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The Glitch

The photo below shows an oil-fired boiler and surrounding details. Take a close look, and make a list of what you would change in this portion of the system.

FIGURE 1

The Fix

1. I suspect most of you quickly focused on the two expansion tanks. There’s nothing wrong with using two tanks of a given size, and piped in parallel, compared to a single larger tank of equivalent acceptance volume. In Figure 1, both tanks are piped in parallel with their air valves on the bottom. No problem so far. However, look at how the tank on the left is supported — or, should I say, not supported. If the diaphragm in the left side tank were to fail, and the tank fill with water, there would be tremendous torque on the tee beneath the air separator, maybe even enough to crack the fitting or the connection to the cast iron air scoop. The fix: Any expansion tank that’s not hanging directly below a fitting or other component should be supported. This can be done in several ways, as shown in Figure 2.
   

   FIGURE 2

   

   

2. On the left of the boiler is a circulator with its motor shaft in the vertical position. That circulator also lacks isolation valves or isolation flanges. When it fails due to worn bushings, or by functioning as a sediment collection device at the lowest point in the piping system, replacing it is going to be “fun” and wet. Don’t put circulators at the low point in systems. Don’t mount them with vertical motor shaft orientation. And always provide isolation valves or isolation flanges.
3. How about that drain valve with an outlet at least a foot above the base of the boiler, as well as the previously mentioned circulator? Maybe it’s there as an afterthought, for some purpose that I’m not understanding. Still, as a drain valve, it would likely serve that unknown purpose better if mounted lower in the system.
4. So much for the action on the left side of the boiler. See any issue over the right side? Look at the discharge pipe on the pressure relief valve. It’s pointing down, but it’s supposed to end within 6 inches of the floor or drain based on most mechanical codes.
5. The stains on the air purger and left expansion tank infer that the float-type air vent on the top of the air purger is leaking. It’s probably going to fail at some point, and when it does, there doesn’t appear to be any simple way to isolate it from the remainder of the system so that a replacement can be screwed in

One suggestion is to put a small ball valve and a short pipe nipple between the vent and the air purger. Take the handle off the ball valve and store it close to the boiler. This prevents curious little hands that like to turn valves from “accidentally” leaving the valve in the closed position.

Another suggestion is to replace the air purger and vent with either a microbubble air separator or a combined air/dirt/magnetic particle separator. Then move both expansion tanks to the wall behind the boiler and support them with either clamps that wrap around the tank shells, or a cantilevered support bracket. Put a tee under the new air separator with a drain valve on the bottom, and the side port leading to the relocated expansion tanks.

6. It would also be a good idea to wrap the copper oil supply pipe with some plastic looming to get it up off the floor and provide some protection.

Reasonable speculation

In the background, you see a work area with spray cans and what appears to be cans of other liquids paints, etc., on the floor. If some of those liquids or vapors from the spray cans contain chlorine, cleaning chemicals or flammable solvents, it would be better to isolate them from the air going into the oil burner. Chlorine vapors, in particular, can form hydrochloric acid within the boiler’s combustion chamber. That acid can quickly corrode the galvanized steel venting on the boiler. Most homeowners have no idea that this can happen. Give them a heads up. It may lead to a “remember that discussion we had a couple of years ago,” when they call you back to replace the vent pipe.