A curious radiator

Jedvard469

I just recently had a Burnham Mega Steam 360 installed (pics included for your critique) on my one-pipe system. From the little bit I know about steam systems (almost all learned from this site) it appears the installers did a decent job. They even corrected some old deficiencies (such as moving the main vents away from the drops).

I had trouble getting steam to the radiator furthest from the boiler. Between skimming, insulating the pipes and balancing the radiator vents I have finally gotten heat to that room. The curious thing is how that radiator heats up. As the steam rises all my other rads will heat up the section by the valve first and make its way across section by section till it gets to the last section with the air vent. On this radiator the first and last section will heat first and the middle sections will slowly catch up. Is this indicative of a problem with the radiator?

Steamhead

Probably a quirk in that rad's design. Post a pic, let's have a look at it.

Jedvard469

Here are the pictures of the radiator in question. It does have a new "Maid-o-Mist" air vent.

KC_Jones

What size vent do you have on it? The hole in the vent looks huge. I suspect you are venting it too fast and the steam is short circuiting. How much main venting do you have? How long and what size are your mains?

Jedvard469

I have MOM #D on that radiator. Once I got heat to that room after skimming I was planning to reduce the vent, just have not gotten around to it.
I have 2 loops, both 2" with one Hoffman Specialty #75 on each. The first loop is 53' and the second (with the radiator in question on it) is 42'.
What is "short circuiting"?
Also - I have a MOM#4 on the rad where my thermostat is. If all the rest of the rooms are getting too warm is it better to downsize the vents in the other rooms or just increase the vent in the thermostat room? Does it make a difference?

Abracadabra

That's a "D" MOM vent. Use a #5 and let us know how it works out.

Abracadabra

Vent the radiators slowly.

Mark N

Short circuiting is when because the rad is vented way too fast the steam just shoots across either the upper or lower nipples between the sections and shuts off the vent.

KC_Jones

Your main venting is completely inadequate. Rule of thumb is 1 Gorton #2 vent for each 20' of 2" main. Those #75 you have vent less than half of a single Gorton #2 so you need at least 5 times more venting than you have now. That is most likely your biggest problem venting that radiator and what led you to put such a huge vent on it. Vent the mains fast and the rads slowly.

Jedvard469

Thanks for the advice. I hadn't considered the main vents as a problem area. I'll let you know how it works out when it gets corrected.

Steamhead

I'd start by getting two Gorton #2 vents. Put one on each main, then add one of your Hoffman #75 vents to the longer main. This will increase the venting of the long main by about 4-1/2 times and the shorter one by 3-1/2 times.

What you want is for the steam to reach the ends of both mains at about the same time, and for this to happen about 1-2 minutes after the boiler starts sending steam into the pipes.

Then you can put a proper vent on that Thatcher radiator and the steam will distribute thru it normally.