How do I fit a washing machine to the plumbing?
Transit bolts, the standpipe and trap arrangement, and getting the machine level so it does not walk.
- Difficulty
- intermediate
- Time
- 2 hr
- Read
- 5 min
- Safety
- warning
Short answer
Remove the transit bolts first — leaving them in wrecks the drum. Connect the cold fill to a washing machine valve, run the waste into a standpipe with a trap at the right height, level the machine on its feet, and run an empty cycle before loading it.
Installing a washing machine is mostly a sequence of small things that each cause a specific and predictable problem when missed, and the first of them is the one that destroys the machine.
Safety
What you'll need
- Washing machine valve on the cold supply, or an existing one
- Standpipe and trap, or a sink waste with a spigot
- Spirit level and an adjustable spanner
- Bucket and towels
Step by step
- Remove the transit bolts.Three or four bolts through the back holding the drum for transport. Running a machine with them in destroys the suspension and the drum. Keep them — they are needed if it ever moves house.
- Check the space and the door swing.Width, depth including hoses, and whether the door opens fully. Hoses need 80 to 100mm behind the machine, which is why machines often stand proud of the units.
- Fit or identify the water supply valve.A washing machine valve on the cold supply, with a lever and a threaded outlet. Most modern machines are cold fill only; a few older ones take hot as well.
- Connect the fill hose without PTFE.The hose has a rubber washer in the nut. Hand tight plus a light nip with a spanner. Overtightening distorts the washer, which is the usual cause of a fill hose leak.
- Set the waste up correctly.Either a standpipe with its own trap, or a spigot on the sink trap. The standpipe should be about 600mm high with the hose inserted no more than about 150mm — this is what prevents siphoning.
- Understand why the height matters.Too low and the machine self-siphons, draining as it fills, so it never washes properly and uses far more water. Too high and the pump struggles. It is the most common waste installation fault.
- Do not push the waste hose down too far.It must not reach the water in the trap, or it siphons. Loose in the top of the standpipe with an air gap is correct.
- Keep a loop in the waste hose.The hose should rise above the machine's water level before dropping to the standpipe. Most machines have a bracket to hold it — use it.
- Remove the knockout if using a sink trap spigot.New sink traps have a blanked spigot that must be drilled or knocked out before connecting. Connecting to an unopened spigot means the machine will not drain and it floods.
- Give it its own wall socket.Never an extension lead or multi-way adaptor. If the socket is behind the machine and unreachable, have a switched spur fitted somewhere accessible.
- Level the machine on its feet.A spirit level across the top in both directions, adjusting the screw feet, then lock them. An unlevel machine walks across the floor on a spin cycle, which is the usual cause of movement and noise.
- Check it is stable on the floor.Push each corner. Any rock means readjust. On a springy timber floor a machine will move regardless, so consider anti-vibration feet.
- Check hoses are not kinked or trapped.Push the machine back slowly and look behind. A crushed fill hose or waste hose behind the machine is a common and hidden cause of faults.
- Run an empty cycle first.A hot wash with no load, watching for leaks at the valve, the fill hose and the waste. It also clears manufacturing residue from the drum.
- Check for leaks afterwards.Dry everything, then look again after the first few real washes. Slow drips take a while to show and are much easier to find early.
Tips
- Transit bolts first, before anything else. It is the one mistake that destroys the machine rather than causing a leak.
- Standpipe about 600mm high with the hose loose in the top. Too low and the machine siphons and never washes properly.
- Level it and lock the feet. Almost every walking or banging machine is simply not level.
Common mistakes
- Running it with the transit bolts still fitted — The drum is bolted rigid, so the suspension and bearings are destroyed on the first spin. It is not a repairable mistake.
- Pushing the waste hose too far into the standpipe — If it reaches the water in the trap the machine siphons, draining as it fills. It then washes poorly and uses far more water, and the cause is not obvious.
If it doesn't work
Machine walks across the floor on spin
Cause: Not level, or feet not locked — Fix: Level it in both directions with a spirit level and lock the adjuster nuts. Check no corner rocks.
Clothes still dirty and cycles very long
Cause: Self-siphoning — waste hose too low or pushed too far in — Fix: Raise the standpipe to about 600mm and insert the hose only into the top, leaving an air gap.
Water on the floor after a wash
Cause: Fill hose washer, waste connection, or a blocked sink trap spigot — Fix: Dry everything and run again watching each connection. Check the trap spigot knockout was actually removed.
Loud banging on spin
Cause: Transit bolts left in, or an unlevel machine — Fix: Switch off immediately and check the transit bolts. If they are out, level the machine.
Will not fill
Cause: Valve closed, kinked fill hose, or a blocked inlet filter — Fix: Check the valve is open and the hose is not crushed behind the machine, then clean the small filter in the inlet.
Questions people ask
How high should a washing machine standpipe be?
About 600mm, with the waste hose inserted only into the top so there is an air gap. If the hose reaches the water in the trap the machine siphons and drains while it fills.
What happens if you forget the transit bolts?
The drum is held rigid, so the suspension and bearings are destroyed on the first spin. Remove all of them before running the machine and keep them for any future move.