We have 2 navien units we installed side by side in our garage this summer to replace out hot water tank. We have a recirc pump set up and the temp set to 140 since the master bath is quite a distance from the Naviens. We are going thru over 300 gallons of propane in 7 weeks which is costing a fortune. Everything I read says that these things are supposed to be more efficient than hot water tanks. Our bills are twice what they were. Does any one have any idea why this is happening? I am ready to rip the suckers out and put in hot water tanks again!