Effect of Air return on heat efficiency

Fizz

Have a Richardson system with 2 loops: one has 137 sf of attached radiation, the other 221 sf. Booth are vented by 1" dry air returns by same vent above boiler. The loop with 221 sf heats less efficiently than other but it's no major problem. Richardson literature stresses need for each loop to have own vent, also, where more than 200 sf is attached the dry pipe should be 11/4" from radiator that puts sf over 200sf. Would changing pipe be wise? Talking about a 16' run to drip. Adding a vent to this line entails cutting-off and dropping a new drip as both loops shared same dry drip. In the past I've removed vent to see if it made a diffenence, it did not.
Fizz

Jamie Hall

The caution applies if the dry returns are not connected together, but drop individually to the wet returns. Where they are connected together as dry returns, it is not a problem.

Steamhead

What vents do you have on your dry returns?

Fizz

Jamie both returns share same vent above boiler and same return. My thinking is to drop aforementioned return to shared return below water line, and supply it with separate vent.

Fizz

Steamhead, . Initially replaced old vacuum vent with maid o mist, then Gorton#2, even open pipe. No difference. currently have system in vacuum and it is the best it's been since I've been here-15 yrs.

Jamie Hall

Fizz said:

Jamie both returns share same vent above boiler and same return. My thinking is to drop aforementioned return to shared return below water line, and supply it with separate vent.

Why bother? First off, if it works, don't fix it. Second, if steam is not getting into those dry returns there is no need to separate them.

PMJ

Fizz said:

Steamhead, . Initially replaced old vacuum vent with maid o mist, then Gorton#2, even open pipe. No difference. currently have system in vacuum and it is the best it's been since I've been here-15 yrs.

That's been my experience with two pipe. Dry returns connected before the drop to wet, one vent/check valve there so vacuum develops between the firings. Nothing else came close to the performance that way.

SWEI

Another data point showing the potential of a (partial, natural, simple, practical) vacuum steam retrofit.

Fizz

Thanks to all, and a Happy New Year!