hot water cylinder

[emmkat]

There's a zone valve on the return pipe if that's not working properly would that cause cold water

 

[halfway]

If the zone valve is for isolating the cylinder, then yes it would. Most zone valves have a manual over-ride lever on them.

 

[emmkat]

Thanks I'll look at that first

 

[halfway]

Good luck with it. Don't forget to let the thread know what the problem was and how you sorted it. That way everyone learns.

 

[emmkat]

one more thing. When I filled the system should I have had the zone valve on manual. I didn't do anything with that.

 

[halfway]

It is always a good idea to do so when filling, but your system may have filled properly anyway. It depends on how the plumbing was done, or if you got an airlock while filling. It may be a good idea to have a plumber look at it at this stage.