Putting a Smart Switch on my Hot Tub heater

[Mdragger88]

My spa is a Jacuzzi J-345 from about 2006, but I know that others have said that their spas also don't heat while the jets are going. My heater is 5.5kW. So that is about 23A at 240V. Adding a couple more kWs for the pumps would be getting up there.

Eventually when I replace my tub I intend to “upgrade” to a 220v (for the jets & heat at the same time reason) but now I am realizing I’ll need to do my homework when that time comes to ensure I can get what I’m expecting.

 

[JoeSelf]

I needed to have 60A circuit to run everything. At 50A heater would not run with both jets on.

 

[Mdragger88]

I needed to have 60A circuit to run everything. At 50A heater would not run with both jets on.

View attachment 545328

This is just the info I needed! Thank you
We will be replacing our panel soon so I want to make sure I account for my future tub. I will also be burying a new conduit & setting a new w/p box near my hot tub at that time so I can easily make the transition when the time comes for replacement.

 

[Dirk]

"Hey bud, I just had a great idea!"
"Do tell, pal."
"I'm going to put a soakin' tub in my backyard."
"Sounds cold."
"No, no, I'm going to heat it up."
"With what?"
"Electricity! I'm going to hook it up to my circuit breakers!"
"That's not going to work."
"Sure it will, I'm going to use 240 volts!!"
"You think that'll be enough?"
"Hmmm, you're right. Better make it 60 amps, too!"

 

[phonedave]

I was under the impression that’s why you’d want a 220v tub - so you could run jets & heat at the same time especially in colder climates. I guess they don’t all operate this way?

My heater works on my jet pump circuit, so it HAS to run at the same time.

My heat comes on when I am using the tub, especially when I is cold out. That is what I meant by my comment.

 

[phonedave]

My Bullfrog needed 50A to run the heater and jet at the same time.

It can go to 30A with limitation

240V~/60Hz 30A Conversion Option: If there is not 50A of electrical service available, an authorized Bullfrog Spa dealer or Electrician can easily convert the spa to operate on 30A(conversion instructions are located inside the Control System Box). Please be aware, spas converted to 30A are only capable of heating the water when pump 1 is in low-speed, not high-speed. This heating limitation is acceptable in most climates as well as indoor installations.


The heater is 5.5 Kw, so that is 23 amps. I believe the jet pumps pull 12 amps each on high. So maybe the heat does not run with both on high? Mine is set up for 50 Amps I believe.

 

[wayner]

IMO the only time that this issue matters if you like really long soaks. If you only go in for 15-30 minutes it is much less of a deal, especially if you don't live in a very cold climate. It took me years to even notice that the heater didn't run when the pumps are on as the heater LED is on when the heater is called to heat, even when it won't kick on because the jets are going.

 

[Mdragger88]

IMO the only time that this issue matters if you like really long soaks. If you only go in for 15-30 minutes it is much less of a deal, especially if you don't live in a very cold climate. It took me years to even notice that the heater didn't run when the pumps are on as the heater LED is on when the heater is called to heat, even when it won't kick on because the jets are going.

We do like our long soaks so it would be nice to keep heating. Our saving grace is that the really cold weather doesn’t last long here so its not a frequent issue. When it’s super cold out & its just me I sometimes just leave the cover over about 1/2 the tub. That seems to help- not sure it retains any heat in the water but it definitely keeps the parts of me above water from getting as chilly for a while longer.

 

[JoeSelf]

Long soaks here too. Usually keep it at 95. I turn it up to 97 when we get in and its cold.

 

[Mdragger88]

Long soaks here too. Usually keep it at 95. I turn it up to 97 when we get in and its cold.

Since I have a 110v - I keep it at 104 and when its cold out I stay in until its 99. Depending upon outdoor temp this may only take 30 minutes.
In the warmer times (fall/spring) I turn it down to 102 since the temp drop doesn’t happen as quickly.
In the mid summer I can turn it down to the 90’s & the ambient temp keeps it around 100 or more anyway . If I forget to turn it down below 100 & theres a hot spell with alot of sun it will end up with an OH warning after a couple days which occurs at 107.
Mine takes a bit of time to heat up so I just adjust for the seasons.
If I don’t keep it at 104 & decide to have two soaks in 1 day in the winter the second one may be a lower temp out of the gate which means I can’t stay in as long.

 

[Forest_Spa]

How is it mondo savings in a spa? How much do the pumps run in a spa?

In a pool that runs 12-24 hours per day I can see that, but in a spa it doesn't run that much, unless you are in the spa for hours per day. And when you are in the spa don't you want the pumps running at full power to give as much pressure to the jets as is possible?

But even in my pool my pump uses about 1kW. I run it around 16 hours per day, and during low price times when the all in cost would average about $0.10/kWh. How much would I save with a variable speed?

I am in northern NY and my electricity is about USD $0.35/kWh after fees and taxes. It would definitely be worthwhile.

 

[Forest_Spa]

Please explain. Why not? Are you talking about AC on the relay coil, or the load?

And which type of relay uses more watts to close?

A mechanical relay for AC is called a contactor. It would probably be cheaper to buy a separate electric metering device for the heater, than semi-conductor switching.

 

[phonedave]

Long soaks here too. Usually keep it at 95. I turn it up to 97 when we get in and its cold.

Since I have a 110v - I keep it at 104 and when its cold out I stay in until its 99. Depending upon outdoor temp this may only take 30 minutes.
In the warmer times (fall/spring) I turn it down to 102 since the temp drop doesn’t happen as quickly.
In the mid summer I can turn it down to the 90’s & the ambient temp keeps it around 100 or more anyway . If I forget to turn it down below 100 & theres a hot spell with alot of sun it will end up with an OH warning after a couple days which occurs at 107.
Mine takes a bit of time to heat up so I just adjust for the seasons.
If I don’t keep it at 104 & decide to have two soaks in 1 day in the winter the second one may be a lower temp out of the gate which means I can’t stay in as long.

OK, so clearly my wife is correct when she says I like the tub too hot. I keep it at 102 F in the summer and now it is at 103 F for the winter, and I would go higher if I could, but that is too hot for her.

When it gets below about 38F I think my tub had a hard time keeping up with temp loss. Totally a guess, but it is based on how often the #1 jets come on when we don't have them manually turned on (the heater uses the #1 jets). Of course it may do fine maintaining a 100F temp at 38F air temp, but I am going to be complaining that I am cold.

I think my heater is on the lower wattage side, since the tub has to run the heater and jets at the same time in order to heat, and it is only a 50A / 240V tub.

I know that when I fill my tub with 50 F water, it takes a LONG time to get it up to temp (as in change the water in the morning, and you are not using it that day at all)

 

[Mdragger88]

OK, so clearly my wife is correct when she says I like the tub too hot. I keep it at 102 F in the summer and now it is at 103 F for the winter, and I would go higher if I could, but that is too hot for her.

When it gets below about 38F I think my tub had a hard time keeping up with temp loss. Totally a guess, but it is based on how often the #1 jets come on when we don't have them manually turned on (the heater uses the #1 jets). Of course it may do fine maintaining a 100F temp at 38F air temp, but I am going to be complaining that I am cold.

I think my heater is on the lower wattage side, since the tub has to run the heater and jets at the same time in order to heat, and it is only a 50A / 240V tub.

I know that when I fill my tub with 50 F water, it takes a LONG time to get it up to temp (as in change the water in the morning, and you are not using it that day at all)

Funny thing is I thought I hated hot water. When we used other tubs in the past it took me a but to acclimate & was uncomfortable at first but my husband thought it was great. I feel like he takes scalding showers. At first I independently measured the temperature because I thought maybe it was wrong but it’s correct. I guess I like the hot water more than I thought based on the temps people report to be comfortable. I can’t stay in for an extended time at 103-104 but I might live in it if it stayed 102
I really bought the tub for him (because I got a new pool) but now I am definitely a hot tub person. If my pool croaked I might be on the fence about a new one especially since the kids are getting older but if I could only pick one (pool or tub) I would pick a hot tub.

 

[phonedave]

Funny thing is I thought I hated hot water. When we used other tubs in the past it took me a but to acclimate & was uncomfortable at first but my husband thought it was great. I feel like he takes scalding showers. At first I independently measured the temperature because I thought maybe it was wrong but it’s correct. I guess I like the hot water more than I thought based on the temps people report to be comfortable. I can’t stay in for an extended time at 103-104 but I might live in it if it stayed 102
I really bought the tub for him (because I got a new pool) but now I am definitely a hot tub person. If my pool croaked I might be on the fence about a new one especially since the kids are getting older but if I could only pick one (pool or tub) I would pick a hot tub.

That would be a tough choice. We use our tub year round. But in the summer I really like the pool. I like to float around in it on a hot day. I'm not sure what I would choose if I had to give one up.

However, my pool is brand new. As in we put the new one in in October and promptly closed it for the winter. I still have to move electric / plumbing come spring time. For some reason I'm really looking forward to the spring and the new pool. But it is basically the same as the old pool. It's 6" deeper, that is about it.

 

[Mdragger88]

That would be a tough choice. We use our tub year round. But in the summer I really like the pool. I like to float around in it on a hot day. I'm not sure what I would choose if I had to give one up.

However, my pool is brand new. As in we put the new one in in October and promptly closed it for the winter. I still have to move electric / plumbing come spring time. For some reason I'm really looking forward to the spring and the new pool. But it is basically the same as the old pool. It's 6" deeper, that is about it.

I do love them both but the hot tub is certainly easier to deal with! Although my pool is not terribly difficult to maintain it’s quite large.
Mainly since the tub has the draw of being useable year round. If I had a fancy inground with an auto cover that would probably sway me lol

 

[phonedave]

I do love them both but the hot tub is certainly easier to deal with! Although my pool is not terribly difficult to maintain it’s quite large.
Mainly since the tub has the draw of being useable year round. If I had a fancy inground with an auto cover that would probably sway me lol

My pool is the opposite. While not quite as big as your pool, mine is still on the bigger end of ABGs. But aside from vacuuming, it is pretty much set and forget. The SWCG keeps the FC where it needs to be, and everything else is rock stable.

My hot tub needs fairly constant nursing, year round.

 

[Mdragger88]

My pool is the opposite. While not quite as big as your pool, mine is still on the bigger end of ABGs. But aside from vacuuming, it is pretty much set and forget. The SWCG keeps the FC where it needs to be, and everything else is rock stable.

My hot tub needs fairly constant nursing, year round.

With the swg in the hot tub I don’t need to do much if I am not using it. My ph is pretty chill too.
We had several big storms this year that trashed my pool in minutes & took days to clean up each time so I am a bit jaded about it this year lol.
I am short so I must enter the pool to reach certain areas like the middle & the unburied side that has no deck. This means I must wade into the disaster.
I also have to fiddle with my steps manually. With only light debris this is usually handled by the bot, the skimmer, & a quick touch of the brush.

 

[phonedave]

With the swg in the hot tub I don’t need to do much if I am not using it. My ph is pretty chill too.
We had several big storms this year that trashed my pool in minutes & took days to clean up each time so I am a bit jaded about it this year lol.
I am short so I must enter the pool to reach certain areas like the middle & the unburied side that has no deck. This means I must wade into the disaster.
I also have to fiddle with my steps manually. With only light debris this is usually handled by the bot, the skimmer, & a quick touch of the brush.

I guess it is all relative. If I had just my hot tub, I would say it was super easy. Daily testing and dosing for about 7-10 days after a water change, and then bleach 4-5 times a week plus whenever we use it.

But compared to my set it and forget it pool, man that thing is a drag.

I'm the only one in my family who can vacuum the entire pool from the outside (I'm 6'4") so if the water temp is too cold to enter the pool, the vacuuming falls on me. A bot is in the plans for this season, mainly for that reason.

 

[Mdragger88]

For my tub if I just use cya & a splash o bleach initially there’s really not much to do following start up -
The ph ta dance is usually over the first day.
the swcg takes care of all but the higher bather load fc needs.
If I use dichlor it takes several doses to get the cya where I want over a week & i stretch out the ph ta dance using the acidity of the dichlor to also get that down.
Depends on what my plans are after startup as to the route I take.