12V DC Time Delay Relay for Furnaces - Reliable Fan Control

In this review of the Dinosaur Electronics 12VDC TDR Time Delay Relay the bottom line is simple: this is a focused replacement part for older furnaces and RV units that need a reliable timed fan control. The reviewer finds it most useful for technicians and DIYers replacing a worn relay on a standard 12VDC ignitor board, because it restores the fan delay and cool-down functionality without reworking wiring. Installation is straightforward and the relay's fixed 4 second start delay and 2 minute cool-down period address the two timing behaviors most people need.

Key Features

• 4 second start delay: Prevents the fan motor from spinning until the heat source has had a moment to build, reducing cold-air blasts at cycle start.
• 2 minute cool-down: Keeps the fan running after the heat cycle ends to extract residual heat and protect the heat source.
• 12VDC compatibility: Designed to match standard 12VDC ignitor boards commonly found in older furnaces and some RV heaters.
• Single unit package: Ships as a single replacement relay, so installers receive exactly what they need without extra parts.
• Simple form factor: The relay's straightforward design helps keep replacement and wiring tasks uncomplicated for field repairs.

Who It's For

This relay is best for HVAC technicians, RV owners, and DIY repairers working on older furnaces or Atwood style RV heaters that use a 12VDC ignitor board and require a timed fan relay. It is particularly suited to situations where the original relay has failed and the system needs the two timing behaviors restored quickly and cheaply.

Those who should look elsewhere include people with modern furnaces that use integrated control modules or non-12V systems, and anyone who needs adjustable timing or advanced diagnostic features. This is a fixed-timing replacement, not a programmable controller.

Pros & Cons

Pros

• Restores essential fan timing with the included 4 second start delay that customers report works as intended.
• Offers a useful 2 minute cool-down that helps protect the heat source and improves comfort after a heat cycle.
• Installation is generally straightforward; customers praised the concise instructions and ease of swap-in replacement.
• Sold as a single replacement unit, making it convenient for one-off repairs.

Cons

• Fitment is mixed for some users; several customers reported alignment or fit issues when replacing particular factory mounts.
• The timing is fixed and not adjustable, so it may not suit systems that need custom delays.

Specifications

Product	Dinosaur Electronics 12VDC Time Delay Relay
Voltage	12VDC
Start delay	4 second
Cool-down period	2 minute
Package quantity	1
Intended use	Replacement for older furnaces with 12VDC ignitor boards

Our Verdict

The Dinosaur Electronics 12VDC TDR is a practical, no-frills replacement relay for older 12VDC furnace controls and many RV heaters. It restores the important 4 second start delay and 2 minute cool-down without fuss, making it a sensible purchase for repair jobs where fitment is compatible. Those needing adjustable timing or a guaranteed form-fit to a specific chassis should verify compatibility first.

Frequently Asked Questions

Will this relay work with my RV furnace?
It will work if your furnace uses a standard 12VDC ignitor board and the original relay had similar timing; check mounting and connector fit before purchase.

Is the timing adjustable?
No, the unit provides a fixed 4 second start delay and 2 minute cool-down period and is not user adjustable.

How many relays are included?
The package contains one replacement time delay relay.