Exactly what is a heat pump?

[JETTA]

I went to the "chain" pool store and they are selling heat pumps for AG pools. I asked a question on how do they work and I kind of got an answer that did not make sense.

I have central air in my home. I was told I need to have this heat pump connected to my heat exchanger portion of my HVAC system. This to me does not make sense. If that was the case that means the only time I would heat the pool would be when the a/c is on.

So how do these work?
Does this connect to my HVAC system in my home?
Is it a DIY install?
Is it worth the cost for a 7,600 gallon pool here in New England?

[CarlD]

Mixing macintosh and jonathan apples.

All a heat pump is is an air condition unit in reverse.--same tecnology. But the extracted heat is used to heat the water and the resuting cool air is dumped into the air. You can heat your home with, then reverse it in summer to be an A/C unit.

There is a system where you can water-cool your a/c, rather than air cool it and have that cooling water be your pool water. This is not a heat pump.

[Poconos]

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

[cleancloths]

I would love to hear if someone had a real-world design to connect the two systems. I cringe in the summer as I feel all the cold air blowing out of my pool heatpump while I had lots of hot air blowing out of the Central A/C compressor. The two units are about 100' apart so I cannot think of an economical way to make this work.

[sailork]

Maybe I'm only thinking about this because my water pipes are in my attic and the "cold" water tap runs about 95 degrees during the day, but somebody posted a link to Solar Attic a while ago. It looks like a really great idea. I'd buy one if I wasn't in @#$ Houston.

http://www.solarattic.com

http://www.poolforum.com/pf2/showthread.php?t=2184&highlight=solar+attic

Maybe you folks who often have "Cold" could use this for something. I'd suspect an attic fan that blew out across a grid of pipes from your pump return would be an even more energy efficient idea since it would bring cold air from outside into your attic through the eves. (Yeah, we do that a lot down here.)

[Poolsean]

Aqua Cal Heat Pumps is a sister company of AutoPilot. Carl and Al explained it well.
We take the heat from the air to change liquid freon into a gas. The gas then goes through a compressor to superheat it. The very hot gas then passes through a heat exchanger (this may be made of either cupric-nickle or titanium) that releases the heat to the water. The cooling of the gas by transfering the heat to the water, changes the freon back into a liquid state.
Titanium is being offered more and more due to its chemical resistance (read bad water chemistry).
What's important (and how you can tell which are more efficient) among heat pumps is the COP rating. This is similar to an air conditioner's SEER rating. The higher the number, the more efficient it is. For Heat Pumps, anything over 5.0 is good.

The best analogy for a Gas heater vs a Heat Pump is a muscle car vs an economy car. Both will get you there. However, the muscle car will get you there faster but use much more gas to get there.
Heat Pumps are better at maintaining the heat. Gas is better at getting the heat into the pool fast.

Why not integrate the attic air to the heat pump? Proper ventilation and air flow. If you block the air flow out of the heat pump, you will greatly reduce efficiency. In fact, you may cause the unit to frost up. Another in fact, if you install it too close to the eave of your roof, you can recirculate the cool discharge air around to the evaporator coil, again, reducing efficiency! You will need the services of an engineer to calculate the proper duct work necessary. Much easier to just operate it as it is designed.

Hope this helps.

[waterbear]

Sean, not to sound like a commercial but I have an AquaCal Heatwave Icebreaker 120 on my pool and spa. It's great. It will heat my spa to 104 in about 10 minutes during the summer and in the winter when it was just below 50 degrees it took my spa from 65 degrees to 100 degrees in about 25 minutes! Still waiting for my pool to get hot enough to try out the reverse cycle cooling feature this summer!