Pool store guy is wrong. They do not HAVE to be connected to the central HVAC system for your house. The heat pump is nothing ore than a refrigeration unit in reverse. That is the condenser (hot end) heats the pool water and the evaporator (cold end) dumps the heat to the air. In a central house air conditioner in cooling mode the condenser is outside and cooled by a fan and the evaporator is inside cooling the house. Now, if you want best efficiency and want to get creative, if you take the heat dumped from the house and use it to warm the pools evaporator, you increase the efficiency of the pool heat pump. Visa-versa, using the pools evaporator air to cool the air for the house condenser, you increase the efficiency of the house AC. IF I had central air AND a pool heat pump, being the cheapo that I am I would certainly tie the two together in a custom fashion to get the best bang for the electric $$. Doing this is not easy or cheap though, but neither are heat pumps and air conditioning systems.
Al