Zone4 - you might not be happy but disclosure wouldn't apply here. There is no code requirement that applies (that I know of) and so there is no breach. It would seem that installing LP for that purpose alone seems a little extreme. One option - which has cheaper run cost and install than the LP tankless option - run a recirc loop from that bathroom to the tank. Have it on a switch. You turn on the switch and the line fills with hot water. The pump is $200, electric should be $200 and extra plumbing is $100. You won't waste water and as long as you shut it off, you won't waste electricity to heat the water. My $100 charges of course are guesses and the plumbing in the slab might be more. The $200 electric is what it would cost me in NC. You can of course put the kitchen sink on the same loop and install a switch at that location too. Recirc loops are done all the time but where you need to be careful is the energy loses because they are usually left on nearly all the time. By having them on-demand with switches, you counter most of those losses. To help with some of this, I would definitely insulate the slab plumbing lines. Another option would be to do solar for the hot water and use a 80 gallon tank. If the incentives are there, solar can be reasonable. I paid less than $2000 all in which is about the cost of your 2 50 gallon heat pumps.

Quite honestly I don’t like any of them, we install them because people want them. I have 50gal water heater at home and love it. It’s kind of like having that V8 pickup truck, will not be super-efficient but doesn’t brake either and goes through anything, and when it does break, it’s easy to fix. There are only 2 things that can break in my heater, heating element or a thermostat, each costing less than $20 to fix. Also I can buy new one for $600-700, Navien will run me $4-5k. So all the efficiency is not that efficient on my wallet in the end. Don’t mean to steer you away, but you asked :)

Thanks so much for the information. We did just find other code violations. Our ducts running through our attic (unconditioned space) are R4.2 and R6. I was informed that supply runs need to be R8 and returns need to be R6. Is this correct? We also found the incorrect zone dampers installed. We have unequal zones 250 sqft. and 750 sqft. We were told we need a bypass duct or relief duct with current dampers. Or, we need to switch to dampers that will open partially to relieve the excess pressure. We were told our coil will freeze or blower motor fail with the current design. Again, this is probably not a code thing, so I'm not sure how we can demand the correct design. We just learned that we only have a single stage AC unit and we negotiated a 2-stage. Also, we have 4 - 90 degree turns in our main trunk / plenum with HARD 90 DEGREE INSIDE CORNERS. I don't believe there is any code violation here, but we have been told this creates a large degree of air turbulence and should never be done. We have also been told that our returns are not sufficient. UGH...not sure where to go from here. Also, can you clarify the requirements for the exhaust pipe for the furnace and the hot water heater? We were told they need to be 3' from each other - and any other opening into the house - 4' from a gas meter - 2' from a condensor unit. Our hot water heater exhaust pipe, furnace exhaust pipe, and bathroom vent are right next to each other in a row...just a few inches apart. Any clarification on this code requirement would be greatly appreciated - I cannot find anything online.

G and sktn, I'm quite fortunate to be a lifelong resident of the best state in the union and I was aware of the proposal (or even passage) of ban on gas appliances by the air resources board. While I think what they envision is a certainty in the future (for all of the US), I think it's unlikely that it can be imposed so quickly. Because the electric power industry and the existing grid infrastructure can't support the increased power usage this would cause. And the cost of retrofitting wiring and home panels to provide the power needed to electrify existing homes is not affordable for lower to medium income level folks. California imposed mandates several years ago for increased sourcing of renewable electricity and with only a few years to accomplish the rules. Utilities scrambled to meet the requirements. Private sector money was raised in a rush to build a number of large photovoltaic sites in the area, including in the very sunny deserts nearby. The result, as I alluded to briefly before - we have more afternoon summertime electricity than we need. A number of the new sites are offline and not feeding the grid. Why? Because also as I said, the issue of the baseline demand that has to be met with 24x7 supply sources has yet to be solved. There's a base load that's always produced and typically by combustion plants. In the old days, there were so-called "peaker plants", essentially jet engines that run uneconomically for constant use but that can fire up with short notice to fill gaps in supply for a day or two. Until the challenge of power storage and base load needs when it's dark or at inclement weather times is solved, there's a limit to how much any region can make use of daytime solar electricity. And, we have neither the wind, nor the running water for much more hydroelectric or wind power, nor are there adequate long lines in place to transmit such power from where it's does produce in the dark to populated areas in my state where it can be used. My prediction is that 2030 will come and go and while there may be statewide restrictions for commercial and new construction (as some municipalities have already imposed), I think gas furnaces and water heaters will be with us for some years to come beyond 2030.