Electric heat contact replacement

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wireman3736

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Vermont/Mass.
I have a customer who is complaining about the sound coming from the electric heat control panel. The panel is next to a family room and the buzzing is annoying as I noticed when I went there today. I want to replace the contactors with electronic relays, the existing contactors are magnetic 120v coil with 30 amp 240 volt contacts. All the heat circuits are under 20 amps. My concern would be heat building up in the electronic relay even though there rated for 40 amp, any helpful information would be appreciated, Here is the relay I was thinking of using for replacement except I would be using a 2 pole if they make them. http://shop.vetcosurplus.com/catalog/product_info.php?products_id=8844

Thanks Stan
 
wireman3736 said:
I have a customer who is complaining about the sound coming from the electric heat control panel. The panel is next to a family room and the buzzing is annoying as I noticed when I went there today. I want to replace the contactors with electronic relays, the existing contactors are magnetic 120v coil with 30 amp 240 volt contacts. All the heat circuits are under 20 amps. My concern would be heat building up in the electronic relay even though there rated for 40 amp, any helpful information would be appreciated, Here is the relay I was thinking of using for replacement except I would be using a 2 pole if they make them. http://shop.vetcosurplus.com/catalog/product_info.php?products_id=8844

Thanks Stan
Click to expand...

Maybe I am missing something but why would that contactor be a problem. If you had a 600 watt dimmer switch for lighting would you think there is a problem with 300 watts on it? I see this as a non issue but I have been wrong once in my life so......:smile:
 
When a contactor buzzes, it has nothing to do with the load. It's the armature sitting less than perfectly against the pole pieces. Ever tried to pry an energized contactor open? It gets angry-loud.

Most armatures have a pivot so the face of the moving parts can align with the face of the stationary part. See if you can expose the armature and spray a bit of WD-40 on the pivot, and loosen it.
 
If you decide to use the solid state relay, use some heat transfer paste and mount it on something metal to assist in heat dissipation. I use them in my shop for various tricks. If left in free air they will burn out. Had 20 amp rated contact go out on a 12 amp load.
 
BryanMD said:
Is it a new problem?
How old is the install and how long have the present owners been there?

was probably installed in the 70's

LarryFine said:
When a contactor buzzes, it has nothing to do with the load. It's the armature sitting less than perfectly against the pole pieces. Ever tried to pry an energized contactor open? It gets angry-loud.

Most armatures have a pivot so the face of the moving parts can align with the face of the stationary part. See if you can expose the armature and spray a bit of WD-40 on the pivot, and loosen it.
Click to expand...

these are open contactors, I took one out and tightened all the components on it but there is allot of play in the arm that pulls in, I just don't want to replace them and still have a complaint.

kspifldorf said:
If you decide to use the solid state relay, use some heat transfer paste and mount it on something metal to assist in heat dissipation. I use them in my shop for various tricks. If left in free air they will burn out. Had 20 amp rated contact go out on a 12 amp load.
Click to expand...

Thanks for the info on the solid state relay, I have read about possible heat problems but I'm not as familiar as I would like to be, I read the literature and it didn't say it required a heat sink but that would be a good idea if I decide to use them.

Thanks for the responses Stan:)
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This will probably be another in my long line of inane posts, but could you use something along the lines of those heat sequencers with the bimetallic discs.
 
wireman3736 said:
I'm not sure what your talking about ...:grin:
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That makes two of us...:smile:

There used to be electric heat sequencers that had three ( or more or less... I don't know) bimetallic disk switches built into them, similar to what you would find on a hot air furnace hi limit..

They were heated up by small 24 volt thermostat wired heaters and when they popped they would turn on one of the three heating elements... they made virtually no noise.

What I had experienced were intended to sequence the start of multi-element electric heaters, but I expect there would be various models.

I don't know how much current they are good for, but I would expect them to be cheap, I know they're quiet, and I dont think heat dissipation would be a problem.

http://www.zettlercontrols.com/products/product.asp?pp=heatsequencers

I can't really find a good example of them, but I bet your local distributor could . Seems to me honeywell made them.
 
I have been looking at those Mercury ones on line, I may go with them unless I hear something bad about them, the snap disks wouldn't work, I said earlier that I need NO but really need NC contacts. The contact panel is for off peak electric heat, there is a set of contacts in the utility meter that closes and energizes the contacts to break the load during peak time,
 
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