Load Shed Hotspring w/ an IQ2020

[geprice]

I am adding a whole house generator.  I want to load shed our Grandee's heater or the whole unit.  My goal is to do this at a low voltage level rather than a contactor for both heater legs.  Is there a sensor wire that I can open or a wire pair that I can short to prevent the heater from turning on for controlled periods?  In theory creating an at temp or over temp condition may be what I am looking for.  Currently it is not wired up as we recently moved.   

[Chas]

Interrupt the pressure switch and the tub will flash the power light and shut off the heat but keep the circ pump running.

Try this before you wire it in: some of the older tubs will require a power down to restart, new models will simply go back to work as soon as the circuit is closed again.

If your tub doesn't have a pressure switch (look for a third grey wire coming out of the end of the heater, same type wire as goes to the two temp sensors) then it should have a simple jumper plugged into the 'p switch' points on the mother board.

 

[geprice]

Thanks for the reply.  I will check that. 

Since posting I was able to obtain the thermistor resistance numbers by temperature.  I should be able to simulate a higher water temp & keep the heater off with a resistor & relay.

[Chas]

I would try the pressure switch first. If you adjust the resistance too high, the tub will go into Hi-Limit (flashing the power light) and will require a manual reset/restart. You can only give it a few degrees before it does this, so, if you have a friend or relative who is unfamiliar with the system and they try to run the temp up manually while the system is off-line, it may very well try to heat, or go into Hi-Limit.

It is very easy to find out if your control box has the right programming: simply power the unit up (you can temp in 110 if it is currently not installed) and look for a pressure switch. If there is no pressure switch, Look for a jumper on the p switch points on the mother board. If there is a jumper, simply unplug it. That is a perfect simulation of what you want your system to do, and plugging it back in will let you know if the programming of your IQ-2020 will restart by itself. Most do.

Here is what the Pressure Switch Jumper looks like - if your spa has a pressure switch, the plug will look the same but have a gray wire going to the end of the heater.



HTH

 

[geprice]

Thanks for the guidance Chas.  I did put a small relay in one side of the pressure switch to open the connection when the generator is on line.  It works.

[Chas]

Awesome! Hope you never need it...

 

[goneaway]

i like it.

I could use something like this.
Get one of those cheapo solar powered garden lights, and strip the batteries out.
Wire the charging curcuit to a 1.5v relay.
When it's daylight, the solar panel will kick out 1.5v, which in turn will power the relay.
Thus turning my heater on.

Might be a project for next year if such a thing as a 1.5v relay exists.

[Spoiledrotten]

i like it.

I could use something like this.
Get one of those cheapo solar powered garden lights, and strip the batteries out.
Wire the charging curcuit to a 1.5v relay.
When it's daylight, the solar panel will kick out 1.5v, which in turn will power the relay.
Thus turning my heater on.

Might be a project for next year if such a thing as a 1.5v relay exists.

Would this work for you, Keat?

If you can find a 3 volt relay, you can wire a switch
up with a large electrolytic capacitor and three
diodes. When you click the switch 'off', it
charges the capacitor to about 1.5 volts. When you
click the switch back 'on', the cap gets put in series
with the power supply, creating a temporary +3 volts
to make the relay 'pull in'. Once the relay pulls in,
the holding voltage (and current) will be much lower
and will probably stay on even at 1.5 volts untill the
switch is again turned off. Once turned off again,
the cap charges up again, ready for the next turn on
cycle.