One pipe steam piping issues

Smith19

Good evening everyone - I am posting for a friend of mine who has just moved into an 1840's apartment building in the East Bay of Rhode Island. The building in question is a three story house. It has been divided into five apartment units. Each unit has its own boiler and electric water heater - two of the units have one pipe steam. All the boilers are atmospheric combustion and gas fired.

My friends apartment unit has four one pipe steam radiators - one in each room. After the first cycle of the season, (It's now quite chilly here in Rhode Island) we noticed that none of the radiators heated correctly - only heating two or three sections in. The vents would operate for several minutes before closing up but the radiators remained cold. After a quick trip to the basement, we found that the boiler was firing and sizzling away nicely. All the mains were scalding hot - however none of the mains appeared to be vented. It did not look like main vents had been plugged, (everything is still under a nice layer of asbestos) it almost appeared as though they were never there.

The boiler's pressure gauge also remained at zero psig even after the mains got hot. So what we have is mostly cold radiators, gauge reading zero, hot mains, and no main vents. It also looks like the near boiler piping is a disaster. Enclosed are photos. Any ideas?

Cheers!

Jamie Hall

What are the radiator vents? And where are they on the radiator? Top, or two thirds down the side where they belong? They may be venting too fast, and allowing steam to rush across the top, closing before the air gets out.

The zero gauge reading may be nothing -- that's the old insurance required 30 psi gauge, and they are none too reliable. However... if the boiler is still firing happily but the vents are closed, you should be building pressure -- which you don't want -- and shutting off the boiler on the pressuretrol -- which is set way too high (the cutin should not be more than 1, and lower if you can ease it down there).

Which leads me to suspect that the pigtail or the opening into the boiler may be clogged and that neither the gauge nor the pressuretrol are "seeing" boiler pressure. So the pigtail should be taken off and cleaned out, and the opening into the boiler cleared.

The near boiler piping is idiosyncratic… at best. But that, at the moment, is something for the landlord.

Another possibility on the merrily steaming away with no pressure, which needs to be investigated and ruled out, is a steam leak. This will show up as having to add excessive water -- anything more than a gallon a week is cause for concern. A gallon a day is a major problem. So that needs to be checked.

Be careful working on the system. Asbestos is a hazard, and the penalties for disturbing it without the proper training, licensing, and precautions can be eye watering.

gfrbrookline

My property is Middletown RI also recently kicked on for the first time this year. It is still relatively warm here so don't expect the heat to come on full force, the heat is only coming on enough to satisfy the thermostat so filling half or less of the radiator is normal. Mine only fully fill with steam when the temperature drops below 30.

That being said.......

The system is very strange in that is only has insulation right above the boiler. The asbestos should be removed and all of the mains should be insulated with a minimum of 1" fiberglass insulation.

The presuretrol is also set wrong. The front dial should be set to cut in at .5 and the inside dial should be set to 1. Changing this alone should make a significant difference.

Smith19

Thanks for the responses. The landlord will certainly not be interested in changing anything - they own dozens and dozens of properties between Bristol, Portsmouth, and Middletown, many of them very old and costly. That being said, the near-boiler piping is obviously extremely screwed up. There doesn't even appear to be a header. It's also obvious that the cut in pressure of 8 is outrageous. Any reason why the mains might not be vented?

ethicalpaul

A house that age must have been coal-heated at one time, and in coal systems, the fire was on for days, weeks, or months at a time, so main venting wasn’t really needed. Many systems went to oil or gas never getting main vents.

Or some knucklehead decades ago capped them off when they failed rather than replace them, or they failed closed.

That’s what I have learned here 🙂

acwagner

How big are these 4 radiators? If they're anything like the radiator in the background of the second photo, which appears to be at least 18 sections long, 5 tube, and 30-something inches tall, it'll take a long time to heat that up completely. The thermostat will likely be satisfied long before those are fully heated.

I used to have a 25 section 20" tall radiator on my system. It would heat maybe the first 5 sections (at most) on a regular call for heat. Usually less.

Smith19

acwagner said:

How big are these 4 radiators? If they're anything like the radiator in the background of the second photo, which appears to be at least 18 sections long, 5 tube, and 30-something inches tall, it'll take a long time to heat that up completely. The thermostat will likely be satisfied long before those are fully heated.

Radiators are pretty massive. But we were only getting one section hot in some cases.


Also - how common is it to have a blocked up pigtail? I feel like I haven't heard of this before. Looks like we'll be re-setting the cut-in pressure for sure.

ethicalpaul

The blocked pigtail is extremely common. It should be checked an cleared annually

acwagner

When you say only one section was getting hot, how long did the system run? Did you turn it off or did the thermostat? You also said the radiator vents were closed--how do you know? Were the vents hot? What kind of radiator vents do you have?

With large radiators and no main vents and a system that hasn't seen any attention in a while, I suspect it will take a significant time for the steam to populate the whole system. From a cold start, I wouldn't be surprised if it takes 30 or 45 minutes before the last radiator starts getting hot.

Pigtails being clogged is fairly common, especially on a system that probably sees little to no maintenance because it's a rental. Worth checking on.

Smith19

What's the best approach to unclogging a pigtail? I assume just removing the presuretrol and gauge and washing it out.

gfrbrookline

yup, a bottle brush can be useful.