No visible traps on two-pipe system using Modine Mfg. combination radiant/convection radiators.

phliphh

Hi,
My home was built in 1931 and used Overbrook, PA central steam until the steam plant closed in 1971. A gas boiler was installed. The original two-pipe system has eight Modine in-wall radiant/convection combination units (see photo), ten finned-only radiators plus three standard cast iron radiators. The only visible traps are on the finned-only radiators. There are new air vents on every radiator.
Several of the Modine and the finned radiators emit air then some steam through the air vents when the heat goes on, usually accompanied by water hammering. All the radiators do produce heat.
I replaced the vent on one Modine combination with a plug. The result was that the hammering stopped but the radiator did not warm up. When I put the vent back on, there was hammering and heat.
Since I cannot see a trap on the Modine return pipe either above or below the floor, my guess is that there may be a built-in trap or a trap in the elbow connecting the radiator return to the return pipe (doesn't look like it though) --or there may be no traps on these units.
This summer I can replace all the traps but don't know what to do about the Modine combination radiators and whether I should remove the air vents.
This is the Modine unit that apparently has no trap.

Advice?
Thanks,
Philip

phliphh

I'll check the supply valves. I'm running 4- 10 opi on the vaporstat and 1/2 to 1 1/2 opi on the Pressuretrol.
Are you familiar with the Modine emitters?

Jamie Hall

Modine? Or Moline? The Moline system was designed to operate on very low pressures (less than 6 ounces) with the heavy lifting on controlling steam flow being graduated radiator inlet valves. It also had a rather ingenious steam ejector at the boiler to remove air from the system, but hold a vacuum when the system was off. Which probably isn't there any more.

It did not use radiator vents. Which makes me wonder a bit just what you really do have.

Can you post some pictures of the inlet and outlet piping of typical radiators? And of the piping around the boiler? Are there any main vents on either the steam mains or dry returns?

clammy

If it’s a true 2 pipe then there’s no air vents on the emitters .i would look and see if you have a main air vent on the dry return piping .As for the convectors w no traps or inlet valves on a 2 pipe I have ran into these on some trane wall convectors systems and usually the convector is orificed . If I was you I would look to where steam is making it into your dry return and pressurizing it stopping all steam distribution . Once you find which convector or radiator is passing steam into the return I would suggest to figure that edr of that radiator or convector and size your trap to it accordingly . Most likely the issue will be because of a non inlet orificed or trap radiator in some cases I have seen it’s usually a small radiator that starts the issue . Be a detective and start your system from a cold and check the dry return or feel your radiator / convector return piping and if it’s piping hot there’s where to start . Don’t be discouraged if after finding and fixing the issue and if you find other rads / convectors bypassing correct it sounds like you have some de knuckle heading to do . Peace and good luck clammy

mattmia2

Did this system ever work right? Did whoever converted it from the district steam do it correctly? Is it still the boiler from 1971? It is possible that someone moved the water line too low and screwed it up too.(although it sounds like you have many problems and people just kept doing the wrong thing and added more problems on top of the original problem they they didn't fix which you will have to work backward through).

Steamhead

That's a new one on me. Not surprised Modine got into the recessed radiator business at some point, but they may not have been in it for long if this is the first time we've seen their stuff on the Wall.

I'm assuming this is the Overbrook near Philly?

phliphh

Hi,
I am in the Philadelphia area west of Overbrook called Greenhill Farms. Here is a link to an article that identifies (almost at the end of the article) the Modine radiant/convection radiator. My system provides plenty of heat. The air vents expelling air and steam are what I an concerned about. I can check the orifices on the Modine units and the traps on the finned-only radiators when the weather warms.
I've prepared a description with photos of the system but have to figure out how to upload it.
Thanks,
Philip

phliphh

Sorry, here's the link.
https://www.pmmag.com/articles/102214-residential-retrofit-maintains-historic-appearance

The Steam Whisperer

Are the "missing" traps down in the basement... that's where we usually find them... buried above the finished ceiling.

phliphh

I’ve posted photos.
Radiators
Five photos: Modine unit 1a, return without a trap above or below floor 1b, air vent 2, steam feed 3 and top of feed valve 4. All of the Modine units are plumbed this way.
Four photos: return (left) 4, trap 5, feed 6, feed valve 7. You can see the original return piping with the air vent and trap. I found the original air vent under the fins and set it on the fins so you could see it. The original was replaced with an 1/8” air vent.
Burnham boiler installed 2004:
Four photos: boiler, boiler plate, return upper, return lower. Photos 8, 9, 10, 11.
Thanks for your help,
Phil Hawkins

phliphh

The upload mixed up the order. Each photo has a label on it. Sorry about this.
Modine unit, return, air valve, feed, feed valve:









Boiler, boiler plate, return upper, return lower:




Thank for your help.
Phil Hawkins

clammy

Any radiator without traps will need to have installed and most likely you will either have to repair or get new traps for the rest of them . Hence why there air vents are on them there , most likely those convectors w traps the traps are done if not the vent system where added as a last desperate act to get some heat . The hammering is from the return being pressurized . I would start by getting traps on the rest of them rads and as stated early turn the boiler on and start feeling around the dry return and any return that’s hot I sure gonna need to have a trap installed . Find the offensive one and replace ,try to get them all being live steam in the return will thrash the bellows on a new trap . It would seem some did some repairs that they had no right to do mainly due to lack of knowledge about 2 pipe steam plus I see some copper so there you go . The boiler piping looks fairly decent and I see you have two pressure trolls are you sure that boiler is not set up as a 2 stage burner . If your unsure just watch it and check the low pressure gauge you could also clock your meter . Are there vents on the dry return and is there a crossover traps . Peace and good luck clammy

phliphh

Thanks very much for your advice.
There are traps on all the finned radiators none on the Modine units. The air vents are on all the radiators. Many but not all let out air then steam then heat up when the system starts. All the radiators do produce heat after the initial hammering. I haven't been able to find any traps near the boiler. I know the copper should not have been used on the return to the boiler and don't know why it was. The two controls are in series. The first is a Vaporstat and the second is a Pressuretrol. I think my first task will be to check the Modine units for orifices that may be clogged. Second will be to replace the traps. I'll have to wait for spring to do this. In the meantime I may turn down the heat and check one of the Modine's for a clogged orifice.
Thanks,
Philip

Steamhead

I'm pretty sure those Webster radiator shutoff valves had orificing built into them, though they are newer than the ones that appear in the Webster books we have. If so, that's what was supposed to keep the steam out of the return lines- as long as the steam pressure did not exceed a certain point, the valves only admitted enough steam that the radiators could condense.

This assumes that the return lines were run close to the basement ceiling, and had vents on the ends of them. I'd have to see the system to be sure. You never know, when it was originally fed from a district steam system.

Not sure there's enough room to install traps in place of the return elbows on the Modine convectors. You might end up using vertical traps underneath the elbows.

The Steam Whisperer

The orificed supply valve concept seem to start being picked up by Manufacturers in the early 1930's after the success of the Moline System. I'd check the valves to see if they have orifices.
I would just orifice the whole system and run it at the proper pressure and get rid of the radiator/fintube traps.

Steamhead

The Steam Whisperer said:

The orificed supply valve concept seem to start being picked up by Manufacturers in the early 1930's after the success of the Moline System. I'd check the valves to see if they have orifices.
I would just orifice the whole system and run it at the proper pressure and get rid of the radiator/fintube traps.

That would have been after Frederic Tudor's patents ran out:

https://heatinghelp.com/heating-museum/european-heating-systems-circa-1907/

phliphh

Thanks,
I'll check both kinds of radiators (with and without trap) and let you know what I find, What supplier would you recommend for the new orifices? Where do I place them in the valve body? I think the valves are all Webster valves like the one on the Modine radiator, but I have to check.
Thanks again for your advice.
Philip

Jamie Hall

I they are all Webster supply valves, you may not need orifices. They can be adjusted to be correct for the connected radiation without them -- provided that a) you keep the pressure down and b) you keep busy fingers from fiddling with them once you get them set (the similar Hoffman valves have the adjustment internal, so it's unlikely that people will fiddle...!).

phliphh

How do I know if these valves are adjustable and if so how do I adjust them?
This valve is on the Modine convector/radiant emitters.

This valve is on the convectors.

Thanks,
Phil Hawkins

phliphh

I've searched around the boiler and followed the feeds and returns in the basement ceilings and cannot find any vents or traps. The current piping to and from the boiler duplicates the Burnham recommendation for "steam boiler piping, gravity return" for the 5006B. It uses the Hartford return and has an automatic water makeup device on the left side. There is also a copper return from upper floors that runs into the return above the Hartford return.







The original piping, radiators and convectors were installed when the house was built in 1933 and depended on a Philadelphia steam plant in Overbrook. The original boiler was installed in 1971 when Philadelphia closed the steam plant. The current Burnham boiler was installed in 2004.

I don't know if the 1933 piping had the air valves on every emitter. All now are 1/8" with adapters to fit the emitters. These have Teflon tape and look pretty new. However, I found an old 1" air valve that had been removed from a convector, so air valves may have been part of the original piping. I also don't know if the 1971 boiler system had vents and traps at the boiler that were removed in 2004.

The 2004 installer, Sgro Mechanical, was a veteran of fifty years of work with commercial, institutional, church and domestic steam installations in Philadelphia and the surrounding metropolitan area. He's now incapacitated so I can't ask him about the installation.

The whole thing is a mystery to me. It all began when I started reading Dan Holohan's The Lost Art of Steam Heating Revisited to solve water hammering on one of the Modine combination units. I read that steam emitters should not have air valves. There was one on the Modine. I removed it and plugged the hole. At the next heat cycle, there was no hammering, but there was also no heat. I put the air valve back, the hammering started, air and steam existed the valve, and the Modine warmed up.
I don't have a clue.

Philip

phliphh

What is the title? I'll get it.
Also, any idea why the Modine convector/radiant unit with no trap lets steam in, hammers and expels air, then some steam through the air valve and heats up but won't let steam in at all and stays cold when the valve is removed and hole is plugged?
Thanks very much for your help.

phliphh

Where should I look for the air eliminator? How would it be plumbed?

mattmia2

i suspect for some reason there is no vent on the returns or steam is getting in to the returns because of a bad trap on a radiator or a metered valve being too far open so steam that shouldn't be in the return but is closes the vent before those radiators can vent. The return could have a sag somewhere that is holding water before the vent as well. The vent could be a conventional vent or a special moline device. The air should get out through the returns if it is working properly.

mattmia2

Take pictures of any devices in the basement connected to the steam piping, either near the boiler or off in some corner somewhere. Are there returns at the floor level or are they all up near the ceiling?

Mark_72

Steamhead said:

That's a new one on me. Not surprised Modine got into the recessed radiator business at some point, but they may not have been in it for long if this is the first time we've seen their stuff on the Wall.

I'm assuming this is the Overbrook near Philly?

I'm on this job now and I have never seen such a mix of fin, cast and convectors in one home. The dead men are rolling over in their graves. Frank & Gordon you two should come up to Philly and see this. Maybe between the three of us we can bring this back to the dead men's intent. Also the boiler is shot and the venting is 10" B-vent run outside.

guzzinerd

@mattmia2 these are the same radiators i have, coincidentally also in 1931 construction.  What kills me is, before we bought the place 2 years ago, that whenever a radiator went cold they called the local plumbers to just rip it out and replace with a cheap baseboard model.. they did that with 4 of them.