Home Improvement → Re: Furnace -- missing water

I realize many systems are not built this way, but if you have zone valves, and zone drains, you may be able to screw a hose-threaded pressure gauge tightly on the zone drain, open the zone drain to pressurize the valve, then close the zone supply and return valves. Then you can see which zone is dropping fast.

If there is any piping under concrete, have you checked for unusual warm spots? I know a couple of slab-dwellers who have accidentally found domestic hot water leaks by walking around in bare feet.

Ok, looks like you have a converted steam boiler there.. I say that, because typical hydronic heat doesnt have a sightglass, or a pressure switch (off the top of the sightglass), and you do have a Taco pump in the bottom right of the photo. And baseboard is almost never used for steam heat.

So, you should never see any air in that sightglass, should always be full. Actually, both valves should be shut off to prevent a possible leak thru the sightglass, because its only made to handle 2-5psi max, not 30psi of a hydronic system.

You should turn on the water filler valve, and bleed all the air out at the radiators. System pressure should be 12-15psi. (should be a gauge in the back right top of the boiler).

If you are losing water, I`d look for a hidden main, or possible underground return line.

Whoever installed that boiler must have liked painting. Thats some old school work there.

good luck

-j

Are you sure it's not a steam boiler with a circulator grabbing hot water from below the waterline?