Electric water heating

mrsyardbroom

I have a little old cottage and it has an airing cupboard with a copper cylinder. The water is heated overnight with an immersion heater. I need hot water in the bathroom and kitchen. I have a shower and a bath. I do sometimes use the bath to wash bigger items and may bath the dog in it if she's rolled in something smelly. I would like some suggestions for a better and more economical electric water heating system. The house is all electric. There's no mains gas and I don't have anywhere to put an oil tank.

BarelySentientAI

Overnight heating on an Economy 7 type tariff is probably the most economic you can have unless you want to spend thousands of pounds getting a heat pump.

I don't know what you mean by "better".

Getting a new tank (with better insulation) might make a big difference to you.

RedFraggle

I have a Gledhill thermal store for heating on E7. I had an external timer fitted to it and only run it for 2 of my 7 hours and it's plenty for DHW. The shower is electric. 

Section62

BarelySentientAI said:

....

Getting a new tank (with better insulation) might make a big difference to you.

...or just adding an insulating jacket if the only issue is the amount of insulation the existing scylinder has -

https://www.screwfix.com/p/essentials-four-panel-hot-water-cylinder-jacket-42-x-18-/43483

OP, you need to be a bit more specific about what the problem with the current arrangement is. If the only issue is that you think it is uneconomic then that probably isn't the case when you take into account the capital cost of switching to a different system.

mrsyardbroom

Thank you. My cylinder is years old and it's large and old fashioned. I mostly only use the water from the cylinder for washing up and cleaning. The shower is electric and the washing machine heats the water.

mrsyardbroom

BarelySentientAI said:

Overnight heating on an Economy 7 type tariff is probably the most economic you can have unless you want to spend thousands of pounds getting a heat pump.

I don't know what you mean by "better".

Getting a new tank (with better insulation) might make a big difference to you.

An example of a better system would be modern storage and a heaterfor the water heated overnight. I know nothing about them.

Section62

mrsyardbroom said:

Thank you. My cylinder is years old and it's large and old fashioned. I mostly only use the water from the cylinder for washing up and cleaning. The shower is electric and the washing machine heats the water.

If you don't use much hot water then changing to a smaller cylinder could reduce your bills after you've paid the cost of changing it - but if it is reasonably well insulated then the amount of heat you lose is not costing you a vast amount, at least not in comparison to the cost of having a whizzy new system installed. 'Old fashioned' doesn't always equate to 'no good'.

You could replace the hot water cylinder with instant heaters, but then you'll pay the day rate for heating your hot water unless you only use it during the E7 hours.  Likewise, having an electric shower when you've got stored hot water isn't the most economic way of doing things, unless you only shower when the electric is on the cheaper rate.

BarelySentientAI

mrsyardbroom said:

BarelySentientAI said:

Overnight heating on an Economy 7 type tariff is probably the most economic you can have unless you want to spend thousands of pounds getting a heat pump.

I don't know what you mean by "better".

Getting a new tank (with better insulation) might make a big difference to you.

An example of a better system would be modern storage and a heaterfor the water heated overnight. I know nothing about them.

At the moment you have a tank and water is heated overnight.

Your example of a better system is a "modern" tank where the water is heated overnight?

No, I'm still confused.

The cost of most changes will take a long time to pay back if you don't use that much.  Likely 'best' option: Insulated cylinder, plumbed in shower (although that could be too expensive to change), and having a tariff with good off-peak rates.

mrsyardbroom

BarelySentientAI I'm not sure what it is you don't understand. I'm paying to heat a large cylinder of water overnight, when I only need a relatively small amount of water in the day. At the moment I have to remember to switch the immersion heater on every night when the night rate starts, and switch it off again in the morning. I can't adjust the water temperature. It's set to very hot and that's it. There must be a more modern cylinder that would be smaller, have an integrated adjustable heater, and a timer. The old cylinder is nearly 50 years old. It's still working but for how long?

FreeBear

Section62 said:

mrsyardbroom said:

Thank you. My cylinder is years old and it's large and old fashioned. I mostly only use the water from the cylinder for washing up and cleaning. The shower is electric and the washing machine heats the water.

You could replace the hot water cylinder with instant heaters, but then you'll pay the day rate for heating your hot water unless you only use it during the E7 hours.  Likewise, having an electric shower when you've got stored hot water isn't the most economic way of doing things, unless you only shower when the electric is on the cheaper rate.

An old uninsulated copper cylinder is likely to be a vented tank. So water pressure for a shower is going to be dismal unless there is a booster pump. Switching to a modern unvented tank would give much better water pressure, but heating a tank just for showers and a bit of washing up can get expensive.

Heat loss from an old DHW tank with a jacket will be around 4kWh per day. A modern insulated tank will loose a maximum of 2kWh, and some are down to 1kWh - If the tank is heated each night, there is a potential to save up to £120 per year based on current E7 night rate.

Up until recently, I had an old vented copper DHW tank with jacket, all be it heated by gas. It only got hot when either the central heating was running, or I specifically fired it up for a bath. The rest of the time, boiled a kettle for washing up and used an electric shower. Even with a shiny new gas combi, washing up is still done with a kettle of boiling water, and the electric shower gets regular use (that might change when the bathroom gets a refit). Currently running at 2000kWh per year for electricity and 3000kWh for gas, so not high consumption.

mrsyardbroom

I have an electric shower and it only heats the water I use. That is heated at the day rate but I don't stay in the shower long. I have Googled hot water cylinders but some cost a £100 while others cost over £2000. I have no idea what I'm looking at. I'm not keen to ask a plumber without any understanding. I could end up spending a lot of money unnecessarily. My current cylinder is insulated with a wrap around jacket.