Where to vent basement baseboard rads


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Old 03-08-12, 02:37 PM
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Where to vent basement baseboard rads

A little background info: I live in a 1920 bungalow with a hot water boiler in the basement and two send/return loops of cast iron radiators on the first floor. They all vent at the radiator and drain at the boiler.

I've added a second zone for baseboards in the basement. You guys were super helpful a few months ago in helping me figure out the heat loss, boiler capacity, pipe size and all that. I settled on running a loop through the ceiling joists that drops down in 4 places for baseboard rads. Each drop with tee off the main loop with a vented ball valve and a drain after the rad. I should be able to drain the rads individually by closing off the valve and draining that section. The main loop can drain from the boiler drain.

My question is, do I need to vent that main loop, and if so, where? My thought was to buy an automatic air vent and place it up in the ceiling (above the boiler) off the send pipe. Does that make sense? Should I put one on the return pipe too?

Thanks!
 
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Old 03-08-12, 03:48 PM
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Can you show us a diagram or pictures of what you did?
 
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Old 03-08-12, 04:20 PM
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Can you show us a diagram or pictures of what you did?
Yeah.. probably should have in the first place

Here's the entire loop from an overhead. The pipe is in the ceiling all the way around except for the drops down to the baseboard radiators/kickspace heaters and the boiler.



EDIT: That was an older image, here's a more up to date plan:



Here's a side view of the drops for a radiator/kickspace. I'll probably put the two ball valves higher on the wall. The ball valves say "drain" but they're just small vents I'm going to use to let air in if I need to drain just one radiator. (NJ Trooper, I ended up using glove valves instead of ball valves along the main loop like you suggested.)



I could put a vent at the top of each drop but the main loop that's in the ceiling will be pretty level so I think I should be able to just vent it once or twice - or maybe I don't need to at all?
 

Last edited by HomeAlterations; 03-08-12 at 04:36 PM.
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Old 03-08-12, 08:50 PM
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If you come directly off of the main in a downward direction use crosses instead of tees and put the vent in the top of the cross. If you use tees going horizontally and then to elbows going downward then use tees instead of elbows with a vent on the top of the tee. You really only need the vents on the return side but ALWAYS install the vents at the high points. Having a short nipple to act as an air collection pot is always a good idea if you have the room. I would also install the isolation valves up high.
 
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Old 03-09-12, 12:13 PM
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If you come directly off of the main in a downward direction use crosses instead of tees and put the vent in the top of the cross. If you use tees going horizontally and then to elbows going downward then use tees instead of elbows with a vent on the top of the tee. You really only need the vents on the return side but ALWAYS install the vents at the high points. Having a short nipple to act as an air collection pot is always a good idea if you have the room. I would also install the isolation valves up high.
Thanks, Furd. I understand your suggestion, however, the ball valves I have on each drop already have vents which I can use to drain the individual drops if I need to. Do I need to vent the main loop at each drop or can I just have one vent since that main loop is all at about the same height? I'd like to just vent it in the boiler room if it's all the same.
 
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Old 03-09-12, 02:33 PM
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You may do whatever you want, it makes no difference to me. You will find that if there is an air bubble in the line the water will NOT go down to the heater and the same holds true with the return riser.
 
 

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