I have no experience with these units, but are you sure the relay can handle the current? 17A is quite a lot, if the relay is not rated for that, it could be a problem. A 20A relay wouldn't be uncommon to have, but I don't know the specs on that unit. I picked up a few solid state relays for my DIY AC control and they are only 2A so I have to be careful what I run through them.