Electric shower

PipingProblems

I got an electric shower installed in our main bathroom a few years back. It wasn't the first one we had in there but after problems with the last one, I moved to just using the shower in the en suite. However, that meant guest coming into the bedroom to use the shower, so I decided to get the main bathroom shower reinstalled. I asked the plumber at the time if it would be worth insulating the pipes coming in to it as the water in the previous one was always cold in the winter but the thermostat had to be turned down half way during the summer. They said it shouldn't be necessary and installed the shower (fed from a tank). I've been having the same problem with this one. I know it's coming back into summer again so shouldn't be an issue much longer but guests are planning to arrive at the end of this year, all things going well.

Is there a quick fix to this, or am I going to have to dig out the pipes to insulate them myself? I'd rather avoid that!

In cases it's relevant, they're two different shower brands and as far as I can remember, they have both been tank fed.

Thanks in advance

Lenar3556

What you describe is a natural characteristic of an instantaneous electric shower, which only have a finite water heating capacity.

Insulating the supply pipe work is unlikely to make any material difference, it’s the temperature of the water in the storage tank that is the variable here and that will also be affected by seasonal changes in the incoming mains water temperature to the cold water storage tank leaving it largely outside your control.

Pumped power showers fed from a preheated hot water tank or combination boiler will provide a much better shower experience, but it is likely a significant project to convert at this stage.

astrofool

What KW is the shower and does the water eventually get warm/hot enough in Winter?

CoBo55

Sorry to hijack your thread. I currently have a T90sr in the bathroom, it works fine but it's very heavy on electricity. Would it be a big job to change it for one that has its own internal pump and uses hot water from the copper cylinder? Luckily the shower is mounted on a studded partition so it should be possible to get a hot water pipe down to it.

PipingProblems

https://www.boards.ie/discussion/comment/118798263#Comment_118798263

Good question! I'm not sure off the top of my head but I'll see if I can find it somewhere.

The only time I've had it get warm enough was eventually after a relatives family of 5 who were staying used it one after each other (after a day of hiking), and that included two teenage girls who had to wash their hair (i.e. took a while). By the last person, it got warm but the rest had a cold to tepid shower.

CoBo55

https://www.boards.ie/discussion/comment/118798700#Comment_118798700

What make of shower is it? That definitely doesn't sound right.

John.G

9kw would be the "normal" electric shower power shower, you can get them as low as 7.5kw and as high a 10.5ish.

We'll use 9kw as the bench mark.

The water temp in winter/summer can vary from say a average of between 7C and 15C, I have measured it as low as 5C and as high as 19C, a tank fed will be a few degrees higher depending on its residence time in the pipework/header tank so you are better off having NO insulation as you might pick up a few degrees from the house temperature but not a lot IMO.

A 9kw shower has a fixed output of 9kw or a economy setting of ~ 5kw. In the winter, if one uses 40C as a average showering temperature a 9kw shower will give a flow rate of (9x860)/60/(40-7), 3.91LPM and in the summer, (9x860)/60/(40-15), 5.16LPM, 32% greater flow. (at 40C).

Electric showers are 100% efficient but of course there is a crossing point where oil/gas sourced HW is cheaper. If only two people then a 8 minute (X2) shower will consume (electric shower) 9x16/60, 2.4kwh, say 60C/day, oil/gas while overall, say 30% of electric cost can be quite expensive relatively speaking as you must (especially in summer) heat up maybe 50 litres water in the boiler/primary circuit to get hot water.

Triton (and others) do make very neat non electric showers with a integral pump that require hot/cold water plumbed in and will only require ~ 150watts to power, of course one will then tend to use the available say 14LPM flowrate as against the ~ 4.5LPM average from the electric shower so no savings practically speaking IMO even if showering a small barracks.

CoBo55

https://www.boards.ie/discussion/comment/118800583#Comment_118800583

Great figures John G, thanks for that, I'll stick with what I have. It's a 9Kw shower so your figures are spot on.

PipingProblems

https://www.boards.ie/discussion/comment/118800145#Comment_118800145

It's a Triton T90sr, so it's 9kw

CoBo55

https://www.boards.ie/discussion/comment/118805576#Comment_118805576

Sounds to me like it's faulty, I'm assuming it's being used in position 2 for heating.