What's new

Best relay for switching A/C ?

caljim

caljim

I'm on the edge. Of what I'm not sure.
Veteran
I run a pair of 5300 btu window air conditioners in flower.

These 2 units are controlled by a 120v thermostat that triggers a 30amp rated motor stater that powers up the A/Cs.

In the last couple weeks the starter has jammed in the open position once, sending temps way up and last night I caught it chattering( could not hold itself closed), until I reset the device.

Is there a more reliable relay that wont stick or chatter?

I'm looking to head down to Grainger and get some new hardware, so please chime in with your :2cents:
 
D

dtfsux

Member
I have used alot of relays/contactors in the past. I usually get them from an electrical supply house.

I have had one or two fail. It just happens. I usually kept a couple around as spares. I do believe they have some better quality ones, but they cost money. I suggest finding an electrical supply house, instead of grainger.
 
D

dtfsux

Member
they were expensive. In hindsight I bought about 20 contactors for my last project, and I got a family member to get them from an electrical supply house at wholesale pricing. So maybe they are not that expensive.
 
B

bipotato

How much did you pay, roughly, and for what type of contactors/ratings? Just curious, because I know I'm over-paying but no idea by how much. Grainger always seems 1.5-2x the price for just about everything else in their retail store, but those aren't electrical parts. :dunno:

Right now I'm using a bunch of $20 Dayton double pole 30A's w/ #10 for every 4 lights. He could use that same double pole contactor to switch those 120v's as well. I use one to switch a 240v A/C, and it's nearly identical to the Hon-Li contactor in my Sentinel HPH4 that cost >$100 I think. Then again not really a valid comparison.
 
D

dtfsux

Member
$20 isnt bad

I think I paid around $15 wholesale, but that was also with pricing of the areas largest electrical contractor. When I bought locally from the supply house, I paid 20-25 I think.


Dont know the brand, they were 30 amp DPST

I just remember looking at grainger and thinking wow, thats alot.

You ever price ballasts from grainger?? makes hydro stores look like wholesalers
 
B

bipotato

Just about everything from Grainger makes hydro stores look like wholesalers.

Just that I had no real other local outlets for contactors, tried a few electrical shops but none carried what I wanted. It seemed like either form a company (or at least DBA), buy from Grainger, or mail order. :dunno:
 
Mulletsoda

Mulletsoda

Member
Ouch... $20 a relay seems intense to me. 5400 BTU ACs aren't too big, are you sure it needs to be rated so high? You said you're using dual pole relays, but didn't say if you were running the equipment at 220V... here's a couple relays I use for various things:

http://www.allelectronics.com/make-a-store/item/RLY-453/120-VAC-RELAY-DPDT-12-AMPS//1.html <~~ Rated at 12A220V, or 1/2 HP inductive load.

http://www.allelectronics.com/make-a-store/item/RLY-482/120-VAC-40-AMP-RELAY//1.html <~~ Higher rated, but single pole.

I use that first relay for damn near everything... from water pumps to lights to AC. One relay per light might seem a little excessive, but they're only $2 a piece.
 
B

bipotato

I've been to their retail store a few times (All Electronics). Thing you should know is that most of what they sell, at least parts like this, are used, pulled parts. If it matters to you. Chances are these relays were in service, likely mounted on a relay socket, and simply popped out for recycling.

A new DP 30A double-break contactor isn't really comparable to a used pull 12A ice cube relay.
 
Mulletsoda

Mulletsoda

Member
http://img249.imageshack.us/img249/8189/img7219q.jpg
http://img684.imageshack.us/img684/8782/img7220o.jpg
http://img268.imageshack.us/img268/7899/img7221l.jpg

That's a few shots of those relays. Yeah, All Electronis is a surplus store, but that doesn't mean everything is pulls. There's lots of excess inventory, old inventory... lots of never used items. They clearly label the pulls, old inventory and new items on the site. I've ordered half a dozen times from them, and have never had anything show up in a condition other than what they stated. I'm a hobbyist, so I'd be comfortable using that sort of thing anyway. Where else could I get the ability to add a 30 voice clip to a photo frame for mother's day, at a cost of only $2? ~~~> http://www.allelectronics.com/make-a-store/item/SAW-3/SAW-3-DIGITAL-VOICE-RECORDER/1.html

A new DP 30A double-break contactor isn't really comparable to a used pull 12A ice cube relay.
Click to expand...

I never suggested that the two were the same thing. I wasn't suggesting to you that you should exchange your heavy duty relays for these ice cube relays, I was making a suggestion to the original poster, who said :

I run a pair of 5300 btu window air conditioners in flower.

These 2 units are controlled by a 120v thermostat that triggers a 30amp rated motor stater that powers up the A/Cs.
Click to expand...

A pair of window air conditioners, only 5400 BTU ea... if they're old, worst case scenario, they're 7, maybe 8 amps ea if they run 110v (being smallish window AC units, I figured safe bet). If that's true, then he can easily use that ice cube relay I linked earlier (which is, not by coincidence, rated for an inductive load).

In the last couple weeks the starter has jammed in the open position once, sending temps way up and last night I caught it chattering( could not hold itself closed), until I reset the device.

Is there a more reliable relay that wont stick or chatter?
Click to expand...

Are you certain this is from the relay? It could also be the thermostat that's on the fritz; if it's sending a rapidly cycling signal, the relay chattering could be the relay responding properly to a bad signal. It could also be a loose connection somewhere.
 
caljim

caljim

I'm on the edge. Of what I'm not sure.
Veteran
Thanks for all the responses and helpful suggestions.

I went in and checked all my connections and the condition of the 120v coil, swapped it out with a spare from another unit. It's been working fine and I'm starting to suspect my thermostat, a C.A.P. Day/Night unit.

It had failed on me in the past, froze contacts closed, when I was running just one A/C @ 6amps for about 6 months. The unit is rated at 15 amps, but I would not trust it with that for long.

When The 2nd unit was added I wired the replacement thermostat to a heavy duty "Square D" 30 amp 3 pole and each A/Cs hot and their common neutral gets switched.

I like to stay away from the cube relays for carrying the load, but the nine pin can be great on the control side.

Thanks again for the input. :tiphat:
 
You must log in or register to reply here.

Latest posts

Latest posts

Top