Solar hot water automatic air vent

Daox · 09-05-21, 11:40 PM

I'm trying to choose an air vent for my solar hot water system. I have 1" PEX supply and return lines. Most air vents I've seen are 1/8" NPT, and I'm wondering if that is going to be big enough while filling the system? Does anyone have any experience with these?

SDMCF · 09-06-21, 01:03 AM

I don't know about thread specs so I don't know if the threads we have are NPT or not, but 1/8" sounds small to me. My system uses 22mm copper pipe and my automatic air vent is 3/8" (unknown thread type). There is no science behind that sizing though; I installed it myself and that is just the valve size I picked up at the store. All I can say is that it works so is big enough.

randen · 09-09-21, 07:56 AM

Yes they do work however with some limitations.
1st the working pressure reduces the volume of air exiting the device.
2nd the addition of anti-freeze also impeads the automatic feature.

1/8 NPT is the size and they can be manually operated. They work but not as effectively as the tiny boiler vent type with a screw driver slot.

Randen

SDMCF · 09-13-21, 01:15 AM

Quote:

Originally Posted by randen

the addition of anti-freeze also impeads the automatic feature.

I was not aware of that. I have had no problems with mine, which have been in use for about 14 years, so maybe the style we have here is not the same as you have over there.

solarhotairpanels · 03-12-22, 06:18 PM

Quote:

Originally Posted by Daox

I'm trying to choose an air vent for my solar hot water system. I have 1" PEX supply and return lines. Most air vents I've seen are 1/8" NPT, and I'm wondering if that is going to be big enough while filling the system? Does anyone have any experience with these?

Where on your system are you planning to install the air vents?
I installed mine inside the house on top of my drainback tank on the pipe coming from the collectors..(I used a ball **** valve for that one, I just leave it cracked open) I also installed a kind of vacum release type vent on the highest point on my evacuated tube collector which allows air into the system while the pump is running so as not end up with a vacum lock when water is draining back down into my basement.

sorry but not familiar with the type of system you're building there. :-)

09-05-21, 11:40 PM	#1
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Solar hot water automatic air vent I'm trying to choose an air vent for my solar hot water system. I have 1" PEX supply and return lines. Most air vents I've seen are 1/8" NPT, and I'm wondering if that is going to be big enough while filling the system? Does anyone have any experience with these? __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

09-09-21, 07:56 AM	#3
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 658 Thanks: 9 Thanked 192 Times in 130 Posts	Automatic air vent Yes they do work however with some limitations. 1st the working pressure reduces the volume of air exiting the device. 2nd the addition of anti-freeze also impeads the automatic feature. 1/8 NPT is the size and they can be manually operated. They work but not as effectively as the tiny boiler vent type with a screw driver slot. Randen

09-06-21, 01:03 AM	#2
SDMCF Apprentice EcoRenovator Join Date: Jul 2014 Location: Finland Posts: 125 Thanks: 5 Thanked 35 Times in 34 Posts	I don't know about thread specs so I don't know if the threads we have are NPT or not, but 1/8" sounds small to me. My system uses 22mm copper pipe and my automatic air vent is 3/8" (unknown thread type). There is no science behind that sizing though; I installed it myself and that is just the valve size I picked up at the store. All I can say is that it works so is big enough.