Location of air vents...

Reply

  #1  
Old 08-25-14, 01:26 AM
Member
Thread Starter
Join Date: Aug 2014
Location: Canada
Posts: 21
Location of air vents...

Not sure if I should start a new thread or not but I am about to start running pex lines for each zone. I'll install air bleeder vents at each radiator (on the return side?)but are there other places in the zone loop which should have air bleed vents?

For example, baseboard along basement wall where the pex comes down from the ceiling to the radiator and then back up again to the ceiling.

Or where a horizontal run steps up with a 90 and then goes horizontal again with a 90.
I've tried the search feature but no luck.

Thanks, Iver.
 
Sponsored Links
  #2  
Old 08-25-14, 05:15 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Hi Iver,

In a well designed system, there should really be no need for air vents on the radiators.

If the boiler near piping is properly arranged so that the circulator pump is pumping AWAY from the point that the expansion tank is connected to the system, and the expansion tank is hanging from an 'air scoop' with an automatic vent on top of it, and there is provision made by means of a purge station and proper valving to isolate the individual zones at the return of the boiler, that should be all that you need.
 
  #3  
Old 08-26-14, 01:15 AM
Member
Thread Starter
Join Date: Aug 2014
Location: Canada
Posts: 21
Thanks Trooper,
Well, I don't know if I have a well designed system or not.
Here is a picture of my work in progress. I have six zones ready for the circulation piping.
Thanks, Iver.
 
Attached Images  
  #4  
Old 08-26-14, 05:31 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
Looks nice and neat...

This is the Allied Mini-Gas boiler, correct?

It appears that the circ pump is on the return side, pumping into the boiler?

You'll be hanging the expansion tank from the air scoop I presume?

Take a look at the following thread, scroll to the bottom... recommended optional valving at expansion tank... easier to service tank (check/charge air bi-annually)

http://www.doityourself.com/forum/bo...sion-tank.html

You do have the 'purge stations' that I mentioned earlier. The fact that these exist means that you probably won't need additional air vents. In any case, do NOT use the 'automatic' variety if you do install any. Use only the MANUAL types. ALL automatic vents WILL leak and when they do can seep for a LONG time before being detected. There can be damage that goes unseen and when is found is often expensive (wood rot, mold, etc).

In general, vents should be placed downstream where the flow turns downward.
 

Last edited by NJT; 08-26-14 at 07:29 AM.
  #5  
Old 08-26-14, 03:21 PM
rbeck's Avatar
Member
Join Date: Jul 2007
Location: Pennsylvania
Posts: 2,438
Likes Received: 1
This will work OK if the tank will be hanging off the air separator. I prefer the air separator on the supply due to air leaving the water as you heat the water. It is easier to eliminate air when water is hotter. I see radiant. If this will be low temperature water it is harder to get the air out on the return side. Low temp I prefer a micro bubbler.
 
  #6  
Old 08-26-14, 03:41 PM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
The install manual for the Allied boilers is a bit lacking in some details.

The fact that the circulator is not only INSTALLED on the return at shipping time (as many boilers are, but doesn't mean that's the correct place for it) but ALSO PRE-WIRED at that location leads me to believe that Allied WANTS it there.

I suspect the reason they might want it there is because this is a tube and fin type of heat exchanger and they want to keep the pressure up inside the boiler as much as possible.

So yes, as long as the expansion tank is on the air scoop, and that pump is pumping away from that point, it should be OK.

I see radiant.
I'm not sure, but I think Iver said he was installing fin-tube baseboard in his other thread...
 
  #7  
Old 08-26-14, 10:15 PM
Member
Thread Starter
Join Date: Aug 2014
Location: Canada
Posts: 21
Thanks for the replies....
Yes, it is the Allied Mini Gas Boiler.

The circulator pump is on the return side. Factory installed.

Actually the expansion tank was supposed to be installed on the fitting directly above the tank shown in the photo. Just after the pressure reducer valve.

There is a valve there to close when replacing the tank.

Yes, this is a fin and tube baseboard system.

Where is the "air scoop"?

I installed the drain valves in the return manifold but otherwise the rest was set up by my boiler contractor.

Thanks, Iver.
 
  #8  
Old 08-27-14, 07:23 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
OK... well, that's just wrong.

First, the tank should not be installed laying on it's side, they are intended to be HANGING with the water spout end UP, and the air fitting DOWN.

You could have problems with air in the system if you install the tank at that location. The object is for the circ pump to PUMP AWAY FROM the tank connection point, and by installing the tank on the air scoop, you will be doing so. Installing the tank at the other location and you will be pumping TOWARD the tank... you don't want to do that.

The black chunk of iron to the left of the boiler in the pics is the air scoop. There should be a 1/2" pipe thread in the bottom of that device into which the tank should be installed.

You need more than a single shutoff valve to service the tank. You also need a DRAIN valve between the shutoff valve and the tank. This drain valve will be used to relieve the pressure on the water side of the bladder when checking and charging the air in the tank. Please look at that thread that I linked to for better understanding. If you don't add that drain you will be forced to de-pressurize the boiler every time you want to check the air charge in the tank.
 
  #9  
Old 08-27-14, 09:09 PM
Member
Thread Starter
Join Date: Aug 2014
Location: Canada
Posts: 21
Thank you Trooper very much....
It is difficult to know what is right when I'm dealing with my own inexperience. I really want to know how the system is suppose to operate so I can deal with any problems.

I printed your last comments and I will mention them to my boiler guy to see what his explanation for the existing plumbing.
I appreciate all you help.
Thanks, Iver.
 
  #10  
Old 08-28-14, 06:56 AM
NJT's Avatar
NJT
NJT is offline
Member
Join Date: Oct 2006
Location: USA
Posts: 23,539
Likes Received: 1
You're welcome.

I printed your last comments and I will mention them to my boiler guy to see what his explanation for the existing plumbing.
Don't be surprised if he takes offense.

Good Luck!
 
  #11  
Old 08-28-14, 10:36 AM
Member
Thread Starter
Join Date: Aug 2014
Location: Canada
Posts: 21
Actually the more I read about your explanation of the air scoop and expansion tank it really
makes SO much common sense. I will be putting in two valves as you suggest to make the servicing easy. Again, it just makes sense.
Thanks, Iver.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes