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.

Saltidog, Dude, chill. I was respectfully saying you had a different opinion - not what your opinion was or that it had anything to do with the heating elements. You can disagree without being disagreeable. I do understand thermodynamics very well, thank you. There is no "trend" and no misrepresentation. Yes, the units have resistive elements as backup, for high demand situations, and when the ambient temperature gets low enough that enough heat can't be extracted using the heat pump (for geospring unit that's 45 degrees F) Saltidog, I don't know what you are getting your panties in a bunch about... yes, I understand your heater works well for you. I would expect that. It's installed in a basement that's at least 700 cubic feet of space. Because it's underground it will maintain a temperature of around 50 - 55 degrees or more if there are other heat sources in the basement. That's enough to allow the heat pump to work just fine. The water heater will work in almost all situations / applications where one would normally install a tank heater. It will even run on the heat pump in most situations. The question is when you have the water heater in a fully conditioned space (not basement) and that space is being heated. At that time, one is shifting the heating load of the water heater to the furnace - which may or may not be more cost effective. I think the water heaters are great - esp if they can work out the reliability problems (which I think are teething pains, not inherent problems). I stick by my assertion that there are three applications whereby they produce the most system efficiency / cost effectiveness.

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.

Wow, thanks for all the good input. I didn't intend it to become a debate about solar, but found that interesting as well. I'm not familiar with the lease program that is mentioned. I'm looking to have an array installed that will be owned completely by me. I can get a 20kw system installed for about $60,000. There is a new Duke Energy program offering $1 rebate for each kw installed, so subtract $20,000. Then there are 55% state and federal tax credits, reducing the investment further to $18,000. The system should generate about $2,500 in energy per year (assuming 9 cents per kwh), resulting in about a 7 year payback. There is also potentially a benefit I can derive from depreciating the asset, but am not sure that is allowed, so need to check with my tax expert. I think the main different between now and before is the $1 Duke rebate. Without that, I agree the payback period would be too long (about 11 years), but a 7 year payback seems reasonable to me. There is always the possibility of repair costs in the first 7 years which could lengthen the period a bit, but the warranties on the panels at least are much longer than that. In any case, I think it is a worth a try. With regard to the water heater question, I agree that two heat pump units might be too many, as the one in the basement might be idle for long times, so am not considering doing 1 heat pump (for the upstairs which will get used daily, but shouldn't use more than 80 gallons per hour as there is only 1 shower), and then a gas powered tankless for the basement. We have natural gas that will be already piped to the house for the stove/grille. Any other thoughts or suggestions are welcome, thanks for the lively debate!