Dear Bob: Thank for writing back. In AZ I like to go a little big on the heat pumps because of the cold nights. Cold nights just sucks the heat out of the pool and then the heat pump runs too long the next day. So keep the heat pump over 100,000 BTU's and use a blanket in cold weather. Most manufacturers bump up the wire size over 100 feet to the next size. They will always say to follow local codes and use a licensed electrician. Some heat pumps need bigger wire than others. It depends on the one that you choose. I or the tech department at the factory can guide the electrician in the right direction. I had a heat pump outside my bedroom for 5 years. I ran it in the day so noise was never an issue. If it falls below freezing out side you need a timer that senses temperature to run the water so that the water doesn't freeze in the heater and void the heat exchanger warranty. Some people just run their water pump 24 hours a day when they get a cold wave. Good if you remember, and you need to hope you don't have a power failure. Shipping is about a week. We ship on the expensive trucks that have a lift gate (not a tail gate as I have seen advertised elsewhere which means nothing) Some heater have a 2 year warrant in AZ where they have 1 year elsewhere. I like at least two years as that is when the heater will have an issue is in the second year. Then they are usually go to go for many years after that. COP is important. I don't think the most important thing though. Any heater in the 5 range is considered good in the heat pump world. the most important think is reliability. This should be a fun thing and not cause you stress. Then I like company reputation, years in business, warranty, efficiency and price. About in that order. A heat pump that defrosts is good. Even if you never use the cooling feature. The Heat Siphons work well in low humidity area with no defrost. They will shut down when they get too cold and then restart when it gets into the 50's. So if you have a spa and you want to jump in when it is 45 and the heat pump had shut off when it got too cold then you won't get the spa warm. In that situation a defrosting heat pump is better. It is always better to heat in the day, as they are more efficient unless you get a break on the electrical rate at night. Some area in AZ get about 50% their day rate. I hope that helps and that I hear from you soon.
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