and one about half way up. One at the bottom goes straight to the mains, I assume as an emergency immersion and the one half way up is tied to a timer for the economy7.

Cheers
Stephen.

I think all Meile washing machines these days are cold fill. i.e. they only use cold water and heat such quantities as required in the machine - virtually all washing machines are cold fill these days.

Most HW tanks(in the last 30 years) have a foam coating for insulation

espresso

Stephenf wrote: »

Thanks everyone have moved it across ot gas only.

However, still surprised by how little hot water we're getting.

Now have set for three hours a day but am only getting one bathful of water - and not a lot of hot really due to it being used by the other half and baby.

After that it's cold. is it possible we're only warming half of the megaflo tank?

Cheers
Stephen.

You are right to switch over to using gas rather than E7 but these heat stores are designed to be on continuously. Having your boiler on for three hours a day is not enough - the gas boiler should be on 24/7 to maintain the temperature of the heat store and this should provide you with as much hot water as you need. Change to a standard electricity tariff.