I have a Gas Tankless water heater with a recirculating pump on it. It is rated at 9.6gpms at a 40F rise if I remember correctly. My showers have 2gpm shower heads, my dishwasher and washers heat their own water. Three adults can take a shower at the same time in the dead of winter without any issues. I have been very pleased with how well this unit has been working. I was skeptical when I purchased it but I did not have the space for a tanked unit. The recirculation is set to run a few hours in the morning and a few hours in the evening. My master bathroom is 50ft from the water heater (tanked or tankless). I never had hot water at sink at this location until I put in a recirculation pump because I just never used that much water to wash my hands at the sink. Good luck!

Here's my take: 1. It may be getting to the end of its useful life, but it sounds like there is nothing wrong or malfunctioning at the moment. My water heater is 17 years old and is still functioning just fine, although I realize it's living on borrowed time. So when it fails, I'm ready to replace it. 2. Your 12 year old water heater will already have a good level of insulation, and, since a new one would be running on electricity also, a new tank is unlikely to be much more efficient. Recent efficiency gains in water heater technology mainly have to do with tanks that have combustion systems, like natural gas. So I doubt that you will see big energy savings from switching to a "more efficient" unit...perhaps a couple of percent, if that. If you switch to a smaller tank, there will be some savings because a smaller tank has less surface area to transfer heat, but the savings will not knock your socks off in your climate. 3. What mainly drives costs is that the groundwater coming in to the water tank must be heated from its inlet temperature to about 120 degrees F. In places that get cold in the winter, that inlet temperature can be below 40 degrees F, which means that the water temp must be increased by at least 80 degrees F; however, you are in the warmest part of the U.S. and your groundwater is close to 80 degrees F already, which means that you only need to use about half as much energy to get the water up to 120 degrees F. And, since your water heater is located inside the living space, the standby losses will be less than someone like me who lives in a place that can approach freezing in winter and has a water heater in an unheated space. 4. It's true that water heaters can lose efficiency over time, particularly if you have hard water and you get mineral scaling building up on the heating elements. However, it's quite simple to replace the heating elements and rejuvenate your tank for not much money: Heating element replacement 5. There's nothing wrong with having an 80 gallon water heater for two people. There are only two of us in my house and ours is 75 gallons. And when two of us take showers, one after the other, we start to run out of hot water. What I recommend is you look at what the energy efficiency label says on your existing tank about annual operating costs, and compare it to the label on a couple of possible replacement tanks. Then compare the amount of annual savings to the total cost of replacing your existing tank now to see how many years (or decades) it will take to break even. I'm not saying that your plumber is lying to you, but he does have a financial incentive to convince you that there will be big savings to switch out your tank soon. My advice is to wait until the old tank fails and and then get a new, efficient one. How big will depend on your lifestyle, and how long your shower runs daily. If you never run out of hot water, you could certainly downsize some, but don't end up decreasing it by a huge amount or you may end up unhappy.

Bruce, you hit on some of my concerns with solutions, which works when you need the hot water during "expected" times. If I need to hot water wash my hands outside of that time then I have to wait on hot water. If I hit a switch as you mention, I'm still standing there waiting for a moment. The house is older and with the basement, it sure seems the pipes will lose the heat of the water causing it all to run more. Some days no one is home all day and other days we are home all day. Seems kinda like the recirculating pump is great for a family with predictable schedule. Is the suggestion for the small inline water heater similar to the ones that are installed under the sink? I'm pretty sure going with the recirculating pump will cost us more in electricity and gas for the hot water heater and if I use timers, I will find myself outside of the programmed times running water waiting for hot. So, kinda like you, it might be just suck it up and wait for both shower and sink or go with the point of use for the sinks to have instant hot water and wait for showers. Unless the in-line suggestion is the better choice. Out of curiosity, why didn't you go with the in-line option? DKB, looking into the 2 gal, I have 3 sinks I would be looking at for this....not sure if it is the right way to go. I have 2 days to decide since the plumber is coming this week. Thank you!

If you know the model of your valve you can look up the instructions online and probably a youtube video to guide you Or just ask the plumber. I know when I was shopping for new fixtures, I ran across some discussions doscussing this exact thing and, if I remember correctly, there are some models that are not adjustable and you’re stuck with lukewarm water.