Electrical Bill Nightmare

[Biz]

Well, it looks like what people have said about the Infinity Sunpeak Hot Tub being an electrical hog is true.

It looks like our electric bill from mid Nov-Mid Dec this year with the Hot tub will be about $270.00. Last year without the tub for the same period, the bill was $153. This year we used 1878 KW for the period, last year we used 1077KW. In summary, the tub used about 800KW this month, costing us an additional $104.00 in electrical bill. For the months of May-Nov though, the tub used an average of 388KW per month, costing us $50.00 additional per month. We have our tub on the Economy mode, with a 2 hour filtering time, every 12 hours.

Seems to me that at least in the New England area, this tub is fine for April-November weather, but is going to be a real electrical hog between Dec-March.

On top of that, many days the temp in our tub will drop to the mid 70's. In order to get it back to 100 degrees, I have to run the heater for about 6 hours during the day for it to be ready, and an additional 1 hour while we're using it. This is boht time consuming and of course, if done on a regular basis very expensive.

It's frustrating to pay an additional $100 per month during the winter and not even be able to use the tub when temps remain below 30 degrees.

if you live in a cold climate like New England, this might not be the tub for you.

[Dr. Spa]

Are you saying your tub will lose THIRTY DEGREES in one day ??????????

[Trigger]

Well at least you have the Costco no hassle return policy.

[spatech (the unreal one)]

Are you saying your tub will lose THIRTY DEGREES in one day ??????????

OMG, I read the same thing. Even in winter, with a well insulated spa you should be able to turn the heater temp setting down low (therefore disabling the heater) and with the cover in place the spa should hold temp pretty well and hopefully lose no more than single digit temp.

That spa really needs to be insulated, quickly. Go to Home Depot and see what your options are. The spa may not end up being in the well insulated category when you're done with it but you can certainly improve on what they've saddled you with.

[Roger]

Well at least you have the Costco no hassle return policy.

I would take Costco up on that return policy. At that rate it won't be long before you have as much invested in that tub as you would a more reliable, quality brand.

I think there are more folks here that are paying as much or more that own one of those type tubs. But they are blind to it.

[r5ran]

Are you saying your tub will lose THIRTY DEGREES in one day ??????????

OMG, I read the same thing. Even in winter, with a well insulated spa you should be able to turn the heater temp setting down low (therefore disabling the heater) and with the cover in place the spa should hold temp pretty well and hopefully lose no more than single digit temp.

That spa really needs to be insulated, quickly. Go to Home Depot and see what your options are. The spa may not end up being in the well insulated category when you're done with it but you can certainly improve on what they've saddled you with.

Just for a comparison.....

A couple weeks ago, I was going to be out of town, so I lowered the temp setting on my H/S Vanguard from the usual 100 degrees down to 80 degrees.

H/S tubs do not have an actual temp reading on the outside, but they do have a bright green light that lights (and we can see easily from our window) when the actual temperature is within 2 degrees of the set temp., so technically when the water hits 82 degrees, the light would turn on.

I had my wife watch this to see how long it would take, and made sure she did not open the cover.

I live in an extremely cold climate, and even though it was just early Dec., we had a cold spell, with the highs ranging from 11 -15 F and the lows ranging from 0- 5 F, so the weather was no help.

I had turned the temp down a Tues night about 11pm, and the light did not come on till about Friday at 8pm. (she checked at 6 pm and it was not on yet). So, it took almost 3 days for the temp to drop that 20 degrees.

My electric bills also back this up...I know these are not defined amounts, but comparing this years bills to last years, my bill has increased, $14, $9, $12, and $24 (refilled tub that month)

for the same 4 months since I had the tub (Aug - Nov). Considering the tub is used every night for about an hour, and usually twice a day on weekends, I am pleased.

Randy

[104 Degrees]

order a 4"to 6" thick cover from roberts hot tubs.this is what i did and it worked great.my tub was down for two weeks one week being warm and the other week being in the teens,when the heater was fixed the tub was 77 degrees after 14 teen days.

[Biz]

Are you saying your tub will lose THIRTY DEGREES in one day ??????????

Recently day temps have been in the 20's with low's near 10 degrees.

We have our tub filter twice daily for 2 hours each time. During this time the heater is on.

this is a typical example of what happens in 24 hours.

Time: 5:30 PM-water temp is 97 degrees

Time: 3:30AM- Tub filers for 2 hours, heater is on.

Time: 5:30AM-Tub stops filtering & heating

Time: 3:30PM-Tub begins next filtering process. Heater is on

Time: 5:30PM-Tub stops filtering & heating

Time: 5:30PM-water temp is now about 85 degrees.

In summary then, within 24 hours, with the heater on a total of 4 hours- the temp will drop from 97-85 degrees, losing abut 12 degrees a day.

In order to maintain the tub water around 97 degrees, I have to turn the heater on an additional 3 hours during the day, in addition to the heater being on a total of 4 hours during the cycling process.

I have just received a floating blanket from RhTUBS, which I hope will help.

We are also waiting for Hot Tub services to return with a new control panel, so we can switch our 4.0KW heater to a 5.5KW heater to helps spped up the heating process. They are also suppose to return to insulate the inside of our cabinet with Thermo Foil panels which I udnerstand will help keep the cold out.

Problem is they came to our home 3 weeks ago, and haven't returned yet.

[grandee1]

All this cycling on and off, heater on at this time and off at this time is IMO non sense that requires way too much analysis and thought. A hot tub is supposed to be relaxing not stressful. A tub should maintain a preset temp not rise and fall. When the tub calls for heat it comes on and the water stays at your temp of choice. This is the most efficient way to heat a tub but this is also assuming the tub is well insulated. My tub is set to 102 and is ready anytime. In NC my 500+ gallon 2001 model HS costs less than 10.00 month in the dead of winter. Granted our winters are very mild but we get our share of freezing weather. When your tub drops so low and has to recover that is where you’re using so much power. In the summer I do set mine back to 80 since it is not used at all and the only thing that runs is the circ pump. This is not even detectible in the electric bill. The old saying….you can pay me now or later holds true, even in spas.

[spatech (the unreal one)]

In summary then, within 24 hours, with the heater on a total of 4 hours- the temp will drop from 97-85 degrees, losing abut 12 degrees a day.

In order to maintain the tub water around 97 degrees, I have to turn the heater on an additional 3 hours during the day, in addition to the heater being on a total of 4 hours during the cycling process.

I have just received a floating blanket from RhTUBS, which I hope will help.

We are also waiting for Hot Tub services to return with a new control panel, so we can switch our 4.0KW heater to a 5.5KW heater to helps spped up the heating process. They are also suppose to return to insulate the inside of our cabinet with Thermo Foil panels which I udnerstand will help keep the cold out.

Problem is they came to our home 3 weeks ago, and haven't returned yet.

A 12º drop in a day when the heater has been on for 4 hours is very bad. The floating blanket will help but if teh spa isn't insualted it's like putting a hat on a person who goes outside without a coat. The hat helps but putting on a coat is the top priority. The foil backed foam should help so I hope they come through for you soon because that spa is pissing $ away.

[Stuart A]

All this cycling on and off, heater on at this time and off at this time is IMO non sense that requires way too much analysis and thought. A hot tub is supposed to be relaxing not stressful. A tub should maintain a preset temp not rise and fall. When the tub calls for heat it comes on and the water stays at your temp of choice. This is the most efficient way to heat a tub but this is also assuming the tub is well insulated. My tub is set to 102 and is ready anytime

Agree , a spa should be ready to use at the preset temperature anytime.

Is there any particular reason why some manufacturers make spas that don't maintain a constant temperature all the time?

[spatech (the unreal one)]

Is there any particular reason why some manufacturers make spas that don't maintain a constant temperature all the time?

He has his set in "economy mode" which means the heater will only operate during filter cycles. That mode doesn't really save much power but it's an OK idea but ONLY useful on a well insulated spa that doesn't drop temp so much.

If I had a spa that was poorly insulated I’d either fix the insulation problem, or mothball until I did so or run it in regular mode and live with the high utility bill before I used economy mode.

[Hillbilly Hot Tub]

Are you saying your tub will lose THIRTY DEGREES in one day ??????????

Recently day temps have been in the 20's with low's near 10 degrees.

We have our tub filter twice daily for 2 hours each time. During this time the heater is on.

this is a typical example of what happens in 24 hours.

Time: 5:30 PM-water temp is 97 degrees

Time: 3:30AM- Tub filers for 2 hours, heater is on.

Time: 5:30AM-Tub stops filtering & heating

Time: 3:30PM-Tub begins next filtering process. Heater is on

Time: 5:30PM-Tub stops filtering & heating

Time: 5:30PM-water temp is now about 85 degrees.

In summary then, within 24 hours, with the heater on a total of 4 hours- the temp will drop from 97-85 degrees, losing abut 12 degrees a day.

In order to maintain the tub water around 97 degrees, I have to turn the heater on an additional 3 hours during the day, in addition to the heater being on a total of 4 hours during the cycling process.

I have just received a floating blanket from RhTUBS, which I hope will help.

We are also waiting for Hot Tub services to return with a new control panel, so we can switch our 4.0KW heater to a 5.5KW heater to helps spped up the heating process. They are also suppose to return to insulate the inside of our cabinet with Thermo Foil panels which I udnerstand will help keep the cold out.

[u]Problem is they came to our home 3 weeks ago, and haven't returned yet.[/u]

Told you that would happen. Now that you have waited for them to come insulate, I thnik it was probabley worth your cost to do it then. You will be at the bottom of the lists with this cold weather and storms since your tub is running and not going to freeze up.

[Biz]

Let me correct my original posting. Actual electric bill was $288 up from $153 at same time last year without our Infinity tub..OUCH!!!!!!!!!!!!!

Well, it looks like what people have said about the Infinity Sunpeak Hot Tub being an electrical hog is true.

It looks like our electric bill from mid Nov-Mid Dec this year with the Hot tub will be about $270.00. Last year without the tub for the same period, the bill was $153. This year we used 1878 KW for the period, last year we used 1077KW. In summary, the tub used about 800KW this month, costing us an additional $104.00 in electrical bill. For the months of May-Nov though, the tub used an average of 388KW per month, costing us $50.00 additional per month. We have our tub on the Economy mode, with a 2 hour filtering time, every 12 hours.

Seems to me that at least in the New England area, this tub is fine for April-November weather, but is going to be a real electrical hog between Dec-March.

On top of that, many days the temp in our tub will drop to the mid 70's. In order to get it back to 100 degrees, I have to run the heater for about 6 hours during the day for it to be ready, and an additional 1 hour while we're using it. This is boht time consuming and of course, if done on a regular basis very expensive.

It's frustrating to pay an additional $100 per month during the winter and not even be able to use the tub when temps remain below 30 degrees.

if you live in a cold climate like New England, this might not be the tub for you.

[KIALDA]

actually that is a lot less than other people have told me. You must have had a warm spell during that month. Wait and see what your bill is for January thru April, I bet you will think this last bill was low.. Keep us informed

[soakerguy]

Try adding "Reflectix" insulation from your local home improvement store. I added the insulation and the heater cycles a lot less then in the past. I will know more the next bill for sure. The total to add the insulation was $50.00 and about four hours to remove the panels, add insulation and seal with tape any air gaps. by doing this you also have complete access to the plumbing and motors when and if needed in the future. Good Luck!

[IACinger]

Try adding "Reflectix" insulation from your local home improvement store. I added the insulation and the heater cycles a lot less then in the past. I will know more the next bill for sure. The total to add the insulation was $50.00 and about four hours to remove the panels, add insulation and seal with tape any air gaps. by doing this you also have complete access to the plumbing and motors when and if needed in the future. Good Luck!

I did the same thing in November...a 48"x25' roll from Menards was about $35, add some aluminum duct tape = less heating cycles. Worth it I think!

[Biz]

Try adding "Reflectix" insulation from your local home improvement store. I added the insulation and the heater cycles a lot less then in the past. I will know more the next bill for sure. The total to add the insulation was $50.00 and about four hours to remove the panels, add insulation and seal with tape any air gaps. by doing this you also have complete access to the plumbing and motors when and if needed in the future. Good Luck!

How did you install the "Reflectix" insulation? Was it stapled to the inside of the panels or did you staple it to the frame inside the cabinet?

Also, have you noticed if your tub water loses less heat yet? We live in a very cold climate in New England. Our tub water is losing about 16 degrees every 12 hours before reheating again. Would like to get it down to more like 8 degrees every 12 hours.

[soakerguy]

Try adding "Reflectix" insulation from your local home improvement store. I added the insulation and the heater cycles a lot less then in the past. I will know more the next bill for sure. The total to add the insulation was $50.00 and about four hours to remove the panels, add insulation and seal with tape any air gaps. by doing this you also have complete access to the plumbing and motors when and if needed in the future. Good Luck!

How did you install the "Reflectix" insulation? Was it stapled to the inside of the panels or did you staple it to the frame inside the cabinet?

Also, have you noticed if your tub water loses less heat yet? We live in a very cold climate in New England. Our tub water is losing about 16 degrees every 12 hours before reheating again. Would like to get it down to more like 8 degrees every 12 hours.

I installed the "reflectix" insulation by simply removing the panels from my spa and stapeling the insulation directly to the framework. The frame of my Platinum II spa already had styrofoam panels cut to fit and installed from the factory so I left those panels in place and simply wraped the whole spa in one pass without modifying anything on the spa itself. The hardest part for me was to custom cut around the radio installed on the skirting and also making sure the panels went back in place correctly. The best way I found to reinstall the panels was to use a awl "small ice pick" to locate the screw holes that are covered by the "reflectix" insulation. By useing the awl, you will easilly be able to line up the panels and pierce the insulation for a no hassle easy fit of the skirting panels. You can do this yourself but it was easier to have a second set of hands to hold the panels in place while I secured them to the spa. Also, I did not tighten the screws completely untill all the panels where installed, that way I had a little room to adjust the panels for proper fit.

[Biz]

Hello everyone;

Back in December, I posted a message regarding our electrical usage for our Infinity Sun Peak.

About 2 months later, Hot tub services finally returned to repair our tub. they replaced our 4.0 KW heater with a new 5.5 KW heater. They also wrapped the entire frame of the tub with what they called Thermo foil.

Well, this past weekend our temps were again in the 20's like I reported this past December. This is the result after the repairs.

We have our tub filter twice daily for 2 hours each time. During this time the heater is on.

this is a typical example of what happens in 24 hours.

Time: 5:30 PM-water temp is 101 degrees

Time: 3:30AM- Tub filers for 2 hours, heater is on.

Time: 5:30AM-Tub stops filtering & heating

Time: 3:30PM-Tub begins next filtering process. Heater is on

Time: 5:30PM-Tub stops filtering & heating

Time: 5:30PM-water temp is now 101 degrees.

In summary then, within 24 hours, with the heater on a total of 4 hours- the temp remained steady, instead of dropping 12 degrees like it did a couple of months ago. (see below)

I understand that you can purchase this foil at Home Depot.

What an improvement..and now I suspect we will see our electrical usage drop as we dont have to leave it on so long to regain temperature in tub.

THIS WAS MY QUOTE FROM DECEMBER 16, 2008

Are you saying your tub will lose THIRTY DEGREES in one day ??????????

Recently day temps have been in the 20's with low's near 10 degrees.

We have our tub filter twice daily for 2 hours each time. During this time the heater is on.

this is a typical example of what happens in 24 hours.

Time: 5:30 PM-water temp is 97 degrees

Time: 3:30AM- Tub filers for 2 hours, heater is on.

Time: 5:30AM-Tub stops filtering & heating

Time: 3:30PM-Tub begins next filtering process. Heater is on

Time: 5:30PM-Tub stops filtering & heating

Time: 5:30PM-water temp is now about 85 degrees.

In summary then, within 24 hours, with the heater on a total of 4 hours- the temp will drop from 97-85 degrees, losing abut 12 degrees a day.

In order to maintain the tub water around 97 degrees, I have to turn the heater on an additional 3 hours during the day, in addition to the heater being on a total of 4 hours during the cycling process.

I have just received a floating blanket from RhTUBS, which I hope will help.

We are also waiting for Hot Tub services to return with a new control panel, so we can switch our 4.0KW heater to a 5.5KW heater to helps spped up the heating process. They are also suppose to return to insulate the inside of our cabinet with Thermo Foil panels which I udnerstand will help keep the cold out.

Problem is they came to our home 3 weeks ago, and haven't returned yet.

[soakerguy]

I hope it works for you! I am waiting to see how the "reflectix" foil bubble wrap insulation works for me.

I also have my spa set on economy mode and usually see the spa drop on average three degrees between heating cycles. before it was easily eight! This also seamed to make my spa very quiet and only noisey with pump one on high and pump two on. otherwise you barely hear the pump.

[Yunus]

Just to give some perspective on your heat situation. My circulation pump recently died on my 2008 Caldera Hawaiian (380 gallons). With the weather between 15-25F in a given day my temps went from 103 on Friday night when the pump died to 93 on Sunday evening. This is a 10F loss of heat in 48 hours with no water movement in the tub and the heater is off the entire time. After 1 week with the temps only going above freezing 1 day the water temperature was still about 70F. It was over 2 weeks before I felt I needed to manually add some hot water to keep it from freezing. Also these numbers reflect no usage of the tub except opening it daily to check the temp. I'm sure using it would have resulted in a much quicker loss of heat.

[avasicek]

Id be more curious about what the spa is set to filter, how its installed (up off the ground on a deck, flat on cement, etc). Direct exposure to elements, wind, etc? I have found some spas installed, raised off the ground, with direct exposure to the lovely ocean breeze, can suck the heat right out of a spa cabinet.

Really, any name brand spa worth a name shouldnt lose temp as fast as noted, or cost as much as noted, cheap or not, dealer or not. I know some are lacking in insulation, but just the physics of cooling water, vs heat able to be generated/retained by a heater, cover, cabinet, heat from the equip...seems like something else is acting on the system.

May not be your particular situation, but for other readers, I find most typically its a misunderstanding on how the tub operates. For instance, Balboa. By default most will automatically circulate twice per day, 2 hours per cycle. If the AVC's are left open, when that spa runs its minimum of 4 hours per day, only tries to heat when its in this mode due to ECON, your cooling it faster then your heating it for 4 straight hours per day (maybe more if the settings have been tinkered with). You have sub 30-degree air pumped right into the water your trying to keep 80+.

Off subject a bit, because you do seem to have a real issue, but again, for others...What are you paying per kWh? One thing many people point to is the "average" $30 a month, based on the old 8cent per kWh average, 400kW per month = $32...but what about California where top tiers are 38cent per kWh? These people get completely blindsided by sky high bills due to deceptive marketing, when the spa is doing exactly what its supposed to do. What is "average use"? I use mine every day, my family uses mine a few times a week (I still dont pay what the poster does, but we live in sunny FL =). Just saying a lot of it is subjective. Ive also seen manufacturers that balance or average the costs for a year round average, knowing, but not disclosing higher winter, lower summer costs.

[Biz]

Thanks for your post...Can you explain further what you mean by Leaving your AVCs open?

Our tub is in Economy mode, filters every 12 hours for 2 hours each time. Our KW costs daily is .13202 cents.

Our climate in the winter is not quite as warm as Fla, as we live in Vermont. In January temps range from low 30s in the day, to as low as 20 below at night.

Our tub is situated on a deck, right off the back of our house.

Since we had the Astro foil wrapped around the inside of our tub, a few days ago, our water temps have maintained its warmth much better. During the past 3 days, it hasnt gone below 94 degrees, and has got back to 100 degrees within an hour....much much better than before.

During the past 6 weeks we used the tub about 4 times since it was so difficult to maintain the water temp near 100 degrees. However, we have used it 3 times, since we just had the insulation wrapped on it.

It was a beautiful weekend, sunny with daytime temps near 30 degrees...a real heat wave.

Id be more curious about what the spa is set to filter, how its installed (up off the ground on a deck, flat on cement, etc). Direct exposure to elements, wind, etc? I have found some spas installed, raised off the ground, with direct exposure to the lovely ocean breeze, can suck the heat right out of a spa cabinet.

Really, any name brand spa worth a name shouldnt lose temp as fast as noted, or cost as much as noted, cheap or not, dealer or not. I know some are lacking in insulation, but just the physics of cooling water, vs heat able to be generated/retained by a heater, cover, cabinet, heat from the equip...seems like something else is acting on the system.

May not be your particular situation, but for other readers, I find most typically its a misunderstanding on how the tub operates. For instance, Balboa. By default most will automatically circulate twice per day, 2 hours per cycle. If the AVC's are left open, when that spa runs its minimum of 4 hours per day, only tries to heat when its in this mode due to ECON, your cooling it faster then your heating it for 4 straight hours per day (maybe more if the settings have been tinkered with). You have sub 30-degree air pumped right into the water your trying to keep 80+.

Off subject a bit, because you do seem to have a real issue, but again, for others...What are you paying per kWh? One thing many people point to is the "average" $30 a month, based on the old 8cent per kWh average, 400kW per month = $32...but what about California where top tiers are 38cent per kWh? These people get completely blindsided by sky high bills due to deceptive marketing, when the spa is doing exactly what its supposed to do. What is "average use"? I use mine every day, my family uses mine a few times a week (I still dont pay what the poster does, but we live in sunny FL =). Just saying a lot of it is subjective. Ive also seen manufacturers that balance or average the costs for a year round average, knowing, but not disclosing higher winter, lower summer costs.

[hot_water]

Alan makes some really good points. His comments are much more valuable than "We told you so, now send it back to Costco". As you've already seen, there are big benefits that can be relatively easily obtained if you're willing to think about the problem a bit and make a few simple mods. Alan is also addressing operation and installation. It's good to see that there's someone in the industry that's actually willing to use his experience and knowledge to help solve the problem rather than justify the incessant Costco bashing.

The "ACVs" - Air Control Valves - are the valves that you open (usually affecting jets at one seating position) to mix air in with the water for that somewhat stronger sensation of turbulence. You should close these when you're not using the jets and when you exit the tub. Leaving them open mixes a substantial volume of (in your case) very cold air into the water piped to the jets and will cool the water down pretty fast when the jet pumps are running. Some tubs (maybe yours?) will run the jet pumps for the four hours per day and only run the heater during the same four hours when in the "economy"mode. If that's the case and the ACVs are open, the heater is trying to heat but the open ACVs are cooling the spa, and might even be cooling faster than the heater can heat! Combined with perhaps not the best heat retention design to start with and it's possible that the spa temp could actually be dropping while the heater is on. For sake of conversation, let's say that the energy input from the heater is exactly balanced by the energy loss due to the open ACVs and not-so-good insulation. Exactly balanced means that the temp of the water isn't going up or dropping during the 4 hour cycle each day. If your spa has a 5.5 kW heater, that's 22kW-hrs per day or 660 kW-hrs per month. At your electric rate, (0.13202 per kW-hr), you are spending $87 a month just to run the heater in "economy" mode - and the water isn't getting any hotter! This figure doesn't include the power to run the jet pumps and doesn't include actual use of the spa, or running it in "standard" mode to get the temp up before you soak. So yes, you will have quite a whopping electric bill to pay for your "cold" tub. If you leave your ACVs open, and your jet pumps are running for hours.... close 'em - it will help. Even if your jet pumps don't run (my spa controller knows to turn the jet pumps off after 5 minutes, relying on the circ pump during the filter cycles) you'll still save $$ by closing the ACVs.

Alan also asked what your spa was sitting on. Many of these thermal pane spas don't have any insulation on the bottom pan. So if the bottom of your spa has some air blowing across it, perhaps due to being on a wood deck with typical space betwen the deck boards, you can transfer a lot of heat from the air in the cabinet to the breeze. Again, the result is that the water temp will drop. Remember, in a thermal pane design the air in the cabinet is heated to more or less the temp of the water. If you lose heat from the air, you're losing heat from the water. If this is your situation, adding some floor insulation (and a layer of shiny metallic stuff) and/or doing some things to the deck to keep air away from the spa bottom pan would be a good thing to do.

Reflectix (or other shiny metallic stuff) is good. You need the foil to control radiation heat transfer (no worries, it's not that kind of radiation) but depending on what is already in place you might consider adding more foam sheets, bubble wrap or something (anything!) to the cabinet. You can get a good idea of your heat loss by monitoring the temperature of the outside surface of the cabinet. I have a $29 non-contact thermometer (that I use for checking pre-heat temp of aluminum before welding) which works well. Ideally, if your cabinet is at the ambient air temp, you're not going to lose any heat from the side walls. No temperature difference means no heat loss. So you want to be as close to the same temp as possible. Focus on adding insulation to the cabinet. Don't pack fiberglass bats near the underside of the shell, try to wrap the plumbing or any of that. If your system keeps the air temp close to the water temp, you gain nothing additional by these other steps. Moreover, these sorts of mods hinder the flow of heat from the cabinet air to the water when the heat from the pumps raise the air temp above the water temp... so don't do that.

Alan didn't mention, but I will, that while some of these spas will benefit from improving the insulation, many of the less successful thermal pane spas have massive cabinet air leaks. If cold air can get into the cabinet and hot air can get out, this defeats the entire thermal pane theory. In fact, at the temperatures involved, convection currents will very actively pump precious warm air out of the cabinet. For this reason, the first thing I would do (even before adding insulation or foil) is make sure that your cabinet is well sealed. If air is leaking out, energy is leaking out and this can be a very large source of expense. On the other hand, if you're well sealed, the pumps can actually heat the air in the cabinet above the water temperature. This is good! Heat, which flows from higher temp to lower temp, will go into the water. Your pumps are thus heating your water, which is a good thing and something that I don't think any of the full-foam tubs can do. If you're "too" well sealed there's a slight concern that the water will get too hot during warm weather or that the equipment will run too hot. You could easily make a panel with air vent to install during the summer months IF this became a problem, but I think it's unlikely. Still, you're likely to do a great job of sealing the cabinet, so I would find some way to monitor air temps within the cabinet during warm months to protect the motors and electronics in the controller "just in case" it gets too hot.

I would be interested in hearing how your energy picture looks after all is said and done. Good luck!

-hot_water