Debris and coarse corrosion inside mains and dry returns

CaptSkinny

Is there ever reason to replace iron pipe mains and dry returns due to corrosion or debris?

Last season I had problems with condensate not returning properly, and I just inspected my piping with a USB snake camera. There's an awful lot of coarse corrosion and debris (iron chunks, old valve gaskets & I don't know what else) that won't flush out with a garden hose and would almost certainly impede the flow of condensate. The worst of it is in a 1" dry return (about 40') and the affected mains are 2".

It's one-pipe steam. The problems I had last season that prompted me to run the camera are:

1. Condensate stacking up in the dry returns, blocking the main vents
   
2. 10 minutes after a cycle, I could still hear my dry returns trickling into the wet return at the boiler
   
3. Water sloshing in some first-floor rads
   

Is it worth replacing pipe sections that are really bad, or trying to clean some other way (maybe pulling a wire brush through it)?

109A_5

Hello @CaptSkinny,

As long as the pipes are not leaking and if you don't think they will leak any time soon. A small Snake then flush out the junk.

JUGHNE

What do you have for wet return piping right at the boiler?
That piping is a trap for debris and prone to plugging more than overhead return piping which should be sloped to drain to that wet return at the boiler.

That may be your slow return problem.

Pictures would be nice.

EBEBRATT-Ed

You seldom find debris in mains. Returns are another issue. You may be able to install a tee and a valve and flush the returns with water pressure and a snake.

If the 40' of 1" is a return with no tees in it it might be cheaper just to replace it

Jamie Hall

Here we go again. One pipe steam does NOT have dry returns. It has steam main extensions, and they must be pitched to drain somewhere (apparently in your situation at the boiler?). Also, in my opinion at least, a 1" iron pipe simply isn't big enough.

Check the pitch on those pipes. It must be the same as the pitch for a steam main of the same diameter serving the same load, and it must be continuous.

ethicalpaul

Here we go again indeed 😅

CaptSkinny

JUGHNE said:

What do you have for wet return piping right at the boiler?

The wet returns are also 1". All 5 returns (3 main branches and 2 direct from radiators) drop directly into a sort of manifold right at the boiler, with a drain cock at the end.

JUGHNE said:

That piping is a trap for debris and prone to plugging more than overhead return piping which should be sloped to drain to that wet return at the boiler.

The wet returns are relatively new (installed in 2010 with the boiler). I haven't put the camera in them yet but when I flush them with a hose from the nearby vent ports, the water seems to flow out the drain unimpeded.

But the 1" dry returns that I inspected with the camera are probably 100+ years old, and when I flush the nasty 40' one (labeled "1" in the attached photo) with a hose (without an upstream valve, so only the force of gravity moving the water), the water comes out from a union at the end of the horizontal run (circled in photo) in dribs and drabs, as I would expect from all the debris I saw on camera.

I'll have to measure the pitch properly, but while this return is sloped towards the boiler it isn't as straight as it once was. One more reason why I thought about just replacing it.

JUGHNE said:

Pictures would be nice.

I've attached a photo of the wet returns for now, I'll try to get lighting up to show more, and to record my inspection video.

In the photo, return "1" is the one attached to the 40' run filled with debris, and the circle shows the union where I inserted the camera to inspect the horizontal run to the left. This is the one where I can hear water trickling into the vertical drop 10 minutes after a cycle.

Return "2" is the one where water stacks up past the air vent.

clammy

Where are your main vents on the end of the mains before you run drop into a wet return or are they at the end of the mains and the dry return as we will call it is unvented . A lot of corrosion happens to mains which are not vented my advise is if you mains vents are not at the end of the main move them there . Mains which are not vented properly tend to get a build up of carbonic acids which help build up crude and rust ,,vent them properly and this tends to lessen it effects over time . This is why when looking at system w unvented above the water line returns they tend to have a lot of repair couplings and pin holes due to acidic water lying in the bottom of the pipe . Check your above water line return lines for proper pitch and a vents 12 to 16 inches before they drop into the wet return . Also hopefully your above the water line returns ,return above 34 inch above the water line And that your not running over 1.5 psi .otherwise there liable to spit water . Also is your boiler piped properly and your system piping insulated ,uninsulated piping tends to form more condensate then it should , which means more condensate in the mains and returns more pipe grooving and more crude ,mud and rust .
Peace and good luck clammy

CaptSkinny

clammy said:

Where are your main vents on the end of the mains before you run drop into a wet return or are they at the end of the mains and the dry return as we will call it is unvented .

There were no main vents at all until the boiler was replaced in 2010. There wasn't even a tee and nipple for them. I don't know how long it had been set up that way but it would have been for at least the 20+ years that particular boiler was there.

Now, the main vents are at the ends of the dry returns, right near the boiler where it drops into a wet return. They're adjustable Heat-Timer/Varivalve vents that look like they belong on a radiator.

I've bought some Gorton vents and I am in the process of installing them just after the last riser, as recommended in Dan's book. That's what got me looking into the pipes with the camera, since I am making changes anyway.

Fred

Doesn't look like there is much pitch, if any on those front two returns (in the picture) and while I see pitch on the return along the wall, it looks like it levels out after the 45degree turn, heading towards the drop to the wet return. Also, pipe labels "2" looks to have little or no pitch???

reggi

Fred said:

Doesn't look like there is much pitch, if any on those front two returns (in the picture) and while I see pitch on the return along the wall, it looks like it levels out after the 45degree turn, heading towards the drop to the wet return. Also, pipe labels "2" looks to have little or no pitch???

OMG it's THE @Fred ... it's been so long, Congrats on the Preservation and all I could remember reading you work for to make the World a bit better..

Fred

Thank you so much, @Reggi ! It has been a long time and I am getting older and I seem to be doing more volunteer work than ever but for the most part I'm enjoying it!!! I hope all of you are doing well too. I am going to try to be more regular here again, if time permits. Take care of yourself. Best Regards

CaptSkinny

Thanks, @Fred.

Fred said:

Doesn't look like there is much pitch, if any on those front two returns (in the picture).

There isn't a lot, but Dan's book tells me I need 1 inch per 20 feet. Is that correct?

The rear-most of those two front returns (#4 in new photo living-room-returns.png is pitched 3.4 in/20 ft. The front-most of those front returns (#3 in photo living-room-returns.png has an overall pitch of 1.5 in/20 ft, but due to joist settling, the pipe hangar is causing a low point in middle (red circle in photo). I will have to adjust that.

Fred said:

while I see pitch on the return along the wall, it looks like it levels out after the 45degree turn, heading towards the drop to the wet return.

The front-most return along the wall (#1 in original photo near-boiler-piping.jpg is pitched about 4.9 in/20 ft after the 45 degree turn. This is connected to the 40 foot run that I think I will replace, as it has good pitch along the wall near the end as shown in the photo, further back it is bowed and has negative pitch in spots. The other return along the wall behind it is pitched 2.7 in / 20 ft after the 45 degree turn towards the drop.

Fred said:

Also, pipe labels "2" looks to have little or no pitch?

This one is actually pitched pretty well compared to the others, 7.3 in / 20 feet.

----

On the subject of pitch, though, I'm concerned about the lack of pitch of the headers coming off the boiler. I've attached a photo from a post I made last year (steam-header-pitch.png showing what was then zero pitch, but in the year since there has been some settling and now has a negative pitch of about 1.7 in / 20 ft (-0.4 degrees). I was advised last year not to worry to much about it, but I'd love to get others' take on it.

Fred

@CaptSkinny that 1" over 20ft is a minimum. I like a bit more pitch, maybe 2" over 20ft but as long as there are no dips or high points in the return that might cause condensate to pool or dam up, it should run back to the wet return. You mention that you can hear water in your radiators. Are they properly pitched towards the pipe end of the radiator? It is unusual for dry returns (steam pipe extensions) to collect as much crud as you see in yours. I looked into mine a couple years ago, when I had a joint leak and it was about as clean as the rest of the steam pipe. 1" returns are small enough that it doesn't take much to clog them. As has been mentioned, try to snake and flush them. I also don't quite understand how those return pipes connect to your mains. Are they tapped into the bottom of each main? or does the end of the main elbow down? or do they run straight off of the ends of the mains? If straight off of the end, that pipe reduction will also cause water to pool at the end of the larger main pipe until it reaches a level that will allow some of it to flow through the smaller return pipe. Also, try to get a little pitch on your header, towards the equalizer. You want the water droplets that fall out of the steam to move towards the equalizer and not back down the risers.

CaptSkinny

Fred said:

You mention that you can hear water in your radiators. Are they properly pitched towards the pipe end of the radiator?

It's only two specific radiators on the first floor. Radiator pitch was the first thing I checked, they're pitched quite a bit (maybe too much?). I haven't yet stuck the camera in the mains or the returns serving those radiators.

Fred said:

I also don't quite understand how those return pipes connect to your mains. .... If straight off of the end, that pipe reduction will also cause water to pool at the end of the larger main pipe until it reaches a level that will allow some of it to flow through the smaller return pipe.

They come off the end of the main using an eccentric reducer coupling, so the bottom of both pipes is at the same level:

Fred said:

Also, try to get a little pitch on your header, towards the equalizer. You want the water droplets that fall out of the steam to move towards the equalizer and not back down the risers.

Thanks for confirming, that's what I thought. Any advice for making that adjustment? Would it all have to be disassembled, or is there an easier way? I suspect the header settled over time because the floor joists holding up the mains are settling.

Fred

@CaptSkinny I think I first try to figure out why those two radiators are holding water. Are the valves fully open? If so, I'd disconnect those two radiators and see if the pipe has a lot of debris at the valve. Steam can get in but there may be enough debris to cause a little damming there.
It also looks like you might be able to disconnect the coupling on the header, on the left side of the picture, maybe add a new riser that is a half inch longer and adjust the other joints along that header to get some pitch.

CaptSkinny

Fred said:

Are the valves fully open? If so, I'd disconnect those two radiators and see if the pipe has a lot of debris at the valve.

The valve is fully open, but the gasket is long gone. I can't see any debris in the short drop down from the valve, and I've flushed out the radiator itself with hose. I'd like to get my camera into that runout and main (the mains I did inspect had bits of old gasket in them) but haven't been able snake it past the 90 degree fittings on this particular runout. I'll give it another try over the next few days.

Fred

@CaptSkinny What size is the pipe that connects to the radiator valve? What is the EDR of those two radiators? A 1" pipe can typically accommodate about 25EDR, maybe 30 before you run into a potential issue with condensate not having enough space in the pipe to return while steam is flowing into the radiator.

CaptSkinny

Fred said:

@CaptSkinny What size is the pipe that connects to the radiator valve? What is the EDR of those two radiators?

The EDRs are 60 and 68, and the pipe to those valves is 1-1/4" (same as the radiator tapping).

Fred

@CaptSkinny 1-1/4" pipe can handle 55 EDR. You are close enough that it shouldn't be a problem.