Home Boiler heating system question

[Norrisville]

Hi,

I have a 4 zone boiler heating system in my home. In one of the zones on the return piping I have a smaller set of pipes that run through a under the kitchen sink heater. The 2 pipes shown in the pictures are those. I have the top pipe with a cap and its starting leaking as the furnace hasn't been running as much with the warmer spring weather. What is the purpose of this cap and is it safe to tighten to see if the water drips stop? Its dripping about a 1/2 cup a day because the furnace has not been running as much. Thanks

 

[Geofd]

Probably an air bleeder, you may want to take the pressure off and replace that cap I bet the water temp is wearing away the rubber under the cap it's not meant to be loose,you may want to clean up that fitting,get all that green stuff off

 

[Norrisville]

Thank You! With the furnace off, can I just quickly replace the cap with new or do I need to drain that zones lines before replacing the cap? What would I use to clean the green stuff off the pipe?

 

[Geofd]

Shut off the water to the boiler, and drain down the zone that the bleeder is on ,I think water and sand cloth(for cleaning copper pipe and fittings....

 

[arctic bill]

yes it is a bleeder or what we call air purger

 

[Norrisville]

Thanks for the help!