Scroll Models = Higher COP, Lower Noise

Piston Models = Lower Cost, Higher BTUH Output

ALL HEAT SIPHONS MODELS NOW
USE SCROLL COMPRESSORS EXCLUSIVELY!!

The Heart of a Heat Pump

is the compressor, which takes low pressure refrigerant gas and squeezes it, raising the pressure and temperature in the process. This hot gas then condenses at the high pressure giving off large amounts of heat for a relatively small amount of electricity to power the compressor's motor.

The more efficiently the gas is compressed, the higher the COP of the heat pump. Both piston and scroll compressor designs have some leaks and because they can't compress 100% of the gas, there are efficiency losses. Heat Siphon Scroll compressor models are about 12% more efficient than competitor piston models.

How a SCROLL COMPRESSOR Works

In a SCROLL compressor the gas is continuously squeezed and theoretically come close to 100% compression, something a piston compressor can't do because the valves get in the way.

Unlike reciprocating piston compressors with many moving parts, SCROLL compressors have only two moving parts - one scroll or spiral orbits a matching fixed scroll. The orbiting motion creates a series of gas pockets traveling between the two scrolls. On the outer portion of the scroll the pocket draws in gas, then moves it to center of the scroll where it’s discharged.

The SCROLL design allows more than one pocket of gas to be compressed at the same time providing a smooth, nearly continuous compression cycle. This enables the SCROLL compressor to operate more smoothly and quietly, with less vibration. The rating for noise is 3 to 5 decibels less than a piston compressor but our experience indicates for the HEAT SIPHON MODELS overall they are more like 1 to 3 dB quieter. In either case - PISTON OR SCROLL - HEAT SIPHON IS QUIETER THAN A POOL PUMP.

Piston vs Scroll

Heat Siphon's goal has always been to design for the highest COP (efficiency) no matter which compressor type is used. When matching the compressor to maximize efficiency in a given heat pump system (the same heat exchangers, air and water flow and control valves) a scroll will have a lower heat output compared to a piston compressor picked for the same system - about 4% more on the 3.25HP models and about 12% more on the 5HP models.

According to the design performance curves, piston compressors are actually more efficient at higher air temperatures than scrolls but they lose out at lower air temperatures. Overall, scrolls are about 12-15% more efficient than the current piston compressors.

The PISTON model compressors are a classic design, more economical to purchase and they have a higher BTUH Heat Output and a lower COP with slightly more noise.

HEAT SIPHON HISTORY - 1983 - The First Heat Siphon used the classic COPELAND CRK model 3.25HP PISTON compressor. It was the highest efficiency compressor available at that time. Scroll compressors would not be mass produced until Copeland introduced the scroll compressor in the late 1980's. In 1992 HEAT SIPHON shipped the first scroll compressor equipped Swimming Pool Heat Pump in the USA.

Scroll Compressor has Long History

Even though the Scroll compressor concept was invented in 1905 by Leon Creux (US Patent 801182) as a "Rotary Engine" design, it was not until the early 1970s that precision machining technology had advanced sufficiently to make a working prototype possible.

Development continued, primarily in Japan and the United States. introduction to HVAC and refrigeration applications began in the mid-1980s, when scroll compressors were introduced in commercial and automotive air conditioning products.

In the late 1980s, Copeland® was one of the first to begin mass producing scroll compressors and HEAT SIPHON was the first in the swimming pool heat pump industry to obtain a sample prototype and ship the first scroll equipped HEAT SIPHON.

In the 1990's scroll compressors had their new product challenges and went through several "design revisions " to get to the current quiet, more reliable and more efficient models but they are still more expensive than piston compressors.