No hot water pressure

[jtc]

Hi everyone. I have just added a larger hot water cylinder, about twice the size of the old one. It is a vented system, does not contain any air blockages but there is practically no flow coming out of the top, it is just a trickle (0.25 litres/minute). Have tested flow up to cylinder feed and that is fine. I suspect that it may be not enough head pressure from the storage tank (about 2m) to flow through the new cylinder. Do you think this is possible and how should I rectify it. I talked to a pump manufacturer and they sugguested a negative pump after the cylinder and before outlets. This is £300 so do not want to spend it if it is something a bit simpler. Thanks

 

[fitz1]

air lock

 

[croydoncorgi]

air lock - probably on a near-level section of the cold feed to the cylinder, probably near the cold tank. (Always assuming the old cylinder worked a LOT better.)

 

[jtc]

Problem solved. it did appear like an air block but I had pumped mains pressure through the drain valve so doubted this was the problem. However I went through every compression nut loosening off and testing for flow, a bit messy but so what. I got to one elbow and there was good flow one side but a trickle the other. The flow to the cylinder feed which previously I thought was ok must have been it just draining from the cylinder. Opening it up I found two small stones and a load of debris. I have just bought the house and it was basically drained down and abandoned for a while before. My guess is that the draining and refilling drew this gunge into the system until it all blocked up in an elbow. An interesting lesson !!