Venting question for 2 pipe system

Koan

I finally have everything running well.

10 radiators from 4 to 14 sections, plus one large 30 section beast. all new steam trap cages on the Hoffman 18s and one oddball Webster (not on the big radiator. Have a big mouth 2CR cross-over on one main (very long main) and a Hoffman 18 as a cross over on the short main (under good advice from the best). The short main rads get hot fast, so the Hoffman 18 as a crossover seems to work fine and is not in question. Dry return vent is a Gorton 2

After skimming I can run the temp from 65deg to 80 deg and never short cycle on pressure. Holds a steady 3oz.
Before skimming the oversized boiler would always cycle on pressure and the last radiator on the long main would not get hot.

Now the last 12 section radiator at the end of the long main gets hot all the way, but the 30 section one near the beginning of the same long main takes a long time to get hot all the way across.

Would putting a B&J 122A rather than the Hoffman 18 on the large radiator be smart, or is the heating delay more because of the fact that it is just so damn big and more an issue of thermal mass?

For reference, the long main supplies the following (5 tube unless noted) radiators in order:
1) 14 section 49 EDR
2) 30 section 105 EDR six feet + (vent in question)
3) 11 section 38.5 EDR
4) 8 section 28 EDR (Webster O2H trap)
5) 7 section 24.5 EDR
6) 6 Section 3 tube 14 EDR
7) 12 section 49 EDR (at end of main)
for a total of 301 EDR

Second shorter main has 4 radiators totaling 98 EDR
Total EDR is 399, boiler rated for 750 EDR.

Jamie Hall

I'd say it's much more a factor of the size of the thing -- some of those big radiators take forever to heat up...

Sailah

If you used one of our cage units in the Hoffman 18 it will essentially work the same as a 122a so would be no different.

Koan

@Sailah

Would a faster vent make any difference?

Also - but separate issue
Can a BJ 2CR be used in place of a Gorton #2 as a main vent on a dry return??

Thanks

Koan

@Jamie Hall

Thanks. Kind of makes you wonder why not use two smaller ones.

Sailah

Koan said:

@Sailah

Would a faster vent make any difference?

Also - but separate issue
Can a BJ 2CR be used in place of a Gorton #2 as a main vent on a dry return??

Thanks

I don't want to wade outside my pay grade so I'll leave the first question unanswered. Probably best answered by someone who has seen your system in person I would think.

The second question, yes the crossover trap you have is essentially a Big Mouth but in 1/2" flavor. The other difference is that the seat in the crossover trap is machined brass vs silicone o ring in the big mouth. We did that because in a trap the outlet would be connected to a return of course and any drips would get back to boiler and not on your basement floor. We went to the o ring in the big mouth to get a 100% seal because the outlet is exposed.

So yes you could use it, but it may leak a few drops. As a vent the only difference between it and a Big Mouth is 1/2" tailpiece and brass seat instead of silicone o ring.

Koan

@Sailah Thank you sir. Are we talking a few drops like a 1/2 el and a nipple 1" long pointed vertically would solve it?

Sailah

It depends. If it's far enough vertical that water has a hard time reaching it then yes. But if it's close to line then it may drip a little, they are designed to do that.

Koan

@Sailah Sorry I was so unclear - I meant on the outlet side like this so any drips just run back into the trap and into the main:

Sailah

Sure that would work

Koan

@Fred
I saw this on a prior post:

"... a 1" pipe is not adequate to support 65 EDR. You may get about 2/3's of that large radiator heated with a 1" pipe on a two pipe system. That and the extended horizontal run on the return are the issues keeping that radiator from heating. As I suggested earlier, in this thread, shorten that nipple under the trap by a couple inches and use a couple 45's (one at the radiator end and one at the trap end of that horizontal) and you will get about 2/3's of that radiator hot. See if that is sufficient to heat your bedroom. If, not, you will have to have a 1.25" supply pipe run to replace that 1" pipe to support that 65 EDR radiator. "

__________________________________________________________________

Does this mean I should consider increasing the diameter of the feed drop off the main to the large 30 section 105 EDR radiator mentioned below?
It is about 8 feet of 1" pipe off the main with one el. The main is 1 &1/2 I think. Or is that short a run of 1" simply irrelevant coming off a larger main and not worth trying to remove a nearly 90 year old bushing.

For reference, the long main supplies the following (5 tube unless noted) radiators in order:
1) 14 section 49 EDR
2) 30 section 105 EDR six feet + (vent in question)
3) 11 section 38.5 EDR
4) 8 section 28 EDR (Webster O2H trap)
5) 7 section 24.5 EDR
6) 6 Section 3 tube 14 EDR
7) 12 section 49 EDR (at end of main)
for a total of 301 EDR

Second shorter main has 4 radiators totaling 98 EDR
Total EDR is 399, boiler rated for 750 EDR.

Fred

Even on a two pipe system, a 1" supply pipe to that 105 EDR radiator isn't going to supply enough steam to heat that entire radiator. I guess my first question would be: How large is the area that radiator heats? That is so large that it may not make a lot of sense to increase the supply pipe enough to try to heat the entire radiator and then try to find ways to slow the steam down because the area is too hot. Having said that, how much of that radiator gets hot with the 1" pipe? A third? half? Does that rad appear to be original to the house? Does the supply pipe to it appear to be original? With a total of 399 EDR, and this rad being over 25 percent of that total, the house can't be terribly large. It's hard for me to imagine they originally installed a rad that large in an average size house and that they supplied it with a 1" pipe or that they put 300 EDR on a 1.5" main. Clearly someone messed up when they put a 750EDR boiler in. That's almost twice the boiler you need.

Koan

@Fred - I have a few quick answers and can check on the rest

1) How large is the area that radiator heats? - biggest room of the house - will get back to you with area
2) how much of that radiator gets hot with the 1" pipe? - All of it - just takes a lot longer than the others
3) Does that rad appear to be original to the house? -Yes
4) Does the supply pipe to it appear to be original? - Yes
5) With a total of 399 EDR, and this rad being over 25 percent of that total, the house can't be terribly large. about 2700 sq ft heated on three floors - end of group townhouse.
6) Did they put 300 EDR on a 1.5" main. - let me check on that.
7) Clearly someone messed up when they put a 750EDR boiler in. That's almost twice the boiler you need. - Yes it is!
Thanks!

Fred

@Koan approximately what % of that rad gets hot during a normal heating cycle? If enough of it get hot and gets that room up to temp, I wouldn't touch it or the piping. If not, going up to 1.25" supply would get more of it hot but the 1" return side should be fine. I probably would suggest 1.5" normally but on a two pipe system, I'm going to leave it up to others on this forum to suggest pipe sizing. I would have never thought a 1" pipe could heat that entire rad. 2700 sq. ft is a good size house.

Koan

@Fred
If the thermostat doesn't cycle or I don't cycle on pressure due to not skimming, the whole thing gets hot. It just takes a lor longer for that one than any other. The main is 2"'. There is 40 inches of 1 inch horizontal then about 3 feet of 3/4 vertical up through the floor. I am guessing those take offs are short enough to be of less consequence. It's all original built in 1928.
I think I'll just let it be. It gets hot all the way, just takes a long time.

Steamhead

Upgrade the trap on that rad first. The B&J 122A that used to be a crossover trap in the garage should work fine.

We find that the 122A vents air faster than a Hoffman #18 with a cage unit in it.

Koan

@Steamhead
Thanks my friend ! I'll give it a shot!

Koan

UPDATE:
I now have the 3BM vent on the main replacing the Gorton #2.
The Boiler has been cleaned thoroughly and skimmed several times.
I undid the plug at the bottom off the Hoffman Differential loop and pure mud ran out. I undid the plug at the top of the loop and fashioned a "Gerry Gill" water wand to put water in the top and flush out the loop - of course I got fresh water in the steam mains.
I cracked open the 2CR crossover in the garage and used my "Gerry Gill" water wand in the return to flush out the wet returns. Lots of gunk there as well. Treated the boiler with 8-way and hit the blow down a few times. Ran the heat and AC at the same time to burn off the oxygen boiling for an hour. The heat has never worked this well - the big radiator heats all the way, no pressure cycling - too bad it's July! All shut down finally for the year.

Kahooli

Grats mate. Enjoy January

gerry gill

whats the inlet valve like?

Koan

@gerry gill - Do you mean the large radiator inlet valve?
It is a Hoffman no7. modulating valve at full open. Looks like they are rated for up to 200 EDR.



The radiator in the living room is a 30 section 105 EDR Pierce and Butler. It has been flushed out thoroughly. wanted to take it to the paint stripper but they would not move it. Have to figure out how to have it refinished like the others.

BTW - thank you for the wand idea. I cannot begin to explain the amount of garbage accumulated in our boiler, and wanding it between sections was the only was to get all the stuff out. Now I use that same tool for flushing the differential loop and the wet returns

gerry gill

i was just wondering as many times we have found radiator valves that appeared to be open based upon the lever but when we cracked the union and looked inside they were mostly closed. Alot of Mouat valves do this after 80 years.

Koan

@gerry gill Good point, particularly with the Hoffman 7 since someone can monkey with it and have it shuttered so that wide open isn't really wide open. I'm going to remove the valves and buff them, when I do I'll check for flow. Thanks for the tip!

Steamhead

Those #7 valves have shutters built into them that you can adjust based on the size of the radiators they serve. This was used to balance the system.

If any are stuck or otherwise don't work, we can rebuild them.

Koan

@Steamhead
I spoke to Gordo about it.. I can't remember how many are stuck. Hopefully I can get them off one at a time, buff them, and evaluate before late fall.

PMJ

@Koan,

You are still going to try cycling this thing this year with the PLC right? Maybe even try some vacuum in between cycles down the road? Truly magical how many of these balance/valve issues just disappear in vacuum - even a little vacuum. I wouldn't have believed it possible until I saw it myself. Sinking into vacuum the steam still in the mains goes more to the rads that are condensing the most and creating vacuum slightly faster than the others. Doesn't make much difference how open the valves are then - just can't be closed. Tiny differences yes, but as we all know that is all it takes with steam. The colder areas end up grabbing much more steam over the long haul and things just even out. Automatic adjustment that continuously factors in sun and wind changes also. My valve fiddling days ended years ago - and of course I have just one vent point. Many of these issues with old valves (yes mine are 80 years old too) just went away. Think about it - no one balance setup in pressure flow is right for all conditions - just isn't. And there is zero balancing going on in all that burner off time while vented - all wasted time.

For you 2 pipe owners out there that run your own systems give it a try. You couldn't pay me to go back to pressure - even really low pressure- my wife would surely throw me out if I did.

MilanD

@PMJ

So your main vent is a vacuum vent?

PMJ

MilanD said:

@PMJ



So your main vent is a vacuum vent?

No. An electric solenoid valve.

MilanD

> @PMJ said:
> @PMJ
>
>
>
> So your main vent is a vacuum vent?
>
> No. An electric solenoid valve.

Ah, even better! Nice!

Koan

@PMJ Yes sir... going to start this year on a natural vacuum.. I'm thinking I'll mount the solenoid down stream of the big mouth main vent, that way the solenoid is protected just in case something goes wrong, and I'll never lose steam if the solenoid fails.

AMservices

Does the big mouth hold a vacuum? If not you'll never make a vacuum.
If you wanted to keep it there I would put a ball valve to isolated the big mouth from the piping, then if the solenoid valve ever fails you can just open the ball valve.

PMJ

Koan said:

@PMJ Yes sir... going to start this year on a natural vacuum.. I'm thinking I'll mount the solenoid down stream of the big mouth main vent, that way the solenoid is protected just in case something goes wrong, and I'll never lose steam if the solenoid fails.

Great.

I think the big mouth will be fine. Without steam it will be just open and basically a threaded elbow won't it?
You are putting these on the dry return with nothing on the steam main right? When you cycle your boiler never allowing it to run long enough in one stretch to fill anything steam in the dry return is basically not possible - but I don't see how the extra protection for the solenoid hurts anything.

Koan

@PMJ yes. The one and only main vent is on the dry return above the Hoffman Differencial loop. The big mouth clamps closed when it sees steam - works great and has a 3/4 in outlet for the air. With the Gorton #2 you could hear the air hiss out, but not with the big mouth. But like you say, if you are timing firing pulses, the steam should not hit the return. Once I am set up later in the fall, may I impose on you to share your programming file?

I may experiment later with a vacuum pump, but I figure that is stage 2.

@AMservices The big mouth will be in series with the solenoid. The solenoid will screw into the big mouth (3BM) outlet. I doubt the 3BM will ever shut as it would only do so if it sees steam in the dry return. This would probably only happen if the solenoid failed open. Because of this I am assuming the 3BM won't have to hold a vacuum As long as the solenoid does hold a vacuum it should be ok. It looks like the 3BM only has one path in and one path out, so the housing will hold a vacuum even if the steam valve does not.

PMJ

@Koan,

Sure, I'll share it. Nothing special about it and I'm sure it can be improved upon. That is what is so good about the platform you are installing - you can change it yourself and try your own control ideas for $150 or so. You are going to have some fun this winter!

AMservices

@Koan The big mouth will be in series with the solenoid. The solenoid will screw into the big mouth (3BM) outlet. I doubt the 3BM will ever shut as it would only do so if it sees steam in the dry return. This would probably only happen if the solenoid failed open. Because of this I am assuming the 3BM won't have to hold a vacuum As long as the solenoid does hold a vacuum it should be ok. It looks like the 3BM only has one path in and one path out, so the housing will hold a vacuum even if the steam valve does not.

Thank you for that description, I see it now.
I would think that you'd be using a power open, spring closed 24 volt solenoid valve, is that correct? If so it's more likely it will fail in the closed position.
" nothing vents better than an open hole" ( except, of course, a vacuum pump)
I read that somewhere and added that last part.
The simplest way I can think of controlling a solenoid valve to vent the air out and create a naturally induce vacuum would go as followed:

When starting the system with atmospheric pressure in the boiler, I would power open my 24 volt solenoid valve, until the call for heat ended and the valve would power closed. With the boiler off, the solenoid valve closed, the remaining steam in the system begins to condense back to water creating the natural induced vacuum. The steam traps open pulling a vacuum on the return piping, where a vacuum switch will be sensing a vacuum is taking place and will then break the 24v line that would normally be powering the solenoid valve open on the next call for heat ( that is if the system is tight enough to maintain a vacuum until the next call for heat). That will stop the valve from opening unless atmospheric pressure is sense in the return piping.
As an extra safety, or an alarm of sorts, I would put a high limit in series with the vacuum switch to also close the solenoid valve when the day comes that a trap fails and starts dumping steam into the return. Or instead of having it close the solenoid valve, you could have it activate a small LED light near the boiler. Or better than that, have a second solenoid valve with the big mouth attached to it, have the main vent solenoid valve closed and the backup with the big mouth open.
I sometimes get carried away and I do things above and beyond what's really necessary.
Old steam piping is very difficult to get tight enough for it to hold a vacuum. That's why I've always been a fan of using a mechanical vacuum pump to controlling the vacuum level and decreasing my startup losses.
If you haven't replaced your boiler yet, I would also put a vacuum breaker on the Block, set to 15-20HG to prevent damage to the gaskets in those old boiler sections.
Just some suggestions. Lots of options. Good luck

Steamhead

Don't forget, this system has a Differential Loop, so by design, steam will enter the dry returns and shut the vent if the pressure gets too high. This would only happen if for some reason the Vaporstat didn't trip when it was supposed to, but still, you want to plan for it.

PMJ

When @Koan cycles his system with the PLC and has natural vacuum between the cycles there will never be enough pressure to measure let alone cause the loop to operate.

Koan

@Steamhead That is a really good point. I just cleaned it out and it was full of gunk. I have intentionally overridden the vaporstat to see when the differential loop starts to gurgle. Looks like about 12 oz psi. The vaporstat is set to 8 oz. psi, but sometimes goes to 9 oz psi. I am running on less that 2oz normally. This is a reason for putting the solenoid after the vent. If everything went wrong, the vent would shut and the solenoid's function is not relevant. Then there is the other good point by @PMJ, the pressures should always be so low that neither the main vent, the vaporstat, nor the differential loop should kick in. I'm glad to have them just in case

Thank you both for sharing these important ideas!