Currently, toilets on the market can be divided into two types: wash down type (i.e. direct flush type) and siphon type according to different flushing methods.
The drop-down principle uses the height difference of the water tank to displace dirt through the gravity of the water flow; the siphon principle uses the siphon principle to discharge dirt.
Both flushing methods have their own supporters: among them, European sanitary ware companies represented by Spain’s ROCA Sanitary Ware have always insisted on using the flush-down method;
Asian sanitary ware companies represented by Japan’s TOTO generally use the siphon method.
American companies represented by Kohler and American Standard have adopted both methods.
I will only make some comparisons between the two from a technical perspective for reference.
1) Specific water consumption
Flush volume Wash down Flushing type Siphon type (new water-saving type) Siphon type (old-fashioned toilet)
Small flush (half flush) 3 liters 4.2 liters 6 liters
Big Chong (Full Chong) 6 liters 6 liters 9 liters
It can be seen that wash down toilets have the advantage of saving water; siphon toilets currently cannot truly achieve 3 liters of flushing.
2) Ratio pipe diameter
Pipe diameter Wash down type Siphon type National standard
Pipe diameter greater than 60mm approximately 41mm approximately 41mm
It can be seen that the pipe diameter of the flush-down toilet is larger and is not easy to block;
In order to realize the siphon principle of the siphon type, the sewage pipe must be close to 41 mm. If there are large foreign objects, it is easy to get clogged.
There is also a very professional issue here, which is the design of the siphon pipe.
The size of the tube wells in the entire curved siphon pipe is not uniform.
In the middle of the pipe, there is a node, technically called a “choking point.”
The pipe diameter at the choke point must be strictly controlled between 36–38mm! Slightly smaller than the diameter of other parts of the upper and lower parts!
If it is too thick, it will not be able to form enough suction; but it should not be too thin. If it is too thin, dirt will easily become clogged.
A few toilet paper or two may cause poor drainage.
Ceramic products will inevitably deform during high-temperature firing, making it difficult to control the size of the choke point.
This is the root cause of the poor flushing stability of siphonic toilets!
3) Specific waste discharge capacity
Sewage discharge distance wash down type siphon type national standard
Sewage discharge distance greater than 15 meters greater than 12 meters greater than 12 meters
Data shows that the average waste transportation distance of flush-down toilet drainage pipes can reach more than 15 meters;
while the waste transportation distance of siphon drainage pipes is only more than 12 meters.
4)Higher than water seal
This is a much more interesting topic! I have heard customers say more than once: “The hole in the toilet is so big!
Water will definitely splash on the buttocks.” In fact, this is even more of a misunderstanding.
In fact, the siphon type has certain requirements for the amount of water in the trap.
The entire hole must be covered, otherwise the water seal is not high enough and air leakage will occur! The falling type does not have this limitation.
To sum up, siphon toilets have high technical requirements, are difficult to manufacture, and have poor relative stability.
The principle of flush toilet is simple and the technology is stable and reliable.
