i went though your same situation 2 years ago. I spoke with 4 different plumbers and, or course, got 4 different answers.
here are the reasons against.
they are not very common yet so when they break it could be awhile before you get parts to fix it.
some units must be sent back to the factory for warranty repairs.
because they are not very common, many plumbers don't know how to fix them.
there is only so much "tempeture rise" the unit can handle, if your ground water is really cold a single unit might not be able to heat up the water quickly enough. in that case you would need 2 units or a solar water heater to preheat the water. that would negate any savings on gas.
new regualar water heaters are more effecient than they used to be, the difference in energy consumption is not enough to justify the cost difference.
they are quite a bit more expensive for a good one.
a fair amount of replumbing and reducting must be done. they require a much larger amount of gas when they are running. they also require special exhaust ducting.
here are the reasons for;
energy savings because you are not always heating water.
they are small.
high gadget factor
they are the future of water heating
if you buy a nice unit like a rennai you can install point of use water temp adjustment panels. that means if you like your shower at 103* you dial in 103 and the water heater only puts out 103* water, saving energy because you are no longer blending hot water and cold water.
one plumber's recommendation was "when your new tank water heater wears out, tankless water heaters will be common and everyone will sell and work on them, install one then." he was a certified installer/repairman for one of the major brands of tankless water heaters.
I was told that a bosch aquastar is a pretty small unit and not really ment for more than an apartment although they market them for houses. Rennai was highly recommended.
I really wanted a tankless, but ended up with a regular water heater. the cost, repairability, and availability were the deciding factors.
here are the reasons against.
they are not very common yet so when they break it could be awhile before you get parts to fix it.
some units must be sent back to the factory for warranty repairs.
because they are not very common, many plumbers don't know how to fix them.
there is only so much "tempeture rise" the unit can handle, if your ground water is really cold a single unit might not be able to heat up the water quickly enough. in that case you would need 2 units or a solar water heater to preheat the water. that would negate any savings on gas.
new regualar water heaters are more effecient than they used to be, the difference in energy consumption is not enough to justify the cost difference.
they are quite a bit more expensive for a good one.
a fair amount of replumbing and reducting must be done. they require a much larger amount of gas when they are running. they also require special exhaust ducting.
here are the reasons for;
energy savings because you are not always heating water.
they are small.
high gadget factor
they are the future of water heating
if you buy a nice unit like a rennai you can install point of use water temp adjustment panels. that means if you like your shower at 103* you dial in 103 and the water heater only puts out 103* water, saving energy because you are no longer blending hot water and cold water.
one plumber's recommendation was "when your new tank water heater wears out, tankless water heaters will be common and everyone will sell and work on them, install one then." he was a certified installer/repairman for one of the major brands of tankless water heaters.
I was told that a bosch aquastar is a pretty small unit and not really ment for more than an apartment although they market them for houses. Rennai was highly recommended.
I really wanted a tankless, but ended up with a regular water heater. the cost, repairability, and availability were the deciding factors.
