Two pipe: concerned about one radiator

Waterbury Steam

Hi, everyone. I'm currently working on getting my old two pipe steam system fixed up. As far as I can tell, none of the traps have been touched in decades, so I'm getting those replaced along with a laundry list of items I decided upon after reading The Lost Art of Steam Heating. I have one radiator that concerns me--it's the only column style radiator in the house, and it was designed for one pipe steam. I think it was added when the house was converted to or back from being an apartment building.



My concern is that the shutoff valve and the thermostatic trap both attach to the radiator at the bottom. I'm worried that when the trap is closed, the condensate at the bottom of the radiator is going to flow into the steam riser and cause water hammer.



After thinking about it for a while, I had an idea to pitch the radiator away from the shutoff valve and move the trap into the garage below, so that condensate can sit in the return line instead of in the bottom of the radiator. I've attached an image that should help explain it.



Will this work?

icesailor

Difference:

What's the difference between how your radiator is piped as you show it and any other two pipe steam connected radiator shown in your book?

Waterbury Steam

Typical 2-pipe setup

All of the other radiators in the house--and everything I've seen in the book--has the steam coming in at the top of the radiator and the condensate leaving at the bottom of the radiator. Since this particular radiator does not have connections between the sections at the top, there's no way to pipe the steam in at the top of the radiator.

ChrisJ

Bang?

Does it hammer or bang now, or have you not had a chance to actually observe it in use?



If it heats good and doesn't bang I'd leave it alone.

Waterbury Steam

Definitely bangs

Yes, we get moderate water hammer in it now. Currently, I'd imagine some or all of the steam traps in the system are failed open, so that may be the cause. Should I just leave it to see if it hammers after the traps are fixed?

Jamie Hall

The proposed solution

may -- or may not -- work.



In fact, the whole radiator may not work as well as it should -- I would expect the trap to close way too soon.



However, leaving that be, if you are getting hammer on it -- even rather mild hammer -- I would check the size and pitch of the runout from the main to that radiator.  If it is sized and pitched as though it were one pipe steam, rather than two pipe, then condensate will have a chance to get back down that feed to the main, and thence back to the boiler.  Not the ideal solution, but it should work.

Waterbury Steam

Preferred solution

My preferred solution is to replace the radiator with a tube style to match the rest of the house, but that won't happen this year. This particular room seems to not have enough EDR anyway by my numbers, so long term it's getting a different rad. I'll just wait and see how this works before messing with it.

Dave in QCA

Should work

I have a few radiators just like this in my 1910 2-pipe system. In proper practice, the outlet bushing that the trap nipple is threaded into should be an eccentric bushing. That is, the 1/2" opening as all the way down inline with the bottom of the radiator passageway. Usually, the inlet is also bushed, and if so, with a regular bushing, thus putting the inlet at a very slightly higher plane than the outlet.



I have one in the system that had a regular bushing on the outlet and so it actually only worked as a vent. Condensate flowed back out the inlet valve. It operated silently. However, I have since installed orifice plates on the inlets and that has raised the effective level of the inlet and so condensate now flows the proper direction. The plates were installed for another reason altogether.



This arrangement may cause the trap to momentarily close early, before the radiator is entirely heated, but it will reopen if condensate is present and the radiator should heat without issues.



If you do not have a eccentric bushing on the outlet, one way to compensate for that is to install the trap remotely as you have shown. If you do that, you should remove the bushing from the outlet of the radiator. The pipe it up with a short nipple, sized to match the full size of the radiator opening. Onto this nipple, use an adapter nipple, 1 1/2" (full size) x 1/2" . Then continue the piping to the trap located below the floor. This arrangement will allow the condensate in the bottom of the radiator to flow out of the outlet with no impediment. Make sure that you don't create any water seals in your piping because that will prevent venting.



I suspect that most of your hammering is coming from other faulty traps. What kind to you have. Some repair parts are easier to find than others.

Charlie from wmass

Why not raise

the inlet valve? Would not that be easier and put the radiator to match the others?

Waterbury Steam

I can't...

I'd love to raise the valve, but this picture will show you why I can't...there's no inlet available at the top of the radiator.



Anyway Dave in QCA is absolutely right--when I went to look, the trap nipple is eccentric and is lower than the cutoff valve bushing. Looks like this radiator should be OK.



To answer Dave's question, most of my traps look like Hoffman 17Cs. There's some oddballs that are older and I'm having all of them changed to make them the same. That way I can just keep a few repair kits around for when one goes bad.

Dave in QCA

Another just like it

Here is another one.



While the photo does not make it completely clear, the section are NOT joined at the top. It is a steam only radiator. It has been moved from its original location, but the piping configuration is consistent with the whole house. A few have connections across the top but most do not. All have the supplies at the bottom and the outlet traps at the bottom.

Waterbury Steam

By the way...

Hello from Des Moines! There doesn't seem to be a lot of steam resources I can find in Iowa. I'm currently working with a local industrial steam contractor that did some work for me at Deere. Appreciate the answers here.

Dave in QCA

Waterbury Des Moines

Howdy! The mental image of Waterbury Rd came into my mind when answering this thread, but didn't give it a second thought. Turns out that IS where you are. There is quire a bit of old steam in Des Moines but I really don't know who the qualified contractors are. So many opportunities to get it wrong with steam. Spent a year in DSM in 1976 then came back again in 1999 to direct work and operations at Terrace Hill. Had a background in high pressure institutional steam. Several years ago we bought a place in DAvenport with a 2-pipe vapor system and found out that everything I knew from pressure steam did not apply. Quite an animal to get your head around but very interesting and rewarding when you do. Our system had every band aid you could imagine and no correct repairs for the last 40 years. Finally got it working like a charm.



Let me know if there is any way I can help.

Waterbury Steam

Update: I've got the work done to the system, and have been testing it out on cooler days. Everything is silent, except for this one radiator which still has moderate hammer. The steam trap is still connected to an eccentric bushing on the outlet side which is lower than the bushing on the inlet side. The hammer feels like it's happening in the first few sections of the radiator near the inlet valve.

I tried pitching the radiator towards the trap with a few quarters under the legs and it didn't help. The pipes below the floor are properly pitched and insulated, and the hammer isn't happening in the pipes. There's no evidence of steam blow-by on any of the traps in the system. Boiler waterline is steady and pressuretrol is set to .5 cut-in with 1-lb. differential.

Could some sludge be restricting the flow of condensate out of the radiator? Should I haul the radiator outside and hose it out? Or do I just need to find a radiator that will let me supply the steam at the top?

nicholas bonham-carter

Greetings from Omaha! I like your Art Museum, and Botanical Garden!
Most two-pipe systems seem to like very low pressures, obtained with a Vaporstat, instead of a Pressuretrol. Have you got a low-pressure gauge to verify the settings?
Is your boiler absolutely clean, and not producing wet steam/excessive condensate?--NBC

Waterbury Steam

My boiler has a 15 and 30 psi gage. The system seems to be balanced fairly well--the only time I see it build pressure is when it's doing a cold startup, and it gets up to 0.5 pounds.

I just cleaned the sightglass yesterday and I'm seeing some droplets forming above the waterline. I think there may be some oil in the system from all of the new traps and some new plumbing that was put in over the summer. I'd like to do a skim by myself, as my steam guys are usually doing commercial and industrial work and can't get out to the house right away. My only concern is breaking the skim port plug free, as it's probably been there for 20 years at least.

Abracadabra

Install a vapor gauge. Something in the 0-16oz. range. It will tell you so much more than a 15 and 30 psi gauge.

Paul_11

I run steam systems between 4oz and 2 psi and abracadabra is right, a 30 psi gauge is useless.
In NYC the code says all steam boilers must have a 30 PSI gauge so i install a 5psi right next to the required 30psi so I can see the small changes in pressure.
I have not found a 0-16 oz gauge you mention.
CAN YOU LET ME KNOW WHERE I CAN BUY THAT 0-16 OZ GAUGE?

SWEI

Try http://www.valworx.com/category/low-pressure-gauges-25-lower-mount

Abracadabra

I get mine from Grainger.

Waterbury Steam

I found a 0-32oz gauge at statesupply.com. I'm ordering it today.