What I did over summer vacation.

Hap_Hazzard

I got some of those fancy sight glasses like @ethicalpaul uses and put them on my return lines so I can watch the condensate returning to the boiler. I piped everything from the sight glasses to the Hartford loop in copper. 

It was pretty cold here this morning, so I thought I’d test run the boiler to make sure the new piping didn’t leak. I don’t do a lot of copper piping, because, frankly, I hate doing it, so I don’t have a lot of confidence in my sweated joints, but I didn’t see any leaks, and the condensate looks crystal clear. 

Here’s a close-up. Ain’t it purty? We’ll see how clear those sight glasses look after a few months. 

So this confirms my suspicion that condensate really is pretty much pure distilled water, which explains why I saw so much rust in my boiler last year after replacing my near boiler return piping with new black pipe. When I removed that black pipe, it showed a lot of corrosion for pipe that was only a year old. Now I see why most of you use copper here. 

Hap_Hazzard

MikeAmann said:

Heat the joint - not the solder. The solder flows towards the heat. Heat where you want the solder to go to.

Thanks. I know how. I even know about flux. I just hate doing it. Some of us would rather screw than sweat.

bburd

That “pure distilled water” is surprisingly  acidic. Carbon dioxide in the air mixes with the condensate to form a weak solution of carbonic acid. That’s why condensate lines rot out before steam lines do. You might test the pH of your condensate to see this in action.

On commercial jobs, the usual specification is schedule 40 black steel for steam pipes and schedule 80 (heavy wall) for condensate pipes.

Hap_Hazzard

bburd said:

That “pure distilled water” is surprisingly  acidic. Carbon dioxide in the air mixes with the condensate to form a weak solution of carbonic acid. That’s why condensate lines rot out before steam lines do. You might test the pH of your condensate to see this in action.

On commercial jobs, the usual specification is schedule 40 black steel for steam pipes and schedule 80 (heavy wall) for condensate pipes.

Yeah, it sure does eat that pipe. The amount of rust I saw last year was alarming, but it seems to reduce somewhat as the rust builds up on the pipe walls. I’m definitely sold on copper though. (Only for return piping.)