PROBLEM

RESULT

NOW EVEN COLD WATER USE ADDS DEMAND ON WATER HEATER. 

Thermostatic valves require heated water contacting the valve to keep it closed. Remove the heated water and the valve returns to its default normally-"open" state.

Remember, any amount of water which exits the hot water line, regardless of it's hot or cold temp, that same amount will enter into the water heater to be heated.

Simple explanation:

Picture a long balloon, the kind used by clowns to twist into animal shapes.  If we put a twist in the middle of the balloon and make a hole in the right half of the twisted balloon, only air from the right side escapes because of the twist in the middle.  Take another balloon "without a twist" in the middle, now if we make a hole in the right end of the balloon, air escapes from both ends of the balloon.

Like the example above, hot and cold water lines joined together with a "normally open" thermostatic valve  and someone or something begins to use cold water, they will receive a mixture of water from both the hot and cold water lines.  This will continue until water hot enough to close the thermostatic valve reaches the valve.  Only then will they receive water exclusively / only from the cold water pipes as initially intended.

Any system which does not allow the homeowner to adjust the temperature set point cannot be optimized to peak efficiency, comfort or savings.  These systems tend to leave the homeowner wishing for hotter hot water or greater readiness and have known to leave owners with discomfort from their cold water line with no means of correcting the discomfort their experiencing aside from returning the product or living with the now waiting for cold water comfort or still having to wait for hot water comfort.  Most users of these systems are under the belief that the discomfort their experiencing is normal when it's actually a limit by design of their system.

Off-scheduled hot water usage forces owners to wait and waste water consuming savings they had achieved during scheduled hot water use.

Systems which use thermostatic bypass valves with a pump mounted a top the homes water heater are required to continuously run and consume energy even after hot water has reached it's destination.  This is a by-design inefficiency many are unaware of when they make a purchase.

Narrow fittings on heater mounted pumps reduce the hot water flow capacity which can affect the homes hot water systems ability to satisfy multiple loads i.e. shower and dishwasher at same time.

Buildup of calcium or mineral deposits are well known to be the biggest problem causing shorter then expect pump life and / or efficiency and comfort.  Some systems require "periodic maintenance"   To prevent voiding the warranty.  Unfortunately, the notice to perform this required maintenance is found in very tiny print on the manufactures install guide and not easily found on their website.  Missing a required cleaning (voids warranty). 

Temperature sensing should be performed at the  "last fixture" since anything past that is not useable by the homeowner. 

Unfortunately, the manufacturer makes no mention of this in their literature to prevent consumers from purchasing something that is obviously not practical in most cases.

CONDITION

RESULT

Hot water at optimum comfort and readiness, maximum possible savings

Flexible / on-demand control options

Increased convenience i.e. scheduled-off anytime "single-cycle" override.  Greater savings.

User receives water "exclusively" from their cold water line.  Positive flow restriction makes siphoning from hot water line impossible.

Less electrical consumption and intermittent demand to water heater vs continuous demand on water heater.

Zero Maintenance, no mineral buildup and longer pump life