DSI Module 5 Minute Delay Fits: Heat N Glo 8000 TR-DSI HHT RAM DSI control module with 5-minute delay for LP and NG units. Does NOT work with Fenwall systems. Works with multiple Heat N Glo models. Check manufactures parts list for compatibility. This is the OEM HHT part number 501-592. 501-592 SRV501-592 501592 If this is a replacement for 459-592, then junction box 100-254a must also be ordered.