Timer For Time Of Use Metering On Caldera Tub

[Harvey1958]

Hi Folks, I have a Caldera Tahitian hot tub that has a sub panel with two breakers; one is a 30 AMP GFCI three wire system, which when tripped, kills all the controls to the tub. The other breaker is a 20 AMP, two wire GFCI that I am hoping goes only to the heater circuit. Tub is on 240VAC.

I recently installed a 4KW solar system on my home and will be switching over to a Time Of Use payment billing rate with PGE to maximize the rate I get for producing solar. This also means that I get charged $.40/kWh for power I use during the summer months between 1 PM and 7PM. I absolutely want to minimize my consumption during those times and I don't ever want the tub to kick in to heating mode between the hours of 1PM and 7PM or I pay $.40/kWh.

I found an Intermatic T104R timer that is a Double Pole Single Throw (DPST) switch capable handling 40 AMP resistive load at 120-480VAC. The instructions and diagrams for the switch are here: http://www.intermatic.com/~/media/files/intermatic/products/instructions/timers/t104%20-%20english.ashx more details are here: http://www.intermatic.com/products/timers/mechanical%20time%20switches/24%20hour%20dial.aspx

Would you be so kind as to confirm, that the two wire, 20 AMP circuit goes just to the heater and this is where this switch could be installed by a licensed electrician?

The tub does have a summer mode setting which shuts the tub down each day for eight hours from when you activate it. But it also requires putting the temp down to 80 F. If anyone knows how to reprogram this to allow a setting of 104 degrees F, with a summer shutdown setting that would work even better.

Thanks,

Harvey

[Harvey1958]

So Watkins Mfg. came back and would not disclose which leg controls the heater, said they will not support any modification to the wiring, and no, they don't have a control panel or mod that will position the operating hours of the tub to coincide with time of use metering.

They did confirm that summer setting will indeed drop the tub totally out for 8 hours following initiation of summer settings, and summer settings can be initiated at temperatures higher than min settings. That will indeed help since my $.40/kWh time period is from 1PM through 7PM through Oct 31.

I left message with and followed up with the Berkeley based Caldera shop, and received no reply from their tech.

I'm hoping to get confirmation back from this esteemed forum in the meantime.

Thanks,

Harvey

Hi Folks, I have a Caldera Tahitian hot tub that has a sub panel with two breakers; one is a 30 AMP GFCI three wire system, which when tripped, kills all the controls to the tub. The other breaker is a 20 AMP, two wire GFCI that I am hoping goes only to the heater circuit. Tub is on 240VAC.

I recently installed a 4KW solar system on my home and will be switching over to a Time Of Use payment billing rate with PGE to maximize the rate I get for producing solar. This also means that I get charged $.40/kWh for power I use during the summer months between 1 PM and 7PM. I absolutely want to minimize my consumption during those times and I don't ever want the tub to kick in to heating mode between the hours of 1PM and 7PM or I pay $.40/kWh.

I found an Intermatic T104R timer that is a Double Pole Single Throw (DPST) switch capable handling 40 AMP resistive load at 120-480VAC. The instructions and diagrams for the switch are here: http://www.intermatic.com/~/media/files/intermatic/products/instructions/timers/t104%20-%20english.ashx more details are here: http://www.intermatic.com/products/timers/mechanical%20time%20switches/24%20hour%20dial.aspx

Would you be so kind as to confirm, that the two wire, 20 AMP circuit goes just to the heater and this is where this switch could be installed by a licensed electrician?

The tub does have a summer mode setting which shuts the tub down each day for eight hours from when you activate it. But it also requires putting the temp down to 80 F. If anyone knows how to reprogram this to allow a setting of 104 degrees F, with a summer shutdown setting that would work even better.

Thanks,

Harvey

[n1oty]

The controls and pumps are on one breaker and the heater is by itself on the other. So, from your description, you'll need to put a timer on the 20 amp circuit. If external to the tub, it shouldn't affect the warranty. It's no different that shutting that breaker off.

John

[arnspa]

Harvey,

We too are on a time of use billing with PG&E, and have a solar electric system. Our 240 volt, 50 amp system is all on one line. Because of the high amperage we used a 110 volt Intermatic timer to control a 240 volt, 50 amp conductor.

You may wish to see the my Topic posted about how to get a timer for this. (Timer for 50 Amp Spa, 15 March 2010)

This system cuts off everything to our spa during summer hours from 10am to 9pm. Ours is 1300 gallons, good cover, and the heat loss is 1-2 degrees.

It seems you wish to avoid heating water during PG&E prime time. Smart, and yet I wonder if like us, you can avoid all electric during that prime time. You might put both lines on timers? Or combine them on one line?

Here's a photo of our installation:

NOTE: You wrote that the PG&E rate was 40 cents kWh?

You may wish to check this. For us (Menlo Park, CA), the summer rates, Monday - Friday, are 29 cents kWh from 1pm to 7 pm, 14 cents from 10am-1pm and 7-9pm, and then 8 cents from 9pm to 10am.

Of course we want to heat and filter in the cheapest hours. But also, in California, PG&E must credit us at the 29 cent rate when we are sending volts back to them during those sunshine hours. So we try not to use a minute of this that we might use at other hours.

Our PG&E bill for last year was ZERO. As soon as I rewire our attic and add some insulation I expect they will be paying us. (As of January PG&E must pay us for any surplus we give them over the year.)

My applause for you getting the solar system. Very smart!

[Harvey1958]

Hi Spa Savant, thanks for your input. I hadn't thought about simply dropping out the entire pool during the peak hours. It's clear if I drop out the controls/filter pump/ozone system, obviously the heater would drop out as well. It's not as clear cut since it's a three wire output from the 30 Amp breaker and I need to research how to incorporate the Intermatic switch into a three wire circuit.

How do you set the timer for the winter months to avoid freeze damage, and to keep the tub warm enough for use when you want it? I have a good cover, but my Caldera Tahitian is only 360 gallons so we have much less water to heat up.

My comment on the $.40/kWh was more around picking out what I thought the blended rate would end up being depending on where I was in the tier. This is the rate sheet you are on as well, correct?: http://www.pge.com/tariffs/tm2/pdf/ELEC_SCHEDS_E-6.pdf

Thanks again for your insight.

Harvey

Harvey,

We too are on a time of use billing with PG&E, and have a solar electric system. Our 240 volt, 50 amp system is all on one line. Because of the high amperage we used a 110 volt Intermatic timer to control a 240 volt, 50 amp conductor.

You may wish to see the my Topic posted about how to get a timer for this. (Timer for 50 Amp Spa, 15 March 2010)

This system cuts off everything to our spa during summer hours from 10am to 9pm. Ours is 1300 gallons, good cover, and the heat loss is 1-2 degrees.

It seems you wish to avoid heating water during PG&E prime time. Smart, and yet I wonder if like us, you can avoid all electric during that prime time. You might put both lines on timers? Or combine them on one line?

Here's a photo of our installation:

NOTE: You wrote that the PG&E rate was 40 cents kWh?

You may wish to check this. For us (Menlo Park, CA), the summer rates, Monday - Friday, are 29 cents kWh from 1pm to 7 pm, 14 cents from 10am-1pm and 7-9pm, and then 8 cents from 9pm to 10am.

Of course we want to heat and filter in the cheapest hours. But also, in California, PG&E must credit us at the 29 cent rate when we are sending volts back to them during those sunshine hours. So we try not to use a minute of this that we might use at other hours.

Our PG&E bill for last year was ZERO. As soon as I rewire our attic and add some insulation I expect they will be paying us. (As of January PG&E must pay us for any surplus we give them over the year.)

My applause for you getting the solar system. Very smart!

[arnspa]

Harvey, YES, we do have the same PG&E rate sheet -- Though I had not seen this new one! I see my current rate for Summer is 30/15/9 cents per kWh, vice the 29/14/8 it was last year.

That is, at our house we use only a fraction of the Baseline and pay at the lowest rate. But indeed I see that one could even be at a 58 cent kWh rate for Summer peak, depending on amount of usage/tier.

I do hope you are mistaken in estimating your Baseline tier and that it will be lower than you guess. (How many teenagers do you have?)

Your questions about freeze suggest to me you may not be close to us in Menlo Park, CA. We had down to 28 dF last winter, hurt the jade plants a little, but we have no worries for the spa. It's set for 100 dF and loses only little even being off for 12 hours. Even if we turned it off for 2 weeks in the winter I'm sure we wouldn't have freeze worries. 1300 gals is a lot of heat and well insulated.

Also, the house has gas furnace, water heater, and drier. So our electric usage is much less than folks who are all-elec. We even have a timer on the freezer in the basement.

The upside of Net Metering is that when the 30 cents kWh rate is in effect for us is exactly when we are sending solar electric back to PG&E. That is, we are not paying them at all, but they have to credit us at 30 cents for what we're giving them. Thus, we don't need zero usage to have a zero bill. We send them our solar surplus at 30 cents, and buy it back at night for 9 cents.

(I'm sure you've heard all this, Harvey. We need to tell others)

--ArnSpa

[For our friends elsewhere: Pacific Gas and Electric has a 'voluntary' Time of Use billing plan, allowing users cheaper rates at night,and higher rates during peak AC days/hours. Good for those who can limit their use during the day, or even, as with solar, to earn big credits at peak time.]

[arnspa]

Harvey, To say more about using an Intermatic timer to control the tub. We have a separate 110 volt line at the site/panel. It controls the separate Schneider 240 volt conductor. The conductor has terminals for more than one device.

So, you may be able to have a 110 timer controlling a 240 conductor that would switch both lines to the tub.

NOTE: I suggest you get some professional electrical advice on this. I would ask some local electricians for bids on this and ask/discover what's the best way to go. Find some that do this sort of work. I was lucky to find one that even gave me tips on where to find cheaper filters.

--ArnSpa

[Harvey1958]

ArnSpa:

I'm up in Pleasanton and do indeed have two sons still in the home. I watch my hourly stats through the PGE website and can see quite clearly when our family wakes up, does laundry and cooks just from the usage. We get cold enough weather to freeze the dog water bowls and annoy the jade plants too. But we don't have the thermal mass that you do of course in our tub. I agree though, it would take more than evening to freeze it up.

I have a Gazebo overhead with 2x2's on two inch centers that I want to center some black 1/2" irrigation tubing on and then drive a DC pump on a 85W solar cell to push the spa water through. The backpressure from the tubing and all the elbows is considerable so the pump needs to be big enough to produce enough head to get to the roof and then push the water through, but I'm convinced it would make a difference. I have about twice the surface area up there as I do on the tub which on some sites seems to be the right rule of thumb. I work for Solar Millennium, so when you work all day on what will be the worlds largest solar thermal project (1000MW Parabolic Mirror) laying black pipe on a gazebo roof seems like a good project.

I'll run some tests on the three wire circuit this weekend and will see and share what might work. Hoping PGE will come out this week for the final approval on my roof system.

Harvey

[ezdraftcohibas]

i am sizing a whole house generator, can anyone help me with the wattage that this tub (tahitian) uses? thanks

[Dr. Spa]

Amps x volts = watts

[ezdraftcohibas]

Amps x volts = watts

so when i read the manual it states 30 or 50 AMPS, which one? thanks