Air in wood hot water boiler

Larry49

Eighteen years ago I installed a wood burning Aqua Therm boiler for a customer. It has three circulators in the system. One circulates the water from the top to the bottom of the boiler. Another does the "shop" and the final one does the "house. Thru relays they are configured that if the house or the shop aren't running the boiler circulator is. If either the house or shop comes on the boiler circulator drops out. The system has a properly sized bladder tank. The system worked fine until this year. The house has three zones, air handler. hot water preheat-er, and sun room radiator. The sun room radiator becomes air bound. If the air is purged it soon gets air bound again. Where is the air coming from?The sun room radiator is the highest point in the house system.

Jamie Hall

Check your system pressure -- sounds obvious, but... if it is low, it could be sucking in air from a pinhole or some such somewhere?

hot_rod

That brand boiler is know to over-heat if the door is ajar, or the door gasket leaking, maybe it's boiling?

They also need a large expansion, sounds like you have that covered, lots of water content to deal with, at least a #60, sometimes a pair of them.

icesailor

Jamie Hall said:

Check your system pressure -- sounds obvious, but... if it is low, it could be sucking in air from a pinhole or some such somewhere?

Or boiling from Cavitation and low pressure.

Larry49

So you are saying that if the boiler creates steam it produces air? Pressure is normal. The system does have an emergency heat emptying system built in. Could it still be boiling from bad door gaskets?

icesailor

OK, we'll call it a byproduct gas from boiling.