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.

There is a LOT of disinformation on these forums about on-demand tankless units, ESPECIALLY the electric units. First, energy cost savings is NOT a reason in itself to make the switch. No reason alone is sufficient. It is the total package, in light of your particular lifestyle, that will dictate the pro-con outcome of the decision making process. First, tankless units save space -- a lot of it, especially electric units that do not need to be vented. In Texas we have no basements, so that can be an important issue. Second, an electric unit is unlikely to blow up, unlike anything using natural gas. Third, there is an endless supply of hot water, which in a successive-morning-shower household like mine, is a really important issue. And finally, yes there is some documented comp fuel savings (electric tankless over electric tanks, or gas over gas), that is really offset by the added initial cost of the unit plus upgraded electrical service or gas supply line sizing. Moreover, there ARE full-house electric units out there that provide plenty of water, unless you plan on taking two showers simultaneously while also doing your laundry and running the dishwasher! And if that's your bag, you can run 2 or more electicals together. Or get a really big gas unit. Bottom line, nearly every nay-sayer of tankless units ignore the pros and focus on a single con - cost, cost, cost. Well, we all don't drive a Ford Focus for a reason. Some of us enjoy our Buicks, Porsches or Camrys even though another car would get us from point A to point B cheaper while using less fuel etc etc etc. Full disclosure: I have a Steibel Eltron Tempra 36 whole-house electric unit. Love it. My electric bill went up nary at all.

I can remember back in the late 50s and early 60Âs when fuel was cheap the water heaters were operated at 180degF and they had no insulation or external jacketing. In those days there was a great concern that people were accidentally bumping up against the water heaters and receiving severe burns. The standards were then amended requiring that all water heaters must have a minimum of ¾" of fiberglass insulation, a sheet metal jacket and under no circumstance could the external temperature of the unit exceed 140degF under normal operation. During the first fuel crisis in the mid 70Âs people were encouraged to install additional insulation blankets to reduce the standby losses from the water heater, however it was soon realized that if an insulation blanket is improperly installed it interferes with the normal function of the water heater thermostats and temperature & pressure relief valves causing very erratic temperatures and in some instances creating safety issues. In addition, quite often when the insulation blankets are improperly installed they interfere with the normal flow of combustion air and result in very high levels of carbon monoxide. In the late 80Âs the plumbing codes were again amended requiring that ALL water heaters must now have a minimum of R-12 insulation. REF: International Residential Code IRC-504.2.1(en) Uniform Plumbing Code UPC-150(j)1A(c ) The codes specifically sayÂ"No external blankets required" Many local codes have amended that wording to say "External Blankets Prohibited". In my jurisdiction there is a $50 fine for even selling a water heater blanket. In order to meet the new insulation standards most water heater manufacturers have discontinued the use of fiberglass insulation and they now use cast in foam insulations, which often far exceed the required R-12 minimum Everyone seems to be fixated on the supposed high energy wasted to standby losses from a tank type water heater, but in reality such is not the case. Two years ago our plumbing apprenticeship class, in co-operation with the local gas company and a number of local hardware stores, appliance dealers and plumbing suppliers set up a project to test the actual cost of water heater standby losses. Twelve different makes and models of residential contractor grade 50gal gas tank type water heaters were installed in an unheated warehouse. All 12 units were fed from a common water line and each water heater is supplied through a separate gas meter. Each water heater is then fitted with one line on the output side that terminates into a keyless hose bib beside the unit, thus there is no demand from these water heaters therefore they represent standby losses only. The water heaters were then filled and left standing with the thermostats set at the code maximum of 120degF. Every month the gas meters are read and the fuel cost is computed at the standard residential rate for this area. After two years of following this project it has been determined that the monthly average standby loss is $5.02. (The worst case in the test is averaging $5.87mo.) I might add that two of the water heaters in this test have specific wording in their installation manuals that states the addition of an insulation blanket will void the warranty.

Besides cost, are there any other big issues? Recovery speed, space, speed of getting hot water to the tap? I can't help you with all of the costs but I can give you some general ideas: 1. Electric hybrid heat pump: Cost of unit is about $1100-1500 generally lowest cost of operation. time to get hot water to tap: Same as standard tank. Recovery rate: Same as electric tank. Design issues: Pulls heat from surrounding air - needs basement/garage/ etc. to circulate air. Makes some noise (like a refrigerator). 2. Tankless Gas: Cost of unit is about $1100-1500. Only slightly more to operate than #1 above. Time to get hot water to tap: about 10 seconds more than standard tank. Recovery Rate: will deliver continuous hot water up to max amount. Design issues: Must have large gas supply to the unit and gas supply to the house must be adequate. Makes some noise. Unit is compact and mounts on the wall. Vents with PVC pipe. 3. Standard Gas tank: Inexpensive to buy ($400-800). Moderate cost of operation. Time to get hot water to tap: Same as standard tank. Recovery rate: Faster than electric tank. Design issues: medium size tank. Standard gas supply. High temp venting can be expensive if new installation. Tend to contribute to air infiltration if not direct vented. Direct vent adds to unit costs but can reduce venting costs if it allows PVC. Requires clearances from combustible materials and air supply. 4. Standard Electric Tank: Inexpensive to buy ($400-800). Very high cost to operate. Time to get hot water to tap: Same as standard tank. Recovery rate: Slowest of all. Design issues: usually larger tank than gas because of slower recovery rate. Can be put in closets and such because there aren't air supply, venting or combustion clearances requirements. 5. Gas Tankless+Tank: Not common but out there. Most expensive to purchase ($1800-2500). Slightly more to operate than #2 above but less than #3. Time to get hot water to tap: Same as standard tank. Recovery Rate: Will allow large amounts of water to be used at the same time up to the tank size. Then will deliver continuous hot water at a max rate lower than #2 above. Tank recovers very quickly. Design issues: Medium size tank + tankless unit makes it bulky. Standard gas supply. Generally requires expensive stainless steel venting (non-condensing). Often can be direct vented. Makes some noise.