Makeup water & condensate pump interlock?

Stuart Rogers

1925 building, 2005 boiler, 25-unit co-op.

I mentioned in a previous posting how I hear water draining after most firing cycles, and how a lot of make-up water seems to be entering the system.

I found this in the files from when the boiler was installed. It's by the consulting engineer who wrote the bid specification (using heat-loss, not installed EDR, by the way). It doesn't make sense to me. He said:

"The water supply pump is directly connected to the condensing tank. There was a new by-pass line with shut off valve installed. Recommendation: Solenoid valve and water pump should be interlocked so that whenever the level in the condensing tank drops below set up value, the solenoid valve will open the water supply and at the same time signal from solenoid valve will engage pump to supply water to the boiler. This control must be installed for the proper boiler operation."

I would have thought that the condensate pump should run only when the condensate level is high, and that the make-up solenoid should only operate when the condensate is (extremely) low. It seems to me that now, every time the condensate pump puts water in the boiler and lowers the level in the tank, the make-up supply comes on, and runs the pump while also trying to refill the tank. So we get lots and lots of fresh cold oxygenated water in the system and too much water in the boiler. (Note -- We do not get high water level alarms. I just hear water draining between firings, and I'm pretty sure it's coming from the boiler, though I could be mistaken. Does the boiler have an automatic mechanism to rid itself of excess water? I do know for sure that the make-up supply runs often.)

thanks!
Stuart