Taco 503 Switching Relay

Mark (PA) · Post by **Mark (PA)** » Mon. Sep. 22, 2008 10:01 am

Hello all, Just a question here to be sure I am doing this correct.

I am hooking up my EFM 520. Currently have a Taco 503 Switching relay that is used with my oil furnace. was only using 2 zones but added a 3rd zone now.

I am wanting to make sure basically I just have to hook both aquastats (one from oil boiler and one from EFM) to the same terminals on the taco controller. The "start" terminals to let the boiler know its time to burn?

The manual for the control of course only shows it with one unit. I would assume it would work the same with 2 units just to the same terminals?

Sounds simple enough

Blackdiamonddoug · Post by **Blackdiamonddoug** » Mon. Sep. 22, 2008 11:38 am

Do you want both boiler to run at once?
BDD

Mark (PA) · Post by **Mark (PA)** » Mon. Sep. 22, 2008 12:50 pm

Blackdiamond
No. the On Off switch on the oil boiler set to off.

I have them plumbed in series and valve off whichever I am not using. I just want the ability to have the other one on should I need it etc. i