Purging System?

Every year I need to purge system at the start of the season. Every year it is a pain in the butt. So I purge all the zones because the heat is just not hot. I did all zones thinking the air is purged, onece auto fill goes back on it appears to return air to system. I'm not sure if my purging approach is wrong or air just gets back into system.

I do have purging valves on the return side for each valve. Does anyone have a sure way to avoid this frustration....it must be my approach?

What is the pressure setting on your autofill? what is the pressure on your expansion tank when system pressure is zero? Circulators are on which side of the air eliminator and how far apart? One or two story house? what are you using for an air eliminator?

waldo

do you have any leaks ? where you are constantly adding some water>\? . I don't have a auto fill as I don't have any leaks and my pressure stays the same day in and day out. do you have a bladder type compression tank? or a open expansion tank that no no bladder just captive air. The air can mix there . If you add water and do not have a proper air separator and vent air will be captured in the system at opportunistic places . Remember fresh water need a couple of cycles of heating to purge it of various entrained gases that will upon being heated be released as gas in the piping system .

When you purge are you pushing bubbly water down drain (or into bucket) until you see it change to a solid stream of water?
Or are you hoping the normal scoop and vents do the job as the pump normally runs?
Purge out can only be as rapid as refill can come in...if refill is not as fast you would create a vaccum and suck air in any opening(s).

I'm purging into a bucket, I've tried purging with auto fill on and off, but can't seem to get air out. It appears to be a cycle, get air out and auto fill puts in new water and new the air follows. As a result, can't get heat going on the three floors. We have three zones plus a zone for the indirect. The indirect is working fine. We have two pre-pressured expansion tanks with a bladder. We have air scoops too, the heat is very faint on the floors I'm trying to heat. I get the bubbles to disappear and then once auto fill starts goes on the air returns when I purge again. This should be a simple task, but I allways have issues at the start of the season..thoughts?

Purge one zone at a time using a garden hose to supply water. Most times the fill valve wont do it even in fill mode. you can isolate your zones? If not ,hook hoses to all three and do them simultaneously. My question is why are you getting that much air between seasons...... something amiss there.

I did replace the expansion tank this year so that may be part of the issue, but I do keep getting air at the start of the season. Should the vortex taco seperator screw on top be open or tight close. I opened that up to release air and I did get some air out?

If there are automatic air vents on top of the air scoops make sure they are closed tight once all the air is out. I have seen in the past where air is let in the air vent in the off season. If you can isolate the expansion tanks from the rest of the system when purging I find that helps. I start by closing all the zones off and purge one zone at a time with a garden hose. Using the fast fill on the feeder or manual fill, get the pressure up without popping the pressure relief to help with purging. I usually put a kink in the hose to feel and hear the air passing through the restriction in the hose. Just remember to make sure that if you close valves for the expansion tanks to open them back up. The expansion tank could have been part of the problem.

Good luck,
Jason

mcguirehg wrote:I'm purging into a bucket, I've tried purging with auto fill on and off, but can't seem to get air out. It appears to be a cycle, get air out and auto fill puts in new water and new the air follows. As a result, can't get heat going on the three floors. We have three zones plus a zone for the indirect. The indirect is working fine. We have two pre-pressured expansion tanks with a bladder. We have air scoops too, the heat is very faint on the floors I'm trying to heat. I get the bubbles to disappear and then once auto fill starts goes on the air returns when I purge again. This should be a simple task, but I allways have issues at the start of the season..thoughts?

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The bigger question is how many gallons per minute are being pumped through the loops?? if its greater than 4 gallons per minute its velocity issue. You cannot pump more than four gallons per minute through a 3/4"pipe loop and expect it to heat properly.

Is the autofill pressure less than the relief valve pressure?

You may just have a large entrained air bubble in the loops.

With all the water pressure off the boiler pour an once of Dawn Dish Soap in the boiler water and no more!!!
It acts as a surfactant, breaking up the surface tension and allows the bubble to be broken up in smaller pieces which are easier to capture and expel.

Why do you have two bladder tanks when you can use one slightly bigger one for the entire system?

If the autovents are shut tight they cannot work properly. You may need a new autovent on your taco air absorber too.

The garden hose trick with all but the zone valved off gets great results since the system's auto-fill is not then a limiting factor.
Without enough velocity air will refuse to flow donward in a pipe system.
Pumping a air water mixture through the circulating pump makes lots of bubbles that get push downstream and then the air can all recombine and gather again due to not being expelled.
A vent/ boiler drain type valve installed at the highest point of system will also help to have the ability to vent air during and after initial system filling.

Installing the piping in such an arrangement with proper isolation vavles and such any system can be "power purged" quite simply to eliminate nearly all but the entrained air.

So we think the solution may be to purge the system with a hose instead of the autofill. I'll have to see how I can do this with my system..hmmm

It sounds like you never got all the air out of the system in the first place, and your further attempts to purge it aren't getting the job done. If your system has overheated and opened the relief valve, that would also explain the air.

You may need to pick up a fitting to connect two garden hoses, or use a washing machine hose. Use this to connect your garden hose to a boiler drain on the system. Close the valve on the return of the zone you want to purge, turn the water on, and then open the purge valve on that zone.

A fyi,

I had a ''auto-fill'' gunk up and not do its job. They have a fine sceen that can plug easy.

So Robs tip on using the boiler drain for a temp feed of water is a good idea.

Dave

I use Spirovent jr I have not needed to burp air out of my zones for years.
They are the best...
http://www.supplyhouse.com/Spirotherm-VJR075-3-4- ... Aiqz8P8HAQ

I use the Jr. model with the 3/4 slip fit solder on connections.

http://www.spirotherm.com/products/air-elimination

They should be available at your local plumping supply house.
Ken

You know how to fix it. Just call me and I'll take care of it.