Unable to get air lock out of Hot water system? Please help!

[tomspenny]

Hello just wondering if any of you can help me, I’ve fit a drain off and double check valve on the CW mains at the base of a twin immersion heater I’ve refilled the cyclinder and unable to get any hot water, I’ve tried the hose pipe trick for 2 hours and still no luck l, also tried turning the cold water taps off and slowly on again while flushing the toilet and still not luck, can anyone give any advice please ?

 

[Stu-B]

Take the check valve off again, why did you fit it

 

[tomspenny]

Take the check valve off again, why did you fit it

Had a legionella risk assessment done and they wanted a back flow prevention valve installed on the CW Mains coming into the cylinder.

 

[snowhead]

Are you only getting cold water out of the Hot tap or no water at all?

Is the pipe you've put the check valve on definitely Mains cold and was it a spring type Check valve?

As above post if in doubt, remove what you've done and start again.

 

[John.g]

Check valve right way round?, a bit surprising that a hose, if connected to the drain wont force the air out, I cleared a neighbours recently by keeping the outlet nozzle blocked and opening the mixing valve "1/2 way" but you have probably tried all these methods.

 

[tomspenny]

Hi guys I’ve now removed the check valve and started from where I begun and still no luck, tried every method I know of flushing out air locks. It has a secondary return with a gate valve and the flow has no gate valve. Any help at all would be much appreciated.

 

[John.g]

Crack open/remove the secondary flow & return and check for water, then remove the hot water top fitting and check for water. Are the electric immersions the only form of heating, just wondering if the flow/return are to a coil for oil/gas heating.

 

[Ben-gee]

Isn’t that a vented cylinder, filled by gravity from a cold water storage tank?

 

[tomspenny]

Yes it is a vented cyclinder filled by gravity from a cold water storage tank, I think the air lock is on the secondary return going to install a gate valve on the flow and try pull it through through the return. Thanks for your replying everyone much appreciated.

 

[John.g]

By "flow"if you mean the hot water outlet on top of the cylinder why don't you just remove it and see if water comes out the top of the cylinder?

 

[Ben-gee]

Didn’t you say you put a check valve on the cylinder inlet? There may not be enough pressure from the tank to open this valve, it is not needed anyway.

just seen you removed it now.

 

[John.g]

If the CWST is full and any isol valves on the supply are open then if water doesn't flow out the top of the cylinder surely it can only be a airlock between the CWST outlet and the hot water cylinder?

 

[Stu-B]

Turn the pump off and open the nearest hot tap to the cylinder, It should gravity flow.

 

[John.g]

Perhaps it should but mine (vented cylinder) on the very rare occasions that its been drained has to be primed in the bathroom by opening the hot and cold taps and blocking the mixer outlet, I am lucky in that I have mains at the cold tap, the air lock is somewhere in the hot pipework.

 

[Ben-gee]

Open hot bath tap and get a wet vac on it , never fails.......honest