Shower pressure

[Newhome25]

Moving into a 2.5 story new build with combi boiler. Have requested a thermostatic shower in the top floor en-suite bathroom. Developer has advised that it would be better suited to an electric shower because pressure for a thermostatic shower would not be good. Any advice? Not keen on having an electric shower but are we better going with this? This en-suite shower would be the only shower in the house, as there would not be one over the bath in the main bathroom, so no issue of having two showers on at once.

 

[steadyon]

1. One advantage of having an electric shower is that you would at least have a source of hot water if the combi broke down.
2. In theory a combi needs around 1.3 bar incoming pressure, at least to pressurise the system. You'd lose around 0.6 bar reaching the top storey of a 2.5 storey property, which should leave you 0.7 bar for a shower at that height. Its not a great deal, and you aren't going to get a "hotel experience" shower from it. It could well be better than an electric shower, but not by a huge amount.
3. If the incoming pressure to the house is a good deal more than minimum, then a mixer shower would give you much better performance than an electric shower.
4. See if the developer has (and will commit in writing) the incoming mains water pressure.

 

[Ben-gee]

You’ll get better performance from the combi.
The mains pressure is the same for either shower , the electric shower slows it down to heat it assuming the combo has > 10.5 kW on the water side it will be better than the electric one.

 

[Timmy D]

Pressure is not a valid reason for choosing electric over combi. The water still has to get up there. The flow will be restricted more by an electric shower than a combi.

Put a mains boost pump in (max allowed is 12LPM). Install it at the stopcock before any other connections and you should be guaranteed a better shower than electric. If you do this, ideally you want a cold water feed from before the pump to supply the toilets so the pump doesn’t kick on during the midnight toilet trip.

You need to know the static/dynamic pressure and flow rate.

I’d only go electric in a combi property of the current combi couldn’t meet the demand (2 showers at once).