Good morning, Would anyone be able to advise another way to switch a 40A underfloor heating mat other than a contactor? The client is question is complaining about the 'clunk' every time it switches on and off. I have tried to different contactors but both makes make about the some noise. The contactor is mounted in a local consumer unit adjacent to the room with the heating. Any help would be much appreciated.
How is the temperature of the mats controlled? The mats I have installed are usually limited to a 16A rated controller/timer. How is this done with 40A?
A 6A control circuit from consumer unit feeds the Thermostat/timer. The load side of the controller feeds the coil of the contactor which energises the 35A load of the underfloor heating .
I think there is possibly some mis-calculation here? The 200W per m2 doesn't sound right to me. I would say that you possibly have 200W per mat. How many mats do you have in total?
Thanks Lectrician, would one of these be suitable http://www.amazon.co.uk/Temperature-Control-Solid-SSR-40DA-24-380V/dp/B0087ZTHZE and if so do I need a heatsink?
Most have derating factors if you don't use a heat sink, look at the spec, you may need a much larger one than 40amp if you don't want a heat sink.
The one you link to is a 32v trigger. http://uk.farnell.com/crydom/a2440/ssr-40a-240vac/dp/1200230?ost=1200230&mckv=3ILDKFVa|pcrid|47052899589|plid|&CMP=KNC-GUK-FUK-GEN-LISTINGS-SHOPPING-SOLID-STATE-RELAYS&gclid=CMbB2ous8MQCFSLmwgodIrIAAg&gross_price=true For no heat sink, the information sheet suggests a 110amp version!
Perhaps getting confused. The most recent one I installed was coiled wire. Both coils totalled 1.8kW each so I had 3.6kW total and that was for a similar floor area. (16A) I don't understand how you have a 35A load that's all.
The one you have linked to seems ideal for the job - Thank you, One last question - does it matter what size the heat sink is? they seem to come in many shapes and sizes??
http://uk.rs-online.com/web/p/solid-state-relays/2912292/ 125 amp version, no need for a heat sink at 40amp load.