How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8429
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

I have a GG-125 Slant Fin Boiler. I have three zone and all

Customer Question

I have a GG-125 Slant Fin Boiler. I have three zone and all the valves operate properly when the thermostat is turned on but I get no flow through the zones.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


If the boilers hot water pump any zone pumps are running that chance that there is air trapped in the high points in the system is nearly 100%.

There are air vents near the tops of all radiators, and at other high points in the system, make sure the boiler has at least 15 psig pressure in it, then open each air vent for a few seconds, if any air comes out, before a squirt of water comes out, you have found the problem.

Bleed all of the other air vents in the system, lift the pressure relief handle on the boiler for 1 second then let go, stand clear of its boiling hot water discharge.

then repeat the bleeding process.

Tell me if you have trouble keeping the boiler water pressure up to 15 psig. and if you have in-floor radiant heat.

This is step one, we can go from there until we get the situation resolved.