I need Help with Sloping Mains - One Pipe

Dooverdixon

So I've learned a lot about my system over the last few years and have made quite a few upgrades and changes from the info I have learned here. But now I need more help!!!! I sprung a pinhole leak in one of my mains today and was trying to figure out why. I got my handy level out and realized I have a hot mess. This leak is because its a low point in the main!!! I got out my trusty "lost art of steam" book and started reading, but now I'm super confused and need some help.

The system is a one-pipe, that goes from a header and splits into two mains. These mains serve risers that service up to 3 floors. When you put a level on the mains coming immediately out of the header they are definitely going UPHILL. On the side with no leaks the mains continue to go uphill or parallel until the last riser where the pipe diameter decreases and it goes downhill back to the boiler as a dry return.

On the leaky side it goes uphill, then downhill, then back up hill, before going down to the boiler as a dry return. Surprise surprise this is the side with all sorts of fiberglass repairs.

Here's my question. UPHILL??? The book seems to clearly state that mains should go Downhill from the time they leave the header until they make it back to the boiler through the dry return. Is my whole system done incorrectly? I need to fix this broken section, but do i need to redo the whole system of mains?

this photo shows the upslope best. The main is far left and return is far right.

The

Heres some photos before Insulation and i can take some of the remaining mains.

Jamie Hall

You have what are called counterflow mains, which are perfectly alright so long as they slope enough. However, they should be dripped to a wet return before they get to the connection with the header, and I'm not sure I see that in your photos.

What they shouldn't do is first slope one way and then the other and so on. You may need to add hangers to any low spots to fix that.

I do have to wonder a little if possibly the slope got reversed when the replacement boiler was installed...

Nor am I particularly enthusiastic about the near boiler piping. It isn't right, but if it doesn't bang much.

mattmia2

So the end of the mains connect to a return somewhere at the opposite ends from the boiler? If so it sounds a whole lot like the piping got dropped down at the boiler when the new boiler was installed. if it is dripped at the boiler and connects to a return at the end it could also slope toward both ends from some high point in the middle.

Dooverdixon

@Jamie Hall & @mattmia2

Thank you both for the reply, yall are fantastic. I've added some more photos to possibly circle back on some of your questions. I believe that the dry returns do actually circle back to a wet return (see photo). Is it weird to have both type of returns as I do?

Regarding the sloping. The photos show were the mains downsize and turn into a return. On the side that works well (the one without all the repair tape) the elbow right before the union is the "high point" and it slopes back to the boiler both directions from there....is this acceptable? And if so, how much "slope" is optimal? 1" over 20ft?? I'll go around with hangers and make adjustments to get the proper setup.

Regarding dropped piping with new boiler install. I think it possible that's what happened, but those mains right out of the boiler are original and there's risers within 6 ft. Seems like it would have been more work to install incorrectly as they would have needed to really wrench on those pipes to make them slope down that much?? i dunno, too late now i suppose.

Lastly, regarding the header. I knew it was weird from previous discussions here. I do have wet steam and i have had some serious issues getting hissing under control (boiler is also oversized), but I have that solved 95% from info ive gotten here. I have a vaporstat, new insulation, tons of main venting, and one of those adjustable on/off timers that let the boiler run for 8 mins on 8 mins off. This helps minimize the hissing.

Yall are the best.

Jamie Hall

Ah. Well, technically, those lines going back to the boiler aren't dry returns (they are found only on two pipe systems) but are steam main extensions. They're fine. And they're slope back to the boiler is just what they should do, provided that they don't join high at the boiler but drop down to the wet return before they get there.

1 inch in 20 feet is kind of a minimum.

There are all sorts of rules and exceptions to them -- it's worse than the French language -- but the bottom line is really pretty simple: any pipe has to have a way that water can flow freely and eventually get to the boiler. If there is a low point in the middle of a main, well... put a drip there so that the water can drop down to a wet return.

Think like water. If I were sitting in the pipe at this point, how would I get back to the boiler under gravity, downhill all the way?

Dooverdixon

this is super helpful. glad i dont need to repipe the whole system!!! I'll work on getting the 1" 20 ft thing sorted out with hangers and repipe the leaky section. Not looking forward to that! good news is...its a problem for spring.

Dooverdixon

@Jamie Hall

One more quick question.  I've been reading about counterflow systems and they all seem to have one thing that mine does not, a wet return for counterflowing condensate before the header...this explains my wet steam issues I've been dealing with (probably).  Given that I have to do a bunch of piping work anyway I'm thinking maybe I'll try to get some more height out the header setup so the whole thing slopes down start to finish?  Or alternatively add a wet return right before the header (this seems like the more difficult option though).  

If I'm going though this trouble, what other changes to the header setup would make sense?  Or is it serviceable as is?  

mattmia2

The mains should have a drip that drops down in to a wet return (separately for each main) before the main drops down in to the wet return so the condensate falls in to the wet return through the drip instead of colliding with and collapsing the steam in the header.

They need to individually connect below the water line so that steam cant flow in to and between them.