Options for replacing hot water tank

correcthorse_2

Hello all, hopefully this is the right place for this post.


I'm moving to a new flat next month, and it currently has an old hot water tank with an immersion heater that needs replacing. I've been wondering if there's a better solution than simply replacing like for like?


The flat is all electric, no economy 7, and my hot water usage is pretty low (I'll fill up the sink once every few days to do some dishes, washing machine/shower/dishwasher are all self-heating) so it seems really wasteful to heat a big tank up just for that.


Would it be sensible to look at some on demand/tankless (not sure about the naming conventions) heaters in my situation? Would I be best fitting one in each room (kitchen, bathroom, showerroom) for the taps in there? Do I need anything special for the bath (it would be used maybe once or twice a quarter)? Finally, who would I want to fit it, a plumber, electrician, or both?


Thanks in advance!

Cardew

so it seems really wasteful to heat a big tank up just for that

Welcome to the forum.

Many people seem to completely overestimate the losses from a hot water tank.

Obviously if you replace your hot water tank will be modern and well insulated. Depending on the size the losses from that tank are likely to be under 1 kWh a day, and for much of the year those 'losses' are not really losses as they warm the fabric of the house - just like any other heater you run on non E7 electricity.

I have recently installed a very large hot water tank. This is rated to lose heat at the rate of 54watts when the water is 65C.(so 1.3kWh in 24 hours). I obviously don't have my hot water at 65C so even with a large tank I will be losing less than 1kWh a day.

The above is with a full tank. You can get tanks with two immersion heaters, a smaller one in the top of the tank that just heats the water at the top. Obviously in time that hot water will mix with the cold water at the bottom of the tank, but it takes a surprisingly long time - if you have enough time(and a degree in Physics!!) you can find loads of articles on the web.

The cost of buying and installing 'instant' water heaters in several locations in your house would be substantial.

CashStrapped

Firstly, do you own the flat?

You say it is all electric but not E7. I assume therefore it has standard panel heaters?

There is nothing wrong with a hot water tank and immersion for an all electric property. Why do you say it needs replacing?

With an all electric property. Your options are limited.

There are instant heat systems. They work on the same principle to an electric shower. They heat the water on demand. One compromise is that you can get very restricted flow. Especially in winter where the mains water is a lot colder.

http://energy.gov/energysaver/tankless-or-demand-type-water-heaters.

Any electric property on a standard rate can be expensive to run.

As long as the hot water tank is well insulated (buy and fit a good jacket if not) I would be tempted to keep it. The outlay of installing a whole new system may not be worth it, even if you could make efficiency savings from this system.

I would also consider installing storage heaters but only when you have a firm grasp of how you use the property, actual annual use etc. You may find your existing system works perfectly well for your needs.

Edit: I wrote this without seeing the post above....we seem to be of the same opinion...

correcthorse_2

Thanks for the replies, I do own it. It has heaters that can be switched on or off as needed, rather than storage heaters. I don't tend to use the heating all that often anyway as I'll usually put on a jumper instead. I work from home regularly and have a lot of daytime electricity use (servers, desktop etc.) so I'm not too keen on E7.


It's not so much losing heat from the tank that I'm worried about, more that given how little hot water I actually use, is it worth having a big tank that gets heated up entirely, if I'm only using minimal amounts? I was thinking an on demand heater would be cheaper in the long run (installation and purchase costs aside), is that right?


The tank needs replacing as it's old and the insulation is quite worn, and there's quite a bit of corrosion around the immersion heater in the tank.


I haven't made any purchases yet so might still go for a tank replacement, but the idea of lower running costs and more cupboard space is quite appealing!

CashStrapped

Insulation is replaceable. £30 for a new jacket. I use ratchet straps to hold it on tight. Immersions are also replaceable items.

It cannot harm to get quotes, work out the full cost. Then estimate what you may save by doing that. It may turn out it will take 10 years or something crazy to make those savings back....

So, you need to ask yourself at that point....is it worth it.

Cardew

In addition to the above, you will almost certainly have to do a lot of rewiring to cope with the load of 'instant' electrical heating.

teddysmum

A couple of kettles of boiled water should provide enough hot water for dishes. We used kettles when our boiler broke down, a couple of years ago, as well as before we had a combi boiler fitted.

correcthorse_2

Thanks all, I'll try to get some quotes and see what the costs are.


Cardew, how much rewiring are we talking about?


I generally use the kettle technique anyway, but I'd be a bit concerned about just switching off the immersion heater completely. Doesn't that cause nasty things to start growing inside the tank?

Cardew

correcthorse wrote: »

Cardew, how much rewiring are we talking about?

That's a 'how long is a piece of string(wire!)' question.

It depends on the existing wiring and consumer unit(fuse box) and the rating of the instant heating appliances you want to fit.

What will suit your purposes is one thing, but will it detract from value when you come to sell - lots of people like baths!

footyguy

correcthorse wrote: »

Hello all, hopefully this is the right place for this post.


I'm moving to a new flat next month, and it currently has an old hot water tank with an immersion heater that needs replacing. I've been wondering if there's a better solution than simply replacing like for like?


The flat is all electric, no economy 7, and my hot water usage is pretty low (I'll fill up the sink once every few days to do some dishes, washing machine/shower/dishwasher are all self-heating) so it seems really wasteful to heat a big tank up just for that.


Would it be sensible to look at some on demand/tankless (not sure about the naming conventions) heaters in my situation? Would I be best fitting one in each room (kitchen, bathroom, showerroom) for the taps in there? Do I need anything special for the bath (it would be used maybe once or twice a quarter)? Finally, who would I want to fit it, a plumber, electrician, or both?


Thanks in advance!

They are referred to as kettles

But if you want hot runing water in your flat, the best solution would be to get the faulty hot water tank replaced.

As it has an electrically operated immersion, look for a plumber with suitable electrical qualifications -most (but not all) will be suitably electrically qualified to wire up an immersion heater

It's going to get migfhty expensive heating that flat with normal electricity. Consider getting night storage heaters fitted, together with E7.

If you decide to go down this route, decide before getting the haot water tank replaced, as a larger one may then be more appropriate to get maximum use of the low rate E7 tariff - this is a tariff where all your electricity will be over 50% cheaper for 7 hours every day.:money:

footyguy

correcthorse wrote: »

Thanks for the replies, I do own it. It has heaters that can be switched on or off as needed, rather than storage heaters. I don't tend to use the heating all that often anyway as I'll usually put on a jumper instead. I work from home regularly and have a lot of daytime electricity use (servers, desktop etc.) so I'm not too keen on E7.

...

I had a feeling you were going to say that about E7.

But the fact is that computers & servers use very little electricity compared to 'heating' i.e. space heating, hot water, etc.

Remember, if the server is on 24 hours a day, then E7 will mean that for 7 of those 24 hours it too will be using electricity at less than half the usual cost.

But if you really don't want E7, don't let me try and convince you otherwise.

But then again, if you don't want cheap electricity for 7 hours every day, then I'm not sure you have joined the right site :cool:

Good luck!