Hot water system, fed off mains, hot water pump shower / tap annoyance

Discussion in 'Plumbers' Talk' started by jamescast, Apr 22, 2022.

  1. jamescast

    jamescast New Member

    Hello,

    I have a water cylinder (120L older style with green foam insulation from factory) which is fed off the mains. I also have a single ended pump (old style salamander CT55 1.6bar) to give the hot water a higher pressure. I was looking at upgrading the pump or soundproofing as it's very noisy when I got thinking if there is a better option?

    I live in a two bed flat and the hot water feeds the kitchen tap, bathroom basin and shower. When I use the shower (standard mixer with hose to shower head) I need to hold the shower head down and turn the mixer to hot, then turn on (pump will kick in) and re-adjust mixer to desired temperature, if I don't hold the shower head down the pump won't kick in. I also have to do similar to activate pump at the basin and the kitchen sink, turn mixer to hot, turn on (pump kicks in) then adjust mixer to desired temperature. Why does this happen? Is there a better way? It's only a minor annoyance and something I have got used to but would like to improve if possible.

    Am I correct in thinking a new unvented cylinder will solve the problem?

    Thank you
     
  2. terrymac

    terrymac Screwfix Select

    Yes ,an unvented cylinder would improve your domestic hot water issues. You would need to establish what your mains pressure and flow rates are to determine if they are sufficient to enable an unvented cylinder to be fitted.
     
  3. jamescast

    jamescast New Member

    Thanks, from measuring the flow rate at the bathroom basin (maybe not the most accurate place to measure) I get around 12l/m. Unsure on the bar as I don't have a gauge.

    Any idea why I need to take the shower head off the hook and hold it down below the mixer (mixer positioned halfway up the wall) for the pump to kick in?
     
  4. terrymac

    terrymac Screwfix Select

    Lowering the shower head increases the pressure ,and flow, a bit ,enough to trigger the pump I expect.
     
  5. jamescast

    jamescast New Member

    Thank you. Would a negative head water pump sort this out, my current one is a positive head pump?
     
  6. terrymac

    terrymac Screwfix Select

    Possibly. Where is the cold water cistern that supplies your hot water cylinder ?
     
  7. jamescast

    jamescast New Member

    Looks like I have a primatic water cylinder so it's gravity fed from the section on the top, so when I drop the shower head below this section the pump kicks in. Photo attached.
     

    Attached Files:

  8. terrymac

    terrymac Screwfix Select

    A negative head pump would be a more suitable replacement for that set up.
     
  9. jamescast

    jamescast New Member

    Brilliant, thank you, was looking at the following. Looks like the 2.0BAR is the smallest sizing salamander sell. My previous was 1.6BAR, would this be an issue?

    upload_2022-4-22_20-45-26.png
     
  10. terrymac

    terrymac Screwfix Select

    Strictly speaking both hot and cold supplies to a mixer shower ,thermostatic particularly, should be at balanced pressures. Currently yours has mains fed cold ,and gravity fed hot ( albeit pumped). As we don't know what your mains cold pressure is ,it's probably wise to have a plumber visit to check out the compatibility before buying the pump .
     
  11. jamescast

    jamescast New Member

    Thank you for all the advice. I'll be sure to do that before I replace. I will probably buy get a measuring gauge and get a reading from my washing machine valve.
     
    terrymac likes this.

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