Pressure problems.. Gravity fed system.

[Jreucassel]

Hi,

I am very inexperienced at plumbing but I am having a real problem with low pressure in my upstairs bathroom.
The problem only affects the cold water taps for some reason, the hot water is fine.

The problem first appeared about a year ago when we had the bathroom redone, the cold water pressure dropped significantly but was still ok to live with (just annoying). I replaced the thermostatic shower this weekend and the pressure has completely gone now, it is literally just a trickle. The hot water is still fine.

My first thought was air in the system or something but I have no idea how to diagnose the problem let alone fix it.

it is a gravity system with the boiler/cold water tank in the loft, the hot water cylinder is on the same floor as the bathroom.

can anyone help.

 

[tamz]

What type boiler do you have? make, model. Can you take a picture and post it up?

 

[Jreucassel]

Worcester Bosch DT10. I think it is air in the system but how do you get it out. I forgot to mention that I completely drained the system when I fitted he shower if that is a possible cause.

 

[Ermintrude]

Is cold from attic? To common to have gravity feed to bath. / shower ? ISo off or blocked? Flush it with mains pressure?

 

[Jreucassel]

I have read about flushing with mains but looks impractical with modern waterfall taps and downstairs being so far away, is there any other way?

 

[Ermintrude]

In loft identify which port on bottom of tank is the one u need to flush. Disconnect ball cock. Connect to to ISo valve with a length of 15mm speed fit attached. Ram speed fit into the hole u need to flush and open ISo. Some one else needs to open and close taps. ( chamfer end of speed fit to make a better seal and make sure u have tank 1/2 empty before u start.) speed fit and mains pressure are not suitable for flushing all holes...... Colonic is usually gravity.

 

[Jreucassel]

Tried this but couldn't flush anything out, there is a LOT of limescale in the tanks so I think maybe some some gone down and blocked the pipe somewhere.

 

[PlumbBobBob]

you could be right in your assumption. possibly blocked at an elbow, trace the pipework until you come to an elbow if it is a fairly short way along you may be able to try and clear the obstruction by using a stiff wire to poke down the pipe.

 

[diamondgas]

Lumps of scale in a modern mixer tap = eeek!! Is it possible to remove the taps and run through the suply pipe only? That'll give you an idea as to whether the issue is within the tap assembly or upstream

 

[Jreucassel]

The poor flow is in both the the sink and the bath so I assume it is higher up the system somewhere. I will look into getting some bendy wiring to try and push it through. Thanks for the advice everyone.