@brickeyee As I've stated REPEATEDLY and CLEARLY in many threads discussing this subject on this forum... A traditional recirc system is preferable to a retro fit if it can be done cost effectively and with acceptable inconvenience. For new construction it is the way to go. Recirc as an after thought can be very expensive and very inconvenient. In those circumstances a retro fit recirc can work well with few compromises and at modest cost with ZERO inconvenience. Your position that the only way is the traditional recirc flies in the face of my 10+ years of perfect service from the Laing Autocirc. How much experience do you have with a retro fit recirc? Any experience with the Watts recirc? The Chillipepper? "If you think having previously heated water with its greater load of contaminants leached from piping in your cold water supply is acceptable go for it" Another excuse but not a reason for not using a retrofit recirc. That water is flushed within the first seconds of opening ANY cold faucet. I've had a chemist buddy take samples and make sure.

You can certainly do a hybrid or combination system. Doing your proposed L/R lay-out, is the only way to go in my opinion, I would still suggest a pipe tying the two sides together. I would put and accessible ball valve in that cross connection pipe so, if for any reason one system went down you could open the valve to have one side support the other, at least temporarily. Do you have a basement under this home or only a crawl space? If you need hot water quickly and not shower volumes in the downstairs rt lav, perhaps a small undercounter electric would do the trick. I hate to suggest that, but you are dealing with geography here. Time, distance & flow rate . The Master Bath will be best serviced by tankless. Your hi flow shower head needs to have a specific flow rate attached to it. A standard shower head will provide 2.5 gpm. In my new shower that means 2.1gpm of 120f water mixing with .4gpm of cold to arrive at my nice comfortable shower temp. I have also seen 20 gpm shower heads. Put a number on the flow of the single shower head please. What is the volume of the tub. What faucet set are you putting on it and is the tub valve going to be a 1/2" or 3/4" connection. With 1/2" pipe you will not get much over 5 gpm. With 3/4" you can get 10-12 gpm. Some tub faucets, the waterfall type, require 3/4". Otherwise the visual effect is not as good. Get the tub volume and compare the flows to the time you are willing to wait for the tub to fill. Yes, you can put tankless in the attic, but understand that you need a pan below them to prevent water damage from any possible future leakage. That is just good sense. Tankless water heaters are compact. As a result people tend to install them in really small spaces. Please keep in mind that this is a mechanical system and must be accessible for inspection and service. I long ago coined the term, "Just because it fits, doesn't mean that is where it goes." You would not believe the places people have installed these. It is a good idea for you to have the "service space" discussion with all of your subs. A lot of duct work gets destroyed by the technician the first time he has to service the heat pump, furnace or air handler. Build all your system to perform well, but make sure everything is positioned for accessiibility. These types of agreements tend to be forgotten when the equipment arrives on the job and the contractor wants to "get it done". So the question to your General and each of the subs is, "How are you going to build and position the equipment so it can be easily serviced". That is a good discussion to have with your architect too. Make your expectations clear and let them know you will be following up to monitor this "agreement". Sorry to get off topic there, but you have what, as I look at the floorplan is going to be a really lovely home. I just want to make sure the cardiovascular systems work well for you too. Another thing, the gas line will have to be sufficiently sized not only for what you are planning for the initial job, but you want capacity for future expansion. I have seen so many places that get undersized gas lines and the owner is blocked from any possible future expansion. This is a big project and even with great care, things pop up.

It is physically impossible for this problem to be a result of thermal expansion. Even if this faucett is in the near proximity of the water heater the line is contantly full of water and water is not compressible therefore, in order for thermally expanding water to enter that line it would need to first displace the volume of cold water already in the line and there simply is nowhere for the cold water to go. It is possible during long static periods that heat from a water heater can migrate into the cold water line without actually moving any water but generally this would be limited to about 6' vertical or 4' horizontal from the tank. Heat migration can be eliminated by installing "Heat Trap dielectric nipples" on the water heater. One common cause of warm water on a cold water line results from the installation of a hot water instant on recircutor that uses the cold water line as the return path rather than having a dedicated return line. These type of units are commonly sold in the big box stores as a simple DIY installation for recirculating hot water. It is also now a common prsctice to install a small tempering valve on the watercloset supply line to keep the supply water to the watercloset tank at room temp to prevent condensation on the tank walls. If the lav in question shares a common line with the watercloset fill valve and if the tempering valve is improperly installed before the lavatory connection it would account for this problem. It is also possible that the cold water line is run in parallel to a heating duct that is not adequately insulated and the water is being heated from heat radiating from the duct.

Yes, a dip tube should carry the returning water down to the bottom of the WH for reheating. Connections: 1. Cold water in 2. Hot water out 3. Recirc return 4. Temperature and Pressure safety relief valve That device with the green knob mixes cold water with the outgoing hot water as necessary to keep the temperature at a safe level for domestic use. There's also a drain valve at the base of the WH that some recommend be used every year or so to flush out any sediment from the bottom of the tank.