Loft installed CCTV cooling help required.

[Mottie]

Purely for practical and laziness reasons I've got my 4 channel Swann CCTV DVR fitted in my loft. All been fine for a few years but a few weeks ago it overheated on that very hot day and stopped working. Being lazy and because I've seen an 8 channel, 4 camera kit on special offer, I'm just going to replace the DVR with a similar unit using my existing camera and maybe adding a few more from the kit when I have the time and inclination. Currently its mounted on a shelf approximately 1 metre off the loft floor so I do plan to site it on the floor as that will be a few degrees cooler.

What I'm looking to do though is fit a thermostatically controlled fan that can kick in when temperatures rise - either a small USB type fan or even a small 240v one to just blow air over it when things get hot. Does anyone have any suggestions apart from 'move it out of the loft'!

 

[foxhole]

You could use an inline stat built into extension lead which will trigger whatever you plug into it. I use one to ventilate a cupboard around a radiator.
https://www.ebay.co.uk/itm/222852243916

or this
https://www.amazon.co.uk/Thermo-Guard-Digital-Control-Thermostat-TH-928T/dp/B00CBUGPS8

Are you sure it was heat that got to it and not choked from dusty loft?

 

[JohnD]

but where will the cold air come from? On a sunny day a loft is generally stiflingly hot. Blowing it around with a fan will not help. I suppose if you had a duct to the north side of the house that would do

 

[Harry Bloomfield]

Does anyone have any suggestions apart from 'move it out of the loft'!

Uninsulated and unventilated lofts do get very hot in summer and very cold in winter. So insulating and venting will make a lot of difference. If you are going to add a cooling fan, the fan would be better drawing in cooler air from outside, or from the house below, if that can be arranged.

 

[secureiam]

Here again we have failure due to heat, blowing very hot air around wont help too much, the question is how hot is it getting?

 

[Harry Bloomfield]

When I boarded out my loft one summer, to make a workshop, just bare roof tiles and rafters, I checked the temperature up there - it got to 45C with the sun shining on the roof. I have since then, added insulation, plasterboard and a Velux - it is much more temperate now.

 

[Mottie]

"Here again we have failure due to heat, blowing very hot air around wont help too much, the question is how hot is it getting?"

I think I'll check the temperatures at the existing DVR position and again at the loft floor. If too hot, I might be able to reposition it in the top of one of the built in wardrobes in the bedroom below. It'll be a bit of aggro as I'll need to get the camera wires from the loft, power to the wardrobe and a HDMI cable long enough to reach the bedroom CCTV (currently has its own TV as a monitor in loft) but it might give me a project to do in the summer.

 

[Mottie]

but where will the cold air come from? On a sunny day a loft is generally stiflingly hot. Blowing it around with a fan will not help. I suppose if you had a duct to the north side of the house that would do

I was hoping that just some moving air across the DVR may help. I'm currently sitting here in my office and its stifling hot but a fan blowing the same warm air around is keeping me cool. Just!

 

[SFK]

Motman,
Yes but you are sweating, and as the fan blows over you its evaporation provides extra cooling to you.

A fan does also work on electonics if the electronics are hotter than the air temp, there will be a improved cooling effect even when moving hot air over it, rather than having non-moving air surrounding it.
SFK

 

[Sally2000]

An external fan blowing on the dvr does make a very considerable difference.
I have a dvr in the loft, it's mounted vertically on a wall with the top cover removed. A 12v computer fan is mounted four inches in front of it, blowing air directly onto the pc board and disk. The tiny built in case fan is disconnected. The fan is controlled by a thermostat that turns on above 12C. Below that temperature no cooling is needed.

Even when the loft ambient has been above 34C, the processor heat sinks were barely warm to the touch.

If you buy a thermometer to do this, make sure you get one that has a back contact that closes above the set temperature. Many thermostats for heating appliances only have a single contact that closes below the set temperature, which is the opposite of what you need.

 

[Harry Bloomfield]

I was hoping that just some moving air across the DVR may help. I'm currently sitting here in my office and its stifling hot but a fan blowing the same warm air around is keeping me cool. Just!

It would be better than nothing, but keep in mind when you are too warm, you sweat. Evaporation of sweat cools you down, but that process is even more effective in a breeze.

 

[secureiam]

Is all about how hot the device is compared to its surroundings and at what temperatures the devices can operate.

Air cooling is not the best cooling available, but when a device has a fan, its usually to get the warm/hot air moved out of its enclosure and replaced with the cooler air in the room.

Put the enclosure in a room that's warming up, the cooling effect reduces as the room heats up and the device is placed under more stress.

Too much stress and the device fails.

How effective the extra fan actually is will be determined on how hot the device is getting and how hot the loft is getting.

Touch is not reliable way gauge how hot something and if it is getting to hot to function properly.

 

[Sally2000]

I can only repeat that in practice the fan is extremely effective. Without the fan the heat sink is too hot to touch. With the fan on it is just warm.

I think the physics behind this is that the heat from the heat sink is being rapidly removed by the vigorous airflow. The temperature of that airflow is of secondary importance. It is not just a question of replacing hot air with less hot air.

If the dvr was still in its case and just had a fan blowing across then I'm sure you would be right. The air inside replaced by its own fan would not be significantly cooled.

 

[secureiam]

Hi Sally, I understand where you are coming from, it would have to be cooler in order for any of it to take affect, ie cool the board down, more vigorous air flow well help cooling but only if the pcb is warmer than the air going past it so heat is transferred to the moving air.

Clearly it does have significant affect in your case, for me there not enough data to apply it safely across the board.

34oC versus 45oC is significant temperature difference wrt to ambient temperatures. Both these temperatures have been suggested for the loft, but say his loft got to 50/60oC (god forbid) and yours didn't get above 40oC that could be significant.

So Firstly check the operating temperature of the device and the temperature for the area you want to place the dvr in, you can then at least know what your working with.

say operating temp is 25oC and its placed in 34oC its asking for trouble, say the operating temp is 50oC, then in theory as long as it doesn't get close to 50oC or above it should be okay.

 

[JP_]

Rather than just a fan, why not hook up an extractor fan and vent to draw air in from outside to blow over the unit? Even when it is hot, the air temperature is relatively cool - mid 20s rather than 40s.

Rather than insulate the loft, maybe make some sort of insulated box to keep it in with a 50mm sheet of kingspan and lots of tape? And have the vent one side of box drawing cool air in, and an exhaust on the opposite side?