One of my many responsibilities at work includes tending the boiler and boiler equipment at the Winnebago County Courthouse. Our building is heated with steam boilers. The boilers are not nearly as old as our condensate pumps–which are original equipment to the building.
We have a pair of Chicago Pump Company “Condo-Vac” condensation pumps. As the steam travels through the building to the radiators it condenses back into water that returns to the boiler room. The water collects in a tank that the pumps are mounted on, and a float inside the tank engages one pump at a time in an alternating sequence to send the water back to the boiler feed water tank to be reused in the steam-making process. Not only can the “Condo-Vac” pump this condensation back to the feed water tank, but it also creates a vacuum that draws air and non-condensable gases out of the steam line to improve efficiency and allow the condensate to flow back faster.
We have had a problem with Condensate Pump #1 for the last couple of years or so that has been gradually gotten worse. The unit constantly needs to be primed. I have to open the top inspection plate and dump water in to get the pump to operate. It used to work for a few weeks before it would stop again. This season I couldn’t keep it primed for more than 15 minutes. My work buddy, Mike, and I were assigned to take the pump apart and see if there were internal issues.
Working on this pump brought back memories of working on our antique Allis-Chalmers farm equipment. Everything was rusty and parts non-existent. We made sure that we used plenty of penetrating oil on all of the nuts and bolts that needed to come off. Out of about sixteen bolts that had some come off, only three bolts broke off and needed to be drilled out. We spent about a whole workday getting the casing opened. These units were built like tanks and weigh as much as one, too!
As you can imagine, there is not a lot of information out there to help us with this project. We have one manufacturer’s brochure, a couple of advertisements and the patent details to help us do this. So this was a learn-as-we-go project. It is not rocket science, but it is always good to have as much information about the machine you are working on before you dive in.
Eighty-one years of rust, corrosion, and other nasty buildup was very evident when we opened this pump up. The packing seals were worn out, but the bearings were still in great shape. We took the impeller shaft out, disassembled, cleaned and put it back together. One thing I learned while fixing tractors is that you always replace any wearable parts when you can! So we replaced the bearings–even though they were still pretty good. We cleaned all of the chambers out of all the stalagmites and corrosion. Mike power washed the top of the casing to get the old paint off, and I put a protective layer of heat-resistant paint on it. We bought a roll of thin gasket material from our local Napa auto parts store and made a new gasket by hand.
We made all new rubber seals to ensure that we were getting a tight and complete seal. We put the pump casing and all of the additional components back together and turned the power back on. Everything held water and the pump ran real quiet. We primed and it ran for a while. It has a much stronger vacuum than it did prior to the overhaul, but it eventually stopped working. It was time to do some more investigating
I opened a cap above the strainer to check that there were no obstructions from the tank to the pump. When the pump kicked on I could feel the strong vacuum pulling air and trying to pull water. I put my hand tight over where the cap is normally bolted down. I could feel it sucking my hand down and some water up, but it wasn’t enough to draw water into the casing and make it operate. I opened my fingers slightly to allow air through and all of a sudden the water began to flow. So there are still a few issues to work out. It seems like the pump is starving for air to keep the air/water/air/water draw into the pump. It may be a clog in the tank itself. In the meantime, I have left the strainer inspection cap loose for just enough air to be drawn in to keep the pump primed.
During the cooling season, we may need to crack the tank open and see if there is an obstruction. If anyone else has any other ideas, share them in the comments section below. This has been a learning experience for us, and I would appreciate any knowledge a reader may have to share.