The waste water fittings fitted to baths are fairly standard although there are various different types of method for fitting them to the waste outlet hole of the bath.
The main difference is the height of the fittings under the bath, this can be important where there is limited space between the bath and floor.
Where baths are positioned on timber floors, the usable height under a bath can be increased by removing short sections of a couple of floorboards immediately under the waste trap.
However, there will be some installation, such as on solid floors, where there will be very limited space and the only option will be to fit a shallow trap; it must be noted that these traps will probably contravene the water regulations for connecting waste pipes into single stack drains as the water seal will be less than the minimum required. For these installations, a separate, deeper trap will need to be installed in the pipe run between the bath trap and the drain stack pipe.
When fitting the waste to a bath, it often makes the work easier if the waste fittings (excluding the trap) can be fitted to the bath before it is put into position.
NOTE: On the illustrations below, a washer is shown inside the bath, under the bath outlet - not all purchase kits include this washer, in which case, spread some plumbers sealant (Plumbers Mate or similar) under the rim of the outlet before fitting it to the bath BUT CHECK BEFORE DOING SO THAT THE SEALANT IS SUITABLE FOR THE BATH MATERIAL IF THE BATH IS FIBREGLASS OR PLASTIC. Once the outlet has been tightened, any excess sealant around the outlet inside the bath should be wiped away.
Where there is sufficient space under the bath, this is probably the easiest arrangement to fit. It consists of an adapter under the bath which is held in place by a screw through the centre of the drain hole grille and into a captive nut in the centre of the adapter.
The adapter incorporates a connection for the bath overflow. Details of connecting the overflow to the bath are given below. When positioning the adapter, ensure that the connection for the overflow is positioned towards the overflow in the bath.
The screw pulls the adapter to the underside of the bath and compresses the washers to give a watertight seal.
There are usually washers positioned between the adapter and the underside of the bath, and under the drain grille inside the bath.
An alternative bath waste fitting uses a deep threaded outlet fitting, (with slots in opposite sides near the top to accept the waste from the overflow which comes via the banjo).
The banjo for connecting the overflow is assembled over the outlet fitting and is held against the underside of the bath by a large, thin nut fitted to the bottom of the outlet fitting and tightened against the banjo. When positioning the banjo, ensure that the connection for the overflow is positioned towards the overflow in the bath.
When fitting the large nut, apply Plumbers Mate to the screw thread on the outlet, fit the nut so that it traps the Plumbers Mate in the thread. Tighten the nut using a large spanner or stilsons to compress the washers to give a watertight seal.
If the outlet begins to turn as the nut is tightened, use a pair of long nosed pliers (with the jaws wrapped in a piece of cloth) pushed through the grille in the outlet to hold it steady while the nut is turned.
Washers are usually placed between the banjo and the underside of the bath, and under the outlet fitting in the bath.
Where there is insufficient space under a bath to fit either of the above types, the only option is usually to use a short waste outlet fitting with a shallow water trap with a connection for the overflow from the bath.
The short waste outlet needs the thread to extend to the rim to ensure that the nut will tighten down onto the washers rather than binding on the end of the threaded section.
The short outlet is secured to the bath by a nut underneath - the nut needs to be tightened using a large spanner or stilsons to compress the washers to give a watertight seal.
If the outlet begins to turn as the nut is tightened, use a pair of long nosed pliers (with the jaws wrapped in a piece of cloth) pushed through the grille in the outlet to hold it steady while the nut is turned.
Washers are usually positioned each side of the bath, under the outlet fitting in the bath and under the nut on the below of the bath.
As mentioned above, using a shallow waste trap will probably contravene the water regulations for connecting waste pipes into single stack drains as the water seal will be less than the minimum required. It may be necessary to fit a separate, deeper trap in the pipe run between the bath trap and the drain stack pipe.
The bath waste overflow is fairly standard, and fitting it is normally straight forward - although it helps to do this before the bath is positioned to avoid having to work in limited space.
The connection consists of an overflow grille (for the inside of the bath) with an internal thread and a mating overflow connector which goes through the hole in the end of the bath from the outside. The grille is screwed onto the overflow connector.
To tighten the grille onto the connection requires care to avoid damaging the finish - the grille can be gripped and turned by carefully using a pair of long nosed pliers with the jaws (wrapped in a piece of cloth) pushed through the grille while the connector is held firm on the outside of the bath. Ensure that the connector for the flexible pipe from the overflow is pointing towards the connection under the bath.
A washer is usually fitted between the grille and the bath surface to provide a water seal.