CH Pump Change & No Hot Water

[cts1975]

I fitted a new pump to our central heating yesterday.
I drained the system and fitted as per the pump instructions and all seemed to go back to normal.
We have an unvented pressurised hot water tank which was fitted 3 years ago due to low water pressure.
It is a "Centerstore Indirect Unvented Hot Water Cylinder"

Since the new pump has been fitted we have water flow from the hot taps at the usual pressure but its cold.
Any help appreciated - if you need more system info let me know.

Edited by cts1975 on Sunday 22 January 15:09

[21TonyK]

I'm assuming the cylinder has an electric immersion heater as well so switch that on first. If that's not working then the valve that allows your heating hot water through the "indirect" coil in the cylinder isn't switching.

Seems a bit odd if both have failed

[cts1975]

Yes it has an electric emersion.
http://www.plumbcenter.co.uk/product/centerstore-i...

The Primary Flow is warm and the Primary Return is cold - is that normal?

I've purged it again this afternoon. I turned the mains water off and the hot taps on, they ran dry after may be 1 or 2 minutes.

[21TonyK]

Can you check the electric immersion is powering up? Ignoring the indirect coil that should be heating the cylinder on its own and as long as water is flowing to the hot taps I can't think of much more that can be wrong.

They're pretty simple things, water in a tank heated by an electric element.

Hopefully a plumber will reply soon!

[cts1975]

I've no way of knowing if the immersion is powered up. There are no lights etc on the tank. I have it switched on via the switch next to the tank. That's all I can tell you I'm afraid.

[finlo]

Have you bled the coil in the cylinder?

[cts1975]

finlo said:

Have you bled the coil in the cylinder?

No - not sure how to I'm afraid.
Just wondering if the 3 position valve is suspect.
The pipe coming of towards the tank is cold?
The other to 2 pipes being hot.....

[roofer]

I'm no plumber, but that sounds like an airlock.

[21TonyK]

Is the pipe coming straight out the top hot? This is your hot outlet.

[finlo]

cts1975 said:

No - not sure how to I'm afraid.
Just wondering if the 3 position valve is suspect.
The pipe coming of towards the tank is cold?
The other to 2 pipes being hot.....

There should be means of bleeding the circs where they enter/exit the cylinder.

[cts1975]

21TonyK said:

Is the pipe coming straight out the top hot? This is your hot outlet.

Just checked - it's stone cold.

finlo said:

There should be means of bleeding the circs where they enter/exit the cylinder.

Just a valve/tap on a pipe going to the separate expansion chamber, thats all I can see.

[Busterbulldog]

Deffo airlock

[cts1975]

Busterbulldog said:

Deffo airlock

How can I solve that?

[Jonesy23]

Asking the obvious question - after replacing the pump did you remember to reopen the isolation valves?

[cts1975]

Jonesy23 said:

Asking the obvious question - after replacing the pump did you remember to reopen the isolation valves?

Yes I remembered.
Can anybody explain the 3 way valve. I'm not convinced that's working correctly. The closest warm/hot pipe to the tank is before the valve, should the hot water not be passing the valve on its way to the tank?

[anonymous-user]

the pipe that comes from the 3 way valve needs air removing, bleed at cylinder...

[Busterbulldog]

If there's no air vent crack open a nut at highest point, there usually is a vent of some kind though. You could try heating off water on and blast it through...have you bled the pump itself ? If all else fails pop up some pics so we can see what will work for you.

[21TonyK]

If you have water flowing under pressure from hot taps but it is running cold then your cylinder is doing what it should except heating the water. If the immersion is not heating then it is an electrical prob. Heating via the coil/central heating loop is secondary.

Put your central heating on max and switch on the immersion. If that doesn't work and you have pressure at hot taps then its a real combination of failures.

[cts1975]

[cts1975]