Considering Costco Cxi80 & Sundance Hawthorne

[hot_water]

[

Thanks for your reply hot water, and you never need to apologize for posting, even if you said you were done.

Do you use a spa blanket? If so what kind?

Also, I know that this would not make a significant difference in your total energy use, but have you figured how much you may save if, after draining your tub, your fill with water heated by your gas hot water heater? I have an extremely efficent gas boiler that powers a radiant heat system in my floors and heats a hot water stroage tank that has no other heat source. When the water tank calls for heat, all heating power is directed to the water tank so, essentially I can't use the water faster than it is made available unless that was my objective and I turned on every hot water tap in the house - I don't know if this would do it. I can run a hose from a faucet in my laundry room and provide hot water for the fill. I haven't calculated how much I would save, but electricity is cheap here. I don't know if I'll mess with it (hose coming out the back door or window) or just use the hose bib on the nearest side of the house and fill with cold. I may save a lttile bit filled with gas heated water, but perhaps the biggest advantage is that the tub would very quickly be hot enough for use after having been drained. With your outrageous electric rates, maybe the savings would be worthwhile.

I don't use a spa blanket.

I can't use my hot water heater. I use a water softener on my main supply that feeds the house (including HW heater) , and you shouldn't fill a spa with soft water. My hose bibs and irrigation do not go through the softener, well except I have one in the front driveway for car washing (no water spotting)...very cool.

My spa heats up at about 7F per hour. Assume incoming water at 60F. So that would take 6 hours -sounds about right. At 5.5kW for the heater, this is 33 kW-hours. At 40.5 cents, cost is $13.37. Every four months.... about $3 and change per month for refills. Not enough to fret about. The water heater is on the other side of the property. Copper pipe and fittings are costly (I'm not into PEX) to the point that it would cost at least $100. Not to mention it would take work. I'll absorb the $3 a month. If your rates are lower, as they most certainly should be, it will of course be even less.

My gas-heated water is comparatively cheap but still not free. The tank size is 50 gallons so I couldn't get too far into filling a 350 gallon spa on that. So in my case the whole thing just isn't practical, even notwithstanding the soft water. I don't know anything about your boiler but would be surprised if you could fill a spa on it, unless your burner is like the afterburner on a J79 jet engine.

[hot_water]

great post Hot_water. One point you left out though. AS I think we would agree that a high percentage of the electricity use is simply to heat water, some tubs use 500 gallons, other maybe only 350. Within a specific tub, I would be filling it with 10% less water would result in close to a 10 % less energy use, or at least 10% less HEATING energy used. So a 350 gallon tub tub probably uses 25% less energy than a 500 gallon tub, everything else being equal...

arf, it won't really save you an amount proportional to the water volume except on the cost to get your spa up to temp from a fresh fill. So in my case, it costs $13 for the initial fill...10 percent, for example, would be $1.30. If you drain and refill every four months that's about 33 cents per month. Not really a big factor. If your rates are not unreasonable like mine here in CA, it will be much less -- clearly not worth considering.

Your energy expense is dominated by the energy loss, and that's not really directly related to the volume. There's a small relationship, not much, and certainly 10% less water will not mean 10% less energy use. With so many much, much stronger effects going on you'll never see that one.

[Roger]

It seems that Roger has not seen a single tub in Minnesota that has such a low operating cost, but he has only seen thousands, so I am sure one will turn up. I think Roger should advise his clients to purchase covers for their tubs and use them, because I can think of no other reason why their real world expereince would be so different from the thoughtful analysis that you have provided.

I'm willing to concede that Hot has put allot of though and anylisis into it. Seems it should be right. Problem is we are not seeing it here. Sure there are high quality tubs that are costing an average of 30 or so bucks a month but only because 5-7 months a year they are at 10-15. Other months they are at 50-60. Any of the value brands including all of the 6-8 that I have owned and ran over the last 10-15 years have been higher, and I see higher all over. 100 bucks is not uncommon with meter proof. and 20-30 in warmer months. Somebody please tell us, or just me, what is missing??????

[DK117]

It seems that Roger has not seen a single tub in Minnesota that has such a low operating cost, but he has only seen thousands, so I am sure one will turn up. I think Roger should advise his clients to purchase covers for their tubs and use them, because I can think of no other reason why their real world expereince would be so different from the thoughtful analysis that you have provided.

I'm willing to concede that Hot has put allot of though and anylisis into it. Seems it should be right. Problem is we are not seeing it here. Sure there are high quality tubs that are costing an average of 30 or so bucks a month but only because 5-7 months a year they are at 10-15. Other months they are at 50-60. Any of the value brands including all of the 6-8 that I have owned and ran over the last 10-15 years have been higher, and I see higher all over. 100 bucks is not uncommon with meter proof. and 20-30 in warmer months. Somebody please tell us, or just me, what is missing??????

I'm going to take a swing at this.

.135 KWh MN

.405 KWh CA

.076 KWh WA

$100 a month in MN is 740.74 KWh which is $300 in CA and $56.29 here in WA. Hot Water and I aren't seeing anything like that. So let's acknowledge two things 1) KWh costs are vastly different and 2) since the MN costs are the ones in question, it's not $9 a month and it's not $100 (at least that gets us where we can discuss.)

I for one cannot tell what impact my spa has had on my KWh used over 5 months. It can't be much more than 10 to 15 bucks a month or I'd notice it on the consumption chart that I posted earlier. So if Hot Water is seeing maybe a $50 a month bill, that's 123 KWh or $16.60 in MN and $9.38 here in WA. Honestly sounds close to what I'm seeing.

So, is it possible, that Strong and Spa's in general behave differently in different climates? Hot Water keep me honest, but thus far everything calculated has been linear. What if diminishing heat retention was logarithmic? Wind chill and temps below say 32 degrees require exponentially more KWh than our relatively mild climates? So MN winters actually cause a like spa to use 5 to 6 times the KWh than in CA. I'm pretty sure I haven't and never will be able to test my tub in negative temps so I won't know for sure, but it would explain the huge discrepancies in personal experience vs the analysis being put forth.

DK117

[arf1410]

great post Hot_water. One point you left out though. AS I think we would agree that a high percentage of the electricity use is simply to heat water, some tubs use 500 gallons, other maybe only 350. Within a specific tub, I would be filling it with 10% less water would result in close to a 10 % less energy use, or at least 10% less HEATING energy used. So a 350 gallon tub tub probably uses 25% less energy than a 500 gallon tub, everything else being equal...

arf, it won't really save you an amount proportional to the water volume except on the cost to get your spa up to temp from a fresh fill. So in my case, it costs $13 for the initial fill...10 percent, for example, would be $1.30. If you drain and refill every four months that's about 33 cents per month. Not really a big factor. If your rates are not unreasonable like mine here in CA, it will be much less -- clearly not worth considering.

Your energy expense is dominated by the energy loss, and that's not really directly related to the volume. There's a small relationship, not much, and certainly 10% less water will not mean 10% less energy use. With so many much, much stronger effects going on you'll never see that one.

Not sure I agree...and maybe this discussion belongs more on a thermodynamics and heat transfer forum (and though its been a while, I have taken up thru Junior level college courses in both those subjects)...

First, in any given month, or 3, if you don't change your water, all your heating costs will be to maintain temp, not to raise water temp from ambient temp to 100+

Thermo 101 states it will take EXACTLY 10% more energy to heat 440 gallons 1 degree than to heat 400 gallons 1 degree. Not sure if it is a linear relationship or not, but cooling is proportional to temperature differential and the amount of surface area of the water, along heat capacities of the water and air. Those heat capacities are not variables in the 440 v 400 gallon comparison. The only variables affecting the calculation for heat loss are gallons of water, and surface area. Assuming the top surface of a spa is a 6' circle, = 28 sqf = 4000 square inches. 40 gallons less water (@230 in^3 per gallon) = 9200 cubic inches...so, lower the water level a little over 2 inches means 40 less gallons. As surface area is a square function to water height - approximating a spa as a 1/2 sphere, SA = 4Ir^2/2 + PIr^2...but bottom line is a spa with 440 gallons will have MORE than 10% water surface area than a SPA with 400 gallons...so it will cool (eg loose BTUs) MORE than 10% faster than a SPA with 400 gallons. My original point was going to be a spa with 440 would take a little less than 10% more energy to heat than 400 g, but actually, I now believe a spa with 440g willl take MORE than 10% more energy to heat than 400g, due to the non linear increase in surface area affecting cooling.

[hot_water]

It seems that Roger has not seen a single tub in Minnesota that has such a low operating cost, but he has only seen thousands, so I am sure one will turn up. I think Roger should advise his clients to purchase covers for their tubs and use them, because I can think of no other reason why their real world expereince would be so different from the thoughtful analysis that you have provided.

I'm willing to concede that Hot has put allot of though and anylisis into it. Seems it should be right. Problem is we are not seeing it here. Sure there are high quality tubs that are costing an average of 30 or so bucks a month but only because 5-7 months a year they are at 10-15. Other months they are at 50-60. Any of the value brands including all of the 6-8 that I have owned and ran over the last 10-15 years have been higher, and I see higher all over. 100 bucks is not uncommon with meter proof. and 20-30 in warmer months. Somebody please tell us, or just me, what is missing??????

I'm going to take a swing at this.

.135 KWh MN

.405 KWh CA

.076 KWh WA

$100 a month in MN is 740.74 KWh which is $300 in CA and $56.29 here in WA. Hot Water and I aren't seeing anything like that. So let's acknowledge two things 1) KWh costs are vastly different and 2) since the MN costs are the ones in question, it's not $9 a month and it's not $100 (at least that gets us where we can discuss.)

I for one cannot tell what impact my spa has had on my KWh used over 5 months. It can't be much more than 10 to 15 bucks a month or I'd notice it on the consumption chart that I posted earlier. So if Hot Water is seeing maybe a $50 a month bill, that's 123 KWh or $16.60 in MN and $9.38 here in WA. Honestly sounds close to what I'm seeing.

So, is it possible, that Strong and Spa's in general behave differently in different climates? Hot Water keep me honest, but thus far everything calculated has been linear. What if diminishing heat retention was logarithmic? Wind chill and temps below say 32 degrees require exponentially more KWh than our relatively mild climates? So MN winters actually cause a like spa to use 5 to 6 times the KWh than in CA. I'm pretty sure I haven't and never will be able to test my tub in negative temps so I won't know for sure, but it would explain the huge discrepancies in personal experience vs the analysis being put forth.

DK117

Wind effects are nonlinear but that's about as far as you can go.

I said in my very first post that I estimated my worst case winter costs, based on electric bills, to be $50-55. IF we use the $55, at my top tier rate, this means my spa is using about 135 kW-hr of energy. Without getting into the gory detail, I believe that this number is actually, if anything, a high side estimate. But call it 135 kW-Hr.

Roger reports that the owner of the CSXi80 (I presume) 100 miles to the south claims a worst case usage of of a whopping 580 kW-hr, and a rate of 15.5 cents. Thus his January bill would be $89.90 - "close" to $100.

580 kW-hr is an incredibly high amount of energy! If we look back at the temperature data, using last year's averages - the max energy usage in Duluth, assuming SAME USAGE, in the worst case month (not average) would 1.8 times my 135 kW-hr CA usage or 243 kW-hr.

We're still off by a factor of 580/243 = 2.4.

The difference could be due to:

(1) My $55 estimate is too low. If that's the problem, my bill would have to be 2.4 times higher, or $132. Well, that would mean that my entire electric bill is due to the spa. Not too likely. Again, I'm pretty confident in my estimate. It's high, if anything.

(2) Maybe the other guy's estimate of $90 is too high. For this to reconcile the difference, his REAL bill would have to be $37.50. THe Hot Spring site quotes $18 and change for International Falls, MN so $37.50, being TWICE that one, seems plausible. But Roger says that best he sees area tubs that do $40-$50-$60 (in two different posts). Well....... you add some wind (neither my figures nor hot springs account for wind) and some usage differences (see the next point) and that gets you close to the range.

(3) Usage differences. Does the MN user run it the same length of time? Does he use the air jets more? Does he close them when he exits? Does he keep his tub in standard mode all the time or does he use sleep mode between uses? Does he use his jet pumps on high? Both pumps? For how long? This is a huge variable. Without data on useage, you will never be able to reconcile.

I wouldn't be surprised at all if the MN user is overestimating his tub's energy cost. From my numbers, as well as Hot Spring's numbers, probably by a fair amount.

Wind WILL make a difference. Neither my analysis nor the HS numbers account for it. Are you going to see enough energy loss due to wind to reconcile the CA to MN figures? No. The biggest effect of wind will be realized with the cover off. All spas of roughly similar size have about the same water surface area so they all perform similarly with the cover off.

Everyone should make their own judgements about all this. Personally, I believe that there isn't a hill of beans worth of difference between any well designed and manufactured tub. The Strong seems to be fine, based on what I'm seeing. Yes, there have been junky tubs sold, and I'm sure that they would perform poorly in severe climate areas. My old Hydrospa was one of these. It was OK in CA, but would have been a nightmare in Duluth. Until it was modified, that is.

For what it's worth. Draw your own conclusions.

[hot_water]

Not sure I agree...and maybe this discussion belongs more on a thermodynamics and heat transfer forum

arf, I'm outta gas on this thread. I've made my comments, take them, discount them, or use as a springboard for further study as you see fit... but you're right, the basics of heat and mass transfer are beyond what it's reasonable to handle on a hot tub forum!

[arf1410]

Personally, I believe that there isn't a hill of beans worth of difference between any well designed and manufactured tub.

I slightly messed up my above calculations, and was typing too quickly to be clear with my calculations, but basically I was trying to say I agree with your point above, with the caveat of

"there isn't a hill of beans worth of difference [in energy use] between any well designed and manufactured tub, that's not due to differences in water volume, everything else being equal."

I do stand by my statement that X% more water volume will take roughly X% more energy to heat, or maintain heat.

[Dr. Spa]

I do stand by my statement that X% more water volume will take roughly X% more energy to heat, or maintain heat.

Nope. Heat loss is based on surface area, not volume. While a spa may contain 30% more water, it probably doesn't have 30% more surface area (top, sides, bottom), hence not 30% more costly to heat.

[arf1410]

I do stand by my statement that X% more water volume will take roughly X% more energy to heat, or maintain heat.

Nope. Heat loss is based on surface area, not volume. While a spa may contain 30% more water, it probably doesn't have 30% more surface area (top, sides, bottom), hence not 30% more costly to heat.

I agree totally, that surface area is more accurate relationship, as I calculated a couple posts ago. However I did say ROUGHLY SPEAKING...more accurately, since surface area is a square function, and volume is a cubic function, a tub with 30% more VOLUME will have only 2/3 x 30 ~ 20% more surface area (and 10% more linear dimension). If you run actually numbers, assuming a semi-spherical spa shape, you will verify this. However, assuming more heat is lost through the top than sides (which is certainly true when in use), and assuming near water level the walls of the spa are close to vertical (in other words the top exposed surface area when water is 35" deep is roughly the same as when 37" deep, that would lessen the 20% v 30% discussion. But if we totally neglect that and assume you are completely right, and all surface area looses heat at the same rate, then a spa with 30% more water would cost ~20% more to heat.

[Roger]

For what it's worth. Draw your own conclusions.

Wind is allot less likely to make a huge difference on a fully foamed in design. Any air leaks on a peremiter insulation design will very quickly dissapate heat from inside the cabinet air space thus cooling the vessel, and remember only 4 hours of pump operation, 20 hours of no pump, heat source or R-Factor. And even without wind any air leaks and convection!!

[hot_water]

For what it's worth. Draw your own conclusions.

Wind is allot less likely to make a huge difference on a fully foamed in design. Any air leaks on a peremiter insulation design will very quickly dissapate heat from inside the cabinet air space thus cooling the vessel, and remember only 4 hours of pump operation, 20 hours of no pump, heat source or R-Factor. And even without wind any air leaks and convection!!

Interesting that you claim you have no bias against perimeter spas, but you never miss an opportunity to post a commercial for full foam which you clearly prefer .

With the cover off, there won't be a significant difference between foam and perimeter. Probably not measureable. The cover off condition is where wind will have the biggest effect on heat loss.

But I actually happen to agree with you on wind being a factor with the cover on. A leaky perimeter spa won't perform well in any case. Nevertheless in my opinion, a perimeter spa is likely to show increased heat loss in very windy conditions even if well sealed. It's very difficult to address the amount of the loss. Also, we're not talking about a gentle breeze... it would have to be going pretty good AND continue for a while to make a difference to your overall energy use. An occasional wind... not going to be a huge deal. 20-40 mph winds in arctic cold on a continuing basis... yes, maybe! But in that case I would get the heck outta there and move to California, You have bigger troubles than your hot tub.

It's true that the pumps run only part of the time. The effect has been quantified. It's absolutely, positively not true... as in utter FUD (a opposed to elmer fudd) .... that this means "no...R-Factor". How many times we gotta do this? THe pump running business contributes to waste heat recycling. It's a small but positive benefit. It doesn't mean that the system doesn't work when the pumps are off! You admit that perimeter can work well. But in the next breath you cite NO R-FACTOR for 20 our of 24 hours? It's just incomprehensible, Roger. Sheesh. You want me to get outta your face? Start talking sense instead of the nonstop biased propoganda. I respect your opinion -- it's as valid as any other... but your rationale is misinformation and / or inapproprite generalization. Give accurate info that is fair to both designs and I will be happy to go bother someone else. Accurate, fair and TRUE. Even if it supports dealer spas or whatever, as long as it's accurate and fair... and true.

Now, on the topic of water volume....

Ok, arf.... it's clear that more volume means more surface area. No one could contest that a spa has a larger surface area than a teacup, thus more surface area, and thus potentially more heat transfer. I say potentially because it's only part of the story.

What is true is that as you seem to have ascertained, the difference in surface area between a spa and one that has marginally more volume is less than the ratio of the volumes.

It's also quite the case that the rate of heat loss is not the same per area unit between top water surface, sides, and bottom. I think you also realize that this is the case, no? In fact, the rate of heat loss is not strictly related to the surface area. Life would be too simple were that the case. The thermal resistance between any two points, along with the temp difference between those points, determines the heat transfer between them, Since a spa is a three dimensional structure, the solution to the problem requires you to establish the differential equations that define this relationship over the complete volume, including the heat transfer to the cover, through the cover, and to the ambinet air... the transfer through the shell, through the insulation or cavity, including an evaluation of free convection, through the cabinet sides... the heat transfer through the bottom. You then have to establish the convective heat transfer coefficient at each surface, which is different between the top and the sides, the area of those surfaces, the interface thermal resistance of the bottom sitting on the deck or pad, and in the case of the bottom surface, the thermal conductivity, thermal mass (heat capacity) of whatever the spa is sitting on.

Once you've got ALL this done, you get to solve the resulting field equations. In practice, for complex geometries the closed form solution is very difficult. In practice, such problems are solved numerically on a computer, using finite difference or finite element techniques. It's not just a question of simple geometry and surface area!

So the conclusion is not that marginal increases in volume are not a factor. Didn't say they weren't. But they are not by any means the only factor. Heat loss is NOT related to surface area. It is related to surface area plus about a dozen other things, many of which are more important. So if you change the volume by 10%, and the surface area changes by 6%, plus or minus depending on the specific geometry, you can't really make any conclusion about the overall heat loss... because the dozen other factors have to be evaluated. Make sense? So yes, there is a geometric relationship between volume and surface area.... but you have to look at the ENTIRE SYSTEM. Hence my statement that volume has an effect but it's a small one.

Now, in the context of this discussion, we're talking about the Sundace Hawthorne v. the Strong CSXi80, right? One is listed at 400 gallons on Costco dot com and the other is listed at 545 at Sundancespas dot com. For the Costco spa, the 400 isn't the actual operating level... because we also see that the difference between the weight of the unit filled v. dry is 2970 pounds. Water is about 8.28 pounds per gallon at 104F, so there's REALLY not 400 gallons in the tub, there's really about 360 gallons. The difference is ten percent right there. Now is the Sundance really 545 gallons running volume? Not enough data on the site (that I found) to know. But relistically, how could it be 200 gallons larger? Doesn't seem likely. So right off the bat I don't think I trut the volume numbers to start with. If you look back to an early post on this thread, I pointed out that different manufacturers determine the capcitied in different ways... this should be clear now. The error is larger than the effect.

Next, look at the dimensions of the Hawthorne v. the CSXi80. They are both listed as 92 x 92 x 36. So the surface area of sides, top and bottom are all the same. If you forget about the water volume for the moment, all the heat loss of the spa happens ultimately at the surfaces in contact with the air (top and sides) and the bottom (deck, pad or whatever), right? And that area is the same between the two. Fact is you can't determine much from these dimensions either... just like you can't determine much from the water surface area BY ITSELF. You have to look at everything together. Get my point? Water volume IS a factor... but it's a small one in the overall scheme of things. I would think it a better use of time to kick back and have a martini. In the tub. While thinking about something else.

Now, when the cover is off, your heat loss is dominated by the free (top) surface area of the water (plus temps, humidity, wind of course). You can't really conclude much about the free surface area by looking at the volume, can you? I suppose if you have a tapered side shell and you run the water level lower, you can argue that the free surface area is less and therefore the heat loss is less. Yes, this is true. Do you know how much less? I bet it's not a lot, but it depends on the specific shell design. And you really can't run the level musch lower... there's the filter weir to worry about and you definitely don't want to uncover any jets. Again, use your energy to shake the martini. Ketel One... three olives, please.

See where this is going? There is more to the problem than volume. Volume IS a factor, but, as I've said like three or four times now in three posts, it's not a major one.

If you're talking about spas of widely different sizes.... yes clearly a large spa will cost more to heat than a small one. That is obvious and doesn't warrant much discussion, right?

If you have deeper tub that has about the same water surface area as a shallower one, then with the cover off the deeper one (more volume) will experience less temperture sag during use than the shallower one. That's a good thing.

And that really is my final word on the topic of small increases in volume. Ok??

[spatech (the unreal one)]

[

Wind is allot less likely to make a huge difference on a fully foamed in design. Any air leaks on a peremiter insulation design will very quickly dissapate heat from inside the cabinet air space thus cooling the vessel, and remember only 4 hours of pump operation, 20 hours of no pump, heat source or R-Factor. And even without wind any air leaks and convection!!

Very true.

[Roger]

Interesting that you claim you have no bias against perimeter spas, but you never miss an opportunity to post a commercial for full foam which you clearly prefer .

With the cover off, there won't be a significant difference between foam and perimeter. Probably not measureable. The cover off condition is where wind will have the biggest effect on heat loss.

But I actually happen to agree with you on wind being a factor with the cover on. A leaky perimeter spa won't perform well in any case. Nevertheless in my opinion, a perimeter spa is likely to show increased heat loss in very windy conditions even if well sealed. It's very difficult to address the amount of the loss. Also, we're not talking about a gentle breeze... it would have to be going pretty good AND continue for a while to make a difference to your overall energy use. An occasional wind... not going to be a huge deal. 20-40 mph winds in arctic cold on a continuing basis... yes, maybe! But in that case I would get the heck outta there and move to California, You have bigger troubles than your hot tub.

It's true that the pumps run only part of the time. The effect has been quantified. It's absolutely, positively not true... as in utter FUD (a opposed to elmer fudd) .... that this means "no...R-Factor". How many times we gotta do this? THe pump running business contributes to waste heat recycling. It's a small but positive benefit. It doesn't mean that the system doesn't work when the pumps are off! You admit that perimeter can work well. But in the next breath you cite NO R-FACTOR for 20 our of 24 hours? It's just incomprehensible, Roger. Sheesh. You want me to get outta your face? Start talking sense instead of the nonstop biased propoganda. I respect your opinion -- it's as valid as any other... but your rationale is misinformation and / or inapproprite generalization. Give accurate info that is fair to both designs and I will be happy to go bother someone else. Accurate, fair and TRUE. Even if it supports dealer spas or whatever, as long as it's accurate and fair... and true.

Seems to me there is an awfull lot of biased propoganda coming from you. Is there a positive effect because of recycled heat? Maybe, but facts will tell you that positive effect is quickly offset with more heat loss during, and yet again I will point it out to you!! The majority of the day when the pumps are NOT running. Hot, you continualy chastize my logic as FUD. Yet you fear aknowledging the points I make as yea maybe legitimate....Hmmmmmmm no FUD coming from you huh? Did it ever occur to you that the perimeter type of insulation skeem you tout as being better for service reasons may have enough heat loss versus fully foamed in designs to very quickly cost tons more in colder climates? Maybe fine for where you are but not so fine here.

And you keep stating my preferences for me. I think a combination of the 2 types of insulation is the best of both worlds. You never asked. It is done by a few manufacturers and very easy for a skilled tech to do with the right tub to start. I have done several, but why bother telling you. It will be labeled as FUD or something by you anyway!!!

Does it suprise you that I agree with your cover off equaling the same heat loss? Only problem is thats what? 1 hour 3-4 times a week! 3-4 hours out of 168 hours, yep insignificant. Filtering, 28 out of 168 hours. Insignificant benifit from recycling waste heat. 140 hours of idle time. Logic tells me that fully foamed to reduce heat loss with a small 75 watt circ pump would make a huge difference and be a significant improvement over the other designs. But I'm gona beat you to it, in your mind thats FUD.....LOL

[hot_water]

Seems to me there is an awfull lot of biased propoganda coming from you.

In this thread alone, I've said:

* There isn't a hill of beans of difference.

* Yes I agree that a perimeter spa would be worse in high wind conditions (and I didn't even say it had to be a leaky one)

* The smaller water volume of the Costco tub won't doesn't make it cheaper to operate than the dealer-sold Sundance Hawthorne

* And of course a bunch of numbers, all of which anyone can verify. Assuming you understand the concept of a yearly average.

What here constiutes bias or propaganda? It seems like just another case of, "If Roger claims it, it must be so".

Is there a positive effect because of recycled heat? Maybe, but facts will tell you that positive effect is quickly offset with more heat loss during, and yet again I will point it out to you!! The majority of the day when the pumps are NOT running.

You have no facts! I have gone through and given a reasonable estimate of the benefits of the waste pump heat and shown that it isn't much, nd even given an analysis of how much MONEY it might be worth. You claim, as usual without any justification, that the other 20 hours more than offsets this gain... but you have no DATA and you present NO ANALYSIS that supports this! You have not presented a SINGLE fact, just your supposition that this is the case! On the other hand, my own firsthand experience, as well as that from several other owners that have posted to this board says that the energy use isn't a problem.

You continually claim in other threads that non-metered data is meaningless. Fact is, Roger - your "metered data" is useless because it doesn't account accurately for actual temperatures, wind, humidity and the 800 pound gorilla, USAGE. But ok. You like only metered data. Then in this case, you trot out someone 100 miles away from you that claims a Strong is costing them $90 in the worst month of the year. No meter, but, per you, "He thinks his caculation is pretty good." So his calculation is pretty good but mine and DK's and other's isn't? Your data is second hand, and one data point. Ours is firsthand, from several users dispersed through the country. But yours, not even metered, is somehow the gold standard of accuracy?? Huh?

And let's look at that data Let's say it really is $90. Since you have four really bad months, you have maybe 8 that aren't that bad. The average annual cost is going to be $50-60!! Which is EXACTLY IN THE RANGE YOU CLAIM YOU SEE WITH GOOD QUALITY TUBS. Are you following this? I don't need to argue with you, you argue with yourself!

So even if we accept your friends inflated data, take YOUR estimates of what a good tub will do in that area, IGNORE my stuff completely, the result shows that the STRONG SPA is just about the same as other good quality spas you've seen! Despite it being a "Big Box JUNK" tub!

And I frankly trust my figures, 'cause I know where they came from.

Hot, you continualy chastize my logic as FUD. Yet you fear aknowledging the points I make as yea maybe legitimate....Hmmmmmmm no FUD coming from you huh?

I don't fear acknowledging your points at all.. When they make SENSE, I will happily agree. FOr example, on the effect of wind on a perimeter tub. If you read closely you will note that I even expanded your point, becasue even if it's sealed well I think it will be worse under that particular condition.

I do not have an agenda. I do not think all dealer tubs are junk (some are) nor do I try to influence anyone towards a Costco tub. But I also REFUSE to just accept crazy and wild statements that can't be justified by either real information or analysis. If you want me to accept your points, please offer up an argument that will ALLOW me to do that... not just "I've been doing this for 100 years", or "All Big Box spas are JUNK. Period!"

Did it ever occur to you that the perimeter type of insulation skeem you tout as being better for service reasons may have enough heat loss versus fully foamed in designs to very quickly cost tons more in colder climates? Maybe fine for where you are but not so fine here.

Yes of course I have. As you can see I've thought about this topic quite a bit. And YES YOU MIGHT BE RIGHT. All you need to do is present either data or analysis that is believable. I don't really expect analysis, but I can't accept nonsense, speculation, FUD about parts quality, and all that other garbage either.

And you keep stating my preferences for me.

You state your preferences, as you have in this latest post. They're clear as can be Roger. Just read the quote above the current one. I'm not putting words in your mouth, but I can read the ones you write!

I think a combination of the 2 types of insulation is the best of both worlds. You never asked. It is done by a few manufacturers and very easy for a skilled tech to do with the right tub to start. I have done several, but why bother telling you. It will be labeled as FUD or something by you anyway!!!

Why not take a break from trashing stuff and give it a try. If you have legitimate data or reasons for your approach I would be interested. If it's good, I might like to do it on my tub. My rates here are nasty.

Does it suprise you that I agree with your cover off equaling the same heat loss? Only problem is thats what? 1 hour 3-4 times a week! 3-4 hours out of 168 hours, yep insignificant. Filtering, 28 out of 168 hours. Insignificant benifit from recycling waste heat. 140 hours of idle time.

It's not insignificant. Waste heat is worth between a few and $10 per month depending on your rates. And no it doesn't surprise me that you agree about the effect when the cover is off... But it's not as simple as 1 hour 3-4 times a week. The heat loss can easily be many TIMES more than you lose in the same time with the cover on. It is very often a dominant factor. Turn your heater off, uncover the tub, turn on the jets and open the air valves. Now come back in an hour and check how much the temp has dropped. It's way more important than your simple time-based comment indicates. In my area, I can lose as much in that hour as I do in 15 hours or more with the cover on and the tub idle, especially when the relative humidity is low.

Logic tells me that fully foamed to reduce heat loss with a small 75 watt circ pump would make a huge difference and be a significant improvement over the other designs. But I'm gona beat you to it, in your mind thats FUD.....LOL

Surprise! I happen to AGREE that a circ pump is preferable. I've said it before, having had BOTH. Foam v. perimeter... not much difference except serviceability and yes, I think foam would be better in a continually windy area. But I would still go for the serviceability, and maybe some mods to the tub. You don't have to pay for my service calls, or get out there and excavate the foam on my tub. I do.

[Roger]

See what I mean. All of the thousands of tubs and customers and there real data means nothing. Hundreds of metered tubs and that data, nada. Your asking for data and I ain't given none so the stuff can't be possible in your mind. Figures.

One things for sure you have more time to cut, paste and type!!!

[hot_water]

Your asking for data and I ain't given none...

Bottom line:

You've got nothing.

[arf1410]

Here's some additional (I think unbiased) energy use reading info:

http://www.energyideas.org/documents/facts...Tubs_Sept08.pdf

Which states (among many other points):

Some spas and hot tubs use a two-inch layer of rigid

foam insulation and fill the rest of the cavity with

fiberglass insulation; this saves a few dollars, until it

gets wet. Once it gets wet, the insulation value drops

very close to zero and the result will be a significant

increase in your electrical bill.

and

Over 95%

of the time tubs are covered and unused, yet this is

when 75% of their energy

use occurs.

[Roger]

Your asking for data and I ain't given none...

Bottom line:

You've got nothing.

I got nothing for you. You remind me of our engineers. Gota run that pipe right here, can't theres a beam there, no there's not. Yea see it's right there! No it's not on the drawing so it's not there.

[hot_water]

I'm bumping this thread because there's some worthwhile info (and a lot of useless bickering - oh well) on the topic or energy use and the effect of rates, climate, etc. But overall it's a good thread, and might be interesting to some in light of recent questions about heating efficiency, foam v. perimeter, etc.