Behind Hot Water Radiator

R-3 and a Radiant Reflector

Note: Installation instructions and illustrated drawings are recommendations only, while proper local construction methods are the responsibility of the installer.

In order to increase the heat transmitted to the interior of a room by a hot water radiator, attach Reflectix® Insulation to the wall directly behind the unit. The product reflects 96% of the energy that would ordinarily be absorbed by the wall. This will result in a more comfortable room at a lower thermostat setting. The product is easy to handle and installs very cleanly.

Recommended Products

Double Reflective Insulation

Reflective/Bubble/Bubble/Reflective – Roll

  • BP24025 (24” x 25’)
  • BP48025 (48” x 25’)


  • R-3
  • Radiant reflector (Reflects 96% of the radiant heat generated towards the wall behind the unit)
  • Easy to install
  • Very clean, finished look
  • Easily withstands the temperature of the radiator when installed properly

Installation Instructions

Installation Instruction pdf: DIY Behind Hot Water Radiator Revised 012021

  • Measure the width and height of the hot water radiator. It is personal preference (if and) to what degree the product extends beyond the top and sides of the radiator.
  • Simply cut the Reflectix® Reflective/Bubble/Bubble/Reflective product to this dimension.
  • Install product flush to the wall and without any contact to the radiator or plumbing.
  • Secure the product to the wall utilizing a double sided tape, Velcro strips, spray adhesive or staples.


Review These Important Safety Guidelines Prior to Installation:

  • ALWAYS check local building codes before installing Reflectix®.
  • ALWAYS check the area you are insulating and make any needed repairs. Any worn wiring should be replaced before you begin installing Reflectix®.
  • ALWAYS make sure work areas are well ventilated and well lighted.
  • ALWAYS use eye protection when operating a staple gun.
  • ALWAYS use caution and common sense when using a staple gun. Be aware of electrical wiring locations. Stapling into a wire can cause severe shock or death. NEVER staple into electrical wiring.
  • ALWAYS be careful when working with large pieces of Reflectix® on windy days.
  • When installing Reflectix® on bright sunny days, it is best to wear sun glasses.
  • Do not work in areas such as attics when temperatures are too hot.
  • Please Note: The intention of these Installation Instructions and 3-D renderings are for the sole purpose of illustrating the correct location and relative position of the Reflectix® products in specific building assemblies. The correct construction methods and techniques are the responsibility of the installer or contractor. The methods outlined are recommendations on location of the Reflectix® products as a guideline. There are no claims on the part of Reflectix, Inc. that these building assemblies are finite standards or meet building code requirements (as they can vary by region).

Testing and Certification

Reflectix® products are thoroughly tested at either nationally approved, independent laboratories or leading universities. Tests are performed to current American Society of Testing and Materials (ASTM) standards when a standard exists. To obtain a copy of our Product Testing Specifications, please refer to the “Additional Resources” tab. The documents are also available by e-mail at or call (800) 879-3645.


Pictured: 1. Double Reflective Insulation, 2. Tools for Installation