I bought a new electric shower from B&Q and installed it only to find that it was pants with hardly any flow.
Water pressure to the house is fine with a brand new poly main but we have a combi boiler with no tank which means no power shower option and this is for a downstairs wet room with no bath, so no mixer shower option either as I can't afford to redecorate.
I understand that the higher the KW the better the flow from the shower, but when I look at electric showers they nearly all say not suitable for comb-boiler/mains set up.
I've seen a few from Triton which have 1.5 bar flow at 10.5Kw and I thought these would be ok for use on mains with a combi boiler (cold fill only) but looking on Plumbworld.co.uk it seems like every electric shower is marked as unsuitable for combi boiler mains water feed.
Completely confused with this now, could do with someone who has the knowledge...help!
An electric shower should be connected to the cold water from the rising main, thats the one that brings the cold water into the house.
The water is heated when the water passes through the shower by electric.
I have one like this, think it's about 6 kw and is a bit slow in winter, but fine in summer, an 8 kw or 10 kw would be much better but the cable would have to be upsized.
That's what I thought regarding the water connection but it seems that the combi boiler set up affects the mains in some way.
Cable is 10mm and the installed RCD is 40amp but can easily be changed for a 45
the only way the combi would affect the shower is if a hot water tap was turned on but its the same if the cold tap is turned on or a toilet is flushed, it can cause a drop in pressure and cause the shower to run hotter.
make sure all the valves on the cold water are fully open and no flow restrictors are fitted, these are mainly fitted to wash basin cold taps.
The big advantage of a combi boiler is that the hot water is at mains pressure... surely the best solution is to run a hot water pipe into your wet room? Don't know what the layout of your place is like, but wouldn't have thought that should involve much more redecoration than a heavy duty mains cable.
Yes ,something wrong there, you have connected an instant electric shower to the cold main so it should be fine,as written before,check vales are open,
no restrictors in inlet to shower.
Take the shower head off,are there enough holes in the head?run it without the head on,,any better?
An ageing test pilot for home grown widgets that may fail at anytime.
I can't run a hot water feed into the wet room without redecorating and I've just paid out to have the wet room re-tiled and decorated so can't afford to do that. The existing cable is 10mm so does not need to be re-run if I get a higher Kw rated shower,
The shower I fitted was brand new so no scale problems etc, it just wasn't powerful enough to provide enough flow to have a shower - I have short hair and it wasn't rinsing the shampoo out so the missus had no chance. That shower was a Mira and when I checked it operated at 0.7 bar which explained the pathetic flow rate.
I just need to know what is the correct type of shower for my set up, the problem is that I can't work out which shower I should get as the information from the suppliers is contradicting
I have a combi boiler and a regular electric shower (7kw I think) with no problems, it just runs off the cold water main supply.
If you turn the water up to "full cold" do you get a decent flow from it?
the way an electric shower works is the more you open the valve the faster the water flows through it, and the cooler the water coming out is.
If you reduce the flow the slower it comes out and the hotter the water is, if I turn my 6 kw shower on full I have a cool shower so I turn the flow rate down to make the water hotter.
So the higher kw the faster the water will come out, the bar rating is the minimum pressure needed to operate the safety switches that are built into the shower so the power is cut off if theres not enough water, it has nothing to do with the flow rate.
a 10.5 kw should be the best for you, me I've no hair so don't use shampoo, so there's another option but I don't think your missus will be to pleased if you shave her head.
:agree chaz. But just to add the flow control is sometimes marked as "Temperature" control, but the effect is the same. The higher the temperature the less the flow for any given electric rating. Also effected by the incoming water temperature, so in winter less flow for a set outlet temperature.
Plenty of pressure out of the feed pipe, all new pipe work from the mains to the shower as well so no problems there. The shower I fitted is now gone as I returned it but yes, it did increase in flow considerably when on cold setting.
I did suggest the 'bic and wig' method and the added cost savings it would bring but the stare was enough to let me know it wasn't an option...
A comfortable shower temperature will be about 40ºC, in winter the incoming water can be about 5º so your heater needs to raise the temp by 35º. Water takes a lot of energy to warm up, 4.2 joules per degree per cc. So a 10.5kW heater will get just 4.3 litres per minute to a comfortable temperate. A decent flow rate for a shower is about twice that.
Unless you can preheat the water somehow, an electric shower is bound to seem a bit feeble in winter.
