Blocked Convector

KnightRider

Hi everyone,
I have a 2 pipe steam system with vents on the main only. Over the winter when we had that bitter cold spell I noticed that the large convector in the living room was only getting partially hot. I went to the basement and found that the supply pipe was hot but the return was cold. I am guessing somewhere in the convector there is a blockage. A few years back when we got the home the same problem existed with other convectors. The heating contractor added a bottle of 8 Way cleaner and had gotten a lot of mud out of the system. I think the only problem was that the mud had clogged the pressure troll pigtail and he had to clean it out with a pipe cleaner. My question is can I add the same cleaner and do it again myself or can I create a lot of other problems? I am mechanically inclined and don't think I would have any major problem.

Thanks

EBEBRATT-Ed

Why not post a few pictures of the convectors and piping. If it's two pipe you may have a bad trap. We need to see what you have

Jamie Hall

Please don't add a chemical...

And do post some pictures, as @EBEBRATT-Ed suggested.

However, I might ask -- was the convector putting out as much heat as you needed for the space? And if not, did you try seeing if the inlet valve was fully open? It is not that uncommon for larger radiators or convectors to not heat all the way across, unless the boiler runs for a considerable time.

KnightRider

Sorry for the delay in responding. I am not sure any of my convectors actually have a trap. The inlet valve only seems to turn 1/4 turn but it is a butterfly valve right? If that's the case then it is fully open. The boiler was running often at the time and the convector was not putting out enough heat for the space. We were having near record cold over the winter here in south central Pa with single digit temps and wind chills well below zero. Here are a few pictures.

nicholas bonham-carter

Maybe the trap is part of the convector, and that would explain the cold outlet.
You would have to check the EDR rating of each convector, and compare it to the heatloss of the room. Conventional radiators likely have a higher output I would think.
In the two pipe system, there are probably additional crossover traps to allow the air to escape, and they must be working as well as a main air vent.
When the Plummmmmer put the cleaner into the boiler, and got a lot of mud out, where did it go besides the pigtail and pressuretrol?
Somewhere there may be an impediment, (not mud-bad traps, sagging pipe, etc.), to the escape of air as the system begins to boil, and that would hold up the steam, so follow the pipes and see what problems there are.—NBC

JUGHNE

IANS, but I believe that type of inlet valve has several turns to open and close. Sometimes the inner workings get jammed up.
Working it back and forth may loosen it. It could be a packless valve that has the bonnet as the only part that might unscrew.

Also you could have a copper orifice in the union above the inlet valve to limit the steam input. Some method has to keep the steam out of the return lines.

Fred

Are all the other convectors, in the house piped the same way? It's hard to tell from the pictures but, the Convector should have a slight pitch towards the return pipe, the return piping should be pitched towards the main, the dry return or the wet return, in the basement. From the pictures, each elbow, in the piping seems to be a single elbow and I'm not sure you can get enough pitch to empty out the condensate.

KnightRider

> @nicholas bonham-carter said:
> Maybe the trap is part of the convector, and that would explain the cold outlet.
> You would have to check the EDR rating of each convector, and compare it to the heatloss of the room. Conventional radiators likely have a higher output I would think.
> In the two pipe system, there are probably additional crossover traps to allow the air to escape, and they must be working as well as a main air vent.
> When the Plummmmmer put the cleaner into the boiler, and got a lot of mud out, where did it go besides the pigtail and pressuretrol?
> Somewhere there may be an impediment, (not mud-bad traps, sagging pipe, etc.), to the escape of air as the system begins to boil, and that would hold up the steam, so follow the pipes and see what problems there are.—NBC

It was actually an HVAC guy who "knows" steam systems. The rest of the mud came out of the low drain spigot by the boiler at the basement floor.

KnightRider

> @Fred said:
> Are all the other convectors, in the house piped the same way? It's hard to tell from the pictures but, the Convector should have a slight pitch towards the return pipe, the return piping should be pitched towards the main, the dry return or the wet return, in the basement. From the pictures, each elbow, in the piping seems to be a single elbow and I'm not sure you can get enough pitch to empty out the condensate.

All of the other convectors are the same way. That convector has a very slight if any pitch down toward the return (nearly perfectly level). The system did have a lot of pitch problems when I purchased the property, but they have all been pretty much fixed and all the water hammer had been silenced. Also the shut off valve for the other convectors only turn 1/4 turn.

Fred

@KnightRider , try and get a little pitch on that convector. That may resolve your problem. Don't add any chemicals. They typically aren't needed and I doubt that convector is clogged except for water that can't get out.

rbeck

First off is there an air vent on the convector. I know it is two pipe and normally there is no radiator vent but i have seen this type system where the returns all connect below the water level so the only place to vent the convector is the at the convector or a vent on the return line before it connects to the wet return.
I really doubt the convector is blocked, 39 years in this industry and have never seen that.
As someone else stated maybe the convector does not need to heat all the way across due to thermostat location, tightening up the home with new windows, doors added insulation etc.
This is only a problem if the room is not warm enough and not a new problem.

The Steam Whisperer

Does the convector heat across all the way right now when the heat is turned way up? This past winter, we appeared to have some convector returns get partially frozen, blocking air and water flow. Once it warmed up a little, everything was fine again. maybe you had the same problem

KnightRider

> @rbeck said:
> First off is there an air vent on the convector. I know it is two pipe and normally there is no radiator vent but i have seen this type system where the returns all connect below the water level so the only place to vent the convector is the at the convector or a vent on the return line before it connects to the wet return.
> I really doubt the convector is blocked, 39 years in this industry and have never seen that.
> As someone else stated maybe the convector does not need to heat all the way across due to thermostat location, tightening up the home with new windows, doors added insulation etc.
> This is only a problem if the room is not warm enough and not a new problem.

There is no air vent on the convector. The returns connect above the water line.

KnightRider

> @The Steam Whisperer said:
> Does the convector heat across all the way right now when the heat is turned way up? This past winter, we appeared to have some convector returns get partially frozen, blocking air and water flow. Once it warmed up a little, everything was fine again. maybe you had the same problem

The convector does not want to heat all the way across at all. By "partially frozen" do you mean actual ice? All the piping for that convector is in the basement warm zones.

The Steam Whisperer

Yes, I mean actual ice. It was quite cold where the pipes run. I'd check for a plugged orifice in the supply of the convector. Also, make sure there is no steam in the return line. Is it steam hot anywhere? A thermal image camera can be helpful.