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quadradeuce 09-28-2010 05:18 PM

Burnham boiler banging/thumping noises
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)

coolmen 09-28-2010 07:15 PM

This should probally be in the plumbing dept thread. add a pic of the set up so it can be viewed.

beenthere 09-28-2010 07:40 PM

You have it piped backwards.

Its not designed to have the water flow running reversed through it.

Plus, you now have the aquastat so it can't sense the true boiler temp.

quadradeuce 09-28-2010 07:44 PM

3 Attachment(s)
Here are pics. The supply line runs horizontally to the pumps, the return line comes down from the ceiling. In the bottom pic you can see where they attach to the boiler. The return connects to the top left tapping along with the drain, and the supply is down on the lower right, with the aquastat (the aquastat on the left is disconnected, but soldered to the pipe).

beenthere 09-28-2010 07:53 PM

The tapping you have a return. Has to be the supply, and the one you have as supply, must be the return.

quadradeuce 09-28-2010 07:56 PM


Originally Posted by beenthere (Post 508581)
The tapping you have a return. Has to be the supply, and the one you have as supply, must be the return.

Thanks! I'll switch them around and see if that solves the issue. I will report back when it's done.

quadradeuce 10-02-2010 09:55 PM

So far so good. Switching the lines seems to have fixed the problem. Thanks for your help!

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