Basics of Flushing

Water conservation is becoming increasingly important and the requirement for saving water has brought many changes to toilets and toilet technology. Toilet technology? Really?

Yes really. When it was acceptable to use several gallons of water per flush designing a toilet was relatively easy but as we have progressed to 1.6 gallons per flush (gpf) and now to 1.28 gallons per flush the design of the flushing system has become critical to achieving an acceptable product. It has been mandated that by 2014 all toilets must meet the 1.28gpf standard making technology more important than ever.

The three major companies, American Standard, Kohler and Toto, have all approached the problem with a variety of solutions.  American Standard has four flushing systems, Champion, Cadet 3 and H2Option as well as pressure assist in their commercial line. Kohler has their single gravity, dual gravity, Power Lite and Pressure Lite systems. Toto has their Double Cyclone, Dual Max, E-max, G-Max and Power gravity systems.

Broadly speaking these systems can be divided into three categories: gravity flush, pressure assist (which uses a secondary tank within the tank) and power assist which use an electrical pump to improve performance. To my knowledge Kohler is the only manufacturer using the power assist; it can be found on their “Fountainhead” and “Purist Hatbox” and a couple of their San Raphael models. The main advantage is that it allows for designing a very low profile toilet. It is a costly system however and so is used only for these high end models.

Pressure assist toilets have been around for many years and became very popular after the mandate for 1.6gpf came into effect. Pressure assist flushing systems have a secondary sealed tank inside the standard tank. This tank works off the house line pressure and uses that additional force to propel water out of the bowl and down the drain line. This is an effective system but has become less popular as the performance of gravity types has increased. Pressure assist systems tend to be effective but very loud. In addition, the pressure tank cannot be easily serviced by a non-professional. American Standard and Kohler both offer pressure assist models. Toto does not.

The majority of toilets sold today are gravity type typically either “siphon jet” or “wash down”.   Siphon jet toilets use a jet to initiate the flow of water into the trap way thus jump staring the siphon action when the flush valve is opened (which happens when the trip lever is depressed). Siphon jet toilets tend to have a larger water surface (which is helpful in keeping the bowl clean) and larger trap way. Wash down toilets work only by gravity. The bulk of the water for the flush is “dropped” into the bowl at once and this triggers a siphon action that clears the bowl. This can be an effective system but may occasionally fail to clear the bowl completely. Wash down systems are often seen on “Dual Flush” toilets, for example the Toto “Aquia”.

This outline gives you the basics of flushing systems but there is much more to it than this. In my next post I will go into more detail about the various systems that each of the “big three” manufacturers has developed and try to give you some tips on what to look for.

Be Sociable, Share!

Leave a Reply

Your email address will not be published. Required fields are marked *

This blog is kept spam free by WP-SpamFree.