The time it takes for the hot water to get to your faucets or shower is related to the distance the water has to travel from the hot water source to the sink and the diameter of the hot water building supply pipe (typically 3/4 inch) as well as the feeder pipe to the sink (typically 1/2 inch). A 3/4 inch pipe holds about 8 ounces of water for every 3 feet of pipe. So if your tank (or tankless) unit is 90 feet away from a faucet, you would have to push out about 1.8 gallons of cold water (plus whatever water is in the feeder pipe, a 6 foot section of 1/2 inch pipe holds about 8 ounces of water) before the hot flows. A typical sink faucet will run at 1.5 gallons per minute maximum flow rate - so you are looking at over 1 minute to get hot water in this scenario. With tankless units, there is also a small delay between the time the unit senses water flowing through it (which triggers it to fire) and the time the unit heats the water up to the set temperature. There are 3 ways you can eliminate the long delay. The first is to put a hot water source (tank or tankless unit) closer to the sinks that are far away from the current source. The second way is to use point of use hot water generators under key sinks that you use. These POU units are very small tanks or tankless units designed to service just once sink. The last method is to install a recirculating loop where you constantly circulate hot water through the hot water building supply. I have a Rinnai tankless system that we installed in the basement directly below the master bathroom. From the time I turn on a shower or sink, hot water is flowing within 10 seconds. That was the good news. The bad news was that the kitchen sink and 3 other sinks that we use often are over 120 feet away from the Rinnai tankless units. Just before we finished the house, we discovered that it was taking several minutes to get hot water at the kitchen sink - and that was unacceptable to us. I wound up installing a recirculting loop. This was not the way I would have preferred to do it, but space and venting in the basement on that side of the house was an issue. You could just live with the delay you have - 1 minute isn't that bad. If you decide to fix the delay, I recommend posting some details on the plumbing forum and seeking advice on how best to correct.

My water heater has 2 flow pipes on top one is for cold and the other is for hot. the cold pipe is making a banging noise and instead for it being cold it is hot. Please advise

Hello. The whine from our neighbor's vent fan, directly opposite our dining room window, has been so severe and at such an unfortunate frequency that its noise could be heard even in the farthest corners of our big house. We tried a variety of acoustic solutions, some suggested on websites like this one - basically following the idea that a longer pipe, or a "tee," or stepping up the pipe diameter, or running it to the ground behind bushes, adequately kills he noise. No go in our case. We ended up piping the vent into an old plastic garbage can filled with discarded fiberfill pillows and comforters. They must be packed loosely enough to allow the very moist hot air to escape freely, but densely enough, obviously, to kill the noise. It's also important to drill air vent holes in the sides, top, and bottom of the garbage can. It's an experiment,but so far, so good. - SL

The coefficient of expansion is different for each size of pipe, but for illustration let us consider 3/4" CPVC. For 3/4" CPVC the expansion is 1" per 100' of pipe for every 1degF of temperature change. Assuming the pipe begins at an ambient temp of 70 degress when you start your shower and the hot water is set for the code max of 125 degF the temperature differential in the pipe would be 125-70 = 55degF. The thermal expansion would then be 55" per 100ft of pipe. We rarely see a run of pipe longer than 50' in a residential system, but even at 50ft the thermal expansion would be 27.5". The CPVC installation handbook suggests a 18" expansion loop at every 30' on a straight run and the loop should be located near the center of the run. To make the expansion loop the pipe is cut and a 90deg elbow is installed. The line is then stubbed out 18" and a 90deg elbow is installed. A short 4 to 6" length of tubing to another 90deg elbow turning back towards the original pipe and then connect the loop to the original pipe with another 90deg elbow. On the ends where the pipe drops down through holes the pipe should be run about 18" to one side of the hole with an 18" offset from the pipe to the hole. IN this manner as the pipe expands the 18" horizontal offsets can flex slightly to absorb the expansion. Insulating the pipe will not prevent the expansion because the temperature differential results from the temp of the liquid in the pipe, however if the pipe is first insulated, then pipe hangers large enough to fit the exterior of the pipe insulation are installed, the pipe is free to move slightly within the insulation. If you have your water lines run through the attic space you definitely want the cold water lines insulated, otherwise as the pipe cools from the cold water moisture will condensate on the pipe and drip down on your ceiling causing water damage the same as a leak.