Electric tankless will require an upgrade as well ... on the electric circuit. A typical electric tank takes a 25 to 30 amp circuit. Electric tankless can be high as 120 amps depending on the needed capacity. Capacity in tankless terms means the heating power required to raise the desired rate of water flow (gallons per minute) from the starting point (lowest tap-water temp experienced during the winter season) to the desired output temperature (typically at least 120ðF for a kitchen with a dishwasher). If your house has a large-enough existing electric drop from the pole, then you'd only have to run a larger circuit from the breaker box. Otherwise you'd also have to upgrade the service drop from the pole.

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.

Tankless heaters have used as a marketing idea that they will increase efficiency by not having hot water sitting around in a tank all day not being used. It's an easy concept for consumers to grasp, but it's not true. On an electric heater, the difference in the energy factor is very small between a tank and a tankless heater. A tank heater will be in the area of 0.93 and a tankless might be 0.95 - not enough difference to talk about and certainly not enough to provide payback. That represents the amount of heat lost through the walls of a well insulated tank. With gas heaters it's different. The vast majority of the efficiency gain is in the lowered flue temps. Second is not having the heat loss through the center of the tank. For your situation, what you should know is that a properly installed and operating electric tank heater is extremely reliable and efficient. Get yours replaced or repaired and the TPV properly routed to the drain so that it doesn't cause damage. Since you have lost confidence in your heater, I would just replace it rather than repair. Make sure that you are addressing thermal expansion issues that might have caused the TPV to open. If you want more space, consider a stacking washer and dryer and eliminating the sink. The front loading LG's are full size (huge inside) stack and don't use much water - eliminating the overflowing washtub issue. That would be a cheaper way to get space than a tankless heater and they are great machines.

Hi bold_as_love. I'm not sure I followed anything you said past "PV". Ok, so let me be clear - there are cases where Point Of Use electric tankless makes sense to provide instant hot water in remote locations. There is virtually no case where whole-house electric tankless makes sense. The amount of current required for a whole-house electric tankless can run 180 amps with at least a 300 amp service. That kind of current almost always means significant upgrades to the electric service. Even then, electric tankless will struggle to provide enough hot water. The savings for Electric Tankless are only about 2-3% over a standard electric tank. Very little standby heat is lost through the insulation on a tank electric heater. An electric tankless heater (or electric tank heater) is NOT something you would ever want to pair up with PV. What is paired up with PV is the hybrid heat pump water heaters. If you look at the energy sticker on a standard electric water heater they will show about $420-500 a year. A tankless electric will be a couple percent less. A hybrid heat pump energy sticker will be ~$110 a year.