Is there a cost difference between the two? Just wondering as we’re taking out an 8.5kW triton and fitting a Mira thermal balanced jobbie fed from a WB 30si combi condenser boiler. Am I going to save money?

Don’t know bout saving money but you will get a far more powerfull shower from mains hot water (boiler fed) rather than a electric shower. That for me would be the main point to concider.

Cost overall….. not sure. However, having done something similar (well, identical except it was a Mira 10kW electric that came out), the difference is huge. Won’t being going back to electric unless I have to.

I’m all ready looking forward to increased pressure. Just wondering about electricity consumption vs gas.

My GUESS is that using the combi will be more cost effective, but whatever it is, the difference will be in the rounding of the overall household consumption (unless you use it for hours at a time each day)

That’s all encouraging news. I’m about to chuck the bath with electric shower over it and replace it with a combi-boiler driven walk in shower.

Gas is half the price per kW compared with electric. Plus you have an 80+ eficient boiler (we have the same model at home with a Danfoss wireless stat). Gas shower all the way…cheaper to run and a better shower.
Get a basic Grohe model.

The combi should be more efficient but you will use more water and energy as it’ll be more powerful and you’ll almost certainly spend longer in there.

Relative efficiency is invariably has a very small effect, the real difference comes from the fact that gas is typically between one third and one quarter of the price of electricity per kWh.

things to consider:-

what source is your gas – living in the countryside away from mains gas mine probably costs nearly twice what an urban dweller’s costs.

The pipe run between boiler and shower head. If its long it’ll be cooling on the way to you (meaning you will use more hot water than cold in your mix than if you were right next to the boiler) and be leaving a number of litres of unused hot water in the pipes afterwards.

volume of water you are heating. Some “power showers” can use 3 or 4 times as much water per min as a small electric one. Very nice and all that but it will cost more to heat more water.

Mainly though it’s the time spent in the shower – a nice one and my wife especially can’t be dragged out of it in the morning. The more water it throws at you the nicer it is and the longer people spend in them – which is a loose loose on costs but a very nice way to start the day!

Electric heating is 100% efficient – all of the heat in your shower element is transferred to the water – whereas your combi will be around 80% efficient for water heating. However, a gas boiler fed shower will be cheaper to run (mains gas is 1/3 the price of electric) and more powerful, assuming your combi has a decent flow rate.

The cost of gas or electric for heating shower water is trivial in comparison to your annual heating bill.

Convert – do you live in my house?

biggest issue is that if the boiler breaks you have no way of getting hot water for washing bar boiling the kettle a lot.

biggest issue is that if the boiler breaks you have no way of getting hot water for washing bar boiling the kettle a lot.

It’s happened to me once in 6 years, causing me to miss a shower for one day. I don’t think it’s really a big issue.

Electric heating is not 100% efficient. Far from it as loses at production are colossal so carbon wise you are probably better off.

The losses are quite scary, eg for coal:
65% loss at combustion
10% loss in distribution

So for every 100J generated in the furnace, only 25J make it to your house!

See http://www.mpoweruk.com/energy_efficiency.htm

I’d also bear in mind that with most combis the flow will be taken by the first ‘drain’ so your shower can deminish hugely if someone runs a tap earlier in the run from the boiler. Not great in my experience unless you’ve a megaflow type system or a super duper boiler….

The losses are quite scary, eg for coal:

There are losses for gas as well, reasonable to assume 1kWh of gas in the home uses half the carbon of 1 kWh of electricity.

So assuming the same efficiency in the home, gas uses half the carbon and costs between a third and a quarter to run for the same heat use.

Combi fed showers all the way

Electric showers are horrible inventions which should never have been allowed past the 1980s

Humm, I was really looking forward to a really powerful shower but to be honest, it’s not really any more vigorous than the electric shower was. Anyone got any suggestions?

Iwe have two showers. One of them is electric, which we specced dileberately as a back up for the boiler I case it goes down.

It’s flow is crap, but it’s adequate

Onzadog – Member

Humm, I was really looking forward to a really powerful shower but to be honest, it’s not really any more vigorous than the electric shower was. Anyone got any suggestions?

Is there not enough hot water flow? Small pipework / lots of bends?

Or is it the combi only produces that much hot water? Try turning the water temp up?

The boiler is 30 litre and just above in the loft. While not directly routed, It’s not excessive. Both hot and cold follow the same route and are full 15mm the full lenth with full bore isolation valves.

Was thinking of turning the heat up but won’t that reduce the flow further?

as an specifier and installer i think i’d disagree with most comments. the mixer shower fed via a combi IS NOT mains fed its delivery is limited to the volume the boiler can produce off the top of my head i think the WB 30si is circa 11 litres per minute, as it cycles you may also experience the hot cold hot effect. energy wise i suspect that costs would be similar.. a 30kw boiler v’s a 10kw shower..
i ‘m also keen to specify the electric shower as it gives a fall back hot water supply should / if/ when the boiler fails

properly installed and correctly wired ( essential to prevent electrical fires which are common) a decent mira shower would be 130 plus installation costs of approx. another 150 if a new installation. a mixer shower of similar quality may be twice the purchase price but installation costs would be half of an electric in a new installation

life cycle wise i’d expect both to easy go beyond 10 years without any maintenance.

Thanks for the info. However, the mixer has just gone in. It’s not a bad shower but I was expecting more. Now just wondering how I can get a bit more umph out of it.