Electric Economy 7 Dimplex CXL 24 replacement storage heater(s)

PJ2000

I'm currently resigned to the fact that my new flat's economy 7 set up requires me to use 40%+ of my electricity to heat water with an immersion heater - and to heat the flat overnight too.
Therefore, it's probably sensible to stick with combi storage heaters for the time being.
The ones I currently have (Dimplex CXL 24 is the main one) and another similar smaller one (I don't use very often) seem to expel most of their heat by the time I require it in the evening and are incredibly old. I'd therefore like to get something new, more economical and stylish - that retains heat better until the evenings.
Does anyone have any recommendations of what would work best and be more economical? Most of the storage heaters I've found online look fairly unattractive and seem to have similar drawbacks to the old models. Any help would be great.

lohr500

Hopefully someone will reply with more experience of storage heaters, but people on the forum seem to speak highly of high heat retention storage heaters like the Dimplex quantum range.

They are expensive, so depending on how long you plan to stay in the flat, if you own or rent, etc, then I guess you would need to consider if the cost is worthwhile.

They also ideally need two electricity feeds, one for the switched Economy 7 circuit and one for a permanent 24 hour supply which controls the timer. Although I gather they can be operated with a single permanent feed so long as you are careful to make sure the timer remains correctly set.

Your CXL24 heater may already have two electrical feeds as it looks like it may be able to operate as a convection heater as well, depending on configuration.

But if on a single feed and you want to utilise the existing Economy 7 wiring to the storage heaters that are already in place, then it is likely some additional wiring work would be needed anyway at the main fuse box to convert the switched Economy 7 circuit to the storage heaters to permanent live. Might also require a timer adding to your hot water heater depending on configuration.

Before spending a lot of money on new storage heaters, have you had the old ones checked out to make sure the thermostat controls and the heating elements are working correctly? 

Cardew

New storage heaters will only be 'more economical' by retaining heat longer - how much longer is ??? They do not produce any more heat for the electricity consumed.

Given the high cost of new heaters, and consequent loss of interest, it might be cost effective to keep your current heaters and using a £10 fan heater in the evening(at a high rate) as required.

However your point about being more stylish is noted.

PJ2000

Thanks for your thoughts and time - I will definitely take ideas like the quantum onboard! We do have 2 switches already - so that’s a good thing hopefully. The heaters are looking very old and tired with marks and scratches etc so I’m keen to replace. Not keen on boxing them in - if that’s even an option.
Also need to move the one in the living room as it’s currently the focal point of the whole room - exactly where a TV Should be positioned. Moving a new one near to the existing switches seems the best option.
I have wondered about using a fan heater when necessary - but from last winter’s experience that seemed to be a very costly exercise!
I really am surprised that there don’t seem to be many modern options for economy 7 users - other than another ugly Dimplex!

CSI_Yorkshire

PJ2000 said:

I really am surprised that there don’t seem to be many modern options for economy 7 users - other than another ugly Dimplex!

There are also Elnur and Stiebel (and a few other smaller names).

Fundamentally though, you can't really change the design too much because you need the heat store.  It's hard to make a stack of bricks look stylish.

If you want an off-the-wall (expensive to do, and possibly rather stupid) idea, what about a wet radiator system with a new, larger, extremely well-insulated hot water tank heated by the immersion during off-peak?  You could pick any stylish design you liked for the radiators then.

BUFF

CSI_Yorkshire said:

PJ2000 said:

I really am surprised that there don’t seem to be many modern options for economy 7 users - other than another ugly Dimplex!

There are also Elnur and Stiebel (and a few other smaller names).

Including Creda - Dimplex's sister company with afaik a slightly simpler & cheaper range of HHR storage heaters.

QrizB

CSI_Yorkshire said:

If you want an off-the-wall (expensive to do, and possibly rather stupid) idea, what about a wet radiator system with a new, larger, extremely well-insulated hot water tank heated by the immersion during off-peak?  You could pick any stylish design you liked for the radiators then.

The challenge there is getting a big enough thermal store.

A Dimplex CXL 24 (as per the OP) stores 24kWh of heat. If you size your radiator to give adequate heat output at 50C and store water at a max of 85C, you've got 35 degrees of delta-T to work with.

Heating 1 litre of water by 35 degrees will store 0.04kWh, so you'll need a tank with a capacity of 600 litres in order to store the same amount of heat as that CXL 24.

That's a huge tank; this example gives an idea of the size, and is £2100:
https://www.coppercylinder.co.uk/indirect-unvented-hot-water-cylinder-600-litre/

For more on this idea, see @Solarchaser and his "wee project":
https://forums.moneysavingexpert.com/discussion/6377030/ditching-gas-going-electric-immersion-only-a-wee-project

CSI_Yorkshire

That's a really interesting project - so it wasn't a stupid idea, just a big and complex one.  And almost certainly not suitable for a flat.

littleteapot

QrizB said:

CSI_Yorkshire said:

If you want an off-the-wall (expensive to do, and possibly rather stupid) idea, what about a wet radiator system with a new, larger, extremely well-insulated hot water tank heated by the immersion during off-peak?  You could pick any stylish design you liked for the radiators then.

The challenge there is getting a big enough thermal store.

A Dimplex CXL 24 (as per the OP) stores 24kWh of heat. If you size your radiator to give adequate heat output at 50C and store water at a max of 85C, you've got 35 degrees of delta-T to work with.

Heating 1 litre of water by 35 degrees will store 0.04kWh, so you'll need a tank with a capacity of 600 litres in order to store the same amount of heat as that CXL 24.

That's a huge tank; this example gives an idea of the size, and is £2100:
https://www.coppercylinder.co.uk/indirect-unvented-hot-water-cylinder-600-litre/

For more on this idea, see @Solarchaser and his "wee project":
https://forums.moneysavingexpert.com/discussion/6377030/ditching-gas-going-electric-immersion-only-a-wee-project

Obviously it wouldn't be remotely suitable for a flat, but it does at least show it could work in theory.

What about using a different coolant - something with a much higher thermal capacity?  Though once you take into account it would have to be fluid enough to circulate and be pumped through the system, have sufficiently rapid heat transfer properties, be non volatile, non flammable and preferably non corrosive and non toxic you would probably very limited in coolant options.

Going back on the track of the OP, if they plan to stay in this flat for 5 years+ then it would probably make sense to change the ancient storage heaters for modern ones. Preferably HHR but also cheaper 'semi-HHR' ones  such as Creda TSRE would be worthwhile for their comfort and some potential energy savings. But if only planning to stay 2-3 years it wouldn't be worth the expense.

If the OP owns the flat, then this may have the additional benefit of making the property easier to sell in future. As currently I don't see any viable alternative for electric-only flats given the restrictions on attaching objects such as heat pumps to the outside of the building.

littleteapot

I meant to add that 10 years+ ago I had an electric-only flat which had a Dimplex CXL24 and a few other smaller XL storage heaters. I found them all pretty dismal in terms of heat retention despite having the knowledge how to configure the controls correctly and check that all the elements were working.

The house I own now is also electric-only but the Dimplex Duoheat and Elnur ECOHHR units that I installed in it a number of years ago are infinitely superior in terms of heat retention and temperature control.

Gerry1

If your NSHs are cold by the evening, start by doing the Storage Heater Sanity Test.

https://forums.moneysavingexpert.com/discussion/comment/79277002/#Comment_79277002