No Main Vent, use Gorton D instead?

AdmiralYoda

Hello everyone, I'm trying to get the most out of my steam system and want to address my venting.

I have two mains, one is accessible and the other is not easy to access. For the main that is accessible I plan to put a Barnes and Jones Big Mouth on it. The other main will get some attention in a couple years as part of a remodel.

For that main that I can't get to now, there is a large radiator at the end of the run. Could I vent it with a Gorton D to help get that air out? Or would it do more harm than good? Thanks!

ethicalpaul

It's worth a try. a D is the same as a #1 vent. If it were me, I'd buy a Maid O Mist #4 or #5 and just remove the orifice which also makes it about the same as a D

It will make that radiator heat up faster, which may be fine especially since it's the last one on the line.

It could introduce some condensation rate issues in that radiator which might cause some gurgling, or spitting, or even a little banging.

but trying doesn't hurt

STEAM DOCTOR

Venting one main and not the other can cause imbalance issues. 

ethicalpaul

Yeah he said he was going to put a B&J Big Mouth on the other one. Although I'd put a MoM #1 ($18) or maybe a Gorton #2 if it's a really long main.

STEAM DOCTOR

Without knowing the lengths of the mains, I would suggest not putting the big mouth on one main until you are ready to properly vent the other main. You can always try it and see what happens 

AdmiralYoda

STEAM DOCTOR said:

Venting one main and not the other can cause imbalance issues. 

Thank you Steam Doctor and ethicalpaul. I hadn't thought about an imbalance.

A while back I calculated the internal volume of the mains. Main 1 (the accessible one) has 1.312 cubic feet of piping. Main 2 has 0.750 cubic feet of piping and ends with a large radiator.

I wouldn't be surprised if the system is already imbalanced. Main 1 has 4 radiators on it and Main 2 only has 2.

The headpipe is wrong too. Instead of a header I have two individual mains coming right out of the boiler. Not ideal at all....but its been heating for quite some time.

Aside from not having main vents and probably undersized VentRite #1's on all the radiators the system runs really well.

The boiler is oversized by 35% and I do run into some cycling on pressure if I set it back a few degrees or if its very cold out. I'm hoping improving the venting will speed things up and prevent that.

AdmiralYoda

I think I am going to answer my own question. I downloaded the "Balancing Steam Systems Using a Venting Capacity Chart" from this website, written by Gerry Gill and Steve Pajek.

They list how much air is in pipes and tell you how to calculate how much air is in your radiator based on EDR. Then you can calculate how much air you need to vent.

What I call Main #2 is really a long runout to the large radiator. If I treat it as such, using their math I can come up with what I need for venting.

When I do the remodel, I can install a proper main vent and readjust the venting on the radiator accordingly.

I'll update this post tonight and see what the results are.