Pulsing Bathroom Pump

Discussion in 'Plumbers' Talk' started by David Quinn, Nov 22, 2017.

  1. David Quinn

    David Quinn New Member

    I am hoping you can offer some advise with a shower pump issue.

    I have a Grundfos Type SSN-2.0B pump, model A96787504 P5 feeding a shower , bath tap and basin tap. At the weekend I had to drain the hot water cylinder to change the thermostatic cartridge in the shower. When filled back up, the pump works fine to pump water, but it continuously pulses (on for roughly 3s, off for 0.5s) when all the taps/shower are off. There is no sign of any leak so I believed that there was air in the system. I followed the procedure on the Grundfos website:

    With pump off switched off and shower head removed and hose on the tray floor,
    Run cold for 5 minutes
    Run hot for 5 minutes
    Wait 20 minutes
    Run shower again
    Start pump

    The problem was still there so I repeated the above running the shower, bath tap and basin taps together.
    Finally, I left the pump switched off overnight and tested it again this morning. It still pulses continuously with no water being drawn off.

    Is there anything else anyone can suggest?
     
  2. CGN

    CGN Screwfix Select

    Try slackening off the the hot and cold feeds at the shower inlet to bleed the pipes. I had a similar problem once and this sorted it.

    Should add, it depends on whether they're accessible :)
     
  3. David Quinn

    David Quinn New Member

    The shower is a Bristan Inset type and the feeds are tiled over so I would have to cut a hole in the wall in the room behind the bathroom. If it comes to it I'll do it but I'm hoping for a more subtle method?
     
  4. andy48

    andy48 Screwfix Select

    If you have one, try using a wet and dry vacuum cleaner on each outlet, with the shower pump switched off. May be enough to pull water through and remove air.
     
  5. DIYDave.

    DIYDave. Screwfix Select

    This won’t help the problem but just wondering why you had to drain the hot cylinder to carry out the work on the shower ?

    Guess there’s no isolation or lever valves on hot and cold supply to pump ?

    Sometimes built into pump hoses or just fitted on pipe - saves a lot of hassle for any future maintenance work

    Where on the tank is the shower hot supply taken from and via a flange ?
     
    The Teach likes this.
  6. The Teach

    The Teach Screwfix Select

    If the pump is valved,they could be turned off and if the pump still pulses the fault is in the pump-reed switch or nrv but could further in the pump.

    If the pump stops pulsing the fault is in the water system,air or even a dead leg.

    Have to assume the shower mixer is not valved or the valves are hidden away.If the valves can be found,turn them offf and see if the pump stops pulsing.

    Could refit the old shower thermostat and see if pulsing stops.

    Happy plumbing.
     
  7. David Quinn

    David Quinn New Member

    Thanks for the replies.

    The feed to the pump is tee'd off the hot water feed from the top of the tank. Researching this I see that the bathroom fitter should have fitted a flange to the tank instead (job was done 8 years ago). The pump feed has a gate valve but it's seized. I have just bought a new one for next time the tank is drained. Fortunately there is a working one on the output of the header tank in the loft otherwise I'd have had to drain that as well. There are no valves on the pump output.
     
  8. nigel willson

    nigel willson Screwfix Select

    You can sometimes take it from the pipe coming off the cylinder ,but you have to alter the pipework so that it rises from the cylinder at 45 degs and tee off the underside of this.
     
  9. David Quinn

    David Quinn New Member

    20171122_195335.png

    This is how the fitter did it and that's the valve that's seized. I wonder if he had a problem with air when he first installed it?
     
  10. CGN

    CGN Screwfix Select

    Certainly took the easy option. Prob best to get the proper flange installed and go from there.
     
  11. DIYDave.

    DIYDave. Screwfix Select

    Again this won’t help you this time David but that new gate valve uv brought ......... find receipt and take it back or bin it !

    They are rubbish and next time you need to turn water off (ok, in a few years time) it will have seized again - sometimes in open or closed position

    Replace with a full bore lever valve - much better :)
     
  12. The Teach

    The Teach Screwfix Select

    Yes but he would have undone a gate valve nut (with gate valve off) and angle up the plastic tee to let the bubbles out then refit it as it is.

    You need an essex flange fitted to supply hot to your pump,not straight forward buy a plumber can do it.
     
  13. Pollowick

    Pollowick Screwfix Select

    WTF ! Why did he not fit a push fit valve? I suggest that is what you do. However, a flange is needed, be it on the side or top.
     
  14. David Quinn

    David Quinn New Member

    Ran into a problem straight away with this. I bought a Salamander S Flange which has a 1" BSP male or female connector to the tank. Having removed the pipework from the tank outlet, it has a 22mm male connection. It is threaded into the tank on a boss with a diameter of 1 1/2" so I bought a 1 1/2" to 1" reducer. Daft error as I since discovered that 1 1/2" BSP isn't 1 1/2" diameter!

    So, next question. What size is that male thread screwed into the tank likely to be or do I have to drain it, remove it an take it to the plumbers merchant out to find out?
     

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