Just had a spa installed, all seemed ok, however it does not heat up although the heater light shows red, and I've got a red background to the control panel currently showing 22 degrees. Dealer is getting advice, thought maybe somebody here could suggest what's wrong. voltage in UK is 230. Any ideas ?

could be a bad or stuck heater relay (contactor) or you might not have voltage to both legs of the heater element.

you were right loose lead into the heater all ok now thanks