Best place to add air vent in this system?

mabo

Hi All. It seems that the air scoop in my heating system is not very effective. I will hear air rush past it and it never seems to eliminate it. I replaced the vent and made sure cap is lightly unscrewed. That did not change anything. I was advised that a better air vent is necessary (like a SpiroVent).

In my system, where would be the best place to install a vent (or vents)? There aren't many horizontal runs of pipe, which is why I ask. In my eye there are three places:
1) Bottom right elbow of primary loop. But there is very little horizontal run to the right in that case.
2) Vertical run up of primary loop. But it's vertical.
3) Horizontal run outside of primary loop on the way to the supplies. But it's outside of the primary loop.

Boiler primary loop:


The whole system:


Also, given the vertical setup of the primary loop T's. Is it possible to install a LLH in that spot instead? If not in the current spot, where might be a good spot?

Rich_49

Please stand a bit farther back and show us more left . Wanting to see the entire system in one shot . Please include model #s of all circs in this system

mabo

Here it is:

Every pump is a 3-speed Grundfos UP15-58. The smaller indirect is not piped up, and is earmarked to be repurposed as a buffer tank in the future.



The original picture is very large, if you right click Open in New Window.

Rich_49

What Prestige boilers are they , 110 , 175 ?

mabo

The left one is a 175. I am running on it exclusively, as it seems to match the theoretical heat loss pretty closely, though a tad small. Theoretical heat loss is 165k versus 133k from boiler, but I can get them to be closer apart if I discount fireplaces from the calculation.

The one on the right is a 110, and it's currently valved off. The short term plan is to see if the 175 keeps up in practice and then keep the 110 as a backup. Medium term, if the 175 doesn't keep up, I would consider cascading them with 110 as master and 175 as slave and have slightly better turn down (each is only capable of 4:1). But this second option seems to be overkill in practice.

HomerJSmith

The best place for an air separator is on the hottest water and that is the hot water supply to the heat emitters.

Don't put it where you indicated on your picture as there is too little space for it to fit and not enough straight pipe before water enters it.

Put it on the vertical supply pipe with the red arrow. Use a Caleffi 5517 vertical air separator and have a least 10 pipe diameters of straight pipe before entering the separator.

https://www.caleffi.com/usa/en-us/catalogue/discalr-air-separators-vertical-or-horizontal-pipes-brass-551705a

HomerJSmith

Make sure that the vertical air separator that you choose to use can handle the flow in terms of gal that your boilers are sending out.

Maybe "Hot Rod" has a video on this product.

HomerJSmith

The horizontal air separator has a lower CV than the vertical air separator.

mabo

The Caleffi 5517 looks promising, but it seems to only come in maximum 1" diameter connection. The primary loop and surrounding piping is all 1 1/4". Can that still be made to work?

Also, would it make sense to have more than one air separator? One on the vertical supply of the primary loop, and perhaps a second one on the long horizontal supply (the one that heads left before looping back around into the air scoop)?