Dometic Atwood Water Heater Pressure Relief Valve | 90028 | 3/4" NPT

Protect your Atwood RV water heater with the Dometic / Atwood 90028 Pressure Relief Valve. This 150 PSI safety relief valve with 3/4" NPT threading is the critical safety device that prevents dangerous pressure buildup in your water heater tank — opening automatically when pressure exceeds safe limits to prevent catastrophic tank failure. A small part that prevents a very expensive (and potentially dangerous) problem.

⚠️ For Atwood Water Heaters Manufactured FEBRUARY 2006 OR LATER

The 90028 fits a specific range of Atwood water heaters. Compatibility is strict and date-based — confirm before ordering:

• Atwood water heaters manufactured FEBRUARY 2006 or later
• 3/4" NPT thread connection
• Look for the red thread protector on the existing valve port — that's the visual cue identifying the newer 3/4" thread size

If your water heater was manufactured BEFORE February 2006, the 90028 is NOT the correct relief valve. Older Atwood water heaters use a different valve with a 1/2" NPT thread — see the next section for the correct part.

Older Atwood Water Heater? Use the 91604

If your Atwood water heater was manufactured BEFORE February 2006, the correct pressure relief valve is the Dometic/Atwood 91604 Pressure Relief Valve (1/2" NPT thread). The 90028 and 91604 are NOT interchangeable — the thread sizes are different, and trying to fit a 3/4" valve in a 1/2" port (or vice versa) will not work and would be unsafe.

What This Valve Does

The pressure-temperature relief valve (often called a "T&P valve" or "PRV") is one of the most important safety devices on any water heater. As your RV water heater operates, pressure builds inside the tank from thermal expansion and external water pressure. The relief valve is engineered to open automatically when pressure exceeds the safe limit:

• Factory-Set Opening Pressure: 150 PSI

Without a functioning relief valve, excessive pressure can cause the water heater tank to fail — potentially violently. Modern relief valves prevent that failure mode by venting excess pressure to a safe location before tank damage occurs.

When to Replace the Relief Valve

Pressure relief valves are wear items that should be inspected regularly and replaced when:

• The valve is leaking at the threads or vent (a leaking valve indicates either over-pressure conditions OR a failed valve)
• The valve has been operating for several years — periodic replacement is preventive best practice
• The lever doesn't operate properly when manually tested
• The valve shows visible corrosion or scaling
• You're servicing or replacing your water heater — a new relief valve is cheap insurance

Manufacturers typically recommend manually testing the relief valve at least annually by lifting the lever momentarily — verifying the valve is free to operate when needed.

Brass Construction

The 90028 features brass construction — corrosion-resistant, durable, and the industry-standard material for water heater pressure relief valves. Brass handles the constant exposure to hot water, mineral content, and thermal cycling without degrading over time.

⚠️ Professional Installation Recommended

Water heater service should be performed by a qualified RV service technician. Improperly installed pressure relief valves can fail at critical moments, creating serious safety risks. Always test the new valve after installation per manufacturer instructions.

Key Features

• Genuine Dometic / Atwood OEM pressure-temperature relief valve
• Factory-set at 150 PSI opening pressure
• 3/4" NPT thread connection
• For Atwood water heaters manufactured February 2006 or later
• Brass construction for corrosion resistance and durability
• Critical safety device — prevents dangerous tank over-pressure
• Compact length: 7-1/8"
• Lightweight: 0.45 lbs
• Backed by a manufacturer warranty

Specifications

• Brand: Dometic (Atwood)
• Item #: 46835
• Part Number: 90028
• UPC: 692931900285
• Type: Pressure-Temperature Relief Valve (T&P)
• Opening Pressure: 150 PSI (factory set)
• Thread Connection: 3/4" NPT
• Material: Brass
• Application: Atwood RV water heaters manufactured February 2006 or later
• NOT Compatible With: Atwood water heaters manufactured before February 2006 (use 91604 / 1/2" NPT instead)
• Visual Identifier: Red thread protector on existing valve port indicates newer 3/4" thread size
• Length: 7-1/8"
• Net Weight: 0.45 lbs
• Gross Weight: 0.50 lbs
• Sibling Part (Older Models): Dometic/Atwood 91604 (1/2" NPT)
• Warranty: Manufacturer warranty