MOst places you see it it's 1 metre, sometimes 2.
Bear in mind that a sealed system eg a combi boiler with failed thermostats will burst polybutylene(grey) plastic pipe. Pex is marginally better. Add an extra pipe thermostat if you want to be a bit safer.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local