Heating Help

I've used a lot of solid state relays, but never for heating/cooling equipment. Some quirks that might cause problems: 1) Heat is their enemy and the larger the load, the more heat they produce--you need a good heat sink and good natural ventilation (forced ventilation if you pack a lot of them in a small area). 2) Pay careful attention to the load rating. Resistive loads aren't as bad as inductive loads but even with resistive loads give yourself at least 25% headroom in the load rating. A filament burning out in a lightbulb will frequently take out a closely sized solid state relay. 3) They're extremely reliable--I had one set of four that probably each switched 40-50 times per hour for 4-5 hours per day for over 10 years. When they fry due to excessive load they fail open. I did however have one fail closed for a reason I never understood--this alone may be a "killer". 4) You can only test them with a load connected. You can't just use an ohm meter. 5) They're available in a number of "coil" voltages--I've only used low voltage DC but believe I've seen them for 110VAC.

mercury contactors

you may consider mercury contactors. look for an industrial electrical supply house. high power solid state will most likely be very costly. heres one: http://www.wolfautomation.com/Product.aspx?ProductID=804&gclid=CL_Qy6uKtosCFSBhgQodiQT8wg

RIB

http://www.functionaldevices.com/ChartPilot.html These are the quietest that I know of , and are available up to 30 amp. Most DIN mounted " ice cube " relays are quiet as well...but do not offer dual coil voltages. If I had to live with 1 relay type , it would be RIB. Also , the brand name " Core " makes nice relays and transformers. http://www.lectrocomponents.com/

SSR's

I've used thousands in 24/7 manufacturing application for heating... maybee changed out 100 or so . As Mike stated they don't like heat and voltage spikes (dead shorts) wipe them out.See PDF on Omrons.

quiet ones

Hello i have installed a few electric boilers and have one that is right behind the master bedroom and have some noise problems. Is there a solid state relay that can be interchanged there to make it quieter? Thanks Mike.C

Contactor

I never seen one but I am sure someone makes them... Just a thought if you have no luck.... Can you move the contactor near the fuse box or out of the boiler room...Or did you try another one.