2-way motorised valve

[OJ]

The 2-way valve on my HW developed an intermittent fault, which was tripping the RCD on my consumer unit, so I was advised to replace the 2-way valve.

I drained down the CH system, removed the old valve, fitted the new one, and released the ballcock to fill the CH system again. I've not been able to bleed all of the rads yet, as the bleed valves are too tight, but I assumed I could still get HW, and sort the CH out another day. Now when I call on hot water, the new 2-way valve moves the lever over to B, the boiler fires up, and then after a few minutes the boiler stops again.

Therefore, I am not getting sufficient HW. Any ideas as to what I have done wrong?

 

[Gasguru]

Feel the flow pipe at the boiler and the airing cupboard...probably red hot at the boiler end due to poor circulation...due to system full of air. Sort out the bleed valves.

 

[OJ]

Feel the flow pipe at the boiler and the airing cupboard...probably red hot at the boiler end due to poor circulation...due to system full of air. Sort out the bleed valves.

Sorry, do I understand you correctly - the amount of air in the CH system is preventing the HW side from working correctly? I thought the HW could work independently of the CH system?

 

[mysteryman]

You still need all the air removing from the complete system.

 

[OJ]

Ok, many thanks guys....

 

[twgas]

More than likely to be an air vent in the airing cupboard, next to the cylinder, that needs venting.

 

[OJ]

Possibly as a result of something I've done whilst doing this valve change, the vent pipe coming from the top of my Hot Water Cylinder now trickles into my F&E tank, causing it to trickle from the overflow pipe....

Any advice, please?

OJ.

 

[ROSSGR]

The pressure of the system not circulating is causing the water to pump over into the tank.

Still need to sort out the air before all will be back to normal.

 

[OJ]

Apologies - I forgot to say that I got all the rads bled in the end, but then this problem started. Where else might I have air?

 

[OJ]

Possibly as a result of something I've done whilst doing this valve change, the vent pipe coming from the top of my Hot Water Cylinder now trickles into my F&E tank, causing it to trickle from the overflow pipe....

Any advice, please?

OJ.

 

[OJ]

I'd appreciate it if someone could offer me some advice here, please, as this dripping overflow is driving me nuts, especially at night...

 

[penfold46]

Have you vented the pump, turn it down to its lowest speed (if its not already on it) and see if the problem persists.

 

[mysteryman]

'... the vent pipe coming from the top of my Hot Water Cylinder now trickles into my F&E tank, causing it to trickle from the overflow pipe.... '

Is that really the case? If so, the heat exchanger [or coil] in your cylinder may be leaking. This vent should be over the main cold feed tank, not the central heating feed and expansion tank. Have you got a leaking balltap?

 

[OJ]

'... the vent pipe coming from the top of my Hot Water Cylinder now trickles into my F&E tank, causing it to trickle from the overflow pipe.... '

Is that really the case? If so, the heat exchanger [or coil] in your cylinder may be leaking. This vent should be over the main cold feed tank, not the central heating feed and expansion tank. Have you got a leaking balltap?

Hi, yes, it definitely runs into the F&E tank, not the main cold feed tank. It is a 4' length of white plastic, coming from a black plastic connection at the top of the Hot Water Cylinder - although I was expecting it to be 22mm copper. I had already replaced the ball-valve on the F&E tank, before I realised that it was this vent pipe which was causing the level to reach the overflow outlet...

 

[OJ]

Have you vented the pump, turn it down to its lowest speed (if its not already on it) and see if the problem persists.

Am assuming that there is no air trapped in my pump, as my rads work perfectly?