By definition a 1 ton heat pump has the capacity to absorb as much heat as a ton of ice absorbs while melting. Therefore your heat pump would theoretically turn your 275 gallons of water into a block of ice in an hour. It would probably take a couple of hours because of the heat transfer from the tank to the ground. Not much surface area on a tank, thats why they use coils of pipe or vertical lengths of pipe for ground source heat pumps. If you could absorb enough heat from the ground source you would have better results submerging your outside coil completely in the water from your groundsource and using the power that runs your outside coil fan to run your circulating pump. Better efficiency would also be achieved because of the elimination of one heat exchanger. It would also increase your efficiency in air conditioning mode.

Southpaw I don't mean to contradict you but your explanation is not quite correct. thus requires a little more information when talking about converting 1 ton of water to ice and vice versa the the conversion figures are based on water in liquid form at 32° f to ice at 32°f commonly used as both the melting and freezing points of water however under certain conditions water molecules may remain fluid at temps as low as -41°f this is termed as super cooled water, which has no relevance here.

The roots for refrigeration are in the ice making industry, and the ice manufacturers wanted an easy way of understanding the size of a refrigeration system in terms of the production of ice. If 288,000 Btu are required to make one ton of ice, divide this by 24 hours to get 12,000 Btu/h required to make one ton of ice in one day. This is the requirement for the phase change from liquid to solid — to convert water at 0°C (+32°F) into ice at 0°C (+32°F). As a practical matter, additional refrigeration is required to take water at room temperature and turn it into ice.

To be specific, one ton of refrigeration capacity can freeze one short ton of water at 0°C (32°F) in 24 hours.

So, a ton of refrigeration is 3.517 kW. This is derived as follows:

The latent heat of ice (also the heat of fusion) = 333.55 kJ/kg = 144 Btu/lb

One short ton = 2000 lb

Heat extracted = 2000 x 144/24 hr = 288000 Btu/24 hr = 12000 Btu/hr = 200 Btu/min

1 ton refrigeration = 200 Btu/min = 3.517 kJ/s = 3.517 kW = 4.713 HP