What is the best way to purge air in hydroair zone?

bill_97

What is the rating on that relief valve ? If it is on the boiler water side , you'll need to change that one out to a 40 psi also . I'm not sure about the Ergomax specs but the additional relief valve might be required . And it's good to have a backup . But first , check and make sure your boiler and indirect are rated for the extra pressure . Most boilers we work with are rated to 50 psi and installation instructions are readily available online if they're missing . And as was suggested , you'll have to increase the expansion tank pressure to match the new cold fill pressure .

If the leaky relief is on the domestic water side , that's a different problem altogether .

Any chance you can take some digital pics and post them here ?

Dan_53

What is the best way to purge air in hydroair zone?

We have a hydroair system with 3 separate air handlers. Each has its own Taco 007 pump. Yesterday, I noticed that our 3rd floor system (highest zone) was blowing cold air. I thought it was a bad pump, but when the gas co guy came out, he said it was airlocked. He bled some air and said that we need to have someone come out and purge the air.
In the basement, the pump is on the outflow leg, and there is also a faucet for bleeding on the return leg with a gate valve between it and the return manifold.
How would I go about bleeding this loop?
I figured I would run the pressure up to 25 with fresh water and then open the faucet in the return line with the gate valve shut off to the return manifold. I got some air out but still no heat although pipes leading away from the pump are getting hotter. Any tricks as to how to purge the zone? There is also a faucet at the air handler in the attic along with an air elimination vent that our installer had turned off (3 yrs ago) because he said they leak and can entrain air.

tom_49

air purge

Dan,

You are doing it correctly, just keep purging until all the air comes out. It has found the high point in the system and could take a couple of minutes.

I would install a good air seperator if you dont have 1 already. This should prevent this from happening again.

Good luck, Tom

John@Reliable_14

Your on the right track.....................

This way never fails me. Do what you already said you did but, put a hose on the purge valve and run it outside or into a sink if handy. Now the trick, put the open end of hose into a bucket and purge away. With the hose into the bucket you can "see" the air coming out. A large air mass(bubbles) will come first, and then the micro bubbles will follow. I wouldn't stop at only the zone not heating, if air is there it's most likely system wide as little micro bubbles. Purge all the zones, for say 15 minutes each for a true air free system. John@Reliable

Dan_53

We have a

spirovent air separator that is installed above our pressure tank just beyond the fill valve. I'm surprised that we have had any air at all, since it's supposed to be the best. We also leave the autofill valve off since there is glycol in the system.
Why would we be seeing air after 2-3 yrs of the system running?

Dan_53

We have a

spirovent air separator that is installed above our pressure tank just beyond the fill valve. I'm surprised that we have had any air at all, since it's supposed to be the best. We also leave the autofill valve off since there is glycol in the system.
Why would we be seeing air after 2-3 yrs of the system running?

tom_49

Dan,

If you have the fill valve off you could have a very small leak somewhere. Fluid is leaving the system and not getting replenished allowing air to enter the system. Just a thought.

And if the gas co. comes to your house to fix your heat, why cant they bleed air? why use the gas co. at all?

Dan_53

We had autofill shut off because with glycol in system,

they said that it could be diluted if there was a small leak (2 air handlers and piping are in unheated spaces).
Gas company service contract specifically does not pay for purging system. I looked up terms online. It just covers equipment failure. But they better not charge me for the call as we still do not have heat upstairs until I finish purging the line.

Joe Mattiello

for your reference I attached a document to help you with your air problem. Hoefully this helps you

Dan_53

Thanks guys.

OK, I purged the system and got a crapload of air from the 3rd floor hydroair unit. we have no leaks anywhere. How could we build up so much air? The air elimination vent was shut off up there so as not to entrain any air.

bill_97

3rd floor air handler ?

and the boiler is in the basement ? Is the air handler in the attic above the 3rd floor ?

Even if the air handler is on the 3rd floor itself , you might not have enough pressure to keep the water that high . On jobs like this we always wound up changing the boiler relief valve to 40 psi and increasing the boiler pressure to between 25 and 30 psi .

Dan_53

Yes, the 3rd floor

air handler is indeed above the 3rd floor (approximately 39 feet above boiler). The boiler has a 30 psi prv. I had asked the manufacturer (boiler is Lochinvar EBN300)at the time that we added on to the attic if we should increase the prv to 40, and they said no. Should we do that and run the boiler at a higher pressure?

hot_rod

oversized piping?

may be the cause. If the velocities are too low, below 2FPS the fluid stream will not carry the air to the high points. maybe it never had a good purge from day one?

a quality brand air vent with iso valve below it should help.

hr

Dan_53

We had a Honeywell

vent at the highest point. Just replaced it with a new one. Also, it had been shut off as the installer said they can leak or pull in air if pressure drops. Currently it is open. The piping is 3/4" copper with a Taco 007 pump.
What do you think about increasing pressure of boiler to 25-30 and increasing prv to 40 psi?
The attic air handler is about 40' above boiler. Currently we have a Watts M335 prv. The boiler is 300K btu. What would be the correct model prv to replace it? I'm thinking a Watts 174A with 40 psi setting. Would that be correct/ Thanks

tim smith

Re: air in system and pressure settings

I would set the prv to 24 psi, thats plenty to get it up 40 ft w/ some extra. Regarding pressure drop. This may have been caused by compressing air out of system over a period of time through spirovent and with no fill valve, you could not makeup the volume of water displaced by venting so in turn, air bound at top. After you have filled now, you may want to keep fill valve on for a few weeks anyway to replenish as air is vented. Then make sure you are at 24+ psi when you turn off. Also make sure your relief is not dripping when heating, this also could be where you are losing water! Tim

tim smith

Re: air in system and pressure settings

I would set the prv to 24 psi, thats plenty to get it up 40 ft w/ some extra. Regarding pressure drop. This may have been caused by compressing air out of system over a period of time through spirovent and with no fill valve, you could not makeup the volume of water displaced by venting so in turn, air bound at top. After you have filled now, you may want to keep fill valve on for a few weeks anyway to replenish as air is vented. Then make sure you are at 24+ psi when you turn off. Also make sure your relief is not dripping when heating, this also could be where you are losing water! Tim

hot_rod

when you increase the fill pressure

be sure to adjust the pre-charge in the expansion tank. Also make sure you have enough expansion volume.

hr

Dan_53

I will set the prv to 24.

It is a Watts autofill 1156F. We have had no leaking from relief valve. When I tried to increase pressure on Watts autofill, I could not screw the little cap with the lever back on. Also, if I set the prv to 24, what should the expansion tank be set to?

Joe Mattiello

Dont forget to adjust the precharge pressure on the expansion tank as well.

Dave_61

Ron,replaced the relief valve with 40 psi unit.

And have pressure now set at 25 cold. However, we have an ergomax indirect tank piped to boiler in primary loop. ergomax tank keeps spitting water out of its relief valve. Do I also have to increase relief valve on ergomax? Since it is part of boiler circuit, does it even need relief valve as boiler will pop open at 40?

Dave_61

It is on the boiler side.....

But with the pressure at 24 to start and rising to 28, there is no popoff presently. I also couldn't find any ratings on boiler or ergomax as far as what pressure they are rated for, but I don't anticipate pressure rising much past 30 when hot. The boiler was quicker to release water than ergomax.
One other thing....the expansion tank is attached below a shutoff valve, and the valve has a thumbscrew on it to purge excess pressure with shutoff valve off. Do i have to actually remove the expansion tank or can I just shut off valve above tank and open the little knob on the shutoff valve to release pressure to get a reading as to the tank pressure. I assume if my pressure in the system is 24 psi, then the tank should be about 20? Thanks again.