Hot tub heater troubleshooting issue

[kwired]

If I did research and figuring correctly it should take an hour @ 1500 watts to raise about 621 gallons of water by one deg F. This assumes no losses, real world there will be some losses even with the cover on.

If your tub holds 621 gallons of water then it would take 40 hours to raise it 40 degrees (say from 60 F to 100F)

Pass that water through the heater at 5 GPM and you are not adding all that much heat to the water as it is passing through

6000 watt heater will heat 2484 gallons by one deg F in one hour. four times rate, of course because you are applying four times the energy.

Again if tub is 621 gallons then one tenth the time would be only 10 hours to raise it 40F. Considering pump probably moves maybe at least 5 GPM through the heater, I don't think you will have enough temp rise across the heater to be able to feel the difference even at 6000 watts and if you measured it would probably be less than a degree F.

Correction to bold item - one fourth the time would only be 10 hours.

 

[Rig84]

Thanks everyone for the reply’s. He made a makeshift cover yesterday to put on it. He called me a little while ago and said it’s up to 102 degrees. Definitely feel foolish for not realizing that the cover was the problem all along

 

[Little Bill]

Thanks everyone for the reply’s. He made a makeshift cover yesterday to put on it. He called me a little while ago and said it’s up to 102 degrees. Definitely feel foolish for not realizing that the cover was the problem all along

Yep, as slow as the tub would heat on 120V, a cover is a must to raise the temp, especially in colder weather.

Thanks for letting us know the outcome!

 

[ptonsparky]

Thanks everyone for the reply’s. He made a makeshift cover yesterday to put on it. He called me a little while ago and said it’s up to 102 degrees. Definitely feel foolish for not realizing that the cover was the problem all along

Thanks for letting us know.

 

[LarryFine]

Thanks everyone for the reply’s. He made a makeshift cover yesterday to put on it. He called me a little while ago and said it’s up to 102 degrees. Definitely feel foolish for not realizing that the cover was the problem all along

Well, you only owe us a cover charge.

 

[kwired]

Thanks everyone for the reply’s. He made a makeshift cover yesterday to put on it. He called me a little while ago and said it’s up to 102 degrees. Definitely feel foolish for not realizing that the cover was the problem all along

what has ambient temps been? If it were middle of summer it may still have trouble reaching set point, but it will probably still get close without a cover. Now it is probably still chilly at least some nights and that will result in high loss. But if you started out with 55 degree water I would think you could raise it at least to 70 maybe 80, will take time though.

 

[Jraef]

Thanks everyone for the reply’s. He made a makeshift cover yesterday to put on it. He called me a little while ago and said it’s up to 102 degrees. Definitely feel foolish for not realizing that the cover was the problem all along

We have a hot tub that is hooked up 240V. We leave it off most of the time but when we want to use it, my wife is constantly leaving the cover open so that she can check the temperature because she doesn't like having to lift it to stick her hand in (she doesn't "trust" the thermostat setting). Even with the full 6500W of heating, there is a significant difference in the heating time if the cover is open. I keep telling her that by leaving the cover open, it's taking a lot longer to heat up and thus costing us a lot more (she complains about the cost too), but she can't wrap her head around thermal transfer rates etc. I've used the argument about how a covered pot boils faster, but it still doesn't register with her. We have similar arguments about heating the house, I have learned to just fight other battles that are more winnable...

 

[ptonsparky]

We have a hot tub that is hooked up 240V. We leave it off most of the time but when we want to use it, my wife is constantly leaving the cover open so that she can check the temperature because she doesn't like having to lift it to stick her hand in (she doesn't "trust" the thermostat setting). Even with the full 6500W of heating, there is a significant difference in the heating time if the cover is open. I keep telling her that by leaving the cover open, it's taking a lot longer to heat up and thus costing us a lot more (she complains about the cost too), but she can't wrap her head around thermal transfer rates etc. I've used the argument about how a covered pot boils faster, but it still doesn't register with her. We have similar arguments about heating the house, I have learned to just fight other battles that are more winnable...

I am impressed! You have winnable battles, with your spouse?

 

[James L]

I am impressed! You have winnable battles, with your spouse?

He didn't say he wins any. He just said some are more winnable. She's just making him think he has a chance

 

[LarryFine]

I keep telling her that by leaving the cover open, it's taking a lot longer to heat up and thus costing us a lot more (she complains about the cost too), but she can't wrap her head around thermal transfer rates etc.

Ask her how long it would take to pre-heat the oven to 350 with the oven door wide open.

 

[kwired]

My wife doesn't usually do this in the house but on a previous vehicle we owned that had temp selection feature - she thought it heated (or cooled) faster if you set it as high (or low) as it would go. I couldn't convince her it would heat/cool as rapidly as possible until it got close to setting then would back off to maintain whatever you set it to.

Guess I didn't care when she driving alone, but if I was with her we have wait to be either cooked or frozen before you could change the setting

Current vehicle more of conventional hot-cold knob though I imagine is more electronically controlled than older cars that actually just manyaually operated a valve or diverter in the ductwork, but same concept applies. Cold when you get in - turn it to highest setting and wait until you are overheated before turning it down.

When I'm driving and alone, there is a mid range that is about where it usually ends up once things are stable - I set it near there from the beginning most the time.

 

[ptonsparky]

My wife’s van has driver & front passenger controls as well as rear. Heaven forbid you should change a setting to be more comfortable where you sit and auto fan control is not even to be considered.

It evens out though, I don’t turn the passenger heated seats on when she rides with me.

 

[James L]

My wife apparently thinks higher fan speed equals higher heater temp in a cold car

6 degrees this past winter and she wants the fan on high speed so we'll get warm faster

 

[Little Bill]

Our latest car has heated seats and front and back heat. My wife could stay in that car. She occasionally would bring me a "blizzard" from the Dairy Queen. This started in the summer. When winter came, she brought home a "blizzard" one night and it was almost totally melted. I asked how ice cream could possibly melt when it was 20 degs. outside? I soon found out, she had the heat set at the highest temp possible, both zones on, and both seat heaters on. I said "no wonder my Blizzard" died on the way home!
She also thinks the higher you set the heat the faster it will reach that temp, that and the fan on high blowing ice cubes out until it warms up!

 

[ptonsparky]

Th blower in my wife’s van stays low until the water is warm enough, then comes up to speed, if in auto. Its an LE, Low End, model. Hate to think what the fancy ones have going on

 

[LarryFine]

My wife apparently thinks higher fan speed equals higher heater temp in a cold car

My mom used to change the fan speed to "adjust" the A/C. I couldn't get her to understand that slower was colder, or how to adjust the temperature using the temperature adjuster.

Speaking of which, why is it that temperature adjustments (including showers), whether they use knobs or slides, go from too cold to too hot in about 5 to 10% of the total travel?

 

[kwired]

My mom used to change the fan speed to "adjust" the A/C. I couldn't get her to understand that slower was colder, or how to adjust the temperature using the temperature adjuster.

Speaking of which, why is it that temperature adjustments (including showers), whether they use knobs or slides, go from too cold to too hot in about 5 to 10% of the total travel?

To a certain extent this will depend on the temp differential between the hot and cold supply lines, and in some cases can change depending on conditions that may change the supply temps. Private well - you don't run too long before you have purged the piping system and get ground water temp on the cold line. Municipal water system with low overall usage at a certain time - lots of water in the system that is all at about same temperature (maybe more than what is coming directly from well though) as the ground temp is at burial depth.

 

[garbo]

Then it should be heating, even if very slowly. Curiouser and curiouser.

I wonder if an element could have an internal break that is arcing without heating.

Worked on hundreds of single & 3 phase liguid heating elements over my 50 years. They either work or burn out. A lot of non electrical workers have a hard time believing 2 things: an old heating element produces the same amount of heat as a new one and they produce 100% of heat at rated voltage. Places that have water with believe a high PH level will cause deposits in the heater causing a slight insulation effect that effects heat transfer.

 

[kwired]

Worked on hundreds of single & 3 phase liguid heating elements over my 50 years. They either work or burn out. A lot of non electrical workers have a hard time believing 2 things: an old heating element produces the same amount of heat as a new one and they produce 100% of heat at rated voltage. Places that have water with believe a high PH level will cause deposits in the heater causing a slight insulation effect that effects heat transfer.

My observation as well, they work or they have an open circuit condition, typically from overheating. That insulating effect of deposits on the element, or situations where no water is present to take heat away, or if there is no flow when there is supposed to be causes overheating and failure. In a hot tub or other situation where GFCI protection is likely to be used, that failure usually also results in enough ground fault current to trip the GFCI.