We recently bought a house that is on well water with pressure regularly between 35-45psi. There is an older water storage tank that resembles a Trident missle (not one of the small blue types). The hot water line then goes into an 'instantaneous' oil burner and from there into another storage tank. The previous owner said this tank was just a reserve. Coming out of this tank is a 1/2" pipe which leads into a 3/4" pipe to various parts of the house where it gets cut down to 1/2" again when going to faucets and fixtures. This itself seems like it could be a potential problem. I expect I should change this to a 3/4" pipe coming out of the tank but I don't know if it accounts for the problem I describe here.
Cold water is always very high pressure. Hot water is mild pressue and varies from day to day. When running hot water from any fixture in the house and turning on the cold water for even a second from any other fixture in the house, the hot water pressure drops to 0. I've heard of people turning on a cold water faucet and the shower gets hotter but this is the opposite. It seems there is a vacumn or something where whenever a second cold water faucet is turned on the hot water pressure drops.
A simple example is in the bathroom we turn the hot water on in the sink and when we turn the cold water on in the bathtub, the hot water in the sink stops flowing.
If anyone else has seen this or has ideas on what the problem could be, I'd really appreciate the input.
Thanks in advance.