Water coming from overflow

Depending on the type of heating and hot water system you have this could be a few things. All are easy to diagnose and range from a few pounds to a few hundred pounds.   Follow the easy steps and we’ll find the problem.

1. Look where the overflowing pipe comes out of your house.  Is it from the eaves of the roof, near a bathroom / toilet  or near a boiler/hot water cylinder.

2.Look at the type of pipe the water is coming from what is the material is it metal of plastic.

Plastic pipe from eaves – constant flow

The water level in a tank is too high so it is running out the overflow.  Go into the loft and  take the lid off each tank.  There are normally two but can be virtually any number depending on the size and type of system you have.   Take the lid off each tank and check how high the water level is in each one.

  •  If the ball valve is passing there will be a constant drip on the valve.
  • If the ball float on the end of the valve has split and filled with water the float won’t float so the valve will not shut off.
  • If the coil in the hot water cylinder has burst the water of the heating system and hot water cylinder will try to find their own level.  This will make the lowest of the tanks overflow.
  • If there are thermostatic mixing valves on your hot water system where the cold comes from the mains the non return valve could have stuck open.

Plastic pipe from eaves – only when radiators are hot

Water level in central heating feed tank is too high when cold.

Plastic pipe from eaves – if water hasn’t been used for a while 

Ball valve has a slight leak that isn’t noticeable when water is being drawn off regularly.

Plastic pipe from near bathroom/toilet 

Water level in toilet cistern is too high.  Could be:

  • If the float valve is passing there will be a constant drip on the valve when you take the lid off the toilet cistern.
  • If the float has split and filled with water it won’t float so won’t close the valve fully
  • If the water level has been set too high the valve will never shut and will constantly overfill.

Plastic pipe near a boiler

Could be the condensate pipe from a modern condensing boiler leaking.

Metal pipe near a boiler or hot water tank leaking

This is one of the safety valves opening on the central heating system/unvented cylinder.  The valve opens to release excess pressure from the system.

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