Purging air from boiler

[gtmtnbiker]

My system has a supply manifold with three circulator pumps and isolation valves. There is a return manifold with a boiler drain and isolation valve for each zone.

From reading the archived posts in this forum and other forums, it's my understanding that to purge all the air from my boiler, I need to do the following:

1. Shut the isolation valves for all the zones on the return side and supply side.
2. Turn power off to boiler and circulation pumps.
3. Working only one zone at a time, do the following:
a. open the isolation valve on the supply side for the zone.
b. put a hose on the correct drain and put end into bucket
c. open drain thereby letting water into bucket
d. open fast-fill valve (actually lever), keeping an eye on the boiler pressure gauge to make sure it doesn't exceed 40 PSI.
e. fill bucket until no more air bubbles come out.

Repeat #3 for the next zone.

On my system, I have slant-fin baseboard radiators. They have bleeder valves. Is it necessary at all to use these bleeder valves if you purge the air via the drains? The reason that I ask is that on most of my baseboards, you cannot take off the cover and expose the bleeder valve. It seems that I would need to put some sort of absorbent rag around it because the bleeder valve is not oriented in the correct direction to use a small container to collect the water.

So I wonder if one can purge the system of air by using the drain valves on the return and not use the radiator bleeder valves.

What do plumbers use to open the bleeder valves? A screwdriver?

 

[Cwhyu2]

You really have no choice you have get to the bleeder valves in order to
have your system working properly.

 

[Sponsor]

 

[GrumpyPlumber]

Not sure why...but I'll assume you want to use the compressor to blow out the zones(?).
Flush them instead...open the draw-off on the return side with a garden hose attached and run outside, close the valve below it...then open the auto-feed...MUCH better than blowing it out with air, water will be much more effective than air at flushing out any sediment (If thats what your looking to do).
The systems circulators don't really put much "push" on the flow ...house pressure will.

Remember???
This also works to flush out the air from the zones.
The boiler itself is purged through the air scoop with can or Spirovent.

 

[GrumpyPlumber]

By the way...what was the outcome on that zone?
Were you able to even out the split or did you have to create a seperate zone?

 

[gtmtnbiker]

Thanks for the reminder. I should have looked at the responses to my previous posting.

I ended up doing what you suggested. That is to run the garden hose outside and flushing it for about 5 minutes until I could no longer hear any air gurgling through the lines. Then I would leave the drain open and check the hose in the bucket. After watching it for a minute and did not see any air bubbles, I would move onto the next zone.

I had watched my plumber purge the zones before. I had asked him why he opened he auto-fill line. He said it was a faster way of putting water into the system. What he did not say was that you *need* to do this in order to generate sufficient force (pressure) to evacuate the air from the lines.

I ended up putting a 3rd zone on the system and not trying to even out the split. It wouldn't have worked in my opinion. Within the original split loop, there was a 3 degree difference between the family room and the rest of the house. This is what they should have done when they added the family room onto the house 30-35 years ago.

I plan to update my original threads with the final pictures and my observations on the whole process along with the mistakes I made and corrected. It was a good learning process and it made me have a better appreciation for the work involved.

 

[gtmtnbiker]

You really have no choice you have get to the bleeder valves in order to
have your system working properly.

I noticed that the bleeder valves are placed on the 90 deg elbow when the pipe transition from horizontal to vertical. I guess when the water goes down, air tends to rise and stay trapped in the elbow.

Does this make sense?

So what do plumbers use to open these bleeder valves on the slantfin baseboard radiators? Is it just a flat screwdriver?

The reason that I ask is that it seems the screwdriver doesn't really fit will. The slot is kind of wide and shallow. The screwdriver tends to slip out of it. On some of my baseboards, there is an access hole so that you don't have to take the baseboard cover off. In other cases, there is no access hole so you have to go through the side. Also, I'm unable to take off the ends of the baseboard covers due to the plaster walls above it. It seems that they mounted the baseboards to the studs and put plaster walls on top of it. So the baseboard covers are wedged in.

I haven't been able to easily open some of my bleeder valves due to the screwdriver or offset driver slipping out of the slot. That's why I'm wondering if something else is used such as a radiator bleed key except this is for H/W baseboard radiators.

 

[Cwhyu2]

I have used a bleeder key that I have since my apprenticeship you may
have to replace the bleeders as they can become carodid on the inside.

 

[Cwhyu2]

We also have dime bleeders but to old school.

 

[GrumpyPlumber]

I noticed that the bleeder valves are placed on the 90 deg elbow when the pipe transition from horizontal to vertical. I guess when the water goes down, air tends to rise and stay trapped in the elbow.

Does this make sense?

So what do plumbers use to open these bleeder valves on the slantfin baseboard radiators? Is it just a flat screwdriver?

We call them "coin valves", bet you can guess why.
They're a VERY good idea on the return side, the air rises and over time too much air constricts circulation.
Circulators aren't pumps, they aren't made to fight or push the air.

 

[Cwhyu2]

Its been so long grumpy I could not remember.Coin valves are self bleeding?

 

[GrumpyPlumber]

Its been so long grumpy I could not remember.Coin valves are self bleeding?

No, I wish, thats a can vent you're thinking of.
Too big for inside a baseboard.