Siphon wet return on two pipe steam CH

Rodney Summers

The trough drain is definitely a nice way to keep lines accessible. It seems you can even rely on the built in slope at the bottom of the trough to provide good condensate line pitch.

In the past, we've done something similar. We cut two 10 inch apart parallel slits in the floor with a diamond cut-off wheel, then broke out the concrete. The edges were sharp and neat, all that remained was to place a cover over. The cover was fabricated to rest on the bottom of the trench which was left as gravel. This avoided rebuilding costs but possible humidity makes your trough much nicer.

However, my customer this time is very cold to the idea of going under his floor. They don't want a repeat of what happened elsewhere in the building where a sewer line had to be gotten to, probably two feet below. The disruption in the gravel and the fact that it could not or was not re-compacted properly caused the floor to crack all around in the area.

So, I would really like a different solution. The Lost Art on pp 95 sqq describes alternative arrangements, one of which, the siphon. I've been thinking all night long about it and some form of automatic priming.

Meanwhile, I also want to look back at the return and see how badly it leaks and actually figure out where it passes, I believe it zig-zags a few times under the floor.

Thanks for keeping ideas coming my way.

Christian Egli

Magic in a pipe

Here is my problem, one of them at least.

A buried return has gone leaky. It is impossible to get to. It was placed before the concrete was poured over it. You know the story.

I can replace most of it with a near-the-floor return except for about 30 ft that has doorways and other inconveniences that really call for an underground pipe.

Nobody wants to bust the 3 inch concrete floor, so, I need magic.

A condensate transfer pump would have to have a really-near-the floor inlet. I can spare 4 inch at most.

A vacuum lift to suck everything up sounds exciting, but lifts are too expensive to operate. Also, I would really like to keep the system free of pumps.

Here is my latest thought:

First, have the condensate collect in a closed pan. This allows for the air to escape trough a pipe on the top. Then, have a wet only return that leaves from the bottom of the pan.

This wet only return would then be piped up and down, at will, over any obstacle with no concern about slope or height. This pipe would lead back to the boiler room which has a pit. The exit of this pipe would pour into a similar pan, set at the same altitude. An overflow type exit from this second pan would then go back into the main return.

Both openings of this wet only return would always be kept below the equilibrium water level of the tanks, thus preventing air from sneaking in. Like in a siphon.

Once my wet only return would be primed at the beginning of the season, I see no reason why it should stop transferring my condensate between the two pans.

Has anyone done or seen such a thing? Does it have a name? What would be the best arrangements for the priming procedure? How about automatic priming? Any quick idea on the pipe size needed, radiation on this branch calls for 1.2 gallons per minute?

Any other ideas and solutions? Am I too near the edge of the wall?

Thanks in advance for thinking along.

Christian Egli

Steamhead

How high

is the lowest steam-carrying pipe over the tops of the doors?

Can you route the return back to the boiler a different way? Since the boiler is in a pit, can you run the return dry rather than wet??

What happens if your proposed return loses its prime?

Christian Egli

High above the floor

The steam mains are 9 ft high above the floor.

The only alternate route would be to use outdoor piping on the side of the building. This way I could run dry returns. I would have to insulate them real well and have to drill many holes in the wall.

Loose the prime? Flood that particular branch and call me.

Thanks

Steamhead

3 inches of concrete

isn't that hard to open up if you have the right equipment. You may want to consider running a larger pipe as a conduit, say 4-inch if your return will be 2-inch, and sliding the return pipe in. This way if it goes bad again it can be removed easily. Leave enough room to make up the joints at the ends.

steve pajek

You need to find a better contractor have him open the concrete

and replace the pipe. As Steamhead said have the new return installed in conduit to protect it. We like to use a trough drain for the conduit and a piece of aluminum diamond plate as a cover for access.