Eccentric - As in 'Not Normal' - Condensate Flow

Usually I write this column at a computer while eating maybe not so healthy snacks sourced from the warehouse vending machine because it has a better selection than the office vending machine. I also get caught up with the guys at the counter. Be nice to them—they are the true heroes in the industry.

Today however, I’m going old school by writing this column with paper and pen from my chair in the chemotherapy treatment room, where they encourage the consumption of their provided healthy snacks, or anything else you can bring in. I brought an apple, pretzels and pistachios for the three hour hookup to an IV line.

This is the start of my second treatment. In retrospect, the initial treatment wasn’t too bad. I don’t want to appear to be complaining or whining about this. It didn’t come close to my dad’s baseline for bad, which was sleeping in a foxhole in northern France during the winter of 1944. Like many of the Greatest Generation, he never provided any details, but one can imagine.

Inspecting the Collections

A few weeks ago, one of my regular customers and sometimes golf partner called to ask me to meet him at a steam job in one of the oldest neighborhoods in town. The older the system, the better I like it. He said I might find it interesting, since the homeowner was a big collector. The boiler was leaking and inoperable, so we met the next day.

We entered though the basement door and I was pleased to notice that all the piping was exposed, but concerned that none of it was insulated. We walked over to the boiler to check the size, which seemed big for a residence. To compare the boiler output to the installed radiation, we decided to go find all them all.

In this instance, I was going to use the net output of the boiler instead of the gross output because it factors in the loss caused by all of the un-insulated piping. Bare metal in the basement equals radiation load.

Upstairs turned out to be very interesting indeed. The bachelor that had lived there for 40 plus years was an organized collector of Lionel trains, toy cars and trucks, Plasticville buildings, and numerous other things I can’t remember. It was just like being an episode of American Pickers. All the rooms, other than the few he lived in, were filled with his various collections.

Not hoarder-style, but so you could easily walk around and see every item. He led us through all three stories. The collections were distracting (with a few vintage photos in his library quite distracting indeed). The house was much larger than I realized. When I added it up, the rating of the existing boiler was fairly close to the net rating of the existing boiler.

An Eccentric Development

I quoted a new boiler and lead time later that afternoon. Turned out the homeowner was tired of a cold house and didn’t want to wait for my brand of boiler to come in. The contractor found a different brand in stock at a rival distributor. When this happens, I assure the contractor that it won’t hurt our relationship if he uses another source and I will still be glad to help in any way.

The above photo was taken on the third return visit. Previously I was called in to lay out the piping, answer a wiring concern and determine the height of the low water cut-off. This day, I was there to consult with the service tech regarding erratic operation.

I was taking a second look at the system piping when I noticed this excellent example of an eccentric reducer. Since they are only used in steam systems when necessary, you don’t run across them very often. This is one of the two steam mains feeding steam to one pipe radiators. The two tees feed steam up to the radiators. The steam, air, and condensate move from right to left.

In the world of steam, this is called parallel flow. When the steam/air and condensate flow in opposite directions, it is called counter flow. At this system, the installing contractor has the steam mains as parallel flow, with the main high at the boiler and lower at the end to maintain good pitch for condensate to flow along the bottom while the air and steam flow along in the upper portion of the pipe. A larger pipe size would have been used for counter flow.

The piping to the one pipe radiators is always counter flow. Steam and air move up from the main to the radiator valve. The steam pushes the air out through the radiator vent and condenses to water as it heats up the radiator. That water has to pass back through the radiator valve and piping back to the main, where it joins in with the flow from the other radiators.

If the pipe reduction in the main was done with a concentric reducer, water would puddle up in the bottom of the pipe to the level of the bottom of the reduced pipe size, or about ¼” to ½”. With the use of the eccentric or offset fitting, condensate flows along the bottom of the pipe to the end of the main without any puddling caused by pipe fittings. He kept the flow nice and smooth.

Any puddle in the steam main will cause water hammer at the beginning of the steam cycle as the steam moving through the main picks up the condensate in the puddle to slam it into the next change of direction in the piping and make that load noise that people complain about. Well, most people will complain, but I’ve had a few eccentric people that like it.

Patrick Linhardt is a forty-year veteran of the wholesale side of the hydronic industry who has been designing and troubleshooting steam and hot water heating systems, pumps and controls on an almost daily basis. An educator and author, he is currently Hydronic Manager at the Corken Steel Products Co.