The Suburban ST-42 and ST-60 heat water on demand but have different burner ratings and model-specific electronic control-board kits. The ST-42 is the 42,000 BTU model 5381A; the ST-60 is the 60,000 BTU model 5382A. Most service parts can be identified from Suburban's factory parts list and the model plate rather than the RV's model year.

Parts pictured in this guide

Select an image for product details, or jump to the parts list. Match the complete model and part number before ordering.

Suburban 233678 Water Heater Controller for ST60 — Suburban ST-42 & ST-60 Tankless RV Water Heater Illustrated Parts Guide

Suburban 233678 Water Heater Controller for ST60Part 233678

Suburban 6285APW RV Water Heater Access Door For ST-42 & ST-60 On Demand Models — Suburban ST-42 & ST-60 Tankless RV Water Heater Illustrated Parts Guide

Suburban 6285APW RV Water Heater Access Door For ST-42 & ST-60 On Demand ModelsPart 6285APW

Factory part numbers and model differences

Suburban part	Service item	Model identification
5381A	ST-42 complete water heater, 42,000 BTU	ST-42 only
5382A	ST-60 complete water heater, 60,000 BTU	ST-60 only
521338	Electronic module-board kit	ST-42; do not use ST-60 board
521339	Electronic module-board kit	ST-60; do not use ST-42 board
233665	Water-flow sensor	ST-42 and ST-60
233676	Manual-reset high-temperature limit switch	ST-42 and ST-60
233675	Antifreeze temperature-limit switch	Verify exact existing assembly
233658	Combustion-airflow sensor	ST-series service part
161357	Schuste gas-valve service part	Match original Schuste valve
525214	Telco gas-valve service part	Different manufacturer valve version
233678	Digital control center	Listed in ST-series factory parts section
233682	Seven-amp service fuse	ST-series fuse; check existing marking
6285AEB	Black exterior access door	ST-42/ST-60
6285APW	White exterior access door	ST-42/ST-60
525175	ST exterior door sealing gasket	Door seal, not a complete access door

What to identify before ordering

Part or feature	Why it matters
Control board	The ST-42 uses 521338 and the ST-60 uses 521339; identify the heater and the original board marking.
Water-flow sensing	Part 233665 detects water demand; the 233676 part is a manual-reset limit switch and serves a different purpose.
Gas-valve version	Suburban lists both Schuste 161357 and Telco 525214 valves. Match the installed valve; do not treat them as universal substitutes.
Exterior access door	The 6285AEB black and 6285APW polar-white doors fit ST-series cabinets; each door is ordered separately.
Electrical and water connections	The manufacturer specifies 12V DC, 0.7 GPM minimum water flow, and 1/2-inch male NPT hot/cold connections.
Temperature probe connectors	Match connector shape and installed part; the 2026 factory list groups female/male probe descriptions under 233685.

Original manufacturer illustration

Suburban ST-series original unit layout and drain connection illustration. Use the full factory manual for the model-specific connection and service procedures.

Enlarge the factory illustration

Open the original manufacturer's PDF to inspect small part positions and labels.

View the manufacturer diagram (PDF)

Before choosing or replacing a component

Select replacements from the actual heater model and serial number. The board kits and gas-valve versions are not interchangeable by appearance. The manufacturer specifies professional service for gas, combustion, electrical and pressure-relief components. The heater must be drained and protected against freezing according to Suburban's instructions.