Replace an electronic component

Hi all,

I'm a beginner in electronics, so I apologize if this is not the right place to ask. I have a heating system, that consists of an electronic controller system which operates the pumps, I have tried to install a relay to control the heating, but got the poles mixed up and seems the capacitor(?) that is on that circuit exploded. Now the heating is always on. Just wondering if someone could point me to the right direction how to ID the component so that I can buy and replace it (attached the photo of the board).

many thanks for the help

Oh, dear. Does the programming / scheduling still work ?

I notice the board fuse seems intact...

The exploding component (arrow on piccy, please?) may be the least of your problems ! You could have a compromised micro-controller and a zoo of potentially fried stuff, not to mention the possibility of zapped traces on the back of the board. And, if a multi-layer board, it gives a new meaning to 'deep fried'.

Best case, an interface chip has died. Bad news, THEY ARE NOT IN SOCKETS. The board is not 'field serviceable' at component level. You face a non-trivial extraction, a tricky replacement and a 'hurt' board that may die when most needed...

Sorry, my unhappy, expensive advice is to replace the entire control box *and* the responsible relay.

Due care, please ??

Thanks for the advice.
Seems that all functionality work, except that the heating is always on, that's why I thought that it might be savable.