I just refilled our 2001 Hot Springs Grandee spa after a summer on Summer Heat control setting. Upon power back up, the red power light was flashing. I powered back down, and when I powered back up after an hour or so, the red light was steady, but the Ready light was flashing. I recycled power once more, and the red power light came on steady. I thought all would be well, but after an hour or so, I realized that the spa wasn't heating, and as best I could tell, the circulating pump wasn't running.

I took the cover off, as well as the cover on the PCB, and here is what I've been able to observe (after first cleaning out the HUGE ratsnake skin that was shed in the pump compartment!):

1. When I turn on power at the breakers, I hear 2 distinct relay clicks.
2. On the PCB, The green LIM OK led is ON, and the red HTR ON led is also lit. However, there's no discernible change in heater temperature.
2a. The pump motor doesn't appear to be running. Hard to tell, though...
3. The mechanical reset button (It's under some clear tape, on the end of the heater housing opposite from the water inlet and outlet - is that some sort of flow sensor?) on the heater was "up" - I mashed it, and it clicked. The heater very obviously came on: the housing instantly got hot to the touch (should it?) and I could see that there is some circulation in the outlet line (some slight air bubble movement).
4. The Silent Flo pump gets very, very hot to the touch, especially in the area around where I'm guessing the impeller is - can hardly bear to keep my hand on it.
5. I don't think there's any flow through that pump, but I'm not 100% sure. Is there an easy way to confirm this? I feel no vibration when my hand is mon the pump, and I hear no noise at all (Maybe a slight buzzing? Can't really tell...). I do measure 115V between the pump white and black wires.
6. Somehting trips - both led's on the PCB are now out, and the red power light is flashing on the control panel. That tells me the temperature limit's been sensed, I think, and the heater's been shut down. Does that sound right?
7. However, as far as I can tell, the heater flow sensor (if that's what it really is) hasn't tripped again. Should this be an instantaneous trip, or do things have to run for awhile before it trips?

My overall question is: do I have a pump problem? A heater problem? Both? Sensor problem(s)?

One final question: If I were to replace the pump myself, do I need to drain the entire system before removing the hoses? I see a drain at ground level, with some sort of black open/close valve knob (on the inside, left floor of the pump compartment) - what's that for?

Thanks for any help I can get!

After the observations I made above, I notice that the hose that's marked "Inlet" and "Control" on the heater (attached to the sode discharge of the pump) is the one that contains hot water; the one marked "Outlet" and "Limit" is still cool. How can that be? Is the pump running backwards?

Also, there are two connectors to the PCB that come from the heater - one from the Control side, and one from the Limit side. since the 2 cables are nicely bundled up and tie-wrapped and I don't want undo Watkins' good work, can anyone tell me which one of those (upper or lower) comes from the Limit sensor?

Once again, many thanks!

Hello. It sounds like you've already figured it out....

Yes, it's very likely the silentflo is "hosed" Just be sure the filters are clean.

The little red button under the tape is a high limit switch. It tripped due to the heater overheating... and that's why it instantly became very, very hot when you re-set the high limit. The NF 600 get very hot normally, as the element heats of the stainless steel housing, and the water is then pumped through the housing. The element never touches water, thus ensuring a longer lifer than traditional heaters, that are subject to water chemisrty issues...However, if the circ pump fails, the heater does not know this, and it will energize. There is no flow switch in this spa. The heater will overheat VERY quickly if the circ pump fails.

The two electronic temp sensors that screw into the end of the heater.. one is for incoming temp- this is how the spa determines the actual temp of the water.. the other is the outgoing temp- it's used for the electronic high limit... (it will make the red light flash if tripped, while the red button high limit located on the heater will not). Each of these have a different thread, and different receptacle, so it's impossible to install them improperly.

It sounds as though the temp sensors are working properly. The green one will flash when the circ pump goes out as well.... the proximity of that temp sensor will sense the warmer than usual temp coming from the very warm circ pump, and determine the sensor is bad (that's why the green light will flash)... when, in fact, it's the circ. pump that's bad.

Good luck!

~Swine

Thanks for your helpful input. This unit is still uner warranty, and I've scheduled a tech to come out with new pump in hand.

What about my question about the "drain" valve on the floor of the equipment compartment - what's that for, anyway?

For those who may be interested, here's how the tech managed to swap the pump out without draining the tub, and without any shutoff vales in the pump inlet and outlet lines (he said that Watkins doesn't put such valves in the system becuase they're afraid users will leave them in the CLOSED position and then turn the spa systems on): he had two small check valves that he placed in the lines after removing them from the pump. He was pretty quick about it, and probably not more than a cup or two of water was lost from each hose when he detached them, and then again when he removed the check valves in order to reattach the lines to the pump.

I should have asked him for the sizes (I guess I could meaure the pump fittings for that) and where those might be available - anybody know?

Hose clamps work much better... better to have the right tool for the job

Thanks for the tip, but I don't think I understand: when you say hose clamp, I think round things that you tighten down to assure a tight fit between a hose and a male fitting. I'm not sure how they could be used to stop the draining from the hoses when they've been disconnected from the pump. What am I missinig about technique here? Why would they be an inherently better tool than quickly inserting a check valve into the disconnected line?

Or, when you're saying "hose clamp", are you referring to some sort of tool (like pliers) that one can use to clamp down and flatten the hose, thereby making sure that no water can go through? If so, is there any danger in putting such pressure on the hose material? And where would one buy such a tool?

Thanks!

Yep... like a doctor asking for "CLAMP!" I get mine from Watkins Manufacturing. No danger to the vinyl tubing. Do NOT use clamps on flexible pvc pipe, only vinyl