Any Plumbers? advice please

[350zedd]

I've got a negative head salamander pump which boosts the hot water to the whole house. System is about 3 yrs old new build.

Recently the pump has started locking out for a few seconds due to aeration.

Nothing has been altered and there are no leaks.

Its worked fine for 3 yrs but has recently been playing up.

Any ideas?

[Rich260]

Possibly pulling in air through an auto air admittance valve? Partial blockage in the feed pipe causing cavitation in the impeller? Are you getting a air through any of the outlets or a reduced flow?

[350zedd]

I dont think there are any auto valves on the system. There is no reduced flow when the pump is running and no noticeable air at the outlets, although when the shower goes on first thing in the morning you can hear a large air bubble going up the pipes.

[Ekona]

Dodgy pump internals? As in, when they spin up to create pressure they're creating turbulence in the pump itself, so essentially it's creating it's own air.

[350zedd]

I cant hear any excessive noise/turbulence in the pump and there's no drop in performance when its running

[Ekona]

Any awkward vibrations? Might be worth taking it out and checking the impeller anyway, easy thing to rule out.

[Rich260]

Would also be worth checking any non return valves or strainers on the system. A drawing of the system layout could help us be a bit more accurate to

[350zedd]

Dan...will probably end up taking the pump out to check if I cant find any other cause

 

Rich...There are no non-return valves or strainers as far as I know.

 

[Ekona]

Check the vent, make sure it's not circulating round into the tank. Very unlikely, but an easy check.

[Rich260]

I'm with Dan, sounds like an issue with the pump.

 

Very unlikely to be pumping over the vent as that should be under negative pressure when the pumps is in operation.

[gsexr]

might help you mate

 

http://www.salamanderpumps.co.uk/faq/

[350zedd]

yep, the vent is on the suction side of the pump

 

gsexr......already been there...thanks.

 

If it was a new installation, then I'd say it needed an essex flange on the top of the cylinder to draw water from further down and miss any rising air bubbles, but its been fine for 3 years. I'll get the pump off when I get chance and have a ganzy.

Thanks for your input so far.

[ioneabee]

its the felange .............. its always the felange

 

 

(I'm sure someone will get the reference )

[350zedd]

its the felange .............. its always the felange

 

 

(I'm sure someone will get the reference )

 

Que?

[AliveBoy]