Raypak 503-2003 manual Gas Supply, Pool/Spa Water Chemistry, Water Hardness, pH of Water

SECTION C: Installation

NOTE: There are 2 separate drains on the MVB that must BOTH be drained to protect the heat exchanger. These are both accessible by removing the lower front door from the heater. Drain any piping of all water that may experience below-freezing temperatures.

Pool/Spa Water Chemistry

NOTICE: Chemical imbalance can cause severe dam- age to your heater and associated equipment.

Water Hardness

Water hardness is mainly due to the presence of cal- cium and magnesium salts dissolved in the water. The concentration of these salts is expressed in mg/l, ppm or grains per gallon, as a measure of relative hardness of water. Grains per gallon is the common reference measurement used in the U.S. water heater industry. Hardness expressed as mg/L or ppm may be divided by

17.1to convert to grains per gallon. Water may be classified as very soft, slightly hard, moderately hard or hard based on its hardness number. The salts in water will precipitate out when the water is heated and will cause accelerated lime and scale accumulation on a heat transfer surface.

Raypak water heaters can operate lime/scale-free using potable water with a hardness not exceeding 20 grains per gallon. Proper operation is achieved by setting the temperature rise/water flow per the guidelines in the installation instructions. If the hardness of the water exceeds the maximum level of 20 grains per gallon special measures must be taken to adjust flow and tem- perature rise. Water should be softened to a hardness level no lower than 5 grains per gallon. Water softened as low as 0 to 1 grain per gallon may be under- saturated with respect to calcium carbonate resulting in water that is aggressive and corrosive.

pH of Water

pH is a measure of relative acidity, neutrality or alka- linity. Dissolved minerals and gases affect water’s pH. The pH scale ranges from 0 to 14. Water with a pH of

7.0is considered neutral. Water with a pH lower than 7 is considered acidic. Water with a pH higher than 7 is considered alkaline. A neutral pH (around 7) is desir- able for most potable water applications. Corrosion damage and water heater failures resulting from water pH levels of lower than 6 or higher than 8 are non- warrantable. The ideal pH range for water used in a storage tank or a copper water heater system is 7.2 to

Total Dissolved Solids

Total dissolved solids (TDS) is the measure of all min- erals and solids that are dissolved in the water. The concentration of total dissolved solids is usually ex- pressed in parts per million (ppm) as measured in a water sample. Water with a high TDS concentration will greatly accelerate lime and scale formation in the hot water system. Most high TDS concentrations will precipitate out of the water when heated. This can gen- erate a scale accumulation on the heat transfer surface that will greatly reduce the service life of a water heater. This scale accumulation can also impede ade- quate flow of water and may totally block the water passages in the tubes of the heat exchanger. A heat exchanger that is damaged or blocked by lime/scale accumulation must be replaced. Failure of a water heater due to lime scale build up on the heating surface is non-warrantable. The manufacturer of the water heater has no control of the water quality, especially the TDS levels in your system. Total dissolved solids in excess of 2,500 ppm will accelerate lime and scale formation in the heat exchanger. Heat exchanger fail- ure due to total dissolved solids in excess of 2,500 ppm is a non-warrantable condition. Raypak offers basic temperature guidelines for operation of a potable water heater on normal to moderate levels of hardness and solids but levels of hardness and total dissolved solids beyond normal limits for operation will require special setup and operation.

NOTICE: Failure of a heat exchanger due to lime scale build-up on the heating surface, low pH or other chemical imbalance is non-warrantable.

Gas Supply

DANGER: Make sure the gas on which the heater will operate is the same type as specified on the heater’s rating plate.

Gas piping must have a sediment trap ahead of the heater gas controls, and a manual shut-off valve lo- cated outside the heater jacket. It is recommended that a union be installed in the gas supply piping adjacent to the heater for servicing. The gas supply pressure to the heater must not exceed 10.5 in. WC for Natural Gas or

13.0in. WC for Propane Gas. A pounds-to-inches regulator must be installed to reduce the gas supply pressure if it is higher than noted above. This regulator should be placed a minimum distance of 10 times the pipe diameter upstream of the heater gas controls.

Refer to Table H for maximum pipe lengths.

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