Amtrol Therm-X-Trol manual Water is not compressible, So pop goes the relief valve, Before relief

DANGER!	BACK FLOW PREVENTER
	BFP

Water is not compressible

Since water completely fills the water heater and system piping before recovery starts, and since it can't be compressed, the expanded volume, even though small, has no place to go.

As a result, the expanding water creates a rapid and dangerous pressure increase in the water heater and system piping, much like the action of a hydraulic ram.

So "pop" goes the relief valve

First of all, the T & P relief valve you installed serves as an emergency con- trol only. It was never designed as an operating control. Once a safety valve is used on a daily basis, it isn't that safe.

Deposits on the seat... deteriorating springs... wear- and-tear erosion can wear out a relief valve in no time at all.

Dangerous pressures

The setting on a temper- ature & pressure safety relief is quickly reached, and the relief valve opens, losing heater water down the drain or, more often than not, all over the floor.

LOST

BTUs

before relief

What most

people don't realize is that

d a n g e r o u s

conditions can exist during thermal expansion long before the relief valve operates.

The illogical practice of operating your safety valve once or twice a day is not only wasteful (you paid to heat the water that went down the drain), it's also dangerous.

Internal pressures repeatedly occurring during recovery periods can collapse the center flue of a gas-fired water heater, creating a hazardous presence of deadly carbon monoxide gas, or even a water-heater explosion.

4 5