Gary: I'm building a new house next year where this 6-head shower will reside. It's the one big indulgence I'm allowing myself. The house itself will be super-insulated and airtight to the point that it'll require no more than 12,500 BTUs to keep the house at 70F when it's -20F outside. I'll basically be able to heat the house with a Zippo lighter, although I'll be heating the place with wood. The shower that I'm allowing myself will be using well water, coming from and returning to my land, which will be preheated both by a loop from the woodburning boiler stove that heats the cottage as well as by a substantial GFX drain heat recovery system to get the Delta T somewhere between 20 and 30 degree (depending on the time of year.) I'm sorry you're skeptical about the performance specs of the GFX, but that's your issue, not mine. I'll also be using a pair of incredibly energy efficient condensing tankless water heaters to heat the pre-heated shower water to the final desired temperature. I've done the math now and have calculated that to take two 30-minute showers per day, utilizing all six shower heads going full bore (450 gallons per shower!), each will require an average of 1 gallon of propane costing approximately $2.40 per shower. This is less than the smallest Starbuck's Latte you probably throw back on your way to work. I'm hyper-aware of my carbon footprint. And I'm willing to bet that the footprint caused by my home will be less than the one caused by yours. I just happen to place a high priority on having a really, really great shower. Bottomline: The calculations you provide are erroneous and based both on a lack of information and a number of false assumptions. More importantly though, your perception of what I'm doing is really myopic. You should be concerned about ones NET carbon footprint, not about any one individual indulgence. Don't be so quick to jump to conclusions. You just end up looking foolish. John

city Agree that there is something not right about the kitchen and laundry room. I would have the plumber check if there are anti-scalding valves on the fixtures. When we first moved in, I had to adjust these to properly work with the tankless units. The problem was that out of the box, the fixtures were set with too much cold water in the mixture, and it took forever for the hot water to overcome the cold water mix. At 15 to 20 feet away, the delay should be less than 10 to 15 seconds or so. The master bedroom is another story. I would check anti scalding valves in the master bath and adjusting those might help a little. But you still have 70 feet of water to push out of the way. There are other solutions besides the water recirculating system: - use small point of use hot water generators underneath each master bathroom sink. If your main issue is getting hot water to the sinks (and you don't mind waiting a little for the tub or shower) then the point of use systems can fix that. They make several types - both tank and tankless. The downside is that you need to run seperate power to those units, but it might be a lower cost option in the long run (see my note below on recirc loops). I have one of these under my butler pantry for generating hor water for tea and it cost 140 dollars for the unit. - If you have 2 Rinnai units, perhaps move one of them to the side of the house where the master suite is. The closer you get the hot water source to the master suite, the faster you will get water. This may not be possible since venting the unit if it is gas can be a challenge. - Add a small high efficiency hot water tank on the master suite side of the house to fee the sinks and shower (let the tub remain fed by the tankless). You can get a small tank sized for your daily sink and shower needs. Then you have the recirculating system option which requires a small tank (4 to 10 gallon electric or gas tank), a small pump, and all lines in the recirculating loop to be insulated. The small tank must be sized properly - not just the amount of gallons it holds but the heating element size - or the system might not work properly. You also have to realize that your monthly energy costs will go up because you must keep the pump running during the times when you need hot water. The cost to run the pump is relatively low - pennies per day - but the cost to keep heating the water as it cools when looping can be significant. If you do go down the recirc loop route, get a pump that has a 2 timers on it. Then you can set the timers for morning and evening use, but turn the pump off when hot water use is not expected. The tank remains enegergized all the time - and turns on based on a thermostat - to keep the water at the set temp but since the water is not looping when the timers are off, the amount of energy required to keep the hot water in the tank hot is minimized. I would find a good plumber who can give you an independent evaluation for solving your issues. It sounds like the builder just wants you to throw money at the problem and that might not be the best way to handle it.

Hi, is the cost of operation an issue? So let's rule out electric tankless from the beginning. It doesn't achieve anything that you want, and adds a lot of cost to the electrical side of things. Your generator would not be able to provide power for electric tankless . Options are: -Standard Electric Resistance Tank -Hybrid Electric Tank (very low operating costs, but needs air from garage, basement, etc from which to pull heat). -Standard propane tank -Propane Tankless (less operating costs than above) A 200k BTU unit at those water temps will provide all the water you need. -Hybrid tankless w/tank (low operating costs compared to standard propane tank, but high volume) I would go with Electric hybrid and avoid propane. Propane has had some crazy cost volatility. Something to consider on your new build is grid tie Solar PV (electric) with battery backup. This might be in the ballpark cost wise if you were otherwise considering a generator and propane install. Grid-tie solar would provide some percentage of your electric power that your home needs and feeding any excess back into the power company. The battery backup would provide you with emergency power. You are in a good part of the country for Solar and since it's a new build, you can do it right

If you're really sure you want tankless (and you kinda seem to be), I'm not going to argue with you. I'll just say a couple of things and then I'll bow out. Disclaimer: I'm not an expert on these matters. They just interest me and I hope to be more energy independent in the future, so I read up on them. I always welcome corrections from knowledgeable folk. First point: IMO electric resistive heating of ANY kind basically just doesn't play nice with PV, off grid or on. The only time it really makes sense is when you're off grid and your system produces more energy during the day than you can store in your battery. This can also apply to some extent if you're intertied and your utility pays you wholesale or less when you sell your power, essentially penalizing you for conserving. Either way, dumping your excess PV energy into water heaters is one way to store it for later use. However, it should be obvious that to store that energy, you have to use traditional storage water heaters, not tankless. Second point: Peak demand matters. It matters to your electric utility, and it matters to your bill. You probably know more about CA rates than I do, but it appears to me that right now California is more into time of use (TOU) metering than peak demand metering. However, more and more utilities are adopting peak demand metering for residential customers (they've had it for business for ages). So even if you're not dealing with it now, it may well be in your future. Demand based metering watches your power (not just energy) usage. The higher it is, the more you pay for all your electricity. In one demand scheme, you pay a surcharge based on your peak power usage (in kilowatts), In another, the price they charge you for every kilowatt hour you use depends on your peak usage -- the higher your peak, even if it's only once in the month, the more you pay per kWh that month. Let me give you an example of the second scheme. Let's say your house's big energy hog right now is an electric range.. Most of the time, you just use one or two surface units at a time. So your peak demand is relatively low, and you pay (say) 14 cents per kWh most months. But when you cook Thanksgiving dinner, you have all the surface units going, plus the oven, and a microwave. On that one day, you have a much higher peak demand. Your utility takes note. And that month, you pay 20 cents per kWh for EVERY kWh you use all month. So even though that month's usage is only a little higher than usual, the final bill for the month is MUCH higher. Now imagine what could happen to your bill if you add an appliance that increases your peak demand every day of every month. Guess what: when it comes to peak demand, tankless electric water heaters are MONSTERS. Think about it. With its mild climate, California is a great place for heat pump storage water heaters. That's what I'd get if I were you. Not tankless, and definitely not electric tankless. And that's all I have to say about that.