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Hello together,

some new buildings use heating and cooling systems which are directly integrated into the ceilings.

What is your experience with these systems? Either from RF perspective and also related to the impact on the hardware. 

How do these systems influence your Wireless Designs?

Is it reasonable to mount access points close to, onto or in between these systems?

There is a lot of water in these systems, the materials might impact the RF waves and also the temperature close to the surface could damage hardware. 

Thanks in advance

Being on the west coast, I have little experience with radiant heaters, although I have seen some interesting effects from HVAC duct work.    That is, in addition to the shielding that it can impose on you signals.

One of the oddest, or most obvious things depending on how you look at it, is how the ducting can mess up your site surveys.   AP's that shouldn't even show up because of their distance, low power settings, or the number of walls between your area and the next will show up unexpectedly.  You can often connect to these AP's, even though common sense says it is impossible.

What is happening is that the AP's signals are entering one end of the HVAC system, via an open duct, and are then being "ducted"  across the building just like an intentional wave guide.    Of course, it is not as efficient as something purpose-built but it does happen, much to everyone's surprise.   

This isn't always a bad thing for the users, but trying to explain it to people can be difficult - especially if the duct work is hidden above a dropped ceiling.

I first saw this in a very large combined office and warehouse environment, where some of the duct work was easily mapped.    Removing tiles and using a ladder confirmed the routing above.

As far as hot and cold are concerned, you should be cautious of  some WLAN equipment manufacturers claims.    Always allow for some margin in your design.   That goes for AP's, cabling, connectors, and antennas.     I can tell you from my own testing that some companies fake their temperature and humidity specs.    The better the company, the more reliable their claims will usually be.

Just as an example, I trust Cisco's specs.   They know what they are doing, have the proper test equipment, and have their reputation to protect.

Areas experiencing condensation can be severely affected due to water intrusion and corrosion.  That applies to both indoors and outdoors LAN/WLAN materials.

Companies like Ventev-Infrastructure and Tessco almost always post their environmental specs, or are glad to provide them if you ask.

I know this doesn't answer your specific question, but hopefully some of it will help.

 Howard

P.S.   I should also add that companies concerned with TSCM (Technical Surveillance Counter Measures) also install baffles and/or screens inside duct work to specifically stop such transmissions - appropriately grounded of course.

And since I'm also into Amateur Radio, I can tell you that effective shielding can be difficult to attain.

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