Closing the Loop – in Hydronics and Life

When I was in the Air Force—before working with hydronics—I really enjoyed the times I got to get in an aircraft, get up in the air and fly around. I worked on ground radar, and for two weeks in Canada we commuted by helicopter to a remote site in the deep North woods, supporting a big war game by shooting a Soviet-style surface to air missile signal to passing aircraft. I enjoyed all those flights.

But as with almost everything, there is an exception. My exception would be the flight back from another war game in South Korea. I can’t remember how many hours I spent sitting on a side sling seat in the back of a windowless C141 cargo plane flying across the Pacific Ocean. Talk about boring. I couldn’t even play my cassette tape player (aka boom box).

Front Seat Ride

The Commemorative Air Force brought some of their planes to Cincinnati over the Labor Day weekend, so I decided to try flying around again. The B-17 front seat ride seemed pretty pricy, so I reserved a front seat ride on a B-25 bomber. That’s me after the flight. When the plane flew its fifteen combat missions, it didn’t have a catchy name or fancy artwork. Both were added with the CAF restoration.

As you can notice, I’m not feeling particularly well. It was a very hot day in cramped quarters. Throw in the backwards slide to get into and out of the front gunner turret, and I got a little queasy. I think the whole experience closed the loop for me and flying around. It was great when I was young, but not so much now that I’m old.

The other shot is of the location of the subject of this column. It is the old money country club in the old money part of town. An old course confined by the surrounding high end real estate, some grand homes with steam or hot water heating systems. The outline of the course is evident from the air because of its brown color. This year they killed all the grass and are in the middle of moving around a lot of dirt.

Last year they made a lot of changes to the club house. They had been heating with steam and cooling with chilled water. I’ve been visiting the boiler room for years, helping first with the steam system then later with the chilled water piping. The big change was converting the steam heating system to hot water. Somehow, I wasn’t involved.

Then I got a call last month. A contractor was asking about why the booster heater on a commercial dish washer wasn’t working. He said it was at the old money country club and that he put in a small steam boiler this summer to feed steam up to the kitchen for the big dishwasher. I suggested that we meet at the job site and take a look.

Old Money Jobs

You always park in the back at old money jobs. We walked in the employee entrance on the ground level and went straight to the old boiler room, where there was now a new residential size cast iron boiler. Through the years, I’ve seen a few boilers like this mis-applied. A cast iron boiler does not last very long on continuous fresh water make-up, so I asked the obvious question, “Is all the condensate returned to the boiler or is some or all used for process?”

He assured me that the steam now fed only one booster heater and that it did have a trap and that it was connected to the return line feeding back into the boiler. The near boiler piping looked great, with a properly sized header, properly drained to the equalizer line, and properly connected to the Hartford Loop. Nothing wrong with the boiler steam supply piping.

I traced the supply main leaving the header to where it connected to the riser going up to the dish room. Then I traced the return main back to the boiler. Something caught my eye, actually the absence of something peaked my interest. I asked if we could take a look at the dishwasher. As we walked through the prep areas and up a flight of steps, I tried not to look too closely. I’ve quit going to a few restaurants after walking through the kitchen.

The Missing Piece

We finally got to the dishwasher and while the contractor was taking off the cover the club manager came over. He is a hands-on kind of guy that I’ve worked with before, not a stuffed shirt like you might expect running an old money place. He reminded the contractor that there are actually three booster heaters working in this dishwasher. The one under the first cover was a small shell and tube heat exchanger.

The steam feeds into the shell of the heat exchanger through a control valve. On the outlet of the shell is a steam trap, which is connected to the return line going back to the boiler. The trap keeps the steam in the shell, heating the fresh water running through the tubes, while passing any air and condensate to the return line.

We looked around and found that the other boosters were hooked up in a similar manner. I still hadn’t found what I was looking for, any type of air vent. On the old steam system, the returns went back to a vented boiler feed tank, so no air vents would have been required at the dish machine. But on the new, dedicated-to-the dish machine steam system, the contractor didn’t allow for venting the air.

As I explained the situation, I could tell that the contractor realized his mistake. He said, “I closed the loop by piping the return that used to go to the vented boiler feed tank, directly to the boiler.” Air couldn’t get out of the way of the steam, blocking any steam flow. The good news was the addition of an automatic air vent to the return line in the boiler room was going to be an easy fix.

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.