What is the small screw cap underneath an outside tap?

[Mutley56]

Good evening all

Occasionally my outside tap doesn’t work. When this starts to happen, It seems to start working again if the kitchen sink tap is turned on and off a few times. Isolation valve is turned on, there is a double check valve after that but out of sight behind the back panel of the sink cupboard and then a check valve in the tap itself. I have removed the tap and sometimes still no water. I have let the water run to flush pipe work when it has when water flows again with the tap removed. I think the double check valve may be faulty. Is that the likely culprit stopping the flow?

finally, what is the small nut / cap underneath the body of the outside tap?

Thanks in advance for your advice.

mutley 56

 

[CBW]

Small nut is a Verifiable check valve

 

[HERTS P&D]

Fit a new check valve, I would also replace the tap with a tap with no internal check valve in the tap, they normally freeze in winter.

Andy

 

[Madrab]

If you look inside the spout of the tap you will see the plastic check valve, that will have burst due to ice, use a hammer and a screwdriver and burst that out. If it still doesn't run then burst out the check valve at the back side of the tap where is screws into the wall plate, that just turns it into a normal outside tap and it will run.

The fit a check valve inside the house. During winter shut off the water and open the tap to stop it freezing.