The units are quiet, easy to operate, versatile and can be monitored across a GSM modem link. They work as leader/followers with chillers or air handlers, and there is automatic selection between heating and cooling. Standard connections quickly attach the units to existing systems, and only one power connection is needed. The units can be used with convectors and plate heat exchangers. Ancillaries include buffer tanks, flexible pipework, valves and t-pieces. We use R134a refrigerant (non ozone depleting) with a variable-speed pump. You can hire a heat pump for remote heating or cooling with air handler or fan coils.