A patent search was done for US patents on antiscald valves. Interestingly, 41 patents
going back to 1917 were reviewed. So a suitable means for alleviating the hot water scald
burn issue has been a concern to some workers on the subject for over 80 years. The use of
antiscald valves is the most obvious manner to fix the problem.
The US manufacturers of hot water heaters could and should incorporate tempering valves
within the heater design. The heater could then have 2 hot water outlet ports.
One hot water port would be for bathroom sinks, kitchen sinks, showers, and bathtubs,
with delivered hot water at a maximum of 115 F. The second port could then have delivered
water at very high temperature (in excess of 115 F), and whatever purpose for that is
unclear.
Reason is that some soaps are made so that clothes can be washed in cold water. Also,
an argument is that water in excess of 115 F is needed for the dishwasher - not so.
As explained in information from the Soap and Detergent Association, the cleanliness of
dishes from the washer depends upon 1. type of soap, 2. how much soap, 3. agitation in the
washer, 4. soak time, 5. length of time dishes have sat dirty before washing, and of
coarse, 6. hot water temperature, but never temperature of the hot water alone.
Further, nearly all of the newer dishwashers have a build-in water temperature booster.
If an old dishwasher is being used, the 115 F hot water to the washer can be more than
compensated for when a judicious choice of soap is used, preferably a soap containing an
appropriate detergent for the job, and a soap that contains a suitable surfactant.
We believe that the hot water heater manufacturer could and should incorporate a
tempering valve within the heater quite simply because of the economics of scale. Our
survey shows that orders by tempering valve distributors is normally in the hundreds, and
an extremely rare order is for quantities of over 1000 units. It does not take much
thought to realize how low the cost would be for orders of one million units or more. The
tempering valve manufacturers could then appropriately tool up, change the design, and
reduce the unit cost accordingly.
We are discussing here both the point of source ( in or near the hot water heater ) or
point of use (at the bathtub/shower). For point of use, one manufacturer retails tempering
valves at $24.99 for the tub spout, $12.99 for the shower head, and $6.99 for the sink.
The plumbing engineer and the plumbing contractor would be well advised to strongly
recommend the use of either a point of source or a point of use tempering valve in all
designs and installations.
Burns
