Hello,

I saw the discussion about whole house backflow prevention devices and I wanted to share some additional information.  In the past I was looking to find a better check valve as the one in use(flapper) I think has too high of a failure rate due to solids blocking the flapper.  This fundamentally is because the valve has a ¾ inch drop in it, therefore the line must be lowered for quite a distance to make this up and still have positive flow.  Not only is that rarely done, but even when it is, the slope is often reduced below the 2 ft/s minimum, and thus either way the installation contributes toward debris accumulation that results in the high failure rate of the flapper style check valve.

After a couple years of searching, I have found the attached check valve.  It was invented in 1995 and deployed in Illinois (I think).  It is approved in five states, with five more giving verbal approval, Michigan is one with verbal approval at this time.  This check valve is leagues ahead of the flapper valve.  The inventor of this check valve states that it was first deployed in four houses in 1995 as the homes were having multiple sanitary sewer backups daily.  The valve has operated in the homes to date daily without a failure yet.

The valve itself is $1120 for the material, the sump bucket and high water alarm are additional charges.  Material costs total $3200 as a total package for valve, pit, and high water alarm.  For comparison, the flapper is usually $200 at a contractor price with all the accoutrements.  I think any Contractor can make their sump pit for the valve rather than buying JR Smiths to keep costs down.  It is pricey option, however I wanted you all to know it was out there as an option after I read about the discussion with Ralph about whole house check valves.  I had heard Ann Arbor doesn’t like them because they feel it has a high rate of failure.  This check valve will operate for  many years without a problem.

In case the attached specification doesn’t make sense, the back water valve is essentially a slide gate that gets pulled up into place when the sewer surcharges(gets higher than the pipe) and this surcharge applies pressure to a diagram that forces the slide gate up by the pressure of the water, then when the sewer drains the counterweight forces the sluice back down.  Essentially the math is 48 pounds of uplift needed to overcome the assembly and counter weight on top of the diagram that pulls a stainless steel slide gate into place slicing any debris in its path.  With a 13.25 inch diameter diaphragm, a foot of surcharge will generate about 60 pounds of upward push to close the valve.  In a whole house check valve system, most of them are 1.5 to 2 feet below the floor.  This valve will have 10 pounds of upward force with a one foot surcharge to slice any debris in the seat of the gate.  With 1.5 feet of surcharge, that force jumps to 40 pounds.  The counter weight is adjustable as it is really just a normal weight a weight lifter would use.

I have been presenting this to anyone discussing a whole house check valve as it is simply just a better mousetrap.  The cost makes it really only of benefit in highly finished basements where sanitary sewer failure is expensive, or in homes with a history of regular backups, so it may not really apply to our situation, however we should all know just what the options are.

Greg Marker