Got some brilliant advice on here a while ago concerning the replacement of my not powerful enough boiler and am nearly all set to go with a combi boiler plus extra radiators.

BUT I see that you can’t have a power shower with a combi!

Trying to look ahead in my crystal ball here: have two bathrooms each with a shower – one is gravity fed and the other is electric. Water pressure drops in Winter with an electric shower so end up with a trickle. In an ideal world I would get shot of the electric shower!

Problem is that I’m worried about getting a combi boiler if it’s going to affect both showers.

Can anyone feel my pain? Or throw any logic into the equation?

As always, thanks. 🙂

The Combi will be mains fed so it should be powerful enough without a pump. we run a Mira Excel off our combi & it’s brilliant.Only problem would be if both showers were being used at once as pressure would inevitably drop.

CG – my experiance with electric showers is that in winter the flow rate drops because the shower cannot heat the water quick enough so slows down the flow. Not a pressure drop , and that was in an expensive electric shower at my parents – in my rental flats one the shower was just cold even at max heat !

Im doing the same thing – conventional boiler out , combi in , thermostatic mixer wet room.

electric showers are the work of the devil – got a 12kw mira in atm and hoping it will see me through winter – or rather the mrs as i shower at work and have a thermostatic mixer of immense power 😀

just dont over spec your boiler was the advice i was given if going for a combi something to do with efficency being crap if you over specify it for size of house.

The electric shower will be unaffected. This just takes cold water and heats it (incoming water is colder in winter, therefore it can’t heat it as quick to a given temp, so the flow is reduced.

Do you actually have a power shower (ie, gravity fed to a pump) A power shower isn’t really compatible with a combi, but it shouldn’t be needed.. what you need is a standard mixer taking the now high pressure cold and hot feeds. If you’ve got a separate pump on the power shower then it may just need bypassing.. if it’s a one box on the wall job then you will need to replace it.

I’ve just installed a Mira Combiforce mixer shower on our combi and it kicks the arse of the power shower I had in my old place.

Jeff

Like others have said, unless you have mains water pressure issues, you should get a decent flow without a power shower.

We have a normal gravity fed mixer shower running off a loft tank/hot water cylinder with no pump, the water head is about 4 metres (tank in loft, shower on ground floor) and we get an excellent flow rate. Our hosepipe at the back also runs off the loft tank and the same water pressure isn’t enough to remove even the sloppiest mud off the bikes without brushing, if we move the hosepipe to the tap at the front of the house (mains fed) it is really powerful, must be four times the pressure easy. So based on this I don’t think a power shower pump would make any difference to the flow….the mains pressure would be high enough to make the pump useless.

Many thanks for the replies. 8)

I looked at the Mira website and read about why it’s different in Winter so really cba’d with a trickle of water! They’re both Mira showers, have replaced hoses and heads, and in other houses Mira have served me well.

Will check out the Combiforce and Excel so good to hear reports of those. Life is never simple is it?

Thanks again. 🙂

The Combi will be mains fed so it should be powerful enough without a pump. we run a Mira Excel off our combi & it’s brilliant.Only problem would be if both showers were being used at once as pressure would inevitably drop.

This for us in old house for years.

I seem to remember the plumber who fitted my Mira shower (a leccy one, not pumped, runs off the cold tank) said all the bits were replaceable / serviceable.

*Touches wood*

– haven’t needed to yet.

Any case for having a mixed supply? If the gas is off there is always an electric shower to fall back on.

I curently have an 8kW electric shower and a combi bolier, they can be run together as others have said. The electric shower runs off a cold only feed and although mine is ok for power is no where neer as good as a mains fed shower. I will look to ditch my electric shower when i upgrade my bathroom.

If i was in your position i would look to have an electric shower in one bathroom and the normal mains shower in the main bathroom. This is mainly because you seem to be in a very hard water area and having a backup if the normal shower or boiler fails would be very handy.

Just make sure you buy a thermostatic mixer for your shower .
One problem is if you are sowing whilst running other stop start demand appliances like a dishwasher or washing machine .
The cold water flow rate /feed pressure drops and can , in some cases switch off the combi . There are flow rate switches that fire them when you turn on a hot tap .
Or never shower whilst using washing machine .

Check your available pressure and flow from the mains BEFORE you do anything.

You are allowed to pump the water main these days in most areas, but only 12l/min I believe.

Two bathrooms sounds like an unvented cylinder and heat only boiler to me.

Remember that a faster flow rate means you are using more water. That means higher water bills and using up a scarce resource. Unless you already have low pressure mains issues, a decent electric shower will be fine – even in winter.

Sorry Druidh – an electric shower is no comparision to one running off a decent combi – which is what I have. Even the latest most powerful ones are a fraction of the water flow.

Personally I would always have a shower running off a combi and two bathrooms is no great issue – you just cannot run the shower in both at the same time

Two bathrooms sounds like an unvented cylinder and heat only boiler to me.

+1

TJ – then what is the point of two bathrooms?

Combis are ok in some situations but they are massively overused and over rated.

as an installer you have two options. if you insist on a combi you need to up the size to 35+ kw should be around 14/15 litres per minute and that ll feed two showers okay.
the real issue is if another hot tap is opened. i’d have to honestly spec a heat only boiler to an unvented dhw tank for what sounds like a large home with numerous potential hot water points.

I don’t rate combis, had one in old house, had to wait ages for hot water in the kitchen if the heating was off i.e. all summer. And had to run electric cold only shower.

Current house has normal gas boiler feeding CH and HW tank, feeding two H&C power showers, and it’s bloody ace.

HW tank also has electric heater as a failsafe if a gas problem.

Oooh more replies, thanks!

The quantity of water coming from the electric shower is akin to a trickle, you know like a dripping tap. I don’t hang around in a shower, am mindful of cost due to water meter but this just all defeats the main reason I bought this darned house. 🙁

It’s not a big house but the ground floor extension has the shower room which means that when I return from a ride, I can just strip off and jump in the shower. No need to traipse filth through the house.

Thank you all again for giving me things to think about. 🙂

I’ve got a lovely unvented system. The shower pressure is awesome…there’s are few more pleasureable ways of using up a scarce resource. 8)

I too hate combis. Had them in rented places, and they were generally pretty pitiful.