Central heating not working after drain down

[tmm]

Hi
I recently drained my central heating system to give it a flush out and replace a couple of radiators. I installed the new radiators, filled the system back up and add the inhibitor. The the problem i have now is when i switch the heating on it turns off after about 3 to 5 minutes. The pipe to the pump gets hot, the pump gets hot, but that is as far as the heat goes.
The system is run from an Ideal heat 18 (non combi) which has a hot water tank and 2 header tanks in the loft the large one for topping the hot water tank and the small one for the central heating system.
Any advice would be appreciated.

 

[Chester]

I take it you have bled everything?

 

[Riley]

Air lock most likely have you bled the pump any air vents need opening higher up??

 

[SimonG]

Airlocked.

 

[tmm]

Thanks for the fast response
Yeah i have bled everything i think.
IMG 0939 copy

 

[tmm]

Air lock most likely have you bled the pump any air vents need opening higher up??

The highest 2 i have are at either side of the pump, as in the attached photo IMG 0939 copy copy Are these the vent that i have circled?

 

[tmm]

Anyone bled/vent
a grundfos alpha 2 l 15-60 central heating pump?

 

[Harvest Fields]

The highest 2 i have are at either side of the pump, as in the attached photo IMG 0939 copy copy Are these the vent that i have circled?

Yes they are mate

 

[Harvest Fields]

Anyone bled/vent
a grundfos alpha 2 l 15-60 central heating pump?

You cannot as they are self venting. The manual for the pump looks like it is on the floor by the pump. Have a quick look at that.

 

[tmm]

You cannot as they are self venting. The manual for the pump looks like it is on the floor by the pump. Have a quick look at that.

Found this in the manual mate
(Venting of heating systems Fig. 12 Venting of heating systems The heating system can be vented via an air escape valve installed above the pump (1). In heating systems that often contain much air, Grundfos recommends the installation of pumps with pump housing with air separator, i.e. ALPHA2 L pumps, type ALPHA2 L XX-XX A. When the heating system has been filled with liquid, follow this procedure: 1. Open the air escape valve. 2. Set the pump to speed III. 3. Let the pump run for a short period, depending on system size and design. 4. When the system has been vented, i.e. when the possible noise has ceased, set the pump according to the recommendations. See 7. Setting the pump. Repeat the procedure, if necessary. TM05 1932 4512 ALPHA2 ALPHA2 L III II I POWERON 1 2 3 III I = 10 Min. Caution The pump must not run dry.)

 

[Harvest Fields]

Why did you see that?

 

[tmm]

Why did you see that?

In the Manual

 

[heatservice]

Are there any air vents in the roof space?

 

[tmm]

Cheers everyone for the help Got it sorted.
You's were all spot on with the air in the system. I opened the lowest drain off valve and just let the system flush through for about 10 mins then closed the valve off, I then switched the pump back on and set it to 3 for about 5 mins to flush air through , i switched the pump back off and opened the air vents as shown in the photo above. Switched the pump back on and it all works a treat
Cheers once again