Arlec 2400W Fan Heater FH809 Questions & Answers

when I switch the heater on it makes a noise similar to a metal noise , although it goes away after a few minutes, this is the second unit that has done the same thing, although when i exchanged the first unit there was no noise during the first couple of weeks, the heater is kept in the bathroom.Have you heard of similar issues with other units. Number is a FH8098 I purchased the first unit from Bunnings in Hastings and I then returned to the Cranbourne store and exchanged for the second unit.