Hot Tub Forum

Original => Hot Tub Forum => Topic started by: gores95 on October 29, 2006, 12:32:27 am

Title: How much heat does your tub lose in cold weather?
Post by: gores95 on October 29, 2006, 12:32:27 am
Hi all.  We have had our tub for almost two weeks now and love it.  We use it every night for 20 minutes up to an hour.  The hotter the better...102-104!  Here in NW NJ temps have been around freezing at night.  One thing we have felt is a noticeable drop in water temp after soaking for a while.  The water actually starts to feel lukewarm and I know after soaking a while one's body gets used to the hot water but the tub thermometer reflects that temp drop as well.

We soak without jets, then with jets...sometimes with air diverters on full and then off.  We also use the air blower on occasion.  I know that adding air to the tub whether through the jets or the blower can and will decrease temp.  We have noticed temps in the tub go down to 100-101 in the time we are soaking...usually after 15 minutes or so.  Tonight was EXTREMELY windy and 40 degrees and the tub temp actually went down to 98 although I think my daughter may have accidentally lowered the spa set temp to 101 so that could explain this dramatic drop.  Wind I would think would lower spa temps quicker, correct?  

We own a Caldera that has two jet pumps (one is two speed), an air blower and a 24 hour circ pump.  The electrical on the Caldera allows the heater to operate with all jets and air blower on as well.  I read this fact on this forum and can feel the 24 hour circ water is still hot when everything is on.  I have not looked under the "hood" to verify the heater remaining on however.

I was just curious if our temp lowering was in the normal range or is it something I should call the dealer about?  He's 45 miles away and I hate to bother him for nothing.  BTW the temp is now back to 103.7 on my indoor thermometer but of course the cover has been back on for hours.  

Those in colder climates, do you refrain from letting excess air enter the tub by not using the blower and turning the air diverters to low or off?  Does having just the jets on without air also work to RAISE temps?  

How fast do you lose your heat???

Lots of questions....thanks or being patient!  ;)

Marc
Title: Re: How much heat does your tub lose in cold weath
Post by: lagator43 on October 29, 2006, 12:52:15 am
Marc,

I was in my tub for around 30 min tonight and the temp outside was about freezing.  I did not have the blower on but the temp went down one degree while I was in it.  I had it set at 102 and it dropped to 101.  

I enjoyed the pics you provided.  
Title: Re: How much heat does your tub lose in cold weath
Post by: Tman122 on October 29, 2006, 04:37:16 am
It comes down to heater size and gallons. My 400 gallon tub with a 5.5KW heater can keep up and actualy heat, down to below freezing, around 10-20 any colder and it struggles to maintain depending on how much air you introduce and how long the jets are on high.
Title: Re: How much heat does your tub lose in cold weath
Post by: Repeat_Offender on October 29, 2006, 06:57:28 am
Surface area has a lot ot do with it. The larger the area the faster the temp drop and evaporative rate. Does the wind make it drop faster? When you blow on your bowl of hot soup does it cool quicker? YES! Running the jets also quickens the cool down rate as it exposes more heat to the water surface. Now the question is is your heater allowed to operate while the pums are on, and what is the heaters capacity or KW  rating. In short, how fast can it recover the inevitable heat loss?
Title: Re: How much heat does your tub lose in cold weath
Post by: gores95 on October 29, 2006, 07:07:59 am
Thanks guys.  Yes my heater should be able to operate with everything on and it is a 475 gallon tub, 89" x 89".  How can you check if the heater is indeed on?  Is feeling the hot water out of the circ pump enough of a test?

Title: Re: How much heat does your tub lose in cold weath
Post by: Vinny on October 29, 2006, 07:20:31 am
My tub seems to drop about 1 degree in 20 to 50 min. My soaks tend to be longer than a jet cycle (20 min) but most of the time I lose track of time, I come in and it's later than I thought it would be.

What I noticed is the temp is usually 1 degree higher than the set temp when I open the cover. It drops almost immediately (10 minutes max) to set temp and by the time I'm done with the soaking it will be 1 degree lower than set temp. The heater is kicking on and if the jets aren't on, heating the footwell first.
Last winter I was impressed that in whatever winter weather we had here in central NJ (never did get a chance to tub in the snow, kids did though) my tub didn't lose too much heat.

As far as the tub feeling lukewarm - your body is probably used to it. I'm sure your tub can keep up with the demands of a 20 minute soak or even a 2 hour soak. BTW, my heater is a 4 KW heater ... it seems on a 220 volt tub this is rather small, most tubs have a 5 or 5.5 KW heater.
Title: Re: How much heat does your tub lose in cold weath
Post by: Repeat_Offender on October 29, 2006, 07:46:52 am
I get about the same results as you Vinny. My tub has a 5.5KW heater and I rarely lose more than a degree from setpoint. I only run the jets for 10-15 minutes and I'm sure that has an effect on heat loss.
Title: Re: How much heat does your tub lose in cold weath
Post by: In Canada eh on October 29, 2006, 07:51:25 am
Gores95

         This is probably an unfair comparison because your tub is alot bigger then ours.   Our tub a Bullfrog 451 with a 5.5 kW heater and about 300 us gallons, only drops about one degree before the heater kicks in.  Due to the fact that its a small tub with a large heater the heater keeps ups just fine.  Temperatures around here have not been to bad yet,  around the high 30's at night.  Southwestern Ontario is considered the Canadian Banana belt ;D
Title: Re: How much heat does your tub lose in cold weath
Post by: hot tub Frank on October 29, 2006, 12:02:39 pm
that is perfectly normal
if you inject air you see a lot of evaporation from you tub.
also we have to consider where where the actual temperatur feeler is. mine is close to the bottom. even with the lid on as soon as i start the pumps my tub jumps up a deg do the fact that the cooler water is on the bottom and the jets will mix it up.  
Title: Re: How much heat does your tub lose in cold weath
Post by: pg_rider on October 29, 2006, 12:12:01 pm
During our blizzard the other day it was around 32 degrees with ~20mph winds.  My Optima started at 102, dropped to 101 within a few minutes, then stayed at 101 with the heater on.  If there's no wind it will hold whatever temperature I want.  Needless to say we plan on putting some kind of windbreak around our tub!
Title: Re: How much heat does your tub lose in cold weath
Post by: tony on October 29, 2006, 12:32:06 pm
Now my Optima will hold temp within a degree or two constantly even in the coldest of temps.  The way the system works is when the water temp drops two degrees from the set temp, the heater will kick on until it reaches the set temp.  Most of the time this will result in the temp guage reading one degree lower than the set temp.  For instance, if you set the temp at 102, the heater won't start until the temp drops to 100...then stays on to 102 and turns off.  Much of this time, the readout will be 101.  You may never see 100 because as soon as it drops out of 101, the heater is on.  You will see 102, but when its cold it will start to drop soon.  If you want to soak at a true 102, you would have to set it at 103.
Title: Re: How much heat does your tub lose in cold weath
Post by: Chas on October 29, 2006, 12:39:00 pm
My spa holds temperature. I don't have what some here would call 'cold weather' though,

a cold evening for us is in the fifties.

 8-)
Title: Re: How much heat does your tub lose in cold weath
Post by: Brookenstein on October 29, 2006, 04:09:23 pm
You beat me to it Chas, I was just gonna post the same thing.   :)
Title: Re: How much heat does your tub lose in cold weath
Post by: bosco0633 on October 29, 2006, 07:56:52 pm
If you like "the hotter the better" then here are two tricks that I have learned over the past year.  This will help when the weather is so cold that the temps in the tub drop a couple of degrees.

First.

I read a post right before delivery last year.  It was about tripping switches to raise the temps in the tub.  I asked my service guy about it and he did it without any questions.  Now my tub  can heat to 107 from 104.

Second.

If you cant get someone to do this to you, sometimes if the tub is at 104, I go outside and turn the pumps on high for 20 min. to 30 min. before I soak.  I shut the lid as well.  Now when I go out for my soak the tub is warmer around 105 to 106.  That way when the temp drops because of the weather, it is still really hot for me.

I agree the hotter the better, especially when it is -26 and snowing.  

Thats just my two cents.
Title: Re: How much heat does your tub lose in cold weath
Post by: gturn on October 29, 2006, 09:31:10 pm
I was in my tub last night for about 25 minutes.  My water temp is set at 103, the temp was at 103 when I got in, after a few minutes it went down to 102 and the heater came on.  When I got out it had come back up to 103.  I was running both pumps on high with air to the jets the whole time (I did not run my blower).  The outside temp was 34 degrees with no wind.  My heater has a LED light that comes on when ever the heater is on, and my 4k heater works when the pumps are on. My tub has TP insulation and the inside cabinet temp got up to 112 while I was using it last night. (I have a remote sensor inside and track all my temps and power usage) When the wind is blowing and it is that cold the temp does drop 1 degree and does not come back up before I get out.
Title: Re: How much heat does your tub lose in cold weath
Post by: gores95 on October 30, 2006, 12:09:03 am
Update from tonight.  We set the spas set temp to 104.  When we entered the tub tonight tub said 103 and inside sensor said 103.7.  After 30 minute soak and just added dichlor and have the lid 1/2 open...temp inside says 102.8.  Not too shabby.  We did not use the air blower tonight but had some jets mixing with air.  Outside temp 40 degrees.

Marc
Title: Re: How much heat does your tub lose in cold weath
Post by: Cgy_Spa on October 30, 2006, 01:45:03 am
I literaly just came in from having a soak.

Outside temp is -11c (12.2F) ambient, and -20c (-4F) taking into account the wind. (Thanks theweathernetwork.com) However, my backyard is partially sheltered, so would not have felt the full force of the wind.

Set temp is 102F, entry temp was 103F.  After a 20 minute soak with jets on high, and full air mix, temp displayed at 102F.  280 gallon tub, 4Kw heater, no air blower.

Sweet!
Title: Re: How much heat does your tub lose in cold weath
Post by: George on November 01, 2006, 11:18:08 am
I tried an experiment while soaking.  I ran my pumps both on high with no air mixed to the jets for 30 min.  My water temp was set at 103. Outside temp was 40 with no wind.  After 30 minutes the water heated up to 104 without the heater coming on.  It is a TP insulated spa, the water heated up from the heat off the motors, even though it was 40 degrees outside.  When I use the air to the jets it will drop to 102 and the heater will come on and it will heat back up to 103.
Title: Re: How much heat does your tub lose in cold weath
Post by: Tman122 on November 01, 2006, 11:36:30 am
Quote
I tried an experiment while soaking.  I ran my pumps both on high with no air mixed to the jets for 30 min.  My water temp was set at 103. Outside temp was 40 with no wind.  After 30 minutes the water heated up to 104 without the heater coming on.  It is a TP insulated spa, the water heated up from the heat off the motors, even though it was 40 degrees outside.  When I use the air to the jets it will drop to 102 and the heater will come on and it will heat back up to 103.

This makes sense Geo I to see a decrease if I run my blower for a long period. If I run the pump on high no worrys it stays stable with no heater use. But when I turn on the 60 CFM air blower, the cabinet air space is evacuated of warm air in a matter of seconds. My pump motor is dirrectly under my entry step. The under side of the entry step is completely void of sprayed on shell insulation. If you sit on it after the pump has been running a while you can notice a difference in seat temp over a seat on the oppisite side of the tub. I monitor around 115 degrees in that area inside the cabinet after 2 hours filtration. So it makes sense that with a set point of 102 the 13 degrees difference under the step would be transfered into the water. Actualy the water acts as a radiator as it crosses the step during circulation to help cool inside the cabinet. A handy water warmer during filtration. Plus the added benifit of radient warmth back towards the equipment if I ever have a problem that needs fixing. But I still have a contigency plan of a small heater inside the cabinet while I wait for parts. After all this is Northern Minnesota and at 20-30 below the whole tub could potentialy be an ice cube in a couple days or so.
Title: Re: How much heat does your tub lose in cold weath
Post by: Jack_L on November 03, 2006, 01:14:26 pm
I got in my tub about 5:30am (it was 29 degrees outside) and was impressed that the top cover was covered in frost.  Good indication the top is doing its part to keep in the heat!

The night before, my wife must have pushed the wrong button, maybe trying to adjust the light and the temp was as high as it would go.   DANG, it was warm.  I bumped it back down to 102.  

HS Vanguard.
Title: Re: How much heat does your tub lose in cold weath
Post by: hottbpete on November 03, 2006, 06:12:30 pm
I have the same issue as everyone else....my question is....can anyone recommend a thermometer, maybe digital, that would be good to double check the Hot tub, When our Niagara is set at 104.   I would expect that it would be almost to hot to get in.....but no issue :o  looking to ensure the new hot tub thermometer is reading correctly
Thanks
Title: Re: How much heat does your tub lose in cold weath
Post by: gores95 on November 03, 2006, 06:34:29 pm
Quote
I have the same issue as everyone else....my question is....can anyone recommend a thermometer, maybe digital, that would be good to double check the Hot tub, When our Niagara is set at 104.   I would expect that it would be almost to hot to get in.....but no issue :o  looking to ensure the new hot tub thermometer is reading correctly
Thanks

Pete,

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 goes into the spa slipped under my filter cover 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.   Works great so far!
 
Necessary?  No.  Cool?  Yes!  

Title: Re: How much heat does your tub lose in cold weath
Post by: hottbpete on November 06, 2006, 03:51:39 pm
Thanks I will check it out.

Pete
Title: Re: How much heat does your tub lose in cold weath
Post by: George on November 06, 2006, 08:30:38 pm
Quote
I have the same issue as everyone else....my question is....can anyone recommend a thermometer, maybe digital, that would be good to double check the Hot tub, When our Niagara is set at 104.   I would expect that it would be almost to hot to get in.....but no issue :o  looking to ensure the new hot tub thermometer is reading correctly
Thanks
Medical thermometers are the most accurate, just try on of those glass thermometers made to take kids temps, no sense buying something real expensive.
Title: Re: How much heat does your tub lose in cold weath
Post by: mattNY on November 06, 2006, 08:56:04 pm
Quote
Quote
I have the same issue as everyone else....my question is....can anyone recommend a thermometer, maybe digital, that would be good to double check the Hot tub, When our Niagara is set at 104.   I would expect that it would be almost to hot to get in.....but no issue :o  looking to ensure the new hot tub thermometer is reading correctly
Thanks

Pete,

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 goes into the spa slipped under my filter cover 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.   Works great so far!
 
Necessary?  No.  Cool?  Yes!  



I love this setup, but I bought the Lacrosse WS-9013U and the additional sensor with probe.  I got the whole thing (station, wireless outdoor sensor, and wired probe sensor) for $45 shipped.  It's not as fancy as the 9119U, but for just temp. monitoring it might be more within some folks' budgets.

Station: http://www.amazon.com/gp/product/B00077AA4M/102-5649905-7436933
Probe: http://www.amazon.com/gp/product/B0000VYJ10/102-5649905-7436933

The price is even cheaper now than when I bought mine, you can get everything for $36 shipped now.  Dang!
Title: Re: How much heat does your tub lose in cold weath
Post by: Bama on November 11, 2006, 01:55:31 pm
Here's my 2 cents...

My experience is that my LA spa actually gains a degree while I'm soaking!
(I think my man is so "hot" and he's heating up the water!!!)  :P

I have a lot of surface area, approximately 8' x 11' of surface area.
I use jets, air, and then I splash around, because I can!
Granted our nights are not freezing, however our spa is located on our back deck which sits high up over the bend of the river.  The north wind blows off that river year round above and below the deck.  So, lots of breezy chill factor, but not so much freezing temp.