Cabinet Temperaturs

[1bad88]

For those of you who monitor your cabinet temperature, I am looking to get data on whether or not I need to insulate my cabinet better. Right now I am averaging 86 degrees F in my cabinet (this increases to 97+ degrees during use) with an outdoor temperature of 24 degree F average 10-15 mph winds and I keep my water temp set at 104 degrees F. Please let me know what your baselines are.

Cheers,

-J

[spatech (the unreal one)]

For those of you who monitor your cabinet temperature, I am looking to get data on whether or not I need to insulate my cabinet better. Right now I am averaging 86 degrees F in my cabinet (this increases to 97+ degrees during use) with an outdoor temperature of 24 degree F average 10-15 mph winds and I keep my water temp set at 104 degrees F. Please let me know what your baselines are.

Cheers,

-J

Do you have a circ pump? If not then the temp of your cabinet greatly depends on when it is measured relative to the two times per day when your 2-speed pump comes on for filtering.

[Roger]

For those of you who monitor your cabinet temperature, I am looking to get data on whether or not I need to insulate my cabinet better. Right now I am averaging 86 degrees F in my cabinet (this increases to 97+ degrees during use) with an outdoor temperature of 24 degree F average 10-15 mph winds and I keep my water temp set at 104 degrees F. Please let me know what your baselines are.

Cheers,

-J

Do you have a circ pump? If not then the temp of your cabinet greatly depends on when it is measured relative to the two times per day when your 2-speed pump comes on for filtering.

And where you take the measuments. On the opposite side of the cabinet of the equipment it may be different. Next to you equipment again will be different. Depending on what your trying to accomplish? If it's 86 during non pump run time and 27 outside with no insulation on the cabinet walls your convection will be high between 86 and 27 resulting in high heat loss coming from your water at 104. Now if you increase the R-Factor between 27 and 86 then you will have less convection and lower heat loss. But in the summer this may become a problem with overheat. If your goal is to reduce heat loss as much as possible you will need to increase r-factor and allow for cooling if your temp next to your motor increases to above the manufacturers max (around 120) depending on the motor. During winter you may never exceed the manufacturers max for the motor no matter how much you insulate the side walls. But you will have to adjust constantly as the outside ambient gets higher. This can be achomplished several ways. Constant monitoring and venting/insulation reduction as needed. Or a thermostaticly controlled fan, damper and duct system. Been there done that. But first a complete seal and R-15 to R-20 on the side walls will need to be established.

First monitor and determine what your temps really are. How hot is your motor getting as the outside ambient changes. I can tell you from experience that as long as you have a well insulated tub your savings will be so minumal that it better be nothing more than a hobby because the adjustments to insulation through labor or the components required will over run the savings to a point of no ROI (return on investment) But if it's a crappy insulated spa then it will be a better investment. How much is your tub costing now? Get it metered for a true cost. You may be better off just getting it to the point of a well insulated spa, if it's not, and don't shoot for better because the better is pennys or dimes max per day. If it's costing you 30 bucks per month average for a year then the work involved in getting it better will only pay back a few bucks a month which relates to 40-50 bucks a year which relates to 500 bucks in 10 years and a fan/thermostaticly controlled system will cost about 6-7 hundred.

I did all this about 6-8 years ago with a brand new Great Lakes tub. Tore all the sides off and insulated to about R-16 air tight, on the side walls and installed a thermostaticly controlled fan and duct system with gravity dampers to only allow air in when called for (air blower or fan). Even went as far as adjusting the sprayed on foam to thinner where the heat source was (above the motor) and sprayed a bit more on in other areas. It worked great and still is but guess what? Still was about 30 bucks a month yearly average. A little less but never did get a pay back when you calculate my time.

Like I said, it better be just a hobby, it was for me. I felt I could build a better mouse trap and I did. But I didn't save any money. The new owner is still using that 4000 dollar tub.

Of course full foam insulation skeem is completely different. This information only applys to Thermal Pane insulation skeems. I made my cabinet so insulated and air tight that a 100W light buld and an increased span adjustment (dead band) would prevent run for heat for 10 hours at 20 degrees F This of course with a winter hard cover, 4"-6" taper and thermal blanket on top where 70-80 percent of your heat loss is going to occur.

[1bad88]

The crux of my question relates to baselines that others have, not necessarily what the numbers are. It is a full foam spa with a 6-4 cover and without a 24 hour circulation pump. I am going to see what my electric bills are once things level out over the next couple of months. I just like running numbers, so I'm not sure that this will go anywhere. I'm just driven by curiousity every now and then.

-J

[KIALDA]

For those of you who monitor your cabinet temperature, I am looking to get data on whether or not I need to insulate my cabinet better.

-J

Let me first start off by saying I am sorry for answering this thread, but I just had to..

For those of you that monitor the temperature between your inner walls of your house and the outside...

For Those of You that have found there is a temperature difference in the glove compartment than the actual cabin of your car....

For those of you that have found the time to inspect chocolate after hours on the slopes, depending if it was stored in an outside pocket or an inside pocket in the snow suit....

For those of you that now have owned a spa for three months and are considered an expert by the guy in the mirror....

For those of you that monitor the temp in a tire that has been driven in the winter and compare it to the temp in the summer only to calculate the swelling and resistance difference on the wheel therefore effecting gas mileage....

Minny To Mickey... Honey, can you just buy us a hot tub so we can spend some quality time together?

[spatech (the unreal one)]

without a 24 hour circulation pump.

That means a LOT. For instance, in your case if you measure at the end of a filter cycle you will get a much higher number than if you measure just before the start of a filter cuycle. Its the same with other people so if someone just says "I measured xxº this moning" what does that mean?

Is it a circ/non circ spa, measured during/after/before filter cyle, next to pumps or not, size of cabinet, etc.?

[1bad88]

I'm sorry that I even brought this up since no one has a legitimate answer. I just brought this up out of f*** curiousity, not to get crucified for it. Honestly, are you people like this? How come you can't just say, hey, I measure it at this point and it fluctuates from this temp to this temp during the day when the out door temp is XX degrees. Why bother wasting your time and my time if you can't post an answer that is helpful? If you don't have an answer move on, otherwise what is the point? I've gotten some very helpful answers in the past from people, but three replies and none of them are constructive? Here's a tip, the next time you feel like posting some pithy comment, or a post that you feel shows your superiority over someone without the experience leve that you have, take it, polish it up till it is nice and shiny, turn it sideways, and shove it up your a**! How about that?

[spatech (the unreal one)]

I'm sorry that I even brought this up since no one has a legitimate answer. I just brought this up out of f*** curiousity, not to get crucified for it. Honestly, are you people like this? How come you can't just say, hey, I measure it at this point and it fluctuates from this temp to this temp during the day when the out door temp is XX degrees. Why bother wasting your time and my time if you can't post an answer that is helpful? If you don't have an answer move on, otherwise what is the point? I've gotten some very helpful answers in the past from people, but three replies and none of them are constructive? Here's a tip, the next time you feel like posting some pithy comment, or a post that you feel shows your superiority over someone without the experience leve that you have, take it, polish it up till it is nice and shiny, turn it sideways, and shove it up your a**! How about that?

Wow, relax on the anger. I thought I gave you constructive, legitimate answers that were helpful by explaining what was involved in your question and why a simple temp would tell you next to nothing.

Since you gave me a helpful tip here's one for you. The next time you feel like throwing something at your computer monitor because you don't like someone's repsonse take a few hours off before you reply.

[spatech (the unreal one)]

OK, I read the other responses and I now see you were a little peeved at someone's elses input.

[1bad88]

OK, I read the other responses and I now see you were a little peeved at someone's elses input.

Thanks for the advice spatech, you usually give me straight answers. I'm not looking for anything scientific here, I am just curious to see what others have seen and I realize that their data has no application to mine. I'm going to keep track of my own data and base my actions on that information regardless of what response I get here. I just thought it was unhelpful to be criticized for having curiosity about the world around me.

[realDrew]

I guess some people have nothing better to do.

But I always say that if you don't like it, big deal, move on. Unless of course you are tied down to a chair with a 40" monitor in front of you flashing web site pages in front of you.

Me? I'm going for a beer and watch a movie in the hot tub.

I'm sorry that I even brought this up since no one has a legitimate answer. I just brought this up out of XXXX curiousity, not to get crucified for it. Honestly, are you people like this? How come you can't just say, hey, I measure it at this point and it fluctuates from this temp to this temp during the day when the out door temp is XX degrees. Why bother wasting your time and my time if you can't post an answer that is helpful? If you don't have an answer move on, otherwise what is the point? I've gotten some very helpful answers in the past from people, but three replies and none of them are constructive? Here's a tip, the next time you feel like posting some pithy comment, or a post that you feel shows your superiority over someone without the experience leve that you have, take it, polish it up till it is nice and shiny, turn it sideways, and shove it up your ass! How about that?

[Roger]

OK, I read the other responses and I now see you were a little peeved at someone's elses input.

Thanks for the advice spatech, you usually give me straight answers. I'm not looking for anything scientific here, I am just curious to see what others have seen and I realize that their data has no application to mine. I'm going to keep track of my own data and base my actions on that information regardless of what response I get here. I just thought it was unhelpful to be criticized for having curiosity about the world around me.

I counted my pages of data during my monitoring and modifications and found 39 pages. And none of it relivent to you. My tub was a partial foam tub with no perimeter insulation when I started. As I made modifications I noted the differences from my baseline. What would you like from me?

But, after getting swore at you may not get it!

[1bad88]

I would like to apologize to Roger and Spatech. I shouldn't have let that other guy get under my skin. You two have given me tons of great advice and information in the past and I appreciate it.

Thanks for putting things in perspective Drew.

Roger, your posts on this board are very technical and I appreciate that you take the time to type out the long explanations to educate those of us who are less educated. Although I appreciate your offer, I don't have the time to browse 39 pages of data, that is a lot more detailed than the daily spreadsheet that I started working on.

[Duker]

Ha, I think he was referring to me, actually. My wife has had it with my nonstop research about hot tubs, and she's insisting that I just go ahead and get one already so that I'll stop reading about hot tubs every night and spend some time with her! A few months ago she said, "$8,000 for a hot tub? That's crazy!" and now she's about to go buy it herself.

Anyway, gotta run, I forgot to check the temperature difference between the inside and outside wall of my house earlier tonight!

[KIALDA]

Although done in a satire version, My post is the most honest, helpful and relevant response to this thread. It was also done without profanity.

[apradman]

Just curious, Thinking about the purchase of an Actic tub with its great insulation but a friend brought up the subject that if the cabinet is so well insulated for the winter what happens in the summer months, does the cabinet overheat. Would love to hear from anyone with experience with Arctic. Read that they have some sort of cool system but the salesmen doesn't talk about the need for it. I live in New York and summers can get hot at times.

P.S.love reading all these posts, you guys are great

[1bad88]

But first a complete seal and R-15 to R-20 on the side walls will need to be established.

I made up the following scenario to practice calculating R value, this is assuming constant outside temp and power off, constant pressure, constant volume, and a monotomic gas to keep things simple. I think that I did something wrong, my answer seems low.

Outside Temp = 30 F

Inside Initial Temp = 90 F

Inside Final Temp = 60 F

Time period = 1 hr

4 side walls at 3' X 8'

Estimated air volume = 70 ft^3 = 1982179 cc

material thickness = 0.75"

Convert from F to K, subtract Temp final K from Temp initial K (16.5)

multiply delta T (in K) by 0.001297 J/cm^3 * K(specific heat of air at sea level) and 1982179 cc to get joules of energy transfer required to decrease the temperature of the body of air inside the cabinet

divide by 3600 seconds to get watts (550)

divide watts by [area (10.7) X temperature differential (33)]

multiply this answer by material thickness (0.01905) in meters to get thermal conductivity of the walls (0.0297 W/M*K)

Divide material thickness by thermal conductivity to get R value of 0.64

Does that sound right?

Thanks,

-J

[Roger]

But first a complete seal and R-15 to R-20 on the side walls will need to be established.

I made up the following scenario to practice calculating R value, this is assuming constant outside temp and power off, constant pressure, constant volume, and a monotomic gas to keep things simple. I think that I did something wrong, my answer seems low.

Outside Temp = 30 F

Inside Initial Temp = 90 F

Inside Final Temp = 60 F

Time period = 1 hr

4 side walls at 3' X 8'

Estimated air volume = 70 ft^3 = 1982179 cc

material thickness = 0.75"

Convert from F to K, subtract Temp final K from Temp initial K (16.5)

multiply delta T (in K) by 0.001297 J/cm^3 * K(specific heat of air at sea level) and 1982179 cc to get joules of energy transfer required to decrease the temperature of the body of air inside the cabinet

divide by 3600 seconds to get watts (550)

divide watts by [area (10.7) X temperature differential (33)]

multiply this answer by material thickness (0.01905) in meters to get thermal conductivity of the walls (0.0297 W/M*K)

Divide material thickness by thermal conductivity to get R value of 0.64

Does that sound right?

Thanks,

-J

Roger<-------Homer Simpson look on his face....dohhhh Sorry 88 you went way over this plumbers head!!!

Did you know they use hot water in an ice machine because it makes the ice clearer??.....LOL

[1bad88]

I hadn't actually heard that one before, so I got the google machine fired up to give me this answer: The solubility of gases in liquids decreases as the temperature rises. So you get fewer air bubbles to cloud the ice.

So, does this insolubility cause a decrease in surface tension, or is it the other way around? I learn something new every day on this board.

Do you have a simple formula for determining the R value that you got for the walls of your Great Lakes tub, or were you just adding up the R values from each material that you added?

-J

[elbrecht]

I finally got around to moving my thermometer so the remote could pick up the signal. They are only 5 feet apart but 5 layers of foil might be my problem. [2 on the tub- 2 on some High-r sheathing on the house- and then on the insulation inside]

But anyway- on my old Thermospa [Phoenix] that I re-insulated this summer with 2" of styrofoam. The original foil covered bubblewrap was still intact.

Anyhow- this morning-

Spa temp 101

air temp 5F, wind chill -11F

Cabinet temp 90.4F

This is a smallish tub [220 gallons], but it has a 5.5kw 220heater. I've only had it up for about 6 weeks, but my electric usage for the whole house has been within the past 6 yr averages. I'm tempted to spend $40 on a meter on ebay to be sure of what the tub is using--- but other than curiousity I'm not sure of the value of that knowledge.

Jim

[spatech (the unreal one)]

But anyway- on my old Thermospa [Phoenix] that I re-insulated this summer with 2" of styrofoam. The original foil covered bubblewrap was still intact.

Anyhow- this morning-

Spa temp 101

air temp 5F, wind chill -11F

Cabinet temp 90.4F

Jim

What would be interesting would be to have the spa in economy mode (vey important) and take the temp right at the end of a filter cycle when the pump and heater has been on for a couple hours and the spa has been heating the cabinet to its max temp. Then take the temp just prior to the next filter cycle when the pump and heater has been off for 8 or 10 hours.

That will give you a good indication of how well the cabinet is insulated as you'll see how well it maintained the heat inside.

[Roger]

But anyway- on my old Thermospa [Phoenix] that I re-insulated this summer with 2" of styrofoam. The original foil covered bubblewrap was still intact.

Anyhow- this morning-

Spa temp 101

air temp 5F, wind chill -11F

Cabinet temp 90.4F

Jim

What would be interesting would be to have the spa in economy mode (vey important) and take the temp right at the end of a filter cycle when the pump and heater has been on for a couple hours and the spa has been heating the cabinet to its max temp. Then take the temp just prior to the next filter cycle when the pump and heater has been off for 8 or 10 hours.

That will give you a good indication of how well the cabinet is insulated as you'll see how well it maintained the heat inside.

I'm here to tell you from experience. All the anylizing and modifications netted a ROI not worth the trouble as long as you had a good tub to start. And if you get a great tub to start your allready there.

[elbrecht]

What would be interesting would be to have the spa in economy mode (vey important) and take the temp right at the end of a filter cycle when the pump and heater has been on for a couple hours and the spa has been heating the cabinet to its max temp. Then take the temp just prior to the next filter cycle when the pump and heater has been off for 8 or 10 hours.

That will give you a good indication of how well the cabinet is insulated as you'll see how well it maintained the heat inside.

No economy for me. Thankfully I haven't found this tub to be expensive to run, because my usage doesn't lend itself well to an economy mode. Sometime between 3-5AM joint & muscle pain drives me out of bed. . . I stumble down to the tub, soak for a 1/2 hour & muddle through the day. On rare occassions we use the tub again in the evening.

A timer might be a slight savings- I could turn it down after the morning soak and have it come on at 3AM. [then Murphy would have me aching at 2 with a cold tub.<g>]

The board in this thing is an 1800D which is pretty plain-jane so I think my only choices are economy & straight temp. [and 101 seems to work for me - down to 15degrees F anyway]

My main purpose of the termometer in there is to make sure the motor doesn't get too hot- and if we have a power outage I can see when to start panicking. [i'm in NY] It does have a high/low memory so I can see what the ranges are over a period.

[1bad88]

I put the thermometer in my cabinet for the same reasons. I put the display in a place that I look at a couple of times a day so I can see if there is an equipment malfunction, breaker that needs to be reset, ect.; I figured it was $10 in cheap insurance.

-J

[Tom]

For those of you who monitor your cabinet temperature, I am looking to get data

There is some published data on temperatures in equipment compartments in this document. Refer to Figure 2 on page 4. With water temperature maintained at 40C and ambient air temperature averaging 20C, equipment enclosure temperatures ranged from about 23C to about 42C. Spikes in temperature occur when the motors run.

I hope that this is the kind of information you seek.