Hot Tub Forum

Original => Hot Tub Forum => Topic started by: gores95 on October 23, 2006, 08:46:14 am

Title: How accurate are spa's built in thermometers?
Post by: gores95 on October 23, 2006, 08:46:14 am
I went out and bought an outdoor thermometer sensor for my hot tub on the advice of one of the forum members.

(http://members.cox.net/barshnik/MainUnit.jpg )

Works great but the sensor is about a degree lower than the hot tub display.  We like the tub hot so we set the temp to 103, the tub thermometer says 103, but my sensor will say 101.7 or 102.3 at the most.  If we have the tub set to 101 for the kids temps show 99.9 on my sensor.  I know its only a degree or so difference but is this typical?

Also if we are soaking for a while (espcially now with 40/50 degree outdoor temps) the water temp will not be able to be maintained.  Even on the spas thermometer the temp will drop from 103 to 102 or even 101.  Have others noticed this?

I know I am being nit picky here but I was just curious how other's temps fluctuate.  I don't want to call the dealer when there is no real problem.

Thanks,

Marc

EDIT...one other note after being covered all night and set to 103 I lifted the cover this morning and the spa's thermometer read 102.  The sensor I bought showed 101.7.  Do you think there is an issue with my spa's heater?  I am concerned that the spa's heater did not reach and maintain the 103.
Title: Re: How accurate are spa's built in thermometers?
Post by: gores95 on October 23, 2006, 10:50:36 am
One thing I had not been doing and that may have affected the spas temps when not in use.  I had not been closing the four air injector valves when the spa is not in use.  Just closed them this morning and I will report back if this helps retain heat better.

Marc
Title: Re: How accurate are spa's built in thermometers?
Post by: Chas on October 23, 2006, 11:28:46 am
I generally am glad that the spas I sell do not have a temp readout - at least one of the brands do not.

The other one does, and I get calls from time to time that sound a lot like your post.

Don't worry too much about it - most companies will have an allowable tollerance for the readout. In other words, if you call and tell them it might be part of one degree off, or even if it is off by one full degree, they will most likely not send out a technician. They may not even do anything for two degrees.

The important thing is that the tub get to the temp you like and stay there, regardless of what the readout says.

I have customers who set the tub for 104 knowing that it is really 103. The tub is always at that temperature, so they are fine. Before, it was reading 102 when it was really 103 and I came out and replaced a temp sensor for them - it just changed the readout to 104 for an actual temp of 103... and we all just decided to live with it that way rather than trying to fix something that really wasn't broken.

 8-)
Title: Re: How accurate are spa's built in thermometers?
Post by: gores95 on October 23, 2006, 11:53:12 am
Thanks for the reassurance Chas!  I am not going to worry about it.  

Regrading the four air injectors do you remommend to your clients to turn them to the off position when the spa is not in use?  Does it make a difference?

Thanks.
Title: Re: How accurate are spa's built in thermometers?
Post by: George on October 23, 2006, 11:54:21 am
Quote
One thing I had not been doing and that may have affected the spas temps when not in use.  I had not been closing the four air injector valves when the spa is not in use.  Just closed them this morning and I will report back if this helps retain heat better.

Marc

I would think 1 or even 2 degree difference in two different devices is normal.  If you want a more accurate temp, test with a medical certified device.  But like others have said it really doesn't make that much difference as long as it heats and maintains temp.  

On your air injectors question, leaving them on can cool the water during the cleaning cycle and cause the heater to have to run longer to bring the heat back up.  If your clean cycle ran just before you checked it this morning that could explain the lower than set temp.    On some models the heater does not run with the pumps on, so those models don't maintain the temp as well during use or cleaning cycles.
Title: Re: How accurate are spa's built in thermometers?
Post by: gores95 on October 23, 2006, 12:23:46 pm
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Quote
One thing I had not been doing and that may have affected the spas temps when not in use.  I had not been closing the four air injector valves when the spa is not in use.  Just closed them this morning and I will report back if this helps retain heat better.

Marc

I would think 1 or even 2 degree difference in two different devices is normal.  If you want a more accurate temp, test with a medical certified device.  But like others have said it really doesn't make that much difference as long as it heats and maintains temp.  

On your air injectors question, leaving them on can cool the water during the cleaning cycle and cause the heater to have to run longer to bring the heat back up.  If your clean cycle ran just before you checked it this morning that could explain the lower than set temp.    On some models the heater does not run with the pumps on, so those models don't maintain the temp as well during use or cleaning cycles.

Calderas run the heater with both pumps running so that should not be the issue.  When we are in the tub with both pumps running I can feel the 24 hour circ jet and it is coming out hot.
Title: Re: How accurate are spa's built in thermometers?
Post by: lskarp on October 23, 2006, 12:28:16 pm
I would also think that the location of the temperature reading should be taken into consideration.  I know that the bottom of the spa will be warmer (at least in sunny South Florida) than the top where the heat is escaping to.

This could account for a 1 degree or so difference in temp.  I like the wet test method for temperature as well.  If it feels good, then the temp is good.  If it is too cool, turn it up, too hot, you get it...

LK
Title: Re: How accurate are spa's built in thermometers?
Post by: anne on October 23, 2006, 01:01:29 pm
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I generally am glad that the spas I sell do not have a temp readout - at least one of the brands do not.


Why wouldn't a person want to know the difference between set temp and real temp? Assuming there is relative accuarcy to both, of course.
Title: Re: How accurate are spa's built in thermometers?
Post by: George on October 23, 2006, 01:12:01 pm
Quote
Quote
I generally am glad that the spas I sell do not have a temp readout - at least one of the brands do not.


Why wouldn't a person want to know the difference between set temp and real temp? Assuming there is relative accuarcy to both, of course.
You only think it is not important if the brand you sell doesn't offer a display.  Hot Springs doesn't tell the temp of the water they just have a LED that comes on when it is within range of the set temp. Since they are number one, it must not be that big a deal to most consumers.
Title: Re: How accurate are spa's built in thermometers?
Post by: Dr. Spa™ Ret. on October 23, 2006, 02:38:10 pm
Here's one reason. This is a true story, and not the only time it's happened.

Someone goes out to the spa and checks the thermometer. It says 104. Unbeknown to them, it's broken and not reading correctly. They just jump in the spa............ It's actually 160+

This is the reason I advise against using thermometers or relying on any kind of temperature display. Stick your finger in the water. Does it feel right? If your finger will not penetrate the surface of the water due to it being frozen, do not get in. If you pull back a bloody bony stump, do not get in.
Title: Re: How accurate are spa's built in thermometers?
Post by: kervis on October 23, 2006, 05:40:43 pm
Quote
Here's one reason. This is a true story, and not the only time it's happened.

Someone goes out to the spa and checks the thermometer. It says 104. Unbeknown to them, it's broken and not reading correctly. They just jump in the spa............ It's actually 160+

This is the reason I advise against using thermometers or relying on any kind of temperature display. Stick your finger in the water. Does it feel right? If your finger will not penetrate the surface of the water due to it being frozen, do not get in. If you pull back a bloody bony stump, do not get in.

 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
Use common sense?!  Puleeeeeeeezzzzz!!  We'd be putting attorneys and lawyers out of work!  
Title: Re: How accurate are spa's built in thermometers?
Post by: anne on October 23, 2006, 06:15:37 pm
Quote
Here's one reason. This is a true story, and not the only time it's happened.

Someone goes out to the spa and checks the thermometer. It says 104. Unbeknown to them, it's broken and not reading correctly. They just jump in the spa............ It's actually 160+

This is the reason I advise against using thermometers or relying on any kind of temperature display. Stick your finger in the water. Does it feel right? If your finger will not penetrate the surface of the water due to it being frozen, do not get in. If you pull back a bloody bony stump, do not get in.


Hmm...with that logic, I should disengage my car's spedometer. But somehow that does not seem like a very good idea to me. I can see where you are coming from, but common sense is gonna have to kick in whether there is a temp read out or not. I'd rather have the info in front of me, and have to rely on common sense to decide if there might be an error, than to simply have no info with the assumption that there would be error.
Title: Re: How accurate are spa's built in thermometers?
Post by: Gary on October 23, 2006, 07:23:58 pm
The real reason Hot Springs does not display current temp is so people will not call and say my tub is cooling down while they use it.

Most tubs will cool some depending on ambient temperature and the users also get used to the water (meaning that is the water is 102 five minutes later is does not feel 102). With a spa that display current temperature people will look at the panel and see if is down 1 degree and say it is cooling down and then they call and complain. With no current temp display they will chalk it up to them getting use to the water (no call to the dealer).

Title: Re: How accurate are spa's built in thermometers?
Post by: Dr. Spa™ Ret. on October 23, 2006, 07:33:04 pm
Well................ over the years I've worked on one lawsuit, and turned down 2 others that are pretty much my exact description. Two of the cases the plaintiffs "said" they checked the thermometer and it looked fine. I know in at least one of these there was a 7 figure settlement. The third, there was no thermometer and the person was getting in slowly. He only made it a little past the ankle. I should also point out, that in EVERY case, alcohol was involved (no, I'm not talking about the alcohol in the thermometer). ?And yes, I do still sell thermometers, I just recommend against them.
Title: Re: How accurate are spa's built in thermometers?
Post by: gturn on October 23, 2006, 07:40:10 pm
Quote
Quote
Here's one reason. This is a true story, and not the only time it's happened.

Someone goes out to the spa and checks the thermometer. It says 104. Unbeknown to them, it's broken and not reading correctly. They just jump in the spa............ It's actually 160+

This is the reason I advise against using thermometers or relying on any kind of temperature display. Stick your finger in the water. Does it feel right? If your finger will not penetrate the surface of the water due to it being frozen, do not get in. If you pull back a bloody bony stump, do not get in.

 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
Use common sense?!  Puleeeeeeeezzzzz!!  We'd be putting attorneys and lawyers out of work!  
If all the tubs had thermometers who would buy those little ducky thermometers.
Title: Re: How accurate are spa's built in thermometers?
Post by: Vinny on October 23, 2006, 07:43:50 pm
Gore,

The Lacross thermometers are accurate to 2º, I think.

Being in the business of calibrating things, there is a "slop factor" involved whenever something is "calibrated".

Everything has tolerences and if the spa says it's 102 but it really is 101.1 and the thermometer reads 100.2 ... they're both correct. The problem lies in those tolerences, both are accurate to within 1º but the total reading is off by 1.8º. The ONLY thermometers that I know of that are considered a "reference thermometer" is a mercury thermometer that has been made to strick tolerences (Lab grade or Pharmacutical grade). I use a graduated cylinder to test some infusion pumps and the cylinders had to be made out of glass and have an "A" on them ... the "A" represents a higher standard of that cylinder.

My advice, is to use the feel method ... whatever temp feels good, use that!  Do your kids actually sit there and soak? My youngest who's 11 1/2 now still has half his body out of the water most of the time.
Title: Re: How accurate are spa's built in thermometers?
Post by: shabba34 on October 23, 2006, 07:54:46 pm
Quote
The real reason Hot Springs does not display current temp is so people will not call and say my tub is cooling down while they use it.

Most tubs will cool some depending on ambient temperature and the users also get used to the water (meaning that is the water is 102 five minutes later is does not feel 102). With a spa that display current temperature people will look at the panel and see if is down 1 degree and say it is cooling down and then they call and complain. With no current temp display they will chalk it up to them getting use to the water (no call to the dealer).

I wouldn't quite say that you're abiding by your avatar phrase because that's hardly an educated opinion.  It's more speculation....False speculation at that.  If you give the end users a little credit, they would just get out of their spa and notice the ready light is not illuminated, which would mean the spa is actually cooling off, which would then lead to the same cause and effect theory that you have on the HS control display. (My spa's cooling off when I use it, I need service.)  Since the ready light is still illuminated 99.9% of the time after 30-45 minutes of use even at the coldest temps, HS customers have no need to call for service.  This isn't the first time you have accused the Mfg of playing reverse phsycology brain games with their customers in regards to the temp display. ;)      
Title: Re: How accurate are spa's built in thermometers?
Post by: geekd on October 23, 2006, 08:05:38 pm
gores95:

What model thermometer did you get?  How does it "connect" with the tub?  Does it have a remote display you can keep inside?



thanks,

geekd
Title: Re: How accurate are spa's built in thermometers?
Post by: dsegel on October 23, 2006, 08:41:33 pm
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Even on the spas thermometer the temp will drop from 103 to 102 or even 101.  Have others noticed this?

I know I am being nit picky here but I was just curious how other's temps fluctuate.  I don't want to call the dealer when there is no real problem.

Thanks,

Marc

EDIT...one other note after being covered all night and set to 103 I lifted the cover this morning and the spa's thermometer read 102.  The sensor I bought showed 101.7.  Do you think there is an issue with my spa's heater?  I am concerned that the spa's heater did not reach and maintain the 103.

Our tub does the same thing.  The display generally will say 1 degree lower then the "set" temperature--even sometimes when I lift the cover first thing.  I haven't tried to take the temperature with another thermometer, I've just lived with it.  I worried at first if 103 would be hot enough (since we can't "set" our temp higher than 104) but I got in at 32 outside temp tonight (with it snowing) and 102 set temp with display reading 101 was plenty warm.   :)
Title: Re: How accurate are spa's built in thermometers?
Post by: Chas on October 23, 2006, 09:49:19 pm
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Why wouldn't a person want to know the difference between set temp and real temp? Assuming there is relative accuarcy to both, of course.
Here's how my customers have done it for almost two decades:

Set the temp. When the spa is new, you may have to try a few different settings until you find one you like.

Enjoy the spa.

Repeat as needed.

 8-)


Title: Re: How accurate are spa's built in thermometers?
Post by: gores95 on October 23, 2006, 10:36:30 pm
Quote
gores95:

What model thermometer did you get?  How does it "connect" with the tub?  Does it have a remote display you can keep inside?



thanks,

geekd

Geek,

Check out this post:

http://www.whatsthebest-hottub.com/cgi-bin/yabb/YaBB.pl?num=1158771765/0

Look for barshnik's message in this thread.  I bought the same unit:  Lacrosse WS-9119U and I had to buy one additional sensor with a corded probe for the spa.  The cord gores into the spa by my filter and stays under water.  The whole unit + probe was around $100.  Nice because I can monitor both outdoor temp and the spa's temp from my family room.  

Necessary?  No.  Cool?  Yes!  ;)
Title: Re: How accurate are spa's built in thermometers?
Post by: barshnik on October 23, 2006, 11:42:27 pm
The temperatures displayed on my Artisian and remote LaCrosse are remarkably consistant.

I look at the min/max readings occasionally so I can see exactly what time of day it has gone low/high - for summer use, I'm using the Artisian 'economy' setting where the heater will only operate between 4pm and 9pm.  Now that it is cooling down at night, I'll switch it back to 24 hour, as the spa temp is dropping to 99 by early afternoon (sometimes I get home early and soak a few minutes.)

I actually bought the LaCrosse to monitor my wine cooler temp, and set the base unit alarm to go off if the wine gets warmer than 65 or cooler than 45.  It really does provide a little reassurance to be able to see the spa temp too from inside, just in case...

I finally had to replace the 2 AAA batteries in the spa remote sender after a year and a half of operation.  Pretty good...

I love being able to press the channel button 3 times and see in a few seconds the indoor temp and humidity, outdoor temp and humidity, wine cooler temp and humidity, and spa temp.  Like he said, 'necessary' - No, but definately a cool toy.

John F
LV, NV
Title: Re: How accurate are spa's built in thermometers?
Post by: Gary on October 24, 2006, 10:45:11 am
Quote
Quote
The real reason Hot Springs does not display current temp is so people will not call and say my tub is cooling down while they use it.

Most tubs will cool some depending on ambient temperature and the users also get used to the water (meaning that is the water is 102 five minutes later is does not feel 102). With a spa that display current temperature people will look at the panel and see if is down 1 degree and say it is cooling down and then they call and complain. With no current temp display they will chalk it up to them getting use to the water (no call to the dealer).

I wouldn't quite say that you're abiding by your avatar phrase because that's hardly an educated opinion.  It's more speculation....False speculation at that.  If you give the end users a little credit, they would just get out of their spa and notice the ready light is not illuminated, which would mean the spa is actually cooling off, which would then lead to the same cause and effect theory that you have on the HS control display. (My spa's cooling off when I use it, I need service.)  Since the ready light is still illuminated 99.9% of the time after 30-45 minutes of use even at the coldest temps, HS customers have no need to call for service.  This isn't the first time you have accused the Mfg of playing reverse phsycology brain games with their customers in regards to the temp display. ;)      


I will stand by my statement and it is based off 18 years of experience. Here is how I came to that conclusion. It is extremely rare that I get a service call claiming my spa heat will not keep up on spas that do not show current temp. For the spas that show current temp it is a common call.

Maybe I am wrong but I do find it odd that 99% of my heat issue calls (with there is nothing wrong with the spa) have spas that display current temps.
Title: Re: How accurate are spa's built in thermometers?
Post by: gturn on October 24, 2006, 11:04:19 am
Quote
Quote
Quote
The real reason Hot Springs does not display current temp is so people will not call and say my tub is cooling down while they use it.

Most tubs will cool some depending on ambient temperature and the users also get used to the water (meaning that is the water is 102 five minutes later is does not feel 102). With a spa that display current temperature people will look at the panel and see if is down 1 degree and say it is cooling down and then they call and complain. With no current temp display they will chalk it up to them getting use to the water (no call to the dealer).

I wouldn't quite say that you're abiding by your avatar phrase because that's hardly an educated opinion.  It's more speculation....False speculation at that.  If you give the end users a little credit, they would just get out of their spa and notice the ready light is not illuminated, which would mean the spa is actually cooling off, which would then lead to the same cause and effect theory that you have on the HS control display. (My spa's cooling off when I use it, I need service.)  Since the ready light is still illuminated 99.9% of the time after 30-45 minutes of use even at the coldest temps, HS customers have no need to call for service.  This isn't the first time you have accused the Mfg of playing reverse phsycology brain games with their customers in regards to the temp display. ;)      


I will stand by my statement and it is based off 18 years of experience. Here is how I came to that conclusion. It is extremely rare that I get a service call claiming my spa heat will not keep up on spas that do not show current temp. For the spas that show current temp it is a common call.

Maybe I am wrong but I do find it odd that 99% of my heat issue calls (with there is nothing wrong with the spa) have spas that display current temps.

That is fine, but I want to see the Temp of my water on the display, that is one of the things that went on the Disadvantages side of the list for Hot Springs when I was shopping around.  I like the Temp display and if I were to buy another tub I would want that on it.
Title: Re: How accurate are spa's built in thermometers?
Post by: shabba34 on October 24, 2006, 11:32:51 am
Quote
Quote
Quote
The real reason Hot Springs does not display current temp is so people will not call and say my tub is cooling down while they use it.

Most tubs will cool some depending on ambient temperature and the users also get used to the water (meaning that is the water is 102 five minutes later is does not feel 102). With a spa that display current temperature people will look at the panel and see if is down 1 degree and say it is cooling down and then they call and complain. With no current temp display they will chalk it up to them getting use to the water (no call to the dealer).

I wouldn't quite say that you're abiding by your avatar phrase because that's hardly an educated opinion.  It's more speculation....False speculation at that.  If you give the end users a little credit, they would just get out of their spa and notice the ready light is not illuminated, which would mean the spa is actually cooling off, which would then lead to the same cause and effect theory that you have on the HS control display. (My spa's cooling off when I use it, I need service.)  Since the ready light is still illuminated 99.9% of the time after 30-45 minutes of use even at the coldest temps, HS customers have no need to call for service.  This isn't the first time you have accused the Mfg of playing reverse phsycology brain games with their customers in regards to the temp display. ;)      


I will stand by my statement and it is based off 18 years of experience. Here is how I came to that conclusion. It is extremely rare that I get a service call claiming my spa heat will not keep up on spas that do not show current temp. For the spas that show current temp it is a common call.

Maybe I am wrong but I do find it odd that 99% of my heat issue calls (with there is nothing wrong with the spa) have spas that display current temps.
I don't disagree with your experiences with other spa control panels and customers neurosis pertaining to spa temps, but it's still not the reason HotSpring does not display the temp setting on it's control panel.  If it were truly the case, they wouldn't even use a ready light to display set temps.
Title: Re: How accurate are spa's built in thermometers?
Post by: drewstar on October 24, 2006, 11:59:11 am
Regarding "the real reason hotsprings doesn't display actual temp = increase service calls/user confusion over 1-2 degrees tolerances...

I thought that too, but the fact is, a lot of OTHER manufactuers display actual temp without issue. So what's the deal with  Watkins?
Title: Re: How accurate are spa's built in thermometers?
Post by: shabba34 on October 24, 2006, 12:26:50 pm
Quote

I thought that too, but the fact is, a lot of OTHER manufactuers display actual temp without issue. So what's the deal with  Watkins?
According to Gary, it's an issue with 99% of his service calls regarding heat.  As far as Watkins, who knows, but it's not brain games with their customers, and Caldera spas display both set and actual temps, so it's a HS thing not Watkins.  If they felt it to be of huge relevance, they would do it.  They follow these forums, so who knows....maybe sometime in the future.  It would probably help me sell 0 more spas a year.