I have a new hydroquip 6100 spa pack installed into a mid 90s Cal Spa. When I first hooked it up, everything appeared to be working fine (jets, blower, heat), but some of the plumbing unions leaked. I shut it down and fixed the leaky unions, then turned it back on.

I quickly got a High Limit code, and discovered I had forgotten to open the gates to allow flow. (Why the flow switch didn't prevent the heater from turning on, I don't understand.) I shut everything down, turned off the main breaker and GFCI, switched it all back on and opened the gates. Since then everything on the spa pack appears to run normally (including the "heater on" light) -- except there's no heat. It's been on all night twice with no increase in temp according to the digital spa controls and the thermometer floating in the tub.

I've been through every trouble shooting list I can find, and every "no heat" post I can find on this board, but so far nothing works. Here's what I tried:

(1) the filter is not clogged, it's brand new, and water comes blasting out the jets; (2) The spa pack is not in backwards - with the pump sucking water through the heat tube instead of pushing; (3) The flow switch works- I tried unplugging the pump from the spa pack, the "heater on" light promptly clicked off. I plugged the pump back into the spa pack, the "heater on" light clicked back on; (4) The spa pack instructions say that in order to reset a High Limit error, you turn everything off and let it cool, then power back up. I did this, and I've had no High Limit errors since (but no heat since, either); (5) I've searched for a manual reset switch on the spa pack, but found nothing outside or inside; (6) Electricity IS getting to the element, because the "heater on" light is wired onto the posts of the element just inside the bottom of the spa pack.

Since none of these remedies have worked, I'm afraid that when I got the High Limit error the element fried ( but the wires to the posts inside the spa pack look fine -- not melted or burned). Also, I don't understand how I got the High Limit error in the first place, since the flow switch should have kept the heater from kicking on when the gates where all closed.

Any ideas, or did I ruin my new spa pack?

Thanks for your time!

That's not a flow switch, it's a pressure switch.
Even with the gate valves closed, you will still develop pressure in the housing.

What probably happened:

Your heater over heated extremely fast, much faster than the sensor can detect, which fried the heater.

Remedy:
Replace the element.

(You could put an ohm meter across the terminals - with power turned off - it'll probably read nothing eg open circuit).

PageUp, Thanks for the quick reply. I'll replace the element and post the results here. I appreciate your time advice!

Update -- I took your advice Pageup, and installed a new element this evening after work. The jets and blower ran fine, just as before. I nervously sat around for an hour to see if the thing was actually heating up this time. 65 minutes later, she's up 7 degrees! After two hours she's up 14 degrees and obviously working great.

Thank you thank you thank you.

I could not have got this project done without everything that I've learned from this board and the people who patiently answer our sometimes crazy and often panicked questions.