New Grundfos Alpha 2L Not Doing The Job

[Mackayzer]

My Wilo Gold pump gave up after a commendable 15 years service and I've installed a Grundfos Alpha 2L 15/50 yesterday afternoon.

The pump services a pressurised heating system within a four bedroomed two story house ( 12 radiators). I've bled the system through and checked that both the hot water and central heating motorised valves are operational. However the radiators seem to take an age to heat up and the hot water is luke warm.

I've left the pump operating in mode III and the majority of the time the discharge pipe work is roasting with the return to the boiler luke warm and the boiler seldom kicking in.

Occasionally there will be a rush in flow (audible throughout the house) and the boiler will kick in resulting in the return leg to the boiler heating up. Then the whole cycle starts over again..

Im beginning to think that the pump isnt big enough and that it's dead heading.

Any guidance would be much appreciated

Thanks
Ian
(Frustrated DIY Man)

 

[dcawkwell]

Air lock or blockage.
It ain't circulating mate.

 

[Mackayzer]

Air lock or blockage.
It ain't circulating mate.

Thanks... I'll try bleeding off again at the bleed on the discharge of the pump and the inlet of the hot water tank.

 

[matt1e]

as above

OP out of interest, what was wrong with the original pump?

Matt

 

[Mackayzer]

as above

OP out of interest, what was wrong with the original pump?

Matt

Hi Matt

The old pump was making a heck of a noise.. so much it could'nt be run. When I removed the pump from the pump housing I tried turning the motor and impeller but they were seized.

 

[Mackayzer]

Have spent the last hour bleeding off at the discharge of the pump. Can't say there was lots of air but it was hard to tell.

Will leave the pump running overnight and check the water temperature in the morning. Hopefully won't be kept awake all night by 'gurggling' pipes !

 

[Mackayzer]

Left pump running over night for hot water and woke up to hot water... Woopee !

However the heating was set on the timer and was supposed to come on at 0600 but the radiators were still cold at 0700.

Checked system pressure and found it to have dropped down from normal operating pressure of 1barg to 0.2barg over the course of the night. Pressurised system back up and radiators began to heat up immediately.

Do I still have air in the system which is gradually being expelled as it circulates resulting in the system pressure gradually dropping ??? The flow through the pipes still sounds be a bit 'gurgly' every now and then

Should I continue to leave it circulating and continue to top up as the air is expelled ?

Sorry for the post being so wordy but just trying to provide as much info as possible.

Any guidance welcome.

Thanks
Ian