Bent pipes

Polycarp

One small follow-up on my last post about replacing my wet return.



The existing wet return has a couple of pipes that have been bent into slight curves to deal with the fact that this system was actually added to the house (yep, my century-old steam system is a retrofit for a failed early gravity air system).  Should I even consider trying to bend pipes to replicate these?  I know it's possible, but don't know if it is practical for me or advisable. 



The only reason I'm not just defaulting to straight runs and fittings is that I think one of the bends can't be replicated with any standard fitting (45 or 90), and I'm reluctant to just leave the existing pipe in place after seeing the condition of other parts of the wet return.



Thanks again.

Hap_Hazzard

To bend or not to bend...

I'd be inclined to bend it, if I could get my hands on a hydraulic pipe bender. It's not that you need that much force on a 1" pipe, but you can do it more accurately and without damaging the pipe. I try to avoid using too many fittings on a wet return because that's where they always start to leak--at the threaded ends. When you thread pipe it cuts halfway through the pipe.



Another option you might want to look into converting it to a dry return. Normally a dry return runs back under the main towards the boiler, then drops just before reaching the boiler to form a water-filled loop before joining the Hartford loop, but it doesn't have to follow the main. Depending on the architecture of the basement, it can make a bee-line towards the boiler instead.



Part of the reason it doesn't need to follow the main is that you can't run drips from each take-off like you can with a wet return, which is actually a disadvantage, but I don't think a lot of residential systems are piped that way anyway.



You can also make part of the return dry and the rest wet. The dry part has to be furthest from the boiler, of course, and once you go wet you can't go dry again, gravity being what it is. The things you need to remember are that you must keep the dry part of the return at least 28" above the maximum water level (typically the top of the gauge glass), and you can't join dry returns from separate main branches above the minimum water line.



It might be easier for some of our pros to make recommendations if you could post a few snapshots of the piping you're replacing and the basement it's going into. There's a wealth of knowledge here, and if they tried to describe all the possibilities they've seen or installed it would take a few months, but if you show them a few pictures, one of them might have an idea that never would have occurred to you or me.

Polycarp

wet vs dry

Unfortunately, the wet return is on the other side of the country and I don't have pictures of much of it.



The problematic bend is above the water line (the others can be handled with fittings). 



That is an interesting suggestion to convert the wet to dry.  It would save me pipe on the drips and get the return more out of the way in the basement.  I certainly have the head-room to get it high enough.  I wouldn't re-route it since the wet return already follows the main pretty closely and the route would probably be best for a dry return too. 

Hap_Hazzard

Drip lines

So the current piping does have drips for every take-off? If so, you need to be careful about eliminating them. Most residential systems don't have them because of the expense, but (at least one would hope) they compensated for it by making sure the main was big enough to carry steam and condensate and ensuring that it had adequate pitch.



Do you know what size your mains are and what your total EDR is?

Polycarp

drips

The house is three stories, which might explain the drips.  The system has drips for every riser, and for a couple of the radiators on the first floor with longer take-offs.



It's one-pipe parallel flow (pretty sure it was originally coal).  The main starts at 2.5" and reduces to 2" about 2/3 from the boiler.  If I remember right, the EDR is 350.  The system has lost a couple radiators over the years (replaced with other point of use heat sources) so everything in the system is over-sized.



I'm leaning toward keeping the return wet.  I worry about changing the dynamics of the system.

Hap_Hazzard

I'd be inclined to agree

Unless one of the pros can offer you some guidance it's probably best to err on the side of caution. You could always run dry until the first drip line, but that probably isn't going to buy you much.



So, returning to the original question, if the bend you're talking about is above the water line, it's hard to picture how it couldn't be replicated with a couple of elbows and a close nipple, but then, I haven't seen it.

gerry gill

Dont know if this will help you,

but back in my Navy days we bent many a black steam pipe by plugging one end with a wooden plug (pounded in), filling the pipe with sand, and putting in another wooden plug with a small hole drilled thru it for venting on the other side..then we would heat it cherry red in one inch increments with an oxy/acetylene torch and bend what we needed..you may be able to do that..