air control or low water

Hammer

I recently purchased a 12 year old house here in central Pennsylvania. During the initial walk thru, I was pleasantly suprised to find that the house is heated w/ a 5-zone base board hot water system (which includes a unit heater zone for the garage), and cooled w/ a ducted A/C system! The previous owners obviously enjoyed their comfort!

Now for the dilema. I started the heating system a few weeks ago and noticed that anytime one of the zone pumps pulls water thru the system there is a "gurgling" sound. It is obviously air related but I'm wondering if it could be from insufficient water in the system and not from a slug of air. None of the 4 "living quarter zones" has experienced typical problems associated w/ a radiator being air bound; we have no problems heating any of the rooms. But the gurgling continues any time a pump kicks on. Also, I don't hear any cavitation or gurgling noises at the pumps when they start; I only hear the noises "out in the system". The system utilizes a Weil-McLain CI, oil-fired boiler, Weil-McLain finned tube radiation, and 5, B&G series 100 pumps on the return side of the boiler. The system has an Amtrol bladder tank, in-line air separator and auto air vent above the boiler. The boiler, pumps, expansion tank, and air vent are all located in the basement. The system also has an integral DHW coil and external storage tank.

One of the limitations I see in the system is that it doesn't contain a lot of isolation valves and there are no gages (except at the boiler). I have lots of experience w/ commerical boiler systems, but very limited knowledge on residential setups. There are Flo-Checks on the supply side of each zone, and a shut off/drain (w/ hose connection) on the inlet side of the pumps. I can't find a manufacturer name on the shut off/drain, but it is a wye-type fitting w/ a Hammond drain valve on the drain end and an integral shut off cock straight thru to the pump. The word "purge" is imprinted on the stright thru portion of the valve body. The shut off operator is a plastic handle and it appears to function like a ball valve. I'm not familiar w/ these valves, so I'm not sure if this is the worng application for them.

The system also contains a cold water make up line w/ an isolation valve and pressure regulating valve connected at the boiler return inlet. Is it possible that the reg valve is not functioning properly and is not allowing any make up water to the system? If I drain some of the water out of the system (at one of the pump drain valves), I suspect that I should hear cold water entering the system thru the make up/pressure regulating connection. I have tried this and haven't noticed anything. Since there are no pressure gages on the system, I really can't tell if the valve is working. Is there any way to test this?

To compound matters, I don't believe there is a vent at the system high point; at least I haven't been able to find one. But again, none of the living area zones suffer from lack of heat. The garage zone does have a vent on the unit heater which is at the ceiling of the garage, but still below the highest baseboard on the 2nd floor. I turned this garage zone on last night for the first time. THis zone does have an air problem b/c I can't get any water to circulate in the loop (even though the pump is running). When I remove the cap on the air vent and start the pump, I can hear air being pushed out, but after 5 seconds or so, the noise stops. The same thing happens when I shut the pump off; I can hear air being pushed out, but not enough is purged to allow the loop to fill, which leads me to think that the system is low on water. Since the pump is on the return side of the loop, I thought about closing the shut off/purge valve to the pump suction, then connect a hose to the drain valve and try to "back fill" the return side of the loop. I would leave the air vent open in the hope that any air would be pushed out by the pressure of the water filling the loop.

Sorry for the length here. I hope that somebody has some ideas. Thanks for your help.

[Deleted User]

Air

Hammer,

An old Holohan joke. "Circulating pumps don't suck. Unless they don't work. Then they really suck."

You are right about the purge valves. They are there so each zone can be purged through a hose, one at a time. Turn off the boiler and pumps. Connect a hose to the boiler drain. Turn off the plastic handle. Stick the hose end into a clear container. Open the boiler drain and run until there are no more air bubbles. Then reverse the process.

If the pressure reducing valve is not feeding, this will tell the tale. Don't like feeding water in at the return. Pumps on, pumps off, do funny things to system pressures. Sometimes to alleviate the end product of the funny things, people set the pressure down. Too low a pressure can result in some air bubbles that just never get moved to that air elminator, or allow you to completely fill that last piece of radiation.

Heating systems love to be filled at the point of no pressure change. Might want to see if any heating pros in your area can find it. Or buy one of Dan's Hydronic Splendors, for the info. Also, just because every residential pressure reducing valve comes set at 12#, that doesn't mean that is the right pressure for you. If the boiler gage is OK, you can read the standing system pressure w/ the pumps off. That will give you a starting point.

Happy hydronicing.