Hot water cylinder problem

[jiffter]

I've just fired up my hot water and heating system after installing a new horizontal tank in the loft. I thought all was going fine, heating works fine but i cant get any hot water. Water flows through the hot taps but totally cold. Checked the motorised valve on the boiler and that seems fine so im baffled as to where i've gone wrong. The water tank and expansion tank are one metre above the hot water cylinder so the height should be okay. The pipe work is more or less like for like on the new tank so the only things i can think of with my limited knowledge is an air lock or the primary flow and return flows have been mixed up when connecting to the tank.
PLEASE any help would be appreciated.

 

[GQuigley67]

if water is flowing through the taps but is cold then you may have "crossed over" some pipes, what kind of cylinder is it ?

 

[pauls]

has the cylinder stat been knocked or turned down.

if you try heating up the cylinder on the immersion heater see if you can get hot out of taps that way

 

[jiffter]

Its a Newark horizontal tank fed with a horizontal coffin tank.

 

[plumbster3456]

auto air vent on flow and return to cylinder?

 

[jiffter]

No auto vent. The only venting comes from the hot water venting pipe as before i changed the tank.

 

[NickH]

Two possible scenarios, the cylinder is not being heated or the hot water is not gettng to the taps. Feel the pipework around the cylinder to see whats happening, is the flow from the boiler getting past the motorized valve and into the cylinder ? is the return from the cylinder hot ? is the cylinder heating up ? feel the vent pipe to check.

 

[jiffter]

The cylinder is stone cold, neither the primary or return pipes are hot and the vent pipe is cold. I'm sorry for my ignorance but if i connected the primary where the return should be what would be the outcome?

 

[Gray0689]

The cylinder is stone cold, neither the primary or return pipes are hot and the vent pipe is cold. I'm sorry for my ignorance but if i connected the primary where the return should be what would be the outcome?

Your heat would be going to return side your coil is probably air locked

 

[plumbster3456]

Your heat would be going to return side your coil is probably air locked

this is exactly what i meant regarding the auto air vent

 

[Gray0689]

this is exactly what i meant regarding the auto air vent

Yes your right mate

 

[jiffter]

I did ask my plumbers merchant about using auto air vents but was told they wern't needed. if i have an air lock as suggested, by installing the auto vents to the primary and return would likely clear it?

 

[plumbster3456]

put it on the highest pipe if you have piped it correctly the top pipe should be the flow

 

[NickH]

If you have a compression joint at or near the high point you can loosen it a bit to let the air out and see if it starts to flow, still fit an auot vent though.