Two things to remember about the TINY heat pump on top of the hot water heater. It only removes heat from the room to replace the BTUs that are removed from the space via hot water going out the pipe. Example. You go on vacation for a week. ZERO net heat is removed from the room. In other words, heat transfers from the stagnate hot water back into the room and then the heater kicks in and removes it from the space and transfers it back into the water... not free, but very inexpensive and absolutely no need for the home's heating plant to make up any heat - as I said, no NET heat loss or gain. Now take the case where you take a hot shower upstairs. ANY heat removed from the basement by the hot water piping remains inside the conditioned household envelope except that which exits via the plumbing drain in the shower. Also, presumably cold replacement water from the street is brought into the envelope to replace that drained water. I have NEVER seen a change in my basement temperature due to the heat pump hot water heater because my subterranean basement is simply a massive heat sink that resists temperature change big time. While I do remove like a pint of water from the air per day in the summer, I have never been able to measure a change in humidity - just the nuisance of having to deal with disposing of the condensate. You're creating an apples and oranges situation when you compare heating with gas and "pumping heat" from the room into the water. With your gas heater, the heat that 'flows' back into the room is not recycled back into the hot water heater, rather it is "replenished" by bring NG into the room and igniting it in a non-recoverable manner. The net effect is to heat the room while you are on vacation... as I suggested there is ZERO net effect with the heat pump hot water heater in my example. I have documented in this forum that my electrical savings for my family of two is approximately $40 per month due to the hot water heater as compared to the electric hot water heater I previously owned. I also have tried, with mixed result, to explain that taking the basement as a system and drawing a diagram show heat in and heat out of that system is helpful. Too many folks that have never owned one of these and have made false assumptions have reached conclusions that are absolute nonsense. My unit is a GE model... I had a compressor leak after 11 months that was repaired under warranty. Reportedly this problem was not an isolated case... and the Model was discontinued. If you have the time, the final math problem (actually rather simple) is to assume some water usage and calculate the enthalpy rise in the heater times the gallons and determine how much heat is being removed from the basement... that is the amount of heat that your heat pump would need to replace in the basement to maintain equilibrium. If I were the OP, I suspect I would opt for the Gas heater because the response time is faster, because it is quieter, and because he will not have to mess with disposing of a pint of water every day during the summer. But, I suspect that you need to caution the OP that his heater is heating the inside of the house during cooling season. :-) I played loose with my terminology re Heat Transfer in the above in order to attempt to better communicate the concepts - by background and education I am capable of using proper terms and terminology, but choose this approach.

I've read endless complaints about noise and unreliability with power vent heaters. Go with b vent. The money spent on the b vent will be at least partially recouped by the less expensive heater.

They're VERY loud IMHO. Totally NOT worth it for that feature alone. My cousin put one in for the garage apartment he did, and we stayed there for a couple of weeks. The heater was in a tiny laundry room space that didn't have the wall and access door put in yet, and the whole place has wood floors, but the bathroom and 1 bedroom were in between us and the heater. We could barely hold a conversation with the door closed while that thing was running. We had suggested a tankless gas fired for the application, as that is what we have and love, but he couldn't find anyone that'd give him a decent install price on it so he went "conventional". At least with a power vent tankless, you'd only hear it when someone was using the hot water. We were there for 2 weeks, and I never did get used to the sound of that thing kicking on in the middle of the night to keep the tank warm. Even in the daytime when you were up and around, it was startling. And,my cousin is kicking himself for installing it and not casting the net a little wider to find someone to do the tankless. What good is saving money when you have to use it to buy earplugs?

ionized_gw: I think that gas tankless has become more mainstream. In addition, the incentives have started to go away. Much of the initial complaints with gas tankless were around bad installation and/or bad retrofitting. I don't think they are sliding in popularity as much as they simply aren't the new kid on the block any longer. On new installs, gas tankless doesn't cost significantly more than a power vent heater and you see them installed on new upscale homes here because of the unlimited hot water. Rheem has addressed the "cold water sandwich" by delaying a "post purge" cycle when the heater is turning off and on frequently. This means that the heat exchanger doesn't rapidly cool off -- eliminating the "cold" part of the sandwich. I insulate my hot water lines also to reduce heat loss between uses. I know I'd never go back to a standard tank water heater. As for electrical requirements on the hybrids - it's the same as a standard electric water heater. The reason is because they sometimes have to fall back to electric resistance heat if the ambient temp is too low or quick recovery is needed. There was some reliability issues on the early hybrids that has since been worked out, I believe. As a side note: Hybrids are being linked up with PV -- meaning that while you would never use solar PV to power electric resistance water heater, it's a good match up for a hybrid water heater. Oil isn't much of "a thing" where I am, so I can't really comment on that. SaltiDawg: The op was seen screaming and running from the building