Hot water is comming from 2 cold water taps and one upstairs toilet, turns to cold after 15-20 seconds, it comes out very hot. Thought it might be Bleeding through faucets, so changed laundry tub and kitchen faucett. still does it. The cold pipes seem to get hot from near the water tank. The dip tube would give the opposite effect? I am fairly handy, but am stumped. The hot water heater( Gas ) was replaced about a year ago, by the gas company. Any ideas??

speedball1

Good morning Gordon, You are correct, the dip tube directs cold water to the bottom of the tank however the cold water supply line is always hot near the tank. This is caused by convection from the heat of the tank heating the copper pipe. I don't think the heater is at fault. Your problem is caused by a cross connection. Have you installed any new appliances lately? Are there any hot and cold valves or faucets left open that are tied together may be feeding each other. I can think of one. Your washer has hot and cold faucet supplies that are left in the open position. If the mixing valve in the washer were faulty that could be your cross connection. Shut the washer faucets off over night and in the morning check to see if that don't help. Let me know what you find. Cheers, Tom

labman

Does all the hot cold water come from the pipe near the hot water heater? Was the vent or any of the pipes rerouted when the hot water heater was installed? Modern hot water heaters are well enough insulated that the heater itself should not be heating up its surroundings. If the insulation was insufficient, your gas bill should have gone up. The old hot water heater was gas too? If the problem seems to be the vent being too close to the cold water pipes, you may want to replace a single wall vent with a triple wall type B vent pipe. You may have to come back before Tom and I figure this out completely.

speedball1

Gordon,  Labman gives very good advice but this time he's way off base.  (Sorry Lab!!) Feel the cold water supply on any operating water heater, electric or gas, and you will find the cold water pipe near the tank is warm if not hot to the touch.  Metal will convect heat and copper is a dandy conductor. Labman blames radiation and that just doesn't happen, there just isn't enough heat that radiates from the flue to heat the cold water to a temperture for it to run hot from a fixture. and unless you have  reconfigured the supply and hot water pipe on the heater recently You won't find your problem in the heater either.  Check your system for a cross connection between hot and cold,  starting with the washer.  Good luck  Tom

gordonhowe

Thanks for your help it was narrowed down to the Price Pfister shower unit, they are sending a new cartridge and shaft from California n/c. Funny that alot of people including plummers are not aware of this. Thanks again - this of course is making the full assumption that this solves the problem- hopefully you won't hear from me again Gord