Which Valves to Close Off to Purge Air

tuck

I bought a house a couple of years ago with a boiler heating system installed back in the late 1980's The boiler can use either wood or oil to heat the water and send it through the rest of the house using a 3 multi-zone system to the base boards. From what I can tell, I now have air in the system which needs to be purged. There are two sets of cut-off valves on each zone and I can't tell which ones I should be closing to purge each zone. I don't have much of a hvac or plumbing background, so my apologies if I'm slow on the update of the names of components. I have attached two files with a picture of the pipes I'm talking about. I can include more if that helps.

STEVEusaPA

First thing is to figure out why you have air, if that in fact is your problem. Bad air elimination? Low pressure? Not pumping away?
Someone did ya dirty and put the purge valves in the wrong spot. You'll have to purge thru one zone and out the other if you can get past the check valves.

tuck

I'm not up to speed on component names yet. Would you be able to elaborate on what you mean by purge thru one zone and out the other? (The check valves are the green Taco components right?)

EBEBRATT-Ed

@tuck

In your picture showing the circulators what does the circulator on the far left do? Do you have an indirect water tank?

The valve to the right of that pump is your water make up valve for the boiler system. You need to open the ball valve above the pressure regulating valve. When the handle is parallel to the pipe the valve is open.

Open that valve and let water in the system. You should get 12-15 psi on the boiler pressure gauge.

Keep the boiler and all circulators shut off.

Attach a hose to one of the drain valve located above the three circulators. Close all three valves under the circulators. Open the drin valve with the hose on it and let it run until it is all water and no air.

When it is solid water shut the drain valve and move it to another zone. Rinse and repeat for all zones. I don't know how they vented the pump on the far left.

Then open the 3 valves above the pumps and start the system. You may need to operate the "fast fill" (the lever on the prv valve to maintain system water pressure while bleeding.

tuck

Hi - I do not know what the circulator on the far left does. There is no indirect water tank. The boiler heats the potable water "internally".

As far as the instructions go:

1) boiler off - understood
2) circulators - the red and blue ones - I assume these go off with the same power switch that handles the boiler
3) Attach the hose - understood
4) Close all three valves under the circulators - except the valves are above the circulators (above the blue/red grundfos circulators)
5) Using each drain valve one at a time understood.

The question comes down to why are the valves above the circulators and what about the three valves next to the green Taco flowchek vales? Do those need to be turned off as well?

Thanks!

hot_rod

Looks like pumps are on the return to the boiler, flo checks on the supply. Ed’s method should work.

Odd about that large piped zone on the left. And why the swing check. Maybe some pics from farther back?

EBEBRATT-Ed

@tuck
The valves near the taco flow checks can remain open. The idea of purging this system is to add water to the return header below the pumps. The water then flows through the boiler and goes out through the flow checks into the system supply through the radiation pushing the air ahead of it. The water and air come back the return line above the circulator and is purged out the hose. You are purging using water pressure.

Lets see some more pictures of the pump on the left and where the pipes from it goes.

tuck

I've uploaded some more pictures. The "left" circulator is attached to a pipe which winding to the left comes from the top of the boiler and winding to the right, attaches to the back, low end of the boiler. The pictures should allow the viewer to see the pipe coming from the top of the boiler that winds to the right receives connections from the three green Taco valves then down through the circulator in question, past the three zones with circulators and the cutoffs to the back of the boiler. Pictures are easy, can always supply more. Thanks all!

tuck

FYI: the pictures did not load in order: Start with jpg 0944945 HTH

EBEBRATT-Ed

You have what is called "primary secondary piping". The red pump on the left pumps water out of the boiler and back into the boiler in a loop. The zone pumps "pick" water off that main loop and bring it back to the same loop where it is fed into the boiler to be reheated. The red (primary pump) needs to be running for any of the zones to be able to heat.

You would bleed the zones as I have described above.

tuck

@EBEBRATT-Ed A primary/secondary piping? Is that the same as a bypass? Regardless, it would appear that you have laid out the steps for purging for me in your previous emails. The only related question on that is that in one of the steps the circulators should be turned off. In the picture marked 20231020 094505.jpg you can see that the wires from the circulators are tied into the circuit box on the left. I would assume that when the boiler is turned off (picture 20231020 094924.jpg) that would also turn off the circulators. Otherwise, should be good to go.