I have a Hot Springs Sovereign I 2002 wired at 110v with an Ozonator. I had a problem with the spa getting warm but not up to temperature. I replaced the circ pump last week, because of bad flow and it was making alot of "rubbing" noises. Once circ was replaced, I remembered what the flow out of the floor vent actually should look like.

Since replacing the circ pump, water is at air temp and no warmer.

I have checked the resistance on the thermistors and they seem to be in spec with a data sheet I found on the net. The heater is not the original, it is a replacement unit from a dealer that I installed just a couple of weeks previous.

The heater light on the circuit board is on. I have also checked the voltage on the relay board on the left side of the control box where the heater plugs into. I think I am doing it right, I am putting one lead on black wire feed and one on the white wire lead. Across them I am only getting 19v, that does not seem right.

Everything else seems to work fine. Main pump, lights, and panel works fine. There is no indication that the high limit switch is tripping.

I think I have tested or replaced everything I could. Is it the relay board that the heater plugs into? Any hints would be great.

Heater relay board is the correct thought here.

I'm assuming that prior to this it was a working tub in the same location with the same electrical hook up?

Same location, same electical hookup.

I just wanted to confirm that I was checking the voltage correctly after reading a few of the other posts.

Best place to get the relay or how much it will set me back?

yes you do measure across the two wires that go to the heater.

relay board:
http://spapartsnet.com/Hot-Springs-Part ... 1_1_1.html

Pageup thanks for the info. The local dealer actually had a board in stock and didn't take me on the price.

I spent 10 minutes putting it in and it looks good.

When I pulled the old board it had a big black char mark on it, so obviously something blew.

Thanks again for the help.

yeah it's called exploding relay syndrome.

Sealed relay cases build up gas internally with age, contacts get older, and hotter... eventually the thing blows the pins straight out thru the bottom of the circuit board.

This stuff never used to happen until mfgrs started using sealed relay cases and running them close to max capacity.