Low cold water pressure after vented boiler replacement

[intamixx]

Hello,
I have a had a gravity boiler replaced from a Potterton 80e to a more recent Valliant ecoplus boiler.
The cold water tank is in the loft space directly above the 1st floor bathroom and the hot water copper immersion tank is in the 1st floor bathroom cupboard space. A fairly normal gravity setup.
In the bathroom upstairs, before replacement of the boiler, I've always had a low flow of water into the toilet (never understood why), whilst the sink and bathtub have a good decent flow and pressure for hot and cold.
Now after the replacement boiler has been fitted, I am getting very low flow / pressure of cold water in the sink (hot is still good) and also a further diminishing flow in the toilet cistern when it's filling up. I've removed the sink taps in the bathroom and can confirm the flow is slow for the cold water supply.
Would anyone happen to know the reason for this? The cold water tank was not touched during the install, but am wondering why this is happening now.
Would a cold water pump be required now?
The ground level sink cold supply has good flow, as I believe it is being fed directly from mains.
Any help would be most appreciated.
Thanks.

 

[Deleted member 120897]

It might be worth checking for a gate valve (a wheel with a red handle), which may have been turned off during installation. Yes your kitchen will almost certainly be from the mains and why it would be unaffected. Check the tank is filling back up too.

 

[intamixx]

It might be worth checking for a gate valve (a wheel with a red handle), which may have been turned off during installation. Yes your kitchen will almost certainly be from the mains and why it would be unaffected. Check the tank is filling back up too.

Thanks for the response.
The cold water tank is filling up as normal with good flow if I manually empty it out a little. I seem to remember a circular wheel valve in the airing cupboard at head height next to the copper cylinder. It was very hard to rotate. The plumber mentioned this was not touched during the install, but will double check.
Thanks.

 

[Deleted member 120897]

If gate valve isn’t open properly, it might be partially snapped and preventing water coming through.

 

[intamixx]

There are 2 circular valves in the airing cupboard (about 30cm distance between them) I attached pictures of them. Are these the gate valves you are referring to? The upper one was very hard to turn. I haven't tried the lower one.

 

[intamixx]

Hello,
Finally sorted it thanks to your help. Managed to connect a 15mm right angle tap connector into cold water pipe under bathroom sink and blast it with hose (coming in through bath window) pressure from garden tap. It removed the airlock straight away and cold flow was back to normal after that. The toilet just needed a new bottom fill valve in the cistern and now that is working too.
Thanks again.

 

[Lou]

(Just bumping a few older threads, they will drop off what is new soon)

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