Having lost one DVR to excessive heat in a previously owned coach, I wanted to make sure it did not happen again. It's a hassle to get a replacement TiVo-capable DTV DVR while on the road. The only practical solution I could come up with is adding supplemental ventilation to the enclosure in which the DVR is installed.
Like everything else, there are trade-offs. The more air to be moved, the more noise there is likely to be. DW is extraneous-noise-intolerant. Size is directly proportional to the amount of air moved and I have to find a way to get it installed within the limited space allocated to entertainment electronic devices.
I had previously tried various muffin-type and small high-RPM DC squirrel cage fans used in computers and electronic devices. They were way too noisy and way too anemic as air movers. Knowing that most HVAC systems use squirrel cage blowers to move as much air as quietly as practical, I searched the web and came up with the model below. These small blowers are used in fireplace inserts and other noise-sensitive, low volume air handling situations.
I found this one on Amazon but they're widely available elsewhere.
Small Quiet Blower
You'll notice that I mention steps taken to minimize the effect of the blower motor's heat on nearby wiring and wonder if all that heat does not defeat the purpose of the blower. Well, after installing this blower the internal temperature of the DVR went from 48c/108f to 42c/118f, a 10f degree drop. That's inside the DVR as reported by the DVR. The reason is that this moves 75 cfm compared to 15 cfm for a muffin fan that does not overwhelm all other sound in the room.
Since there were switches on the panel face from the previous attempt to get additional ventilation I used then to enable powering up the blower separately. Noise is not an issue now but with the previously installed fans, we wanted to turn them on only when necessary.
Around the top-front of the cockpit there is a hollow duct-like structure that I wanted to push air from the electronic entertainment cubby hole through. The air exits out the original TV enclosure.
All's cool and quiet in the entertainment electronics enclosure now.