My house is heated by a 1982 Burnham P-207 gas boiler (162k BTU/hr). The house originally used a gravity heating system, but was converted to circ pumps at some point. To do this, the pumps were positioned on the return pipe, and water was pumped INTO the boiler, heated, and then forces out the supply line.
In anticipation of some renovations (including a new boiler in a few years) I made some alterations to this system:
Added manifold to supply and return lines.
Reversed pumps and flow-check valves so that pumps pull water away from boiler.
Moved aquastat from the return line tapping to supply line tapping.
Added Spirovent to supply manifold, before pumps.
Disconnected antique expansion tank in the attic, and added new diaphragm expansion tank, tapped into bottom of Spirovent.
Added air vent to pipe stub where old expansion tank connected to top of boiler to free trapped air.
With this setup, the pumps pull water from the lower tapping on the boiler, and the return line connects to the upper tapping. Now when I fire up the boiler, it runs normally until it starts to get to full temp. At that point it starts to make thumping and banging noises, and the temp in the boiler spikes (according to the gauge by the return line at the upper tapping).
What has gone wrong? Do I have to switch which tapping the supply and return lines connect to? Does the upper tapping always have to be the supply? Or is my aquastat shot and the boiler is creating steam? Can air bubbles get trapped in the boiler?
Any help would be appreciated as it's starting to get a bit chilly out!
Thanks much!
James (Wisconsin)
In anticipation of some renovations (including a new boiler in a few years) I made some alterations to this system:
Added manifold to supply and return lines.
Reversed pumps and flow-check valves so that pumps pull water away from boiler.
Moved aquastat from the return line tapping to supply line tapping.
Added Spirovent to supply manifold, before pumps.
Disconnected antique expansion tank in the attic, and added new diaphragm expansion tank, tapped into bottom of Spirovent.
Added air vent to pipe stub where old expansion tank connected to top of boiler to free trapped air.
With this setup, the pumps pull water from the lower tapping on the boiler, and the return line connects to the upper tapping. Now when I fire up the boiler, it runs normally until it starts to get to full temp. At that point it starts to make thumping and banging noises, and the temp in the boiler spikes (according to the gauge by the return line at the upper tapping).
What has gone wrong? Do I have to switch which tapping the supply and return lines connect to? Does the upper tapping always have to be the supply? Or is my aquastat shot and the boiler is creating steam? Can air bubbles get trapped in the boiler?
Any help would be appreciated as it's starting to get a bit chilly out!
Thanks much!
James (Wisconsin)