No heat in one zone - troubleshooting help needed

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Old 12-04-16, 02:06 PM
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No heat in one zone - troubleshooting help needed

We have a boiler system with 3 zones. 2 are working, although we suspect heat output may be diminished (not sure), one is not. We have replaced zone valve head assembly (honeywell 8043E), including motor and end switch, and ball valve. We have ruled out thermostat and wiring. Finally thought it might be an air lock. We tried purging air, but didn't get much water (~0.5 gallons) from any of the zones. Seems like purging the air is a simple process, but it didn't work. Can't figure out what we're doing wrong. Any ideas? Details and drawing on blogpost:
Skye Cooley Fine Woodworking

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Old 12-04-16, 02:35 PM
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H,
How are you purging. Where is your boiler fed and with what. Are you opening your ZV when purging. If not opened manually water will not get by to draw off.

Hope this helps.
 
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Old 12-04-16, 03:46 PM
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hilary –

I don’t think that is the correct procedure, but I’m no expert. I think you have to have a water source to push water through the zone to force out the air. I don’t think you do it via gravity. It seems to me between steps e-f the fast fill lever on the Pressure Reducing Valve is supposed to be lifted to force water through the zone.

I never had to actually do it myself so I’m not absolutely sure. Maybe one of the knowledgeable guys will weigh in here.

Also when you set the air pressure in the expansion tank I think you actually have to bring the pressure in the system down to zero before you can set the pressure in the tank. I think it may be unknown now what the air pressure is in that tank. I think the pressure in the tank is supposed to be set somewhere around 12psi. Again, maybe one of the knowledgeable guys will jump in here. Hope so. (I get cold just thinking about AK! And Wow – what great art work).

3.) Attempted to bleed air from system following these steps...

a. Shut of power switch for boiler
b. Shut off all 3 return valves
c. Connect hose to basement zone drain valve
d. Grab 2 buckets
e. Push basement zone valve lever to Open (to the right), make sure it hooks in and stays put
f. Slowly open basement zone drain valve to let water start to flow
g. Let water flow until no air comes out (we got less the 1 gallon from basement zone)
h. Shut off drain valve to hose
i. Repeat process for next zone (valves, hose, lever, bleed)
j. Pull up on pressure value to increase pressure (no effect, no change on dial)
k. Return pressure valve back to original position
l. When all successfully(?) purged, open valves, return valve lever to Auto, and turn on boiler switch again.

>> Result - Purging air from basement zone yielded less than 1 gallon before water stopped flowing. Purging other zones next yielded almost no water. We suspect we are either doing it wrong or too much air is in the lines to allow purging this way.
 
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Old 12-04-16, 07:34 PM
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Thanks Spott. Boiler is fed via well. Yes, opening the ZV when purging. I followed the following instructions to purge:

To purge the zone of air, do this:
1.turn the switch off to the boiler
2. Open the valve on the fill line and allow the boiler to pressurize to at least 12 psi. More would be better (20 psi), but that would involve adjusting the fill valve or opening its manual bypass lever which can over-pressurize the system and pop the relief valve.
3. Connect a hose to the black handle boiler drain valve circled in the pic.
4. Place the other end of the hose where it can discharge water safely - like outside.
5. Close the red handle valve circled in the pic.
6. Move the manual open lever on the zone valve to where it latches in the open position. It's under the wire terminals and will offer resistance when moving it open.
7. Open the black handle boiler drain with the hose on it allow it to discharge until a solid stream of water comes out with no air. Do it for at least 3 - 4 minutes, but keep an eye on the boiler pressure gauge. If it drops below 8 -10 psi, close the boiler drain until it gets above 12 psi. Keep doing it until no air is coming out of the hose.
8. Close the zone valve. Leave the red valve closed if you need to do the other zones.

We can't get the pressure to get any higher than 12 psi no matter what we do.
When we've purged, all we got was a quick dribble of water and then nothing. Pressure dropped to about 10 psi. I closed the drain and waited, then tried again - same thing.
 
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Old 12-04-16, 07:38 PM
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Thanks zoesdad.

I did have the water feed valve open when we purged, so there was a water supply. still nothing!
 
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Old 12-05-16, 04:43 AM
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purge

Hi, It sounds to me like you're not getting enough flow through your auto-fill pressure reducing valve (assuming your pressure gauge is correct- read the sticky at the top of the page re: verifying) When you lift the lever on the valve you should get increased flow and pressure into the system. Be sure the shut-off valve feeding the boiler is open. Those auto-fill valves have a screen in them that can get clogged. You need good flow in order for air purging to work. Good luck, Steve
 
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Old 12-05-16, 11:38 AM
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You must get pressure into the zone in order to force the air out. 12PSI will not do it with any degree of success. You should have at least 25 PSI or so as long as you do not reach 30 as that is where your relief valve will blow off. This step is very important because the final objective when bleeding a system is when done no more fresh water gets introduced into the system as that is what brings air into your system.

By trying to bleed with 12 PSI as the water comes out fresh water replaces it because that is what your feed valve is set at. You bleed at higher pressure and when done drain what excess there is to get you back to normal pressure. I like to run around 18-20 PSI.

You mentioned bleeding the basement zone. I'm guessing the return line is above the heat along the walls. Remember, water WILL NOT flow up hill by gravity or at least not in MA. haha. You will need pressure especially to bleed that one. If you cannot get it from your boiler feed valve get a hose and feed the boiler externally.

If you have a faucet that excepts a hose connection, get a garden hose and a washing machine hose because you need 2 female ends. You can feed the boiler from the faucet to the boiler drain at the bottom of the boiler. The well pressure being greater than the boiler pressure the water will push through that zone to remove the air.

Be careful of the high pressure in the boiler as to not reach 30 PSI when doing this. Should use 2 people that can communicate. One to bleed, 1 to operate the faucet.

Hope this helps.
 
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