Loose Wire System Sizing Guide

In order to determine the type of underfloor heater and number of thermostats required for your floor, measure the area to be heated.

Remember not to include areas under permanent kitchen or bathroom fixtures. Please refer to the table below for sizing details.

USDW-120V (Loose Wire):

 

Net Heated Area (sq ft)	kW @120V	Amps	Warmup® Heaters Required
15 - 24	0.36	3.0	1xUSDW360-120 + Thermostat
25 - 34	0.48	4.0	1xUSDW480-120 + Thermostat
35 - 44	0.72	6.0	1xUSDW720-120 + Thermostat
45 - 59	0.95	8.0	1xUSDW950-120 + Thermostat
60 - 74	1.20	10.0	1xUSDW720-120 + 1xUSDW480-120 + Thermostat
75 - 89	1.43	12.0	1xUSDW950-120 + 1xUSDW480-120 + Thermostat
90-104	1.67	14.0	1xUSDW950-120 + 1xUSDW720-120 + Thermostat
105-119	1.90	16.0	2xUSDW950-120 + Thermostat
120-134	2.15	18.0	1xUSDW950-120 + 1xUSDW720-120 + 1xUSDW480-120 + Master/Relay
135-149	2.38	20.0	2xUSDW950-120 + 1xUSDW480-120 + Master/Relay
150-164	2.62	22.0	2xUSDW950-120 + 1xUSDW720-120 + Master/Relay
165-179	2.85	24.0	3xUSDW950-120 + Master/Relay
180-194	3.10	26.0	2xUSDW950-120 + 1xUSDW720-120 + 1xUSDW480-120 + Master/Relay
195-209	3.33	28.0	3xUSDW950-120 + 1xUSDW480-120 + Master/Relay
210-224	3.57	30.0	3xUSDW950-120 + 1xUSDW720-120 + Master/Relay
225-239	3.80	32.0	4xUSDW950-120 + Master/Relay

 

USDW-240V (Loose Wire):

 

Net Heated Area (sq ft)	kW @240V	Amps	Warmup® Heaters Required
15 - 24	0.33	1.4	1xUSDW330-240 + Thermostat
25 - 34	0.42	1.8	1xUSDW420-240 + Thermostat
35 - 44	0.65	2.7	1xUSDW650-240 + Thermostat
45 - 59	0.90	3.8	1xUSDW900-240 + Thermostat
60 - 74	1.07	4.5	1xUSDW650-240 + 1xUSDW420-240 + Thermostat
75 - 89	1.32	5.6	1xUSDW900-240 + 1xUSDW420-240 + Thermostat
90-104	1.55	6.5	1xUSDW900-240 + 1xUSDW650-240 + Thermostat
105-119	1.80	7.6	2xUSDW900-240 + Thermostat
120-134	1.97	8.3	1xUSDW900-240 + 1xUSDW650-240 + 1xUSDW420-240 + Thermostat
135-149	2.22	9.4	2xUSDW900-240 + 1xUSDW420-240 + Thermostat
150-164	2.45	10.3	2xUSDW900-240 + 1xUSDW650-240 + Thermostat
165-179	2.70	11.4	3xUSDW900-240 + Thermostat
180-194	2.87	12.1	2xUSDW900-240 + 1xUSDW650-240 + 1xUSDW420-240 + Thermostat
195-209	3.12	13.2	3xUSDW900-240 + 1xUSDW420-240 + Thermostat
210-224	3.35	14.1	3xUSDW900-240 + 1xUSDW650-240 + Thermostat
225-239	3.60	15.2	4xUSDW900-240 + Thermostat

*For areas larger than 240 square feet, please contact your nearest Warmup reseller for further information.