Hi there, We have a house without a backflow preventer on the main, a water softener, a whole house carbon filter, and a hot water tank with a check valve on the cold water inlet. The softener and filter are installed upstream of any toilets, appliances, taps, or the heater. During times when there’s a high demand for cold water (usually a combination of washing machine/dishwasher running, and toilets flushing), it seems like the system is trying to pull the additional cold water from the hot water tank. The check valve gets pulled up and gets stuck. Cold water can come in and fill the tank, but it’s at a slower flow rate than typical. When we first turn on the hot water under these conditions, the pressure is fine for a few seconds, and then tapers down into a lower pressure. The cold water pressure is unaffected. We can usually fix this (reset the check valve) once the heater is refilled, not running water anywhere else in the house (to maximize pressure), and turning on a hot water tap full blast. Sometimes it takes a few tries. In one or two bad instances, I’ve had to take off the inlet pipe and loosen the check valve manually. Is there anything we can do to stop this? It seems to be getting worse and I replace the carbon filters often. We need the water softener and carbon filter as the town uses a lot of chlorine to clean/disinfect the water, and it tastes and smells bad without the filter (and is likely bad for the appliances). I was thinking of adding an expansion tank but I don’t know if it would do anything (perhaps it would if we didn’t have the check valve on the heater but we do and it’s a rental, and while I’d like to swap it out for our own, finances aren’t great right now, and I’d prefer to wait a few months once we start pulling in some more money). Thanks in advance, Matt.