400 BTU pool heater and gas flow rate question

marlinmanMarch 13, 2011

We are building a new house and pool at the same time. I had my builder put power and Cat5 lines for the pool, but some how we forgot to run LP line. We can tap into the 3/4" line that is supplying the tankless water heater, but will there be enough gas flow if the water heater and the Rayvac 400 btu pool heater are on at the same time?

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Not likely. What the plumber will likely do is run a medium or high pressure line near the heater and use a regulator to feed it the proper pressure/quantity of gas. This is how my heater is connected to my tanks.


    Bookmark   March 13, 2011 at 8:18PM
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You need to contact your propane supplier and make sure your tank and line are big enough for that size heater. Although a 250gal might work, we usually put in 1000 gallon tanks for that size heater.

    Bookmark   March 14, 2011 at 4:45PM
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General rule of thumb is about 1 gal per hour per 100,000 BTUs.

FWIW, my heater is a 300K and I have a pair of 125 gallon tanks. They will only fill them to 80% of capacity so there is space for the vapor to accumulate. It's the accumulated gas that is sent down the line, not liquid. In the tank, the liquid boils, forming more gas as the pressurized gas is vented to the heater.


    Bookmark   March 14, 2011 at 9:08PM
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Its 91,330 BTU per gallon . According to the DOE.

A 3/4" line at 100' of pipe run will handle 2,134,000 BTU @ 10 PSI Which is what most first stage tank regulators here run at.

200' is 1,509,00 btu. Which should handle most larger tankless heaters with a 400,000 BTU pool heaters.

    Bookmark   March 14, 2011 at 11:51PM
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