Testing hot tub heater element

[earl84]

We bought a new to us house in May that came with a hot tub, something we would probably never buy for ourselves, but it sure is nice to have.
Anyway, it heats water just fine, but it seems to cool off too quickly as we are using it. It’s definitely worse if the wind is blowing or the outside temp is cooler, but it seems like it should be able to keep the water hot. Water will decrease from 104* to 100* in about 15 minutes.

I put a voltmeter on the two leads going to the heater, and both show 120 volts input to the heater. How can I tell if the elements themselves are actually working? Or what else should I be looking for? I’m no electrical genius, obviously, but not a complete dummy, either. Or maybe I am and just don’t know it, haha.

 

[gungatim]

is this a 110v or 220v unit? did you lose one leg of the 220? nothing wrong with the element if it is heating, they either work or they don't.

when the temp drops, does the element come on? (light on your control panel will show, and you should hear the contactor click).

high limit could be tripped and not allowing it to kick on again if not.

also the flow/pressure switch will not allow the element to turn on unless there is sufficient water flowing, it could be bad or is your pump turned off?

 

[wyliesdiesels]

Need more info as asked above.

If its a 120/240v tub then the heater would be 240v. Try measuring voltage between the 2 leads on the heater not one lead and ground or neutral. You should get 240v

 

[SGKent]

if it is cold outside, and the bubble blower is turned on, many heaters on less expensive models cannot keep up with the loss of heat that is caused by injecting all that cold air into the water. If it is a 240 V model there is probably conduit going to it from a box near it. If it is a 120V model there may just be an extension cord that is plugged into a GFCI plug. Water and electricity do not go together. Be very careful - all you don't need is to be measuring voltages and a mouse or spider runs by you making you jump and touch a wire. I try to keep one hand behind my back when I am working with voltage, and wear rubber soled shoes, no rings or jewelry, chains etc..

 

[fitter30]

Is there a bubbler for the jets are you running it because it is injecting air temp into the water cooling it off. You can purchase a amp probe and measure the amps that the heater is using for $20-25.

 

[Bretny]

Some 120v models dont even have a heating element. They use friction of the pump to make heat...yes they take for ever to heat up.

There should be a tag on the control box under the tub. Take a picture of it.

 

[earl84]

Thank you everyone for your response.

It is a 220v hot tub. Has a small 50A (IIRC) sub panel wired just for the hot tub with conduit going to the hot tub control box, then out to the heating element. Pump and everything seem to be working as they should, just cools off too quick. We have friends with hot tubs and they say theirs stay warm for hours. Not sure why they want to be in it for hours, but to each their own. Once we put the cover back on, it heats back up to 104* fairly quickly.
Not sure what a bubbler jet is, to be honest. I’ll try to get a picture later of the tag.

 

[dcg9381]

So it heats up just fine.
But using it, temp drops... IE - heating elements are not running while you're "operating" it, correct - that's the issue?
That seems like some sort of control function to me if it can't run and maintain temp.

How quickly it loses heat would be a function of insulation and outside temp..... Is it well insulated?

 

[Bretny]

How did you measure the voltage going to the heater? One test leed on each stud of the element?

If its running and the element is getting hot i would think it should be 240v or off. There may also be a option for a 120v element in your control board. A switch or jumper or something of the sort.

The air bubbler is an air pump that puts air bubbles in the jet output. On some you can turn this off. Adding cold air into the water cools it quick.

 

[Bert_]

You say it's a 240-volt hot tub so the heater will be 240. But you only measured 120. That's the problem right there. It's either missing a leg or miss wired. That 240 volt heater will only put out 1/4 the heat on 120.

 

[ard]

I put a voltmeter on the two leads going to the heater, and both show 120 volts input to the heater.

You say it's a 240-volt hot tub so the heater will be 240. But you only measured 120. That's the problem right there. It's either missing a leg or miss wired. That 240 volt heater will only put out 1/4 the heat on 120.

OP isnt too precise on this. "both show 120" could mean he measured one wire at 120 and then the other wire at 120.



OP should clarify.

 

[walta]

Where you put the probes matters to what you will read. The voltages in this picture are what you would see if heater were running. If you put one of the probes on a ground or the white wire you will never read 240 volts.

It would be interesting to know the voltage across the 2 heater terminals and the current flow thru one of the wires going to the heater measured with a clamp on amp meter.


Walta

 

[earl84]

I appreciate all of your guys help, I really do. I’ve been slow responding, because, well life. I don’t have an amp probe, so I need to get one to correctly respond.
Coming from the control board are two wires that go to the heater element. I placed the red probe on each of those individually, while placing the black probe to ground. I read 120v on each.
I guess I am an electrical dummy, haha. But I’m learning.

 

[Bretny]

You should have 240v on the lugs of the heater like you measured. Do you have 240v coming into the tub controler? Knowing the amps its really needed as by the looks of it you have a voltage problem.

If you have 240v coming into the controler make sure theres not a 120/240v switch on the controler some where. If theres not its prob time to start pricing out a controller.

 

[Innovate1]

I appreciate all of your guys help, I really do. I’ve been slow responding, because, well life. I don’t have an amp probe, so I need to get one to correctly respond.
Coming from the control board are two wires that go to the heater element. I placed the red probe on each of those individually, while placing the black probe to ground. I read 120v on each.
I guess I am an electrical dummy, haha. But I’m learning.

Better to place red probe on one heater terminal and black probe on the other. Should get 240V. If the heater isn't getting power you will still get 120 to ground on each but no voltage between the two heater terminals so measuring each to ground may give you confusing info.

An amp reading would tell you if it is drawing the right amount of power. Might be that the heater is partially damaged but I think they usually go completely out when they fail.

 

[Bert_]

I appreciate all of your guys help, I really do. I’ve been slow responding, because, well life. I don’t have an amp probe, so I need to get one to correctly respond.
Coming from the control board are two wires that go to the heater element. I placed the red probe on each of those individually, while placing the black probe to ground. I read 120v on each.
I guess I am an electrical dummy, haha. But I’m learning.

Since the heater is straight 240v it could care less about the voltage to ground. It could have some really crazy voltages to ground but as long as it has 240 line to line it will work fine.

So the only useful test is to check line to line for 240. This is true for all 240v equipment. If it doesn't use the neutral then don't use it to test.

 

[wyliesdiesels]

I appreciate all of your guys help, I really do. I’ve been slow responding, because, well life. I don’t have an amp probe, so I need to get one to correctly respond.
Coming from the control board are two wires that go to the heater element. I placed the red probe on each of those individually, while placing the black probe to ground. I read 120v on each.
I guess I am an electrical dummy, haha. But I’m learning.

so you measured incorrectly.

Go back and put the probes on the heater leads- red to one and black to the other.

voltage to ground means nothing

 

[earl84]

Back to this troubleshooting. I put the voltage test leads across both heating element studs and got 240 volts, so that is correct. I also purchased an inexpensive amp clamp, tested each individual leg, and was seeing about 17 amps on each leg. This was done while the heating element was actively heating the water. I don’t know what this range should be, but that’s what I had.

It seems everything is working as it should (unless the amp draw is low) and my only real problem is really poor insulation. Unless anyone has any more helpful information, I think it’s safe to close the loop on this. Thank you all so much.

 

[wyliesdiesels]

Back to this troubleshooting. I put the voltage test leads across both heating element studs and got 240 volts, so that is correct. I also purchased an inexpensive amp clamp, tested each individual leg, and was seeing about 17 amps on each leg. This was done while the heating element was actively heating the water. I don’t know what this range should be, but that’s what I had.

It seems everything is working as it should (unless the amp draw is low) and my only real problem is really poor insulation. Unless anyone has any more helpful information, I think it’s safe to close the loop on this. Thank you all so much.

what does the nameplate on the heating element say?

 

[grounded-b]

Back to this troubleshooting. I put the voltage test leads across both heating element studs and got 240 volts, so that is correct. I also purchased an inexpensive amp clamp, tested each individual leg, and was seeing about 17 amps on each leg. This was done while the heating element was actively heating the water. I don’t know what this range should be, but that’s what I had.

Volts x Amps = Watts ( on a single phase circuit )

So you're producing 4KW of heat. Is that what the nameplate says?

Steve

 

[Bretny]

Voltage checks out good on the element. At least when you tested it. You could check to make sure your element is covered in water deposits. You can actualy buy just the element for these and not the stainless tube assembly.

What temp do you run the tub at? Could it be that your just getting use to the hot water thus making it seam like the tub is cooling off.

We run ours at 104* on a 30* night with the lid open its not uncommon for the tub to show 102*. Also when the jets or heater is on the tub drops in temp for a bit. We have a insulated tub, cover and i set the tub on 2in of foamboard.

 

[Lightning rod]

I agree with Bretny
Sounds like it’s working fine under the circumstances

 

[Davefr]

Some hot tubs disengage the heater when the jet's are on. The combination of no heat w/jets and loss of heat from the spa's action is what's probably happening. The other factor is that you're getting used to the heat. It always feels hotter when you first jump in.

 

[earl84]

Volts x Amps = Watts ( on a single phase circuit )

So you're producing 4KW of heat. Is that what the nameplate says?

Steve

The nameplate says 4KW, so I guess everything electrically is as good as it gets.

The hot tub was here when we bought the house, I don’t think there is any insulation under the pads it sits on. The insulation around the sides might as well not be there, it is so bad. I know you get used to heat the longer you sit in it, but I can read, and it goes from 104* to 100* in about 15 minutes some days. I regularly set it at 104*, and it shows 104* when I open the cover. Goes down quickly sometimes. Windy days are the worst.
I do believe that with your guy’s help, we have done as much as possible, and I just need to add insulation somehow, since electrically, it is as good as it gets. I have no way to turn off any air bubblers or jets, I have been through the menus a hundred times. I thank you all for your input.

 

[Bretny]

Heater off when jets are on is not true. It needs water to flow across the heating element to work.

The first stage of my dual stage pump comes on when it calls for heat.

 

[SGKent]

The nameplate says 4KW, so I guess everything electrically is as good as it gets.

The hot tub was here when we bought the house, I don’t think there is any insulation under the pads it sits on. The insulation around the sides might as well not be there, it is so bad. I know you get used to heat the longer you sit in it, but I can read, and it goes from 104* to 100* in about 15 minutes some days. I regularly set it at 104*, and it shows 104* when I open the cover. Goes down quickly sometimes. Windy days are the worst.
I do believe that with your guy’s help, we have done as much as possible, and I just need to add insulation somehow, since electrically, it is as good as it gets. I have no way to turn off any air bubblers or jets, I have been through the menus a hundred times. I thank you all for your input.

If the insulation below it wasn't there, the cover would not work as well as it does. The spas I have owned all went up in temp even when used just from the movement of the water. The air bubbler, and air injection valve lower the temp because colder air is injected that carries the heat away. Most spas have two speeds as well and the temp controls can vary with those speeds. Do you have a manual for it?

 

[ard]

Same as two posters above: what should the watts be? Once you tell us that, divide by 240Volts and it tells us if the 17 amp is correct.

How about a model name and number? Maybe we can look up a schematic....(not just connection instructions)

 

[earl84]

The hot tub is a Hot Spot SX. I have a manual. I can try to turn the jets down to a lower speed. I think my biggest issue with cooling is when the wind blows, it seems to be the only factor that I can correlate with any consistency to the water cooling fast. Example: yesterday we used it, outside air temperature was about 15*F, twenty minutes later water temp was still 102*. No wind. Perfect operation.
Anyway, attached is a pic of the heating element, and the schematic from the manual. It seems as if all is well in the actual operation of the heating element.
4000 watts divided by 240 volts = 16.66 amps, exactly what I’m seeing.

And thanks again, everyone.

 

[Bretny]

Have you seen if the element is covered in hard water deposits?

My balboa controler uses the same 4kw element. 7 person hottub.

 

[ard]

A 'connection diagram' that describes how you wire UP TO the spa, is not a 'schematic' of the spa itself...just FYI

Heres the manual, I think: http://hotspring-2017.s3.amazonaws....16-owners-manual-60hz-document-303761.16b.pdf


I have seen spa's that will throttle back the heater when the pump is on high speed. Was your 17A reading with the pumps running at full? It looks like your spa does this when using the lower voltage configurations..... maybe something not set right? but let us know if you got that 17A/240=4kw at full pump. and or what it drops to at full pump

 

[earl84]

That 17A was at full pump.