The problem with a caravan or motorhome is that often the usage is in summe= r and you have a roof vent open rather than use any form of aircon. Typical scenarios detailed in this article ... https://www.telegraph.co.uk/news/uknews/crime/11068184/New-spate-of-attacks= -by-sleeping-gas-gang-caravanners-warned.html There have also been reports of persons of 'high net worth' waking up in th= eir hotel rooms to find a similar groggy feeling and finding their valuable= s have been stolen. Before we moved to the UK in '97 there were reports of similar things happe= ning on trains in eastern Europe and Russia. When we travelled overnight be= tween Moscow and St Petersburg the train attendant issued us with a plastic= 'lock' that fitted over the door knob inside the compartment to prevent so= meone from using a security key to unlock the door from outside, as similar= attacks using gas had been known to happen on this route. -----Original Message----- From: piclist-bounces@mit.edu On Behalf Of James = Cameron Sent: 19 August 2019 10:47 To: Microcontroller discussion list - Public. Subject: Re: [EE] flammable gas detector blues Both the caravans and exploding house scenarios may benefit from heat recov= ery ventilation, where a structure containing a heat exchanger is used to e= nsure the inside of the box never has an atmospheric mix unlike the standar= d planetary atmosphere. On the other hand, if it is standard an attacker could figure out where to = insert their attack. -- James Cameron http://quozl.netrek.org/ -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclis= t --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .