@autophile, if you paid that much for gas bills, I think its cheaper to get a geyser on your expense, keep the broken one and when you switch places leave the old one. Because when the landlord is such an *** he does not deserve a gift and you never know the condition of the geyser at the next place, you might be better off using the one you know.
As far as heaters go, only use good brands like Rinai, the flow and materials matter a lot, I also found a good balance between gas and electric heaters where combined utility bills never cross Rs. 2000/- if you happen to visit Brabus Cafe they have those electric heaters which look like pedestal fans, they also retail them, consumption is 800W.