Boiler piping

Old 04-14-19, 07:57 PM
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Boiler piping

I moved into a home with a high efficiency boiler but one thing about the piping has me perplexed. Outside the boiler is a section of pipe directly connecting the supply and returns. The installation guide for the boiler shows this as well. What could be the reason for this as it seems cool return water will get recirculated before being reheated.

Diagram attached
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Old 04-14-19, 08:18 PM
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Not a boiler guy but have learned a few things from the guys....

It's a boiler bypass. It tempers the return water temperature so that cold water doesn't enter and crack the boiler housing.
Old 04-15-19, 04:33 AM
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It is someone's attempt at installing a primary and secondary loop. Something I can not see is the pump for the boiler piping. If there is one inside the boiler panels that is not shown on your drawing, then that is OK. Also, I may be mistaken but each pump loop or zone should have it's own flow control valve. The way your drawing shows, you could get some water flow through the other zone if the pump circuit's do not have check valves. Your heating system may work the way it is installed, but I am skeptical. Other guys will be along to offer their opinions shortly. Are you experiencing problems with your heating system?

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