salamander pump - pulsing

[scottie]

Have just replaced an 8 year old salamander RHP75 pump with a new one as the old one was making a horrbile noise.

When i turn off the hot tap the pump continues to pulse (on/off) and the only way to stop it is turn the pump off and on again or turn the tap on again and off slowly. Appears that turning the tap off quickly causes the problem.

Any one know what's causing this and how to stop it (other than telling every one to turn taps off slowly)

Pump feeds a bath in one room and sink, shower and toilet in another room.

 

[seco services]

where is the pump located at the base of cylinder or above ?

 

[ChrisR]

COuld just be air in your pipes which will get better by itself, unless you have a high pipe where air can't get out?

 

[scottie]

where is the pump located at the base of cylinder or above ?

pump is located at the base of the hot tank with feed in coming from the top of tank.

 

[seco services]

if your sure any air that maybe be in pipework has been released, fitting a nrv on the hot pipe exiting the pump useally cures that problem.
dont what ever put it on the supply to the pump as the pum needs to vent back to the cylinder

 

[scottie]

if your sure any air that maybe be in pipework has been released, fitting a nrv on the hot pipe exiting the pump useally cures that problem.
dont what ever put it on the supply to the pump as the pum needs to vent back to the cylinder

Just found i've got the same problem with the cold water as well - so NRV's on the hot and cold exits from the pump then

Surely if the water is coming through all taps then then there can't be air in the pipes or can there?

 

[ChrisR]

How long has the new pump been in?
SOmetimes the problem takes a couple of days to fade away. I assume it's little bubbles stuck to the pipe walls, but without perspex pipes...!

Are there any "deal legs" on the pipework, or taps which haven't been used for a while?

 

[seco services]

can be air in pipes if you have pipes going up into loft and back down to bathroom so air gets trapped at the highest point. and will just move backswards/forward and cause it to pulsate.
have you got bleed vents at the pipeworks highest point.

 

[scottie]

How long has the new pump been in?
SOmetimes the problem takes a couple of days to fade away. I assume it's little bubbles stuck to the pipe walls, but without perspex pipes...!

Are there any "deal legs" on the pipework, or taps which haven't been used for a while?

replaced pump yesterday - don't know what you mean by "deal legs" - orinal pump fitted 8 years ago with no problems and all taps in constant use - could be air in the pump/pipes but surely leaving the taps running for a while should have removed this

 

[scottie]

can be air in pipes if you have pipes going up into loft and back down to bathroom so air gets trapped at the highest point. and will just move backswards/forward and cause it to pulsate.
have you got bleed vents at the pipeworks highest point.

pipes do run up to loft and back down again with no bleed vents - so could be air in pipes but would have thought this would be removed by running taps for a while - no air appears to be comming through

 

[seco services]

air will only rise not fall. A dead leg for example is a length of pipe that is capped off that can have air in it and can act as a shock absorber. This can make the pump pulsate.

 

[scottie]

air will only rise not fall. A dead leg for example is a length of pipe that is capped off that can have air in it and can act as a shock absorber. This can make the pump pulsate.

in that case no dead legs - unless you included pipes running to other taps which are off at the point the bath is running and therefore could be "dead"