Excess Flow Elimination Unit

Mark Eatherton

Wallies, a fellow wallie asked me for a picture to clarify the application of a device I invented many years ago. I called it an EFEU (Excess Flow Elimination Unit) pronounced F EWE (just like F you, but softer) :-)

I will warn you that this product is NOT recognized or accepted by any known codes, although it should be required on every commercial hydronic heating installation. Here is the excerpt of the note I sent to the fellow Wallster.

Ross, it just dawned on me that I forgot to address your question on the Excess Flow Eliminator Unit.


Theory of operation is this. To fill system, open bypass around backwards check valve. Fill and flush as per normal. Upon completion of filling and topping off, close bypass valve around check valve. Under normal considerations, the minor loss of water associated with leaking packing glands on valves, auto air vents etc. are made up with no stoppage.

In the event where a pipe is broken, or the system breached in whatever reason, (freeze burst, relief valve popping, residents watering marijuana plants from purge cock in baseboard…) excess flow will attempt to run through the backwards check valve whose swing gate is being held open by gravity, resulting in the check valve slamming shut and stopping major flow.

The intended use of this device (EFEU) is for larger apartment complexes where it is virtually impossible to quash all known points of leakage and evaporation. On smaller residential systems, I’d never apply the EFEU, but always applied the PIG make up unit. This avoids inadvertent system lock out due to continual small losses and lockout associated with the PIG’s operation caused by the low pressure cut out.

BTW, PIG came from the term Pressure Induced Glycol, which is (as per the article) why we developed it and deployed it.

END EXCERPT.

If anyone has any questions, please let me know. If you are a member of the RPA, this information is available on the Members Only portion of the web site. Good reason (among may others) to join!

Have a good day.

SWEI

Thanks, Mark. You've mentioned the angled swing check here before, but this is the first time I've seen that photo. What does the spring check add?

RobG

@SWEI I assume it is there if you open the isolation ball valve?

Mark Eatherton

Correct. It allows the swing check to be reset if it is activated.

Thanks for asking, and enjoy!

ME

RobG

Mark, have you ever implemented this system or is it theoretical?

Mark Eatherton

Implemented on every commercial job I did under the cover of Advanced Hydronics, Inc.

Works like a champ, until someone who doesn't understand it bypasses it… Which happens on a regular basis. One complex in particular kept losing water pressure. Upon a SURPRISE investigation in rental units, found tenants were watering their marijuana plants with water out of the heating system by latching onto a purge cock that was under the cover of the baseboard.

We asked management to put out a letter (in 5 different languages) stating that the water in the heating system contained dangerous chemicals, and the water loss ceased. The residents who were cultivating had a legal MMJ license, so they were warned, but not incarcerated.

In numerous cases, due to poor installation practices, the baseboard beneath some stair well landings was exposed to freezing conditions, and actually froze and broke the pipes. The unit worked exactly as it was designed to, saving a significant amount of water damage in the process.

If you decide to employ it, I would STRONGLY suggest a full set of operating and reset instructions be placed in a water proof envelope and placed right at the Fill Safe device.

ME