Heater is new, installed at grade on above ground pool that is 48" deep so pressure switch is 3' below the water line. With pressure switch adjustment turned fully clockwise the heater will run without the pump on. Pressure at switch is approx 1.5 PSI. Is the switch faulty?

unless heater is below water level or above water level switch should be ok syphon loop might be clogged

The purpose of the pressure switch is to verify the pool pump is operating properly and water pressure is present in the heating chamber. When water pressure is not present, the heater control system is designed to not allow initiation of flame. The pressure switch is preset at the factory for deck level installations. When the heater is located below the level of the spa or pool, the pressure switch may require an adjustment to compensate for the no-flow static head.

CAUTION: The Hayward Pool Heater is essentially a furnace. A trained technician should be consulted to repair it. DO NOT OPERATE the Hayward Pool Heater without a properly functioning and calibrated water pressure switch. The pressure switch adjustment requires both the pool pump and the heater be operational. As a result, extreme caution should be used during this procedure since sources of energy can not be isolated during the procedure.

The following procedure is recommended to calibrate the pressure switch.

1. The water pressure switch is located behind the front service panel. The pressure switch is typically on the left side, above the burners.
2. Be sure the water filter is clean before making the adjustment.
3. With the pump and heater system switch on, carefully turn the pressure switch adjustment dial clockwise, until a click is heard from the gas valve.
4. Turn the adjustment dial counterclockwise 1/4 turn.
5. Turn the pump off and on several times. The heater should shut off immediately when the pump is shut off. If the heater fails to shut down when the pump is off, repeat the steps above until the pressure switch is properly adjusted.
6. If the adjustment process fails to produce proper results the pressure switch should be replaced.

above ground pools have to be erected on perfectly level ground. If you have one side 3 inches lower than the other then all the weight of the water is against that lower side and eventually the water will overcome the air pressure in the ring and it will collapse and let the water out especially if the ring has a small air leak and looses pressure. You are lucky that you do not have a pool with 4ft sides as the loosing water effect is remarkable and will wash away any thing in it's way. Use the water in the pool as a level and adjust the base ground so that the pool sits level all the way around.

Did you bleed the gas line of air? In a nw installation it is not uncommon to sit there 20-30 seconds with the gas line union open and the shutoff open to get all the air out and a good flow of gas present. If that doesn't work post a comment with what else happens.

John

leak is prolly from pressure switch connection or heat exchanger...... if from heat exchanger buy a new heater

Yours is an in ground pool, right???

Break the return line between the filter output and the pool. That is where your heater goes. If you have a chlorinator ... it should be between the heater output and the pool (chlorine is the last thing to go into the water before the pool). You will need a fuel line of appropriate size for the heater and either 110 or 220 volts of power. Your heater shold have a safety built in that prevents its operation unless there is water pressure.

What kind of pump are you using?
Sounds like the Intex is restricting water flow there by heating up your pump and shutting it down..
You may need to re plumb everything to handle the flow.
Intex hoses and fittings are different than the industry standards just so the can make you buy from them
Do what ever it takes to get good flow

This blog has information about sinking an above ground pool. It is normally recommended that you do not sink the pool entirely into the ground becuase of pressure concerns and the risk of collapse. Generally, you leave 1-3 feet of the pool above the ground and install a deck or similar feature to make the pool appear to be in the ground. The type of pool liner that you have (expandable) is best for this practice, but it can be done with overlap or regular beaded liners also.


http://backyardcity.wordpress.com/2009/06/02/the-above-ground-pool-goes-underground/

The maximum flow rate for that heater to be installed in without a bypass is 125 GPM. The owner's manual can guide you thru gas pressure adjustments or adjusting the set point of the water pressure switch. Please note that unless you are installing the unit below or significantly above the water line you should not have to adjust the pressure switch. Whenever you do adjust it, be certain to turn the pump on and off several times to be certain the heater reacts to the pump condition...failure to shut down when the pump does can be a serious and dangerous condition.