We are using city water and from the looks of it, The person who had this before me, totally cut out the hot water heater and is running the water through our gas heater. Something I have never seen before.
We have low pressure, if you turn on a sink while someone is taking a shower or flush the toilet, the shower pretty much shuts off and you might get a dribble out of the faucet
We found our culprit. We have flex piping running our water though a small oil burner... our hot water heater was totally disconnected! Fun stuff I know