Expected rate of heating?

[Alicatt]

I'm back from a break back home in Scotland and back to sorting out my tub

Today has been the first day that I have let the tub run for any length of time. The water in the tub was 5°c (41°f) at the start and after an hour it was just touching the 10°c (50°f) mark on the thermometer.
For a 3kW heater heating 1700l (449gallonsUS) of water is that good bad or indifferent?

Thanks
Alistair

[bud16415]

Sounds about the same rate of climb as my tub that is a similar size. You could do the math / physics if you want.

[Alicatt]

Thanks,
I let it warm up to 24°c and then switched it off, left it off all day yesterday as I was not feeling well and spent most of the day in bed. This morning I went out and checked the temp and it was at 20°c, I have all the sides off the tub just now as I'm stripping the varnish off, yesterday it was really quite bad weather with rain and a cold wind, so the temp hold was not too bad but I am going to enhance the insulation anyway.

This morning I turned the tub on again and it is now sitting at 36°c and should be warm enough for our first splash this evening, we have a clear sky and a big bright moon so I'm looking forward to it

[Alicatt]

Tub was 40°c when we went in, we tried out each of the positions: 5 sit and 1 lounge and they all hit different spots.

Putting on the heater with all the jets would be more than the wiring could handle so it was switched off while we were in, over the hour and a half the temp dropped by 4°c to 36°c, you could feel the diffrence.

It is a big success with the wife, she was not really in favour of it, but by the end it was difficult to get her out of the tub

So far it has been well worth the money spent on it ... so far less than €100

[bud16415]

Something I have noticed with our tub and heat loss. If it is a cold winter night and we have the tub set to 103F and we get in for a normal 20-30 minute soak the temp stays pretty constant and at the 20 minute point your body has soaked in enough heat and people will start moving to higher seating to lose a little heat. Around that time people will say I’m good and get out even. The tub has done its job. Now other times we get in with friends or like you did want to stay in for an hour or more and after that first 20 minutes people reaching their limit don’t mind a gradual cooling of the water. If it drops to 102.5 after 30 minutes and to 102 after an hour that is more or less perfect as it allows you to stay in longer and keep enjoying.

What you will find with a tub 1F degree is a big change in temp compared to 1 degree in air temp.

Glad your wife is enjoying.   

[Alicatt]

That sounds reasonable,

This morning the top of the water was at 32c and the footwell was at 18c so today was spent stuffing insulation in and around the tub while still allowing free space for the pump motors. I lined the walls with foilbacked polystyrene and then put 50mm insulation around the base and frame then stuffed the spaces left with rockwool that I had stuffed in plastic bags, I'll see how that helps. I was not going to bother with insulating the tub until I found out if the wife liked it or not. but as she does then it's full stuff ahead.

Now I have to sort out one jet that didn't work, I can turn it on and off but no water comes out of it, I havn't packed that part with insulation yet, 

[tlippy]

to 103F and we get in for a normal 20-30 minute soak the temp stays pretty constant and at the 20 minute point your body has soaked in enough heat and people will start moving to higher seating to lose a little heat. Around that time people will say I’m good and get out even.  If it drops to 102.5 after 30 minutes and to 102 after an hour that is more or less perfect as it allows you to stay in longer and keep enjoying.

I am keeping mine at 100°F.  The outside temp has been 50°F.  Have never cranked mine above the 100°F mark.   For me, 100°F is comfortable.  I stay in, with the air jets on and the pump on HIGH until the pump goes to LOW which is 15 minutes.  I usually stay in another 15 minutes - at least till I finish my 2nd drink.  I have been wondering what temp most people enjoy. Maybe some will comment?

[bud16415]

to 103F and we get in for a normal 20-30 minute soak the temp stays pretty constant and at the 20 minute point your body has soaked in enough heat and people will start moving to higher seating to lose a little heat. Around that time people will say I’m good and get out even.  If it drops to 102.5 after 30 minutes and to 102 after an hour that is more or less perfect as it allows you to stay in longer and keep enjoying.

I am keeping mine at 100°F.  The outside temp has been 50°F.  Have never cranked mine above the 100°F mark.   For me, 100°F is comfortable.  I stay in, with the air jets on and the pump on HIGH until the pump goes to LOW which is 15 minutes.  I usually stay in another 15 minutes - at least till I finish my 2nd drink.  I have been wondering what temp most people enjoy. Maybe some will comment?

The temp of the water is totally related to the outside air temp. like you when it is 50f out 100f water temp is great. In the summer our tub has a mode we use where the heat stays off all day and comes on for evening. We use the tub to cool down when it is in the 80’s or 90’s. On the other hand when it is zero or -10f you would freeze in a 100f tub this winter we had a couple sub zero nights where 103 was not warm enough and 104 was right. The part of your body out of the water the outside temp and wind speed all play a part.

[tlippy]

Do U keep the air on during the winter and turn off during the summer?  My guy says that leaving he air on all jets during winter sucks the warm air generated by the pump and saves energy.  During the summer turn off the air to keep the tub from getting too warm.

[bud16415]

Do U keep the air on during the winter and turn off during the summer?  My guy says that leaving he air on all jets during winter sucks the warm air generated by the pump and saves energy.  During the summer turn off the air to keep the tub from getting too warm.

We have the air on or off to taste / feel all year. I don’t think you will get enough extra heat off the motors and pumps to notice.

[icenogle]

I like 102.  The wife likes 100.  This is here in Seattle.  I plan on retiring in the Las Vegas area in 6 yrs and 1 month.  Wondering if we will still like those temps during summer in Vegas. Do plan on having a hot tub down there.

[Tman122]

Do U keep the air on during the winter and turn off during the summer?  My guy says that leaving he air on all jets during winter sucks the warm air generated by the pump and saves energy.  During the summer turn off the air to keep the tub from getting too warm.

The problem with this logic is the warm air inside your cabinet is put in the water in the first few seconds. Once that "warm air" is used up, again the first few seconds, then it's outside air being put in the water as the warm air drawn from the cabinet is replaced with cold outside air.

[Alicatt]

I had to turn on the air to help reduce the temperature in the tub quicker when my youngest son tried it for the first time, it was at 102f when we went in but he said it was far too hot and wasn't comfortable until it got down to around 97f (my thermometer is in c not f) but still he was in and out the tub to try and cool off, it wasn't a warm night and we stayed in the tub for about an hour.

Earlier in the week I had got the tub up to 41c or 105f it was starting to get a bit warm for me then, and the wife point blank said she wasn't a lobster

[Tubby]

Unfortunately, soaking in hot water for extended periods can be unhealthy for certain risk groups like elderly, very young, diabetic, etc.  (and probably all people if it's too hot, or if you're in for too long).  Your organs start to "cook".   To keep it safer, try it at 98F (36.67 C).  That keeps it at, or a touch below, natural body temperature.   It should feel plenty warm when you get in, especially compared to the surrounding air.   It's the jetting of the water that really massages the muscles. 

Tubby

 

[bud16415]

Unfortunately, soaking in hot water for extended periods can be unhealthy for certain risk groups like elderly, very young, diabetic, etc.  (and probably all people if it's too hot, or if you're in for too long).  Your organs start to "cook".   To keep it safer, try it at 98F (36.67 C).  That keeps it at, or a touch below, natural body temperature.   It should feel plenty warm when you get in, especially compared to the surrounding air.   It's the jetting of the water that really massages the muscles. 

Tubby

Tubby

I can tell you first hand that if my tub was set to 98f and the outside temp was zero you would be freezing cold within minutes. The outside temp plays a big role in what the water temp should be because all your body is not under water. The blood supply regulates your core temp by warming what is out of the water and cooling what is in the water.

In the summer we use the setting where the tub stays shut off all day. When it is quite hot outside cooler water is perfect. On a nice summer night 98/99 is very nice, but at -10 I want my tub at 103/104 and nothing is getting cooked.

I do agree children are a whole different story as are elderly on some meds. It is good advice to contact your doctor for advice before doing any hot soaking.