The top five smart gadgets to invest in for your home - and five others to not bother with

How it works: Control hot water and heating from your smartphone. How it works: A lightbulb you can dim, or turn on and off, using your phone. How it works: A smart speaker you control by speaking to Alexa, an intelligent'virtual assistant'. Functions include answering questions and playing music. How it works: Be alerted on your phone when someone rings your doorbell, and speak to that person via a video link, regardless of where you are.