I have a baseboard heating system, with two radiant heat zones. I am trying to purge the air out of one zone, because one zone is not heating. The thermostat is on, the zone is on of the TACO switch relay, the circulator pump was hot, but still no heat at the baseboard itself... so I assumed air trapped. I had this problem 2 years ago and bleeding out the air helped, but I simply don't remember the process of doing the bleeding.

I pulled down the shutoff valve to close the circuit and then opened the return screw valve, but no water comes out. I tried this on the other zones that are working and still no water comes out, so it's something I'm doing wrong. Now after watching multiple videos on YouTube there is a step to manually open the zone valve... except I don't have any zone valves. I have TACO circulator pumps on each zone and TACO Flo-Chek valves above each pump. But I have no typical zone valves with automatic/manual switch options. I'm assuming the flow check valves are acting as the zone valves, but how do I open them up to allow water to dump out the return spigot? or is there something else I'm supposed to be doing?

I've attached pictures and am hoping someone can clear this up for me.

Thanks for any help or clarification. I hope I am referring to the different parts correctly, so please pardon my ignorance.

 

What do you mean by 'radiant' ? Do you mean tubing in the floor? Please explain.

I see at least FOUR zones.

And hopefully not frozen pipes. Never say never.............

I don't know what you mean by 'screw valve'... do you mean the drain spigot to which the hose is attached?


Yeah, so forget about the reference to zone valves then...

No, not exactly... the flow check valves simply prevent flow in a zone when ANOTHER zone pump is running. This is possible with individual pumped zones. If there were no check valves the running pump would pull through the other zones and give heat where it's not needed.

So let's start with more of an overview of your system and more pictures.

We need to know how many zones you really have, and some pictures from a distance so we can see how everything fits together.

What I see so far looks like you've done the right steps... we can figure this out.

 

While you are at the boiler, please take a look at the pressure/temperature gauge and tell us the readings.

 

Ok, so after all that... turns out I had a frozen pipe. That's why I wasn't getting any water return on that one zone. I had set my thermostat to a schedule to drop the temperature at night to save on heating costs. We had one below freezing night a few days before this problem. It was enough to freeze one pipe to that one zone. The other zones were actually giving a water return after I double checked them (I fooled myself with those quick release valves I had put on to make this process easier, but without a hose attached the quick release valve you get no water flow). So, just that one zone/pipe wasn't returning water and that one zone was on a schedule. Once the pipe thawed, I got return of water and then the heat resumed.

I have 4 zones of baseboard heating shown in the picture, with 4 circulator pumps and 4 flow check valves above each pump. And two radiant heating zones, tubing through the floor, not pictured (also with pumps and flow check valves). Thank you for the explanation on the flow check valves, by the way.

So my only remaining question is my system doesn't seem to have zone valves. Is that normal? What is the need of a zone valve?

 

And that's why I say "Never say never" !

As cold as it's getting the next couple days, you better turn that thermostat UP!

Two ways to zone a system.

Individual pumps for each zone. (yours)

ONE pump and electric zone valves.

So, yes, it's normal to not have zone valves in a system with individual pumps.

 

Thank you NJ Trooper. Your knowledge is truly valued.

 

You're welcome, and thank YOU!
Good Luck!