I LEARNT THE HARD WAY A FEW AGO HAD 2 WEEKS OFF FOR CHRISTMAS THEN FROST SET IN FOR ANOTHER 2 WEEKS ,IT IS OK TAKING THE CHILL OUT OF YOUR VAN BUT WHEN THE WATER STARTS TO RUN THROUGH IT IT FREEZES IN THE PIPES, I GOT MYSELF A HEATWAVE COUPLE OF YEARS AGO REALLY GOOD, OVERNIGHT YOU HAVE A FROST SETTING AND IF IT DROPS TO 2 DEGREES IT SWITCHES ITSELF ON AND CIRCULATES HOT WATER AROUND THE SYSTEM AS YOU PLUG HOSEREELS BACK INTO THE TANK,THE AMOUNT OF MONEY I LOST HAVING TWO WEEKS OFF WITH THE FROST COST ME THE SAME AMOUNT FOR THE HEATWAVE, KEEPS ME WORKING ALL YEAR ROUND, NO WORRIES OVER THIS WINTER