What do you do with the old hot water tap when connecting a cold fill washing machine?
The old hot water tap should ideally be capped off by screwing a special blanking cap onto it. This is wise because I’ve heard of several cases where the unused hot tap has eventually started to drip, or even where the lever has been accidentally knocked partially on later. This can happen if the hot tap is in the kitchen sink cupboard. I’ve also seen cases where the washing machine itself moved about and knocked the lever when the hot tap was behind the washing machine. This isn’t so likely if your old hot water tap is a proper screw type but the ubiquitous red and blue lever taps are more prone to these issues and it’s safer to blank off any old unused washing machine tap, especially if they are installed out of sight.
Warning about buying blanking caps from DIY stores
I visited several major DIY stores including Wickes and B&Q trying to find a blanking cap for my old hot water tap. They only seemed to stock one blanking cap that looked anything like what I was after but after buying it and opening it, it was just fractionally the wrong size. Presumably it’s designed to cap off some other plumbing requirement. If I remember right I think it was 22 mm – I can’t recall, but I remember taking it over to an actual hot tap at Wickes and through the plastic packaging of both parts it did appear to be the right size. It wasn’t. The size you need if you want to try and source one from a shop is – 3/4″ Brass blanking cap and washer (which is around 19 mm).
Recommended source to buy blanking cap: It took me several wasted visits to large DIY stores, one wasted purchase (of one that was the wrong size) and a lot of time searching the Internet to find this product and I found a good source and linked to it. Sadly it appears they have closed down now, so the best I can recommend is that you search Google for “3/4″ Brass blanking cap and washer” or specifically ask for that at DIY stores or plumbing merchants. The seal is needed for proper sealing off of the old tap but if you don;t get one, try using one from the old hot fill hose.