Dimension A

Marko34

Hi guys!

I have a little issue that I'm scratching my head with and need your help. I have the old piping on the back of my boiler that came with the house. It's hard for me to make a conclusion as to where the Dimension A is.

If you look at the pictures, dry returns 1 and 2 in red are 36" and 32" from NWL, when they have a 90" vertical drop to a yellow pipes which are 21" from NWL and run parallel with the back of the boiler and then drop 90 again and become wet returns.

My question is: what determines in my case the Dimension A, the red pipes distance to NWL or the yellow ones? This vertical drop between the red and yellow pipes are confusing me as who determines the Dimension A in this case.

Thanks all!
Marko

the_donut

Are those lines trapped further back? Are you sure they are dry returns?

DanHolohan

It would be from the yellow pipes.

nicholas bonham-carter

Where are the main vents for those lines? There seem to be two dry returns connectected together before the drop.
Is your waterline stable as pressure begins to rise? There can be a problem with any horizontal return whose height is so close in height to the height of the boiler waterline. As pressure rises in the boiler, the waterlevel in the wet returns will rise 1.76 inches for each ounce of pressure, and filling the horizontal element will hide a considerable amount of water, sometime triggering the LWCO.
It would be better to drop those dry returns individually straight down to the floor to avoid this.
Connecting a vertical clear hose to the boiler, or return drain will show you the rise in level as the pressure rises when first firing.—NBC
I should add that the hidden water reappears as soon as the boiler flame cuts off, as the pressure goes to zero or below.

Marko34

@the_donut Yes they are dry returns.

@DanHolohan Thanks for clarifying this Dan!

@nicholas bonham-carter NBC, sorry but the picture is dark as its in the boiler room and may sway you that the dry returns are connected together, but they are not. They run individually parallel to each other in the drop and then they unite at the mud leg as you can see on the 2nd picture. As far as the main vents, I have Big Mouth on an elbow on each dry return before the drop. See the new pic. Putting them 15" before those elbows was too expensive of a job. As far as Dimension A being at 21", I have no water rise when pressure rises. The heating is working with no issues. I have normal water fluctuation of about less than 1/2" during heating cycle.

However, I will raise the those horizontal (yellow) pipes above 28" to obtain Dimension A.

My only question is that copper pipe in picture 2, which is an independent dry return from a baseboard heater. Do I need a vent on it, and so, which one, Gorton #1 or something smaller?

rbeck

Not a great place for the vents. They should ar the very least be 6" from the tees to keep water out of them.

Jamie Hall

On that copper pipe from the baseboard heater -- yes, there should be a vent on it. Otherwise, how does the air get out? The real question then is what size -- and, oddly I would treat it in much the same way as if it were a single pipe radiator: size the vent to get the heat I wanted out of it.

JUGHNE

For the air vents you have, if you replaced the street 45 ells with 90/nipples and headed back towards the returns with a 6" horizontal nipple then a 90 up with nipples as high as possible you get the vents away from any water hammer/debris effects. Just so the horizontal nipple is pitched to drain condensate back to the return.

This in effect gets them removed from the "bad" spot. IMO

Marko34

@rbeck It's the camera angle that made the nipples leading to the vents look short. The distance between the tip of the 90 elbow and bottom of the vent is actually 7 1/4", when I measure it at 90 degree angle

@JUGHNE That's a great idea, but I don't have a clearance for such a "maneuver". On one return I have a chain that is holding the pipe and on the other a perpendicular pipe right above it that blocks your idea. I'm at 7 1/4" height now from the elbow. Thanks for the input though, it's genius!

@Jamie Hall Thank you for your input! Your idea is absolutely logical threating the return like a radiator. It's a 10' baseboard that didn't have return vent prior to me moving in the house. I did put single Gorton #1, since I had 2 laying around, on that return few days ago and A. I didn't notice a change in it's performance before or after main vent implementation in that return, it was still warm like it used to and supposed to be, and B. It actually broke nice radiator equilibrium that I achieved thru a lot of changes in the syatem. All of a sudden the further radiators were not getting warm enough. It's most likely Gorton #1 the culprit being too big maybe and that radiator being the closest one to the boiler. I gotta try smaller vent, but I don't know which one...