improve pressure from unvented electric water heater?

Discussion in 'Plumbers' Talk' started by cuppatea, Aug 18, 2017.

  1. cuppatea

    cuppatea New Member

    Hi folks,
    I have an Ariston Lux 15 litre 2kW electric water which I bought from Screwfix and to be honest I am very impressed with it, it's a great value piece of kit which totally fulfills my modest needs...
    The only thing I would like to improve is the pressure in my shower. The heater relies on mains pressure and mine is a bit low. Adequate for the sinks but a bit weak in the shower.
    My question is, is it possible to fit a pump to improve the shower pressure, either before or after the heater? If so, what type and pressure would be appropriate? The emergency relief valve is rated at 6 bars, if that makes any difference. The heater feeds the shower and two sinks. I am imagining the type of pump that switches on by detecting the difference in pressure when you open a tap.
    If a pump is out of the question, is there any other way to improve the shower pressure?
    Thanks :)
     
  2. cuppatea

    cuppatea New Member

    Home Boost mains pump maybe?
     
  3. kiaora

    kiaora Screwfix Select

    Hi
    2 kw water heater, will not be able to provide a flow of water for a shower, ,
    You may well get a flow of say, 10 lt/min, but for only until the tank is empty.

    And with a 15 lt tank, it's not long!

    For a shower, it's either higher kw, or larger cylinder.

    Regards
    Peter
     
  4. cuppatea

    cuppatea New Member

    Thanks, but unfortunately I can't increase either; my electrical supply is limited and 15L is the largest unvented water heater which can be fitted by a 'competent person' without informing the local authority. I only need to boost it a little bit... but yes I understand after a bit of reading that this is an issue of flow rather than pressure.

    I haven't have any issues with capacity, currently this water heater daily gives us 2 showers of about 10 minutes with only short gap in between, and then provides hot water to the sink for washing up shortly after that. I have it turned up to full temperature, so when mixing with cold water the hot goes further. Also the heater heats more water going along so the tank doesn't get empty.

    I was surprised at how well it performs, the shower is certainly not a pathetic dribble, could just be a tiny bit more powerful. I will try a 'low flow' shower head to see if that will help, and I will see if the pipework which brings water from the mains can be enlarged to 22mm as I've heard that can also make a difference.

    But really my question is whether it is safe to fit a pump in an unvented system, I imagine that it might not be safe to fit one after the water heater, but perhaps a mains pump fitted to the supply such as the Salamander Home Boost would work? It claims to provide up 12L per minute and adjusts according to requirements.
     
  5. The Teach

    The Teach Screwfix Select

    You could pump your mains water to increase the flow but the more water passing the heat element will decrease the working available shower temperature so its a little hit and miss.

    maybe consider a shower head designed for low pressure or water saving these give a good evenly distributed fairly high flow of water,they have only 1 flow setting (my previous water supply company sent these shower hand held units free as in effort to conserve water) your shower hose needs to be not less than 14mm ish internal diameter as less slows down water production at the shower head.

    TT
     
  6. cuppatea

    cuppatea New Member

    Thanks TT
     

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