Marquee Heaters

Direct Fired = Cheap, deficient, clean, noisy and Condensation

Indirect = Expansive to buy and run, quiet, go wrong more often and no condensation.

Two small heaters are always better than one big heater because if one stops working only 50% of the heat is lost!

I would always go for 4 smaller heaters rather than two lager heater for the same reason and because the heater near the doors will be running almost all the time and the heaters in the middle of the marquee will be off most of the night as the number of people in the marquee heats it up. Large heater will mean guest near the heater or thermostat will be two hot and further away will be too cold.

When hiring out I've always used a mixture of the two, this is because :-

1) If it is not windy the indirect heater can heat the marquee with no condensation

2) If it is windy you need 4 times the heat so the indirect heater produces more heat per £ and no condensation because of the flow of air through the marquee.

Just my personal opinion if you know better please tell me!