Posted by UniHeat, Your Shipping Warmer Experts on 30th Sep 2025
7 Ways to Improve Heat Retention in Your Shipments
When shipping live animals, tropical fish, or other temperature-sensitive items, keeping the box warm and stable is critical. Even the best heat pack can lose effectiveness if the shipping environment isn’t prepared correctly. Here are seven proven ways to maximize heat retention and ensure your shipments arrive safely.
1) Use insulated liners or Styrofoam boxes
The first line of defense against cold air is insulation. Foam panels or full Styrofoam boxes prevent heat from escaping and create a protective barrier around your shipment.
2) Select the right UniHeat pack duration
Match the duration of your shipment with the correct UniHeat warmer—40 Hour for short trips, 72 Hour for standard 2–3 day routes, and 96 Hour for long-haul or international shipping.
3) Pre-warm the shipping space
Assemble and prepare your box indoors at room temperature. Starting with a warm environment gives your heat pack a head start and helps retain consistent temperatures longer.
4) Place heat packs properly
Position warmers on top of insulation with space for airflow. Never place them directly against bags or containers—this risks overheating and prevents even heat distribution.
5) Reduce empty space inside the box
Fill voids with newspaper, kraft paper, or padding. Less empty space means less air for the heat pack to warm, which improves efficiency and consistency.
6) Seal the box securely
A well-sealed box helps lock in warmth. Use strong tape on all seams and flaps. While you need airflow for the heat pack, prevent drafts from slipping through large gaps.
7) Avoid weekend or delay-prone shipping days
Even with the best packing, extra days in transit can overwhelm your setup. Ship early in the week and check weather forecasts to reduce risks from storms or delays.
Recommended UniHeat warmers
Pair your packing methods with the right heat pack:
UniHeat 40 Hour Warmer
Good for overnight or short shipments in mild winter conditions.
Shop 40 Hour
Frequently Asked Questions
1) Do I need multiple heat packs in one box?
In very large boxes or extreme cold, using two warmers on opposite sides helps balance heat coverage.
2) Can I wrap heat packs in newspaper?
Yes, but always allow airflow. Wrapping too tightly can smother the pack and reduce performance.
3) Will insulation make the box too hot?
No, if you select the right duration and size of warmer. Insulation helps maintain stable, not excessive, warmth.
4) How long before shipping should I activate the pack?
Activate 30–45 minutes prior to packing. This ensures the warmer is producing steady heat when sealed inside.
5) Are UniHeat packs reusable?
No. They are single-use, designed to provide consistent heat for the listed duration only.