Good afternoon everyone, the area in which I live the government is offering a rebate for homeowners to replace their 'inefficient' Conventional (Standing Pilot) hot water tanks with 'energy efficient' tankless systems. So I am contemplating this because the rebate is about $1000 as well a local supplier is offering to match that rebate if the work is done by them. Also given that our hot water tank is only 40 gallons and 16 years old is another reason. However I am concerned that our main gas line from the meter might be under capacity given that tankless systems require anywhere from 17K~200K BTUs. I have done some rough calculations and with my limited knowledge seem to have determined that we may be limited to around 240K BTUs. I believe that the gas line from the street going into the meter is 1.5 inches but is immediately sized down to 1 inch, then runs through the meter and the meter outputs a 1 inch line 40 feet to our first appliance (a 81,000 BTU input/61500 btu output furnace) I think it is scaled down to 3/4 inch at this point, then another 3 feet of 3/4 inch to the next identical furnace, and then a scale down to 1/2 inch for the 36K BTU hot water heater. The tankless system that is being suggested does state is fine to work on a 1/2 inch line but given what has been listed for the BTUs of the 2 furnaces would we be running into a problem if all 3 appliances kicked on at the same time? I should also make note that we are also looking to add a gas line for a BBQ as well. I think the total BTU on that guy would be around 69K BTU. So with the calculation of 240K BTU on our main line does that mean that so long as we dont have an appliance that requires more than 240K BTU we are ok or does it mean that we are only allowed up to a combined sum of that main line BTU, so 81K+81K+36K=198K means we are under 240K BTU, where as 81K+81K+200K+69K=431K = BAD? Thanks for any input and advise

Hi all In a previous thread, I asked whether my furnace was 'behaving properly'-- it was letting temp drop 5-6 degrees before turning on (even though thermostat indicated it was calling for heat much earlier). Well, I was sick last week and was freezing, so I called in a service. They took apart the thermostat and there was no battery. That said, once they put it back together, the furnace now kicks on before the temp drops even one degree from the setting--MUCH better. Suspect there was a bad connection in the stat itself... They looked at the control board as well, and discovered that the furnace (while 2 stage) is only wired for one stage (the thermostat can only accommodate one stage). I have a thermostat that I planned on installing after the heating season that will accommodate 2 stage furnaces, but I have to pull new wire (hence the wait). Here is my question: is there any reason to NOT wire the furnace for two stage? I am admittedly unversed in forced hot air, and am eager to learn more. I would think that two stage is supposedly 'more efficient'? Appreciate any and all info on this. I hope to pull cable in the next month. The furnace is a Lennox G60UHV-36A-070-06