Replacement for Hot Water System

paanibay

I live in an all electric flat. Our water is heated using Pulsacoil 2000, a heat exchanger, running on Economy 7, which gave more than enough hot water running for 3 hours overnight (two showers - one long - washing up etc). Unfortunately the cyclinder has split (but not leaking very much as far as I can see, downstairs have not complained!) and have been told it must be replaced. A similar replacement system is £2.5k including installation (£1.5k as is). 

 

Any advice on an alternative replacement which would be economical to run (preferably overnight) and advice on getting it installed, would a different one need expensive changes to the installation?

Thanks for your help.

CliveOfIndia

If it's just a replacement hot water cylinder, then as far as it goes, pretty much most standard cylinders would do the job.

paanibay said:

Any advice on an alternative replacement which would be economical to run (preferably overnight) 

Any electrical heating is 100% efficient.  There are really just 3 things you need to make sure of.

1)  Make sure the heating element is connected up to an E7 supply.  Electricity is pretty much the most expensive form of heating there is, so if you have no choice but to use electricity, then at least make sure it's running from off-peak rates.

2)  Make sure it's properly insulated.  Any new cylinder will probably be pretty well-insulated, but that's one area where you can potentially reduce losses.  So you want it to heat up overnight and lose as little as possible until you need to use it.

3)  Make sure it's sized correctly for your needs.  There's little point in heating up 100 gallons if you only need 50 each day.  Yes, in theory, any unused water should remain pretty hot for a reasonable period, if the tank is well insulated.  But you'll still lose a bit of heat.  Conversely, if the tank is too small for your needs, you'll find yourself having to "top it up" with peak-rate electricity.

Albermarle

As a general comment, three hours seems a very long time to have the have the heater on, just to heat up one tank of water.
Unless maybe the heating element has a low power rating, or the tank is huge?

FreeBear

CliveOfIndia said:

If it's just a replacement hot water cylinder, then as far as it goes, pretty much most standard cylinders would do the job.

Pulsacoil is a thermal store and doesn't actually heat the DHW directly. Replacing with a direct heated cylinder would probably be cheaper.

WIAWSNB

paanibay said:

I live in an all electric flat. Our water is heated using Pulsacoil 2000, a heat exchanger, running on Economy 7, which gave more than enough hot water running for 3 hours overnight (two showers - one long - washing up etc). Unfortunately the cyclinder has split (but not leaking very much as far as I can see, downstairs have not complained!) and have been told it must be replaced. A similar replacement system is £2.5k including installation (£1.5k as is).  

Any advice on an alternative replacement which would be economical to run (preferably overnight) and advice on getting it installed, would a different one need expensive changes to the installation?

Thanks for your help.

I'm not up to speed on these systems, but what I've now read is a surprise. I cannot work out the supposed benefit of having a heat-exchanger for the DHW supply? The only obvious benefit is that it doesn't require a G3 installer as for unvented systems. Any other?! It is far more complex than a basic unvented cylinder, and has a PCB and a pump. And the actual cylinder is copper, and seemingly not that great

Paanibay, if you do decide to replace like-for-like, then shop around for alternatives to the Pulsacoil, as you can get ones in SS for possibly even less, and they are typically warranted for 25 years. But you are still talking around £1.5k for just the cylinder, so over £2k after fitting.

Personally, I'd go for a straight-forward 'unvented cylinder', and these can be had from around £400, Since they are designed to handle mains pressure, they are typically Stainless Steel construction, and carry 25 year warranties.

They operate differently; the whole cylinder is at mains pressure, so no pump or exchanger is required. It'll provide mains-pressure flow, just like your current system. It needs an expansion vessel, but that's included. And a 'G3' qualified installer, so possibly a bit more expensive than a regular plumber, but it's still a very straight-forward replacement.

Worth getting quotes, Paani. First, decide what capacity you require, based on your current model and how well that serves you. It'll operate in exactly the same way - two immersion heaters, one lower down for the overnight charge, and a higher element for daytime top-ups if needed.

Eg: https://www.plumbnation.co.uk/gledhill-direct-stainless-120l-unvented-cylinder-303-17358

That would surely be an all-in install for less than £1k?

I'd first get a figure for the size of cylinder you require, and then call up 2 or 3 recommended G3s in the 'hood for quotes. Ask them to explain what difference in operation you might experience - I can't think of any, but do ask.

Bendo

If its leaking,  I'd suggest moving quickly It's probably corroded and will likely get worse very quickly...

The Pulsacoil is effectively just a boilermate but without the support for central heating and only "charging" via the immersions.

Unvented is probably better for the use case these days but back when they were installed, house builders loved them as they were relatively easy to install and didn't need the G3 qualified plumbers.

When my boilermate started leaking my gas guy wanted to replace with unvented, but I went with another thermal store, mainly because the option to run the central heating off electric when Octopus  Agile pricing is low / negative appealed to me.

WIAWSNB

Hopefully the OP's is actually drained, and not still in use! 

paanibay

Thanks for all your advice, will look into them.

RedFraggle

The advantage of a thermal store is you get hot water at mains pressure which a heated tank won't deliver. They were typically installed in 2 bath flats so both showers can run at once.
We have a pulsacoil that's about 4 years old and expect to get another 6 years from it. The older ones lasted longer.
We pay 50p a day for hot water for two of us. We use the electric shower in the en suite but there's plenty of hot water if a guest uses the main bathroom. 
I'll be replacing it like for like when the time comes. 

WIAWSNB

RedFraggle said:

The advantage of a thermal store is you get hot water at mains pressure which a heated tank won't deliver. They were typically installed in 2 bath flats so both showers can run at once.
We have a pulsacoil that's about 4 years old and expect to get another 6 years from it. The older ones lasted longer.
I'll be replacing it like for like when the time comes. 

The £400 stainless steel unvented cylinder I linked to earlier will also deliver at the full mains rate. And will cost the same to heat.
No pump, no PCB, lasts 'forever', and no moving parts.
It's a third the price, better made, more reliable, and has triple the expected life, and you are still going for a Pulsa?
I'm curious as to appeal of the Pulsacoil systems. The only 'advantage' I can see is that any plumber, or DIYer, can install it.
Have I missed something?

RedFraggle

I prefer it from a safety perspective and lack of drainage. If I wasn't in a first floor flat with it in the middle it might be different. The pulsacoil is allegedly lower running costs but that's outweighed by additional cost.