I have a inground spa attached to pool. It has its own main drain and 3 jets. It has a short wall dividing it from the pool. So water from the pool spills into the spa. In front of pump there are 3 valves: Pool main drain, pool skimmer and spa main drain. In order to heat the water, should I close the 2 pool valves and open the spa main drain valve? It seems to make the pump work harder when I do that, but I'm trying to heat spa as fast as possible. The spa is about 400 gallons. I also want to know how long it should take to heat up.

Any suggestions?

The spa is set at a lower elevation than the pool? I don't know that I've seen that before. Could you post back with information about your heater? (what type... brand/model/BTUs) Also, could you be more specific about how you know the pump is working harder? Because it's louder? Increased PSI at the filter gauge?

Can't imagine trying to heat a spa without isolating it from the pool... you not only don't want pool water feeding into your pump (so closing off pool valves and opening the spa drain valve that go in to the pump is right) but you want to be sure that instead of water returning to the pool it is supplying the spa.

The plumbing experts may have more to say about your configuration and different questions to ask you.

In This Order:

Open Spa Drain. If it's on a 3 way valve, that should isolate it from the pool. If there are individual 2 way valve, open the spa drain 1st, then close the skimmer and main drain valves.

Open the spa return valves and close the pool return valves. It is not unusual for the pressure in the filter to increase some.

Turn on the pool heater.

That should do it.

Scott

Thanks guys I will try those things when I get home. I didn't turn off jets to pool, I know. I will let you know the outcome.

That's how I do it.....takes about 10 minutes to get to 100 degrees. Shut the whole pool off.

If you forget to shut off the pool returns, you will know quickly because the water level in the spa will start to drop. And if you are not paying attention, the pump will run dry when the spa is all drained. Unless your spa really is lower than the pool, but I'm thinking you meant to say the spa overflows into the pool.

On a non-plumbing related note: Is the spa covered? At the very least a solar cover would be very helpful. Full thermal foam covers are also custom made for in-ground spas. A very good majority of heat is escaping from the surface so a cover would fix this.

If this were a contest (tongue in cheek):

My method: Get some fuel rods from the nearest Nuclear Power plant and drop them in. Might anger some people but it would heat it so fast, Josh's spa cover would blow off!

Scott