Electric shower: Pumped vs Mains

ULMarc · 27-03-2023 8:11am #1

I'm choosing an electric shower at the moment. And I'm wondering if there's a preference for pumped vs mains showers?

Mains pressure is between 4 and 5 bar.
Flow rate is over 16 l/min.
The shower will be 9.5kW.

With that my preference would be to install a shower off the mains. I think a pump would be unnecessary. But still looking for thoughts and experiences.

John.G · 27-03-2023 9:09am

You should have no problems with that sort of mains pressure if you install a mains supplied electric shower, that 9.5kw showere will only need a flowrate of max 7LPM in the summer to give a showering temp of 40C from mains at a very max of 20C.

youtheman · 27-03-2023 9:16am

If you have the mains pressure then you don't need a pump. So the shower is a lot less noisy (eventhough pumped shower are getting a lot quiter lately). One disadvantage of the pumped shower is that during the winter the feed supply is a lot colder, so you have to wind the flowrate back to get the required outlet temperature. Also, if there is another demand for water from the mains (e.g. toilet) then the pressure can drop, with the flowrate, and the temperature can then fluctuate. This is the reason why I went form mains to pumped shower.

ULMarc · 27-03-2023 9:38am

https://www.boards.ie/discussion/comment/120405264#Comment_120405264

Thanks

Just to clarity on your point regarding supply temperature, because I think you mixed up your words there. You're saying the main supply temperature is lower in the winter than the cold water tank? That was a concern I had. I was wondering if the flow rate is drastically worse, or acceptable. Because that wouldn't go down well with some people in my house :)

I do like the idea avoiding the pump due to the noise. I accept that pumped showers have gotten quieter. But I do still like the idea of avoiding the pump if possible.

youtheman · 27-03-2023 1:39pm

By 'feed' I mean 'supply to the shower', not outlet from the shower. These electric shower are normally 'constant power'. So, for example, if you want the outlet to stay at 40 degrees C for a hot shower, and the inlet temperature drops with the ground temperature, you have no choice but to reduce the flowrate. When I had a mains fed shower (albeit a good few years ago) the flowrate in the winter was noticeably lower than it would be in the summer.

cnocbui · 27-03-2023 1:56pm

If you got a HW cylinder that was rated for 6 -10 bar, you could dispense with both a pump and power shower. No noise and high flow rate, even in winter.

In Australia, there is no such thing as attic tanks or everyone would be dead from amoebic meningitis.

ULMarc · 27-03-2023 4:15pm

https://www.boards.ie/discussion/comment/120406621#Comment_120406621

I get you yeah, thank you. I was just double checking since you had said, "One disadvantage of the pumped shower is that during the winter the feed supply is a lot colder" I had been wondering if the cold water storage tanks was also susceptible to a similar temperature drop.

https://www.boards.ie/discussion/comment/120406759#Comment_120406759

Yeah. an unvented cylinder. I'd been considering one. But it increases the scope of the job. And I didn't want to derail my question on electric showers. It does sound like the best job for a quality water supply though.

My partner is particular about the shower. She's insisting on an electric shower. I asked her earlier if she recalls any of the showers she's been impressed with being electric (pumped or otherwise). She said she doesn't. So maybe she's had the wrong expectation this whole time!

John.G · 27-03-2023 7:05pm

Just to emphasize that a 9.5kw electric shower, mains or pumped, will only thermally give a flowrate of 4.0LPM in winter (here) with a required showering temp of 40C from mains at 6C, 9.5x860/60/(40-6) and up to 6.8LPM at a mains temp of 20C in summer, 9.5x860/60/(40-20), so a huge difference, you can input your own numbers. A pumped shower will give a slightly higher output as the stored water will be a few degrees higher, depending on usage.

You can buy a shower like a Triton Novel(SR) or its equivalent which uses cold stored water and hot from the vented HW cylinder, it has its own inbuilt silent running (SR) pump and will give a flowrate of up to 14LPM, they are very neat.

youtheman · 28-03-2023 7:39am

https://www.boards.ie/discussion/comment/120407425#Comment_120407425

In a mains fed shower the water entering the shower is basically at 'ground temperature' (as the mains is buried underground). In a pump fed shower the water entering the shower unit will be at 'attic temperature', assuming it is fed from a attic tank. As you shower the attic water will be replaced by mains water, but the will have little overall affect. The attic temperature is bound to be a few degrees higher than the ground temperature, hence (for a given kw power output) the temperature at which you shower is bound to be higher for the pumped version.

GreeBo · 28-03-2023 7:57am

Actually I would say the opposite, its warmer when you go a 2-3 feet underground, if you go beyond about 12 foot the temperature underground doesnt change from winter to summer.

I have a triton SR and the temperature is noticeably different in winter vs summer.

ULMarc · 28-03-2023 8:16am

https://www.boards.ie/discussion/comment/120409654#Comment_120409654

I think it's fair to say that there's a water temperature difference in the seasons regardless of the supply alright.

We've a pumped shower in one bathroom at the moment. If our attic is anything to go by then I would safely say it's very cold in the winter, and I'm struggling to quantify the difference between that and the ground supply. But, that's why I'd asked really.

At this point in time I'm facing a dilemma. Do I continue with the electric shower or consider committing to upgrading the rest of my system to accommodate non-electric showers? I could still see the benefit of keeping one electric shower in the house of course.

My head's spinning now. 😅

cnocbui · 28-03-2023 12:59pm

If you want a great showering experience and don't want to change the cylinder, fit a 3 bar Stuart Turner dual pump and quality fittings in the shower. I have this and with the 180mm Hans Grohe shower rose the flow rate is season independent and enough that I usually don't have it maxed out.

GreeBo · 28-03-2023 1:02pm

Having used both I would always favour a pumped shower from a pressurized, heated cylinder over an electric shower.

There is no comparison in the experience imo.

ULMarc · 28-03-2023 2:50pm

I'll be taking this feedback to the boss 😎. Thanks all.

Sleeper12 · 28-03-2023 3:31pm

I don't think there is a right or wrong answer here. Some attics are colder than others. I have 300mm insulation on the attic floor and the roof is vented so my attic temperature would be close to the temperature outside the house. There are six vents. It can actually be windy in my attic. The water in my attic tank would be colder than the mains supply (I think) first thing in the morning after a very cold night. Someone else's attic would not get as cold as mine so mains water could be colder than the tank water.

ULMarc · 29-03-2023 10:14am

https://www.boards.ie/discussion/comment/120411964#Comment_120411964

Ours is much the same. And the previous owner decided to put the hot water tank out there instead of inside the thermal envelope. 🙄 Another part of our puzzle. Kind of a reason why I'm a bit nervous at the idea of trying to keep that tank hot for showers every day in its current state.

Sleeper12 · 29-03-2023 10:28am

I hate to see boilers or hot water cylinder in the attic. I've seen an immersion go on fire in the attic. No one harmed but major damage to the house. Family had to live in a hotel for a few months while house was repaired.

If you have an electric appliance in the attic it's very important to have a fire/smoke detector up there. That's my lecture for the day 😄

ULMarc · 08-08-2024 9:11pm

I cannot believe how long ago it's been since I've asked this question. (well, I lie, I absolutely can really)

I've just installed a 3 bar twin impeller pump. It's boosting the whole house now. 9.5 kW shower in en suite. Big auld thermostatic mixer in the main bathroom. Delivery for both is great. Perhaps even pushing a bit too close to the high side for the 9.5 kW shower, I'm monitoring the situation.

I have the pump sort of half-installed at the moment as I only whipped it in to try it out for size. It's producing considerable noise throughout the structure of the house. So I'm planning to improve its location and sound isolation. Though, it does have one quirk I was a bit concerned about: it has a point near low flow where it shuts off. So taps can sometimes be a bit finicky to set when you only want them a bit open. I'm either going to have to get used to it, or consider moving some branches back to the gravity supply. This, and the noise, is something that would have been avoided if I'd gone with the unvented approach.

Sleeper12 · 09-08-2024 6:50am

They quality of the pump dictates the volume of it in a lot of cases. Plastic body ones are cheaper than brass but a lot louder. I have a 3 bar brass body Stuart Turner Monsoon in the hot press. I sleep with my head less than a foot away & a 4" wall between me and the pump. It's not loud enough to wake me or anyone else in the house. There are sound / vibration absorbing mats but with a good pump it's isn't needed

Electric shower: Pumped vs Mains

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