Theory Verification (or invalidation)

Steamhead

you need more vents. I'd start with two Gorton #2 vents and go from there.

If the last takeoff is only a couple feet or so past the main vents, you can probably get away with keeping the vents where they are. Steam will overshoot the vents a bit. If they're further away than that, you need to relocate the vents.

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Thad English

Steam Theory Verification (or invalidation, as the case may be)

I have a 2-pipe air vent steam system that has been working fine but with the boiler just kicking on for the season I am noticing a little oddity. The 2.5" main is insulated and vented with a Hoffman 75 (I also have a Gorton #2 that I may switch out the 75 for). The main runs around the perimeter of the basement and is about 100' in total length. The oddity is that the rads that are tied to the last takeoff on the main are not getting nearly as hot as the other rads on the same floors. For example, only 2 rungs on the last-takeoff rads are warm while 6 rungs are warm on the second-to-last-takeoff rads. These 2 rads are only about 10' apart on the second floor. The last takeoff is piped to the main 'after' the main vent. My theory is that I need to add another main vent somewhere so that the air isn't trying to be vented through the last takeoff. It can be added to create a "tree" or should it go somewhere else? Is my theory sound? Does anyone agree? or is something else afoot?

Thad English

thx

Thanks Steamhead. The last takeoff is only about 18 inches beyond the vent. Currently the hoffman 75 is atop a 16" high 3/4" black steel pipe coming off a tee on the main. Can I unscrew that 16" pipe and replace it with a "tree" of the 2 Gortons? I was thinking about going off the main using a 6"-10" long straight piece of black steel going into a Tee then a 90 off each end of the tee, then a reducer to 1/2" and finally connect each Gorton. Essentially a Goalpost shaped tree. Will this work? Or is there a better way to get shape the tree?
Thanks in advance,
Thad

Matt Undy

If it was working before, maybe the vents on the final 2 rads have plugged slightly? Are the valves open all they way? Maybe larger vents on the rads would help balance things out too?

Matt

Thad English

That was my first thought too, so I made sure the valves to the rads were all the way open and then I took the steam vents off and blew through them to make sure no debris was lodged in there. All to no avail.

Steamhead

That should work fine

let us know how well it does!

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Thad English

tree is in

Last night, I put in the "tree" as described but I am using the 75 and the Gorton rather than 2 Gortons. All I can say is the system is heating super fast now. I am getting steam to that last takeoff very fast, but the radiator is still not heating at the same rate as its sisters. I think there may be some sort of blockage in the supply line or just inside the radiator itself. The supply pipe was hot mere minutes after I fired up the boiler with the new vents on the mains last night but the rad itself was slow to heat. Pulling it and cleaning it out may have to wait until after this heating season. I don't imagine there is a DeadMen's trick to cleaning out a radiator without removing it from the system.......or could I just crank up the steam pressure for a little while and try to use the steam itself to clear the blockage?

Matt Undy

Let me get this clear..

There now is only one radiator that isn't heating well, correct? How does it heat if you pull the air vent altogether and allow it to fill without whatever restriction is built into the valve? I'm still thinking the air vent valve is restricted or too small. There is also the trick of driling and taping a second vent below the original vent to make it vent faster.

The slow venting mains might have given the radiator more time to fill and now that you've fixed that you need to fix the vent that was too slow in the radiator.(are you completely convinced that the vent has the flow that it had when it was new in its open position and hasn't gotten some scale or particles in it somewhere?)

I'm reluctant to say its a restiction becuase it would probably collect condensate and bang at the restriction.

Matt

Thad English

It heats at about the same rate whether the 1 season old Gorton is on the rad or laying on the windowsill next to it so I don't think it is the vent. I blew through it yesterday and it sounded okay. I think I have a spare of the same venting rate or bigger so I'll swap that out tonight just to be sure and see what happens. I hadn't thought about the condensate banging at the obstruction, though. I haven't noticed it, but then again maybe I just wrote it off as hot steam meeting cold iron. Tonight I'll crank the thermostat back up and see if I notice anything on that rad. What I haven't checked, though, is whether or not the rad on the same takeoff but one floor up has a bad vent. That would slow down the venting on this entire take off since they are both piped into it. Thanks for the ideas, Matt.





-Thad



PS: Go Blue!! (class of 93 myself)

Thad English

d'oh!!

Something else JUST occured to me and I think I may have been driving myself batty for nothing: In July, I had the exterior walls and steam chases in the house filled with cellulose insulation. The house is a big 96 year old Tudor that had no insulation between the plaster interior and the stone exterior. But we didn't do the chase that the 'last-takeoff' runs up because it cuts through the kitchen which is going to be gutted in the spring. We didn't want to spend the money to do it only to have it all over the floor in 6 months during demo. The other chases are going to transmit the steam to those rads nice and fast since there is low loss. The last in the line does't have the insulation and thus, loses btus in the chase, condenses, and doesn't make it to the radiator as fast. At least that is what I think is happening. What do you think, Matt? Maybe Steamhead will weigh in with his opinion too.....

Steamhead

That might be it

but also check the pitch of the pipes from the main to the radiator to see if water is laying in them, and see that they are the right size.

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