XPost: uk.d-i-y   
   From: Briang1@blueyonder.co.uk   
      
   I have seen so called snubber networks across motors and when I asked they   
   told me it reduced sparking on switch overs, but whenpressed to explain they   
   were more vague, but certainly you will get a pulse after disconnection  of   
   any inductive load.   
    Brian   
      
   --   
   From the Sofa of Brian Gaff Reply address is  active   
   "harryagain"  wrote in message   
   news:l6saph$l44$9@dont-email.me...   
   >   
   > "Gefreiter Krueger"  wrote in message   
   > news:op.w60jrhnjiunomv@red.lan...   
   >> When I moved in 13 years ago, there was a central heating system   
   >> utilising only radiator stats.  I fitted a room thermostat (the basic   
   >> bi-metallic strip variety), which connected live to the motorised valve,   
   >> which in turn switched on the pump and boiler.  For some reason, it would   
   >> often arc when switching off, which heated the bi-metallic strip up a   
   >> little and it never managed to go off.  Problem solved by using an   
   >> electronic thermostat which contained a relay, causing cleaner switching.   
   >>   
   >> Similar problem now, with the heating system extended so it does the   
   >> garage, aswell as the house, with a seperate electronic thermostat.  The   
   >> problem this time though, is because I could only find a motorised valve   
   >> for the garage which did not have contacts inside it (only one which   
   >> fitted my odd diameter of pipe), I had to fit a relay to switch the   
   >> boiler and pump on and off (if I'd connected the output of the garage   
   >> stat straight to the pump, boiler, and valve, then the valve would open   
   >> every time the boiler and pump ran for the house too).  Anyway, it worked   
   >> fine for a year, then the relay started behaving like the old bi-metallic   
   >> strip thermostat - it arced when switched off, and took ages to do so,   
   >> making an alarming noise.  So I replaced the relay with a big industrial   
   >> contactor which is working for the moment.  The relay I replaced says it   
   >> can take up to 2HP motors, way more than my pump.  Any idea what's going   
   >> on?   
   >   
   >   
   > Arcing is caused by stored emergy in the system (usually coils/electric   
   > motors.)   
   > You will often get a tiny spark when switching motors, this is normal and   
   > not enough to affect a bimetal strip.   
   > Most switches have a "snap action" to minimise this.   
   > Just what do you mean by arcing?   
   >   
   >   
   >   
      
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