Oct 24th 2026
Used RV Water Heater Parts: What’s OK to Buy Used (and What to Buy New)
BUYING GUIDE · USED PARTS
Used RV Water Heater Parts: What’s OK to Buy Used (and What to Buy New)
Saving money on used parts makes sense for some pieces and is a bad bet for others. Here’s how we’d split it, and what the manufacturers say about the safety parts.
The short version (our advice)
- Fine used: doors, door hardware, covers, brackets and trim, if they fit your model and aren’t cracked.
- Buy new: anything that controls gas, heat or pressure: gas valves, thermostats/ECOs, thermal cut-offs, relief valves, electrodes and ignition boards.
- Always new: anode rods, gaskets and drain plugs. They’re cheap and they’re what keeps water in the tank.
- A used whole heater is a gamble: you can’t see inside the tank.
Why the safety parts should be new
- Thermal cut-offs are one-shot: Atwood’s 93866 trips once at 190°F and must be replaced, so a used one may already be done.
- Relief valves aren’t serviceable: Dometic says to replace a faulty P/T valve, and a used valve’s seat may be scaled or corroded.
- Thermostats and ECOs: a thermostat that doesn’t open lets the water overheat until the ECO trips. You can’t tell how close a used one is to failing.
- Gas valves and boards: they control propane and ignition. Suburban’s and Atwood’s troubleshooting assume known-good parts; a used part adds a variable.
- Aftermarket shortcuts: Dometic warns aftermarket elements can lack critical safety controls and void the warranty.
Used whole water heaters
A used tank may have sediment, a spent anode (Suburban) or corrosion you can’t see. Suburban’s current warranty is 2 years on the unit and 3 on the tank for new heaters; a used heater usually has none. If you go used, get the model and serial from the data plate so you know its age (on Suburban, the first four serial digits are week and year), and check it holds pressure and lights before you install it.
How to find the right new part
STEP 1
Read the data plate
Suburban: silver plate on the right side of the control housing behind the door. Atwood/Dometic: data plate on the heater; the gas valve has its own rating plate.
STEP 2
Match model and serial
Many parts change by serial number (Suburban gas valves and elements, for example).
STEP 3
Ask if unsure
Send us the model and serial and we’ll confirm the part before you order.
Parts for this repair
Suburban 520814 Ignition Control Board (SW series)View part →
Suburban 525007 12VDC Thermostat / Hi-Limit (SW series)View part →
Dometic 91447 Front Mount ECO/Thermostat Kit (DSI)View part →
Dometic/Atwood 93866 Thermal Cut-Off KitView part →
Suburban 525045 P&T Relief Valve, 3/4 in. NPTView part →
Suburban 233514 Magnesium Anode Rod (SW series)View part →Shop by category: All water heater parts, Suburban part finder, Dometic part finder.
FAQ
Is it safe to buy used RV water heater parts?
For doors, covers and brackets, usually yes. For gas valves, thermostats, ECOs, thermal cut-offs, relief valves and ignition parts, buy new.
Can I reuse an Atwood thermal cut-off?
No. The 93866 is one-shot; once it trips, it must be replaced.
Should I buy a used RV water heater?
It’s a gamble: you can’t inspect the inside of the tank, and there’s usually no warranty. If you do, check its age from the serial number and test it before installing.
Not sure which part fits? Contact us with your model and serial number from the data plate and we’ll confirm it before you order.
Our recommendations, based on Suburban and Atwood/Dometic manuals and warranty terms.