Hi,
We are currently heating part of a greenhouse with a 500w mains fan heater which in the recent cold UK weather is taking about 5kw per day or 200w per hour.
Looking to provide a backup source for up to 4 hours that can be automatic, so that effectivlely means it must be derived from 12v caravan batteries.
Bottled gas and paraffin ruled out because of the fumes etc.
The problem is we cannot find any air heating elements that run from 12v.
Had thought about an inverter but to drive the 500w main heater would probably need an inverter rated at 1000w which are not cheap.
So far the only possibilities seem to be using one or two of the ceramic fan heaters sold in car shops which do not seem built to last for 5 minutes never mind 4 hours, or possibly the use of four standard 12v 50W halogen bulbs with a pc fan behind them.
Power resistors are another option but work out very expensive.
Would be interested to know if anyone has tried any of these methods or can suggest a more robust 12v heater without breaking the bank.
thanks
We are currently heating part of a greenhouse with a 500w mains fan heater which in the recent cold UK weather is taking about 5kw per day or 200w per hour.
Looking to provide a backup source for up to 4 hours that can be automatic, so that effectivlely means it must be derived from 12v caravan batteries.
Bottled gas and paraffin ruled out because of the fumes etc.
The problem is we cannot find any air heating elements that run from 12v.
Had thought about an inverter but to drive the 500w main heater would probably need an inverter rated at 1000w which are not cheap.
So far the only possibilities seem to be using one or two of the ceramic fan heaters sold in car shops which do not seem built to last for 5 minutes never mind 4 hours, or possibly the use of four standard 12v 50W halogen bulbs with a pc fan behind them.
Power resistors are another option but work out very expensive.
Would be interested to know if anyone has tried any of these methods or can suggest a more robust 12v heater without breaking the bank.
thanks