Advice on replacing Hot water cylinder in small cupboard space

[LizGreen]

I have a very small depth airing cupboard that can only take a max 350mm diameter cylinder. The current one even has some of the insulation shaved off to help the door close!

I want to fit a shower pump to boost the pressure a bit and have been advised I need to least a 120 - 150L tank(current one is about 90L) to do that or the pump would drain the tank too fast. The problem seems to be finding a narrow diameter tank with a larger capacity.

I live in a large block with the cold water tanks on the roof which feed into each flat. The central heating is separate and heated from boilers in the basement. The current tank is an direct immersion heater which therefore just feeds the kitchen and bathroom. It takes about an hour to heat it to hot. Usually there is only me here and even with a guest we seem to manage 2 showers ok (without a pump). I do find it is not quite as hot as I like, though am told that is because I have a thermostatic mixer on the shower that is not very good with this type of cylinder.

One plumber has told me if I want a larger tank & pump I should ideally fit an Economy 7 Cylinder with 2 immersions for cheaper heating at night & one for on demand heating. However apparently these don't come in the narrow width. (I do have quite a lot of height I can use in the cupboard and could got to 1600 or even 1800mm high)

He has said that it isn't worth installing a cylinder smaller than 120L as especially with a pump that would be expensive to reheat the tank and still not provide enough hot water so would not be much better than what I already have.

Obviously I appreciate if he is giving good advice (after all if I don't go ahead he won't be getting the job!). However I want to check that he is not being too focused on the electricity cost. After all I don't have Economy 7 now and am heating my current tank a few hours a day at least at an ordinary tariff.

Can anyone advise
1) Do I really need a bigger tank if I install a smallish pump? Would the current tank not be ok?
2) do I really need an Economy 7 cylinder? Does it really save a lot of money? Would a bigger tank cost a lot more to heat?
3) if Economy 7 is not essential, what other tanks come in the narrow size and would be over 120 litres and suit my set up?


Thanks a lot, advice gratefully recieved.

 

[cr0ft]

Just my opinion, appreciate you may have solved this now as the post is quite old.

1.) 90L is far too small a cylinder for a pumped shower. Most pumped shower manufacturers ask for a 200L + cylinder nowadays. Exact hot water storage capacity can usually be found out by calling the shower manufacturers.

2.) Without an Economy 7 cylinder you could expect your bill for heating your hot water to jump between 2-3x the cost it is now.

3.) I couldn't even find a 350mm cylinder on Google but maybe someone else knows where you can get a large one. Can't help you on this one.

If you have a large cold water storage cistern (CWSC) on the roof then this exact situation is what pumped electric showers are designed for. Something like the Triton T80si. It just connects onto the existing pipework from your CWSC and will give you a decent shower. Try and go for the 10.8KW one if you can as the less powerful ones are like a rat's ****.

 

[stevetheplumber]

you can get 350 d cylinder but 300mm is more common tallest ist normally 72inches flow rate can be reduce by the use of low output shower heads