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What’s the difference between a ‘power shower’ and a ‘shower pump’?

I went to see a customer in Brixton, SW2 recently, who wanted a quote for a ‘power shower’, and when I was there we got talking about the various other options available to her, so I thought I’d try and put it all into a blog for people who might be looking for a similar solution.

Basically, she wanted to be able to set the water temperature to her desired temp, and it would stay at that temperature, because at the moment it fluctuated sometimes which was a real pain mid shower (and mid winter). Then she also wanted to boost her shower pressure as well. She had a ‘gravity fed system’, so a standard hot water cylinder in the airing cupboard, and cold water tank in the loft, and she had a bath / shower mixer on the bath, with a flexible hose attached to it. Pretty common setup really, and a pretty common problem for a lot of South West Londoners.

So, we settled on these three options, each with their own pros, cons and costs involved, and I’ve detailed each of them below.

Option 1. Install a ‘power shower’

Power showers work in the same way as mixer showers in that they combine water from the cold and hot supplies. The difference is that power showers have a built-in pump which boosts flow – great if your home has low water pressure – and also offers you greater control over the temperature and pressure than a normal mixer shower. Power showers are designed to work with gravity-fed systems (so cold tank in the loft + hot water cylinder in the cupboard), instantly boosting the flow.


  • Fairly easy to install, but may need to remove a few tiles and chase the walls, to run the hot and cold pipes up to it though, and the power cable. And MAY need to remove the bath tub aswell, depending on if the wall is solid brick / plasterboard or whatever).
  • They will give you a decent, consistent flow of water, even when you have low water pressure (But please note won’t be AS powerful as a shower pump could be OR as boosting your whole houses water pressure may be).
  • Thermostatically controlled hot water, so you can set the shower to your desired temp and it should stay at that temp for the duration.


  • Uses more water than traditional gravity fed systems as the water is being pumped, so it’s drawing more from your tanks, and your hot water MAY run out. If you have a water meter, you will probably notice an increase in your water bills.
  • needs it’s own dedicated hot and cold feeds from the hot water cylinder and cold water tank in the loft respectively. This can also be a problem in a finished house where the shower is quite a distance from the tanks.In this case it wasn’t too bad actually, the cylinder was a few feet away down the hall and the carpet and floorboards could come up quite easily to run the 2 new pipes.

Aside: How ‘power showers’ differ from electric showers…

Basically a power shower has a hot and a cold feed coming to it, and it boosts those (so it doesn’t heat the water, it just pumps it). It needs it’s own dedicated hot and cold feeds from the hot water cylinder and cold water tank in the loft respectively. This can also be a problem in a finished house where the shower is quite a distance from the tanks.

An electric shower has just a cold feed going to it (either mains fed / tank fed), and it heats that water instantly (BUT doesn’t boost it). Can come straight off the main usually (as won’t pump anything stronger than 12 litres per minute…the legal limit to pumping the mains).

An electric shower requires a separate fused electrical supply circuit, meaning we’d need to run a new 10mm (usually) thick cable all the way from your main fuse board, to the shower, so the shower is the only appliance on that circuit. Most electric showers require a 40 or 45amp fuse / circuit breaker. To work out what you need, using a 9kW shower or 9000watts, divided by 230volts = just over 39 amps…so you’d need a 40amp fuse. (Quite a handy calculation to know).

You also need RCD (a residual current device) fitted, as all showers must now be RCD protected. The RCD provides additional protection against a fatal shock in the event of a fault. If you have a really old fuseboard, this MAY need upgrading!

Option 2. Install a shower pump

This involved fitting the pump at the base of the hot water cylinder (positive / negative head pump), or under the bath maybe. Either way is fine, as long we can get power to the pump; we can then run a dedicated hot water feed to the pump from the hot water cylinder; and a dedicated cold water feed to the pump from the tanks in the loft (same as the requirements of a power shower really).

In this case we could go for a ‘positive head pump’ as there is sufficient distance between the top of the shower head, and the bottom of the cold water tank in the loft. I would go for a 2 Bar pump or above, always, as anything less is not really worth it. (The typical main pressure we find in flats especially is between 1 and 2 Bar anyway). The best place in this example was probably to fit the pump in the airing cupboard, and run new hot and colds over to the bathroom. This required lifting floorboards, and running about 4m of pipe for each.


  • Good pressure, at 2 Bar, this will outperform the power shower


  • Although you can find “quiet” pumps, they are more expensive and never really that quiet anyway.
  • A decent pump can range from £300 – £600.
  • Quite a bit of work to install (but comparable to the power shower)
  • Required an additional thermostatic bath / shower mixer to be installed as well…to automatically set / control the shower temperature (as per the customers requirements).

Option 3. Install a thermostatic bath / shower mixer + 2 x in-line shower booster pumps

The water pressure wasn’t THAT bad, and to be honest it wasn’t any better than the power showers could give you (12l per minute).

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