I've got a pretty ancient 'Dolphin 1000' electric shower (so only cold feed to shower) which is plumbed via a small satellite header tank to the main water tank. The supply is boosted by a real noisy pump sited next to the small tank in the loft.
The shower seems to be gradually dying - pitiful supply of water and cuts out ocassionally. The pump is also very noisy (does not help that it is connected via copper pipe to tank and can slip slide around as has no rubber feet).
My questions are
1) What is likely to be causing the pitiful performance, the shower or the pump?
2) If I replace the shower should I replace the pump?
3) Should I replace the copper pipe feeding the pump with a flexible one and if so will this diminish the noise?
4) Could I move the pump from the shower and site it next to the bath fed from the loft tank?
5) Could I just abandon the whole pump thing and fit a 9.5kW electric pump instead? Would the water pressure from my loft tank be sufficient for this 1st floor bathroom shower?
6) Would I notice much of a difference between a pumped 10.5kW electric shower and a non-pumped 9.5kW electric shower?
7) Finally where does the switch that operates the pump live? In the pump, or as I suspect is it likely to be the switchy looking thing attached at the junction of the water inlet and the shower........
There could be several problems causing the faults you describe.
1. The header tank is not filling quickly enough.
2. The pump is furred up or faulty.
3. The filters on the shower if fitted have become blocked.
4. The shower unit is become filled with limescale which is reducing the flow.
It is tempting to say junk the lot and fit a new electric shower supplied directly from the mains, but as someone has gone to the trouble of fitting an extra header tank, do you have a problem with low water pressure in your main?
Obviously, the shower size is limited to the diameter of power supply cable. Normally, a 6.0mm cable can only supply up to an 8.5kw shower. Any larger, and the cable will need to be 10.0mm with a corresponding trip or fuse in the distribution board.
Don't forget electric showers are always run at full power and the temperature of water is adjusted by increasing or reducing the water flow so if you have poor water pressure, it may be difficult to have shower with a 10.8kw as the water may be too hot.
Pumps can have integral sensors, sensors fitted into the feed pipes somewhere, or remote sensors fitted within the shower unit mixer unit.
The present shower is a 10kW one and looks to wired with 10mm cable.
I simply don't know if there is an issue with low pressure, the cold kitchen tap runs as well as our previous house so I expect pressure is ok.
I've assumed that the reason for the pump and header is that they wanted a higher pressure shower (i.e more squirt!) but I could be wrong........
Feeling that a 1 bar shower 9.5kW shower would be the way to go, just so I have the fallback of plumbing direct into the rising main should the pump be the problem. Looks like I'm taking back the 10.5kW one to Wickes
Providing your property has reasonable mains water pressure, then a mains fed shower will always beat a pumped arrangement hands down (squirt value). Most pumps are 1 -1.5 bar whereas mains is 3 or more.
I personally would dump the tank and pump and just install the new shower direct to the mains. The volume of hot water produced by an electric shower is always going to be restricted by the size of the heating element not the feed rate. This point is particularly noticeable in the winter when users experience reduced flow because the incoming water is colder than in the summer.
If you have a 40amp trip fitted install a 9.5kw. For a 50amp you can fit up to 10.8kw.
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