Regulations require a double check valve when fitting an outside tap..not as hard as it sounds!
How to install or fit an outside tap on your property in accordance with the building regulations which say you must fit a double check valve? It is incredibly useful to have an outside tap for watering the garden or cleaning the car. Learn how to install a garden tap and understand what is in a outside tap kit so that you will have everything you need before you start your project.
When fitting an outside tap, most are plumbed into the domestic cold water feed under the sink, where hopefully, there is enough room to work. Some installations are challenging!
The connection does not have to be made under the sink but it is ideally made to a cold water pipe which is carrying cold water under mains pressure. To feed an outside tap from water coming from your cold water tank will seriously affect other peoples use of the water coming from this tank. The exception being when you have a combi boiler or an unvented hot water cylinder installed, in which case the water pressure will typically be around 3 bar throughout the house.
In a conventional system ( cold water storage tank in loft space),when mains water comes to a property it must feed at least one tap with mains pressure before it goes up to a cold water tank so double check that the pipe you want to connect to is under mains water pressure.
There is usually a tangle of waste pipes and hot and cold water feed pipes under the sink which make connection of an outside tap difficult so in many cases it may be easier to look between the units, or even behind them to source a cold water feed to the outside tap which is a little easier to work with.
How to Install a Garden Tap Yourself ?
How to install or fit an outside tap on your property in accordance with the building regulations which say you must fit a double check vale. It is incredibly useful to have an outside tap for watering the garden or cleaning the car. Learn how to install a garden tap and understand what is in a outside tap kit so that you will have everything you need before you start your project.
What is a Double Check Valve?
A double check valve is a valve within the body of the tap which only allows the water to flow in one direction. In this case, that is outward, towards the tap itself.
The reason for it’s installation is that sometimes, without a check valve, it is possible to (for example) run a hosepipe out to a paddling pool Should anything happen to that water supply and a vacuum be caused in the pipes behind the tap it would be possible for water to be sucked back into the system without a valve to check the reverse flow commonly known as backfeed.
This could be likened to siphoning petrol out of a tank by giving the hose an initial suck, then letting the vacuum pressure do the rest. To avoid contaminating the water supply, a double check valve is used.
Using an Outside Tap Kit
The simplest way of installing or fitting an outside tap or garden tap is to use a full kit. This kit is available from the DIY Doctor toolstore, and a link is available a little way down the page. You could a suitable kit with double check valve and tap by clicking here.
The DIY outside tap kit provides everything you need for fitting your outside tap. The only other things you will need is a length (2m should do it) of 15mm copper pipe and a length of 22mm copper pipe to act as a sleeve through the wall. You will also need a Tee piece to connect to your mains water and possibly some bends.
All of the above pipes and fittings should be readily available from your local plumbers merchant or DIY store.
Sleeving Copper Pipes Through Walls
The water carrying pipe (the 15mm pipe) should be allowed to expand and contract without fear of erosion or puncture and the only really safe way of doing this is by placing it in a sleeve through the wall.
The easiest way to make a sleeve is by using a length of 22mm pipe or though you can purchase a ready made sleeve with tap fitting already in place here: https://www.screwfix.com/p/hose-union-back-plate-15mm/56415