heater-photo.webp
Photographer: Jugraj Singh Sehri
Source: https://commons.wikimedia.org/wiki/File:1985_Vulcan_Quasar_Gas_convection_heater.jpg
License: CC BY-SA 4.0 ? https://creativecommons.org/licenses/by-sa/4.0
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

boiler-photo.webp
Photographer: Turbojet
Source: https://commons.wikimedia.org/wiki/File:Wall_mounted_boiler_in_kitchen.jpg
License: CC BY-SA 4.0 ? https://creativecommons.org/licenses/by-sa/4.0
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

plant-photo.webp
Photographer: Roger McLassus Installateur Notdienst Wien
Source: https://commons.wikimedia.org/wiki/File:2006-02-15_Piping.jpg
License: CC BY-SA 3.0 ? http://creativecommons.org/licenses/by-sa/3.0/
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

control-photo.webp
Photographer: Raysonho @ Open Grid Scheduler / Grid Engine
Source: https://commons.wikimedia.org/wiki/File:NestLearningThermostat.JPG
License: CC0 ? http://creativecommons.org/publicdomain/zero/1.0/deed.en
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

sealing-photo.webp
Photographer: Oregon Department of Transportation
Source: https://commons.wikimedia.org/wiki/File:Window_Seal_(5981333909).jpg
License: CC BY 2.0 ? https://creativecommons.org/licenses/by/2.0
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

hero-photo.webp
Photographer: BOOM Photography
Source: https://www.pexels.com/photo/hand-of-a-person-turning-the-radiator-valve-12644994/
License: Pexels License ? https://www.pexels.com/license/
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

vent-photo.webp
Photographer: Tony Webster
Source: https://commons.wikimedia.org/wiki/File:Drop_Ceiling_HVAC_Air_Vent_and_Office_Lighting_(53076027164).jpg
License: CC BY-SA 2.0 ? https://creativecommons.org/licenses/by-sa/2.0
Changes: cropped, resized and converted to WebP. Derivative retains the source license.

Photos illustrate topics, not supplied product models. The vent photo shows an HVAC grille before insulation; it is not a photograph of a fitted winter cover. Never obstruct combustion ventilation or flues.