Fitting mono-block (single hole) mixer taps

Single hole mixer taps (usually referred to as Mono-block taps) fit into a single 35mm mounting hole and have 10mm screw connections for the water supply connections.

The taps usually come with 2 short (about 20cm/8 inch long) copper connector pipes with plain 15mm pipe at one end for connecting to the water supply pipes and with 10mm screw connectors at the other end for screwing into the body of the tap.

Mono-block, single hole mixing tap mountingA typical mono-block installation is shown to the right.

Due to the often restricted space underneath a fitted tap, it is often a good idea to fit the connecting pipes to the tap before mounting it to the surface and to use compression fittings (rather than solder type) for connecting the other ends of the connector pipes to the rest of the water supply pipes.

It is also a good idea to fit shut-off valves somewhere along each supply pipe which comes via a storage tank - this will make repairing or replacing the tap easy as there will be no need to drain the storage tank(s).

Connect the short connecting pipes into the body of the tap using the rubber 'O' rings (normally supplied with the tap). Tighten each pipe into the body of the tap using a spanner - the 'O' ring will slightly compress to form the seal, be careful not to over tighten them as this will damage the rings and cause leaks.

Under view of mono-block tap
Underside showing the 'horse shoe' mounting plate

Carefully feed the supply pipes through the hole in the mounting surface and locate the tap in the mounting hole. Typically a 'horse shoe' fixing plate is used against the underside of the mounting surface to stop the tap body from rotating. The plate being secured to the tap by a nut and washer on a fixing stud screwed into the base of the tap. The shape of a typical fixing plate is shown right.

Before finally tightening the nut to secure the plate, make sure that the body of the tap is lined up as required.

After the tap body has been secured to the surface, the water feed pipes need to be connected - but first the hot and cold water pipe runs need to be work out.

Any mixer taps can have the hot and cold pipes connected to either input, there is no standard for whether the cold tap is on the left or right, however, keep it consistent within a property. In the UK, there seems to be a sort of informal standard - the hot tap being 'by tradition' on the left in the south and on the right in the north !.

Run the rest of the supply plumbing to underneath the mono-block tap.

Now connect the bottom of the connecting pipes to the rest of the plumbing using compression fittings.

Finally, and if necessary, swap over the 'hot' and 'cold' handle indicators to reflect the actually supply connections made.