Navien NR-240A - How much can I expect to save/what are the savings?
I'll be posting more information as I get my gas bills. However, I can tell you in the first month, my gas consumption dropped by 10 cubic meters. Based on this imperial conversion site, there are 35.3 cubic feet per cubic meter - meaning that 10 cubic meters would be equivalent to about 353 cubic feet. How many therms (100,000 btu) are there in a cubic meter? A: about .36 therms. You should be able to guestimate your savings by filling in the local gas rate in your neighbourhood.
Because the previous month had been an estimated reading (where the gas company guesses at my consumption as opposed to reading my meter), this number may not be all that accurate. However, the month was a typical month around my house, so presumably the estimate would be fairly accurate, and thus the bill I received as well.
Savings will vary. Because a tankless water heater doesn't use any (or a very little amount to heat the 2L holding tank) gas when it is not in use, the more it sits idle, the more you'll save. Strangely, the opposite is true. The more you use a tankless (assuming you would have used your old tank for the same amount), the more you save as well. The following issues are points to consider:
1) While you are away from your house e.g. on vacation, you will save more money. You tank water heater would have the pilot burning gas all the time while you were gone. The tankless does not.
2) Your Navien NR240A consumes electricity, so your electric bill will actually go up by a small amount.
3) You only pay for heating the water you use.
4) You can put your water heater on a timer and save some of the electricity (but beware - see next point).
5) If you live in an area that gets cold weather, your tankless water heater may consume more electricity as it has a heating unit in it that draws power to make sure nothing freezes in the unit. I'll be tracking that this winter too.
There are many factors here, but to see a detailed breakdown of how to determine if tankless is the way to go for you (using real figures) go here: