Different fluid pressure on each meter

RonV_2

Maybe I'm just paranoid, but here's the situation. I have two hydronic system boilers on a primary loop, so they share the same fluid. One runs most of the time and the other only when backup is needed. Each boiler has a pressure gauge on the front and I have been looking at that gauge pretty much every month for the last 6 years (its a long story). I just noticed that while boiler #1 reads as it always did (about 18 or 19 psi) the gauge on boiler 2 is now showing about 15 psi, where it always used to show about 19. Thinking that the gauge is going bad, I put a temporary gauge on a bleeder valve at the inlet to each boiler to see what it read. On boiler 2 is showed 13 psi and on boiler 1 it showed 15 psi. So now I have three gauges all reading different values. I can see how the fluid pressure might vary around the loop since boiler 2 is further downstream from the circulator than boiler 1, but I don't understand whether my system pressure is now actually lower than it used to be or not. Is it possible that the pressure regulator on the inlet water line is going bad? Is there anything in the fact that the backflow preventer on that makeup water line has developed a drip this year where there wasn't one before?

I've attached my system schematic just in case.

Any advice for this amateur hydronics enthusiast?

Gary Fereday_3

10 cent gauges?

Most oem dauges are not all that accurate. I'd get a very good one and KNOW that it is calibrated. Useing only that gauge check the pressures on each boiler, With the system in an "off" Not running mode. Then they should read the same. Pumps and valves can up set the balance when running. Are the boilers at the same elavation? that could cause an off symentrical reading. If the system is working, I'd not be too concerned about the difference in what the oem gauges are saying.