Installing Natural Gas Heater on AG

[crek31]

I have a Pentair MasterTemp 400,000 btu heater to be hooked up to an Intex. In reading through the heater manual, it talks about the "pressure switch" needing to be adjusted if the heater will be "below water level." I don't see that the manual explains this. I don't understand how to compare the placement of the heater to the water level - what part of the water should I consider relative to what part of the heater? That is; the bottom of the pool, the top of the water, or an inlet or outlet port?

My pool will sit on a concrete pad. The pool equipment will be on pavers that will be close to level with the concrete the pool sits on, but I'm sure the grade is not exactly level between the concrete and where the pavers will be. Can someone tell me how to know if my heater installer (a freelance guy who supposedly knows pools) is supposed to adjust for below or at water level?

Here is an excerpt from the manual:
CAUTION
BELOW OR ABOVE POOL INSTALLATION
The water pressure switch is set in the factory at 3.00 PSI (± 0.75 PSI). This setting is for a heater installed at pool level. If the heater is to be installed more than 1’ above or below, the water pressure switch must be adjusted by a qualified service technician. See page 34, Figure 29.
FLOW SWITCH
If the heater is installed more than 5’ above the pool or more than 4’ below the pool level, you will be beyond the limits of the pressure switch and a flow switch must be installed. Locate and install the flow switch externally on the outlet piping from the heater, as close as possible to the heater. Connect the flow switch wires in place of the water
pressure switch wires.


Thanks!

 

[JasonLion]

The height is measured from the surface of the water to the top of the heater manifold. The manifold roughly corresponds to the location of the inlet and outlet pipe connection on the heater. You can see a diagram showing this on page 18 of this manual. A few pages before that it explains how to adjust the pressure switch. That manual might not exactly correspond to your heater, but yours should be quite similar.