May
24

Dual Flush Retrofit Kits for Dual Flush Toilets – Do They Work?

By

Sadly, no.  This is one to file under, “Too Good to Be True.”

There are several aftermarket retrofit kits available today that promise to transform a standard toilet into a dual flush model that can “save more water than a high priced high-efficiency toilet.”

Unfortunately, these gadgets simply regulate the amount of water entering the bowl and do nothing to alter the water flow in or out of the bowl.  Since bowl design is the most important factor in a toilet’s performance – and even more critical in low-flow toilets – these kits promise far more than they deliver.

As the Professor has previously explained, standard and dual flush toilets have different flushing mechanics.  While standard toilets depend on siphonic action to “pull” waste out of the bowl, dual flush toilets rely on the “push” of water to clear the bowl.  More advanced technology, such as the WaterSense-certified H2Option Dual Flush Toilet, combines the traditional siphonic “pull” force with the newer “push” action associated with the washdown flush.

Because standard toilet bowls are not specifically engineered for less water, homeowners will have as much luck using these retrofit kits as they would adding a brick to the toilet tank.  Both strategies try to “trick” toilet science and will likely result in incomplete flushes.  Worse, users will likely overcome this problem by – you guessed it – flushing again.  Multiple flushes eliminate any possible water savings.

In addition to voiding the American Standard warranty on toilets, installing these types of gadgets will frustrate homeowners and discourage any future use of proven water saving technologies such as HETs and dual flush toilets.

Physics, as it turns out, is it right up there with “can’t fool Mother Nature.”

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9 Comments

1

Makes sense, Haven’t heard much about these gadgets in the field yet, but one would think that it is a design failure.

2

My wife insisted we retrofit our dinosaur toilets to help save water (and ultimately, money on our water bill). We compromised, and installed one in our master bathroom. I hated to admit it to her, but it actually does work. I think they key was to not only find the right brand, but also have the right type of older model system. We had no luck at all with the American Standard product, but DID have luck with a product from . So far, we are saving water – I measured since I was sure I was going to be right about this – and we may attempt to do the same with our other 2 systems.

3

We just installed one of these in our home earlier this month and haven’t had any issues with it. Our toilets were installed in 1985 when the home was built and hadn’t been altered in any way (we purchased from the original homeowner).

4

The professor isn’t quite right. The best toilets that used the least water were the old wall hung units. Recently I was changing out all of the flush mechanisms in a local Bed and Breakfast for dual flush units( that all flush better now with less water)and two of them I left alone. They were the old style high units with the tanks six feet off the floor. it turns out that they only use about a gallon of water to get the job done. This is part of the principle behind the dual flush kits. When installed the water level is left to the old height or even a little higher. The water force is increased because the water force from the top of the tank is pushing it better. Quite a bit different than a brick. Also, most of the dual flush toilets on the market are using the same design as the 1.6 gallon toilets that came out as far back as 1992. There are a few high tech ones out there that are very expensive. I challenge you to read what actual customers of our dual flush kits are saying. Those are real experiences by real customers

5

Thank you Bruce, JD, Andy and Carl for your input. As any politician knows, if you take a stand, you’ll have opponents. Taking a stand in favor of the retrofit kits would bring in the comments from the other side!

A few points to ponder: There are a lot of different toilets out there, so results differ on old 3.5 gallon per flush (gpf) toilets vs. old 1.6 gpf toilets vs. new 1.6 gpf toilets vs. the old wall hung bowl with a flush tank mounted six feet high in the air.

The recommendation comes because while it may look like retrofit kits are working properly, some consumers may not realize it if the water doesn’t come back to seal every time so that sewer gases don’t get into the room. Or if it overfilling the bowl and putting wasted water down the outlet. Or if there is sufficient carry-out into the drain line so that the pipe won’t eventually get stopped up?

That said, some of these new retrofit kits look like they are more sophisticated than some of the original kits that came on the market. The Professor is back in the lab doing more tests.

Finally: yes we do remove brand mentions from comments. Nothing personal.

6

Have you completed anymore studies to see if the dual flush retrofit for 3.5 gallon toilets is effective? I’d like to use one of these but I’m afraid it is like you said….too good to be true. I have an older 3.5 gravity fed toilet.

7

I’ve been looking at kits and reviews of these products since seeing one installed on the PBS show some time ago. My toilets were new when this house was built in 1967. Google led me to your last year’s review and promise to do more tests. Have you modified your original take on the kits?

Thanks

8

I have to disagree with you on the dual flush retrofit kit. Although some are certainly better than others, there are several on the market that work very well. Some toilets are more suitable to the conversion.

AP
http://www.AskAquaPro.com

9

PURCHASED FLUIDMASTER DUAL FLUSH KIT TO RETROFIT OUR 1.6GPF TOILET; WORKED AT THE START BUT PLUNGER STARTED STICKING ON THE LARGE DOWNFLUSH. I THOUGHT THE POSITION OF THE FLOAT ASSEMBLY WAS THE PROBLEM I.E. CAUSING STICKING OR CABLE ASSEMBLY; ROTATING THE FLOAT ASSEMBLY AND LUBRICATING FLUSH HANDLE ASSEMBLY MADE NO DIFFERENCE. I CHECKED HOME DEPOT SITE TODAY AND FOUND AT LEAST TWO OTHER CUSTOMERS HAD HAD THE SAME PROBLEM AND ONE ADVISED HIS HOME DEPOT NO LONGER SELLS IT. I BELIEVE THIS WOULD BE THE S2DBLC MODEL. I LIKE THE IDEA BUT THE MECHANICS OR EXECUTION APPEAR TO NEED MORE WORK. I WILL BE STRIPPING MINE OUT AND RETURNING IT TO HOME DEPOT. I WILL BE CHECKING THE REVIEWS ON DUAL FLUSH KITS, NOW, BEFORE I PURCHASE ANOTHER…IT APPEARS FROM COMMENTS THAT THERE ARE GOOD CONVERSION KITS OUT THERE.

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