Hot Tub heating and cycle time question

[manfacro]

Hi all, new to hot tubs, one came with the house we bought and just now starting to clean and power it up. I had a air lock that I was able to fix, but my next quandary is it doesn’t appear that there is a heater installed. It this typical? I can move water, jets work and even the control panel has a temp setting, but looking at the pump and control board I see nothing that looks like a heater.

Balboa VL200 is the control panel
Mach - 7 is the control board.

Second, when it’s plugged in the jets start up right away, the light under the jet button lights up and if I try to push the button, I can kinda feel a click but I’m not 100%sure the button is actually working. Will a stuck button just keep the jets on forever? I’m guessing I could get a new button pad. Is there a way to test? I suppose I could disconnect the key pad from the control board and then power up to see what happens.

Thanks for any pointers.

 

[Jimrahbe]

Re: Hot Tub or maybe it’s a Spa questions

m,

I assume this is a standalone, fiberglass spa...

If so, it would be hard to believe it does not have a heater.

What is powering the tub?? Some tubs can be powered by 120 volts or 220 volts. When running on 120, the Jets and heater can never work at the same time. If the jets are always on, then the heater will never engage.

Tell us more and show us a couple of pics of the "guts" under the maintenance doors..

Thanks,

Jim R.

 

[manfacro]

Re: Hot Tub or maybe it’s a Spa questions

It is a standalone, plastic shell.


http://vomitcomet.net/images/bubbletub/controlboard.jpg
http://vomitcomet.net/images/bubbletub/controllabel.jpg
http://vomitcomet.net/images/bubbletub/pumplabel.jpg
http://vomitcomet.net/images/bubbletub/controls.jpg
http://vomitcomet.net/images/bubbletub/tempprobes.jpg
http://vomitcomet.net/images/bubbletub/thehole.jpg

I see power coming into the control board
1) Lights out
2) Pump out
3) Keypad in
4) Two temp probes

No heater?


Thanks for any help

 

[Oly]

Re: Hot Tub or maybe it’s a Spa questions

Some units are designed with friction flow heating systems. As I understand it pumps water through a device which generates friction and that heats the water. I find it hard to believe myself and am not sold on the concept but admit I have no experience using or inspecting a unit with this design. Search spa friction heater for more details.

 

[jseyfert3]

Re: Hot Tub or maybe it’s a Spa questions

What are those two pairs of white and black wires running off to? What does the board say by the plug? (Can't read it due to the picture angle)

Some units are designed with friction flow heating systems. As I understand it pumps water through a device which generates friction and that heats the water. I find it hard to believe myself and am not sold on the concept but admit I have no experience using or inspecting a unit with this design. Search spa friction heater for more details.

Any energy that goes into any pump has to come out. It comes out in two ways. Inefficiency of the motor makes the motor hot, which is some of the energy you supply the pump. The rest of the energy goes to actually moving the water. All this water moved eventually stops moving due to friction, this friction generating the heat. Whatever energy isn't lost due to motor inefficiency therefore heats the water. You won't notice this on a pool, as 1000-1500 watts of heat is nothing. On a well insulated spa on the other hand, it can be noticed.

At work the equipment we use needs closed loop cooling. We've got some fair sized pumps for the loops, probably a few horsepower at least (high pressure, low flow compared to pool pumps. Typically we run them at ~120 psi output at 10-15 GPM). These push water through a heat exchanger to cool it, then through the equipment to remove heat, and back to the heat exchanger. If you run only the pumps (no equipment heat load) and don't have cooling water to the heat exchanger, the loops will get pretty toasty after a half hour or so, due to the friction heating of the water!

All that said, I was under the impression spas that use friction heating are the cheapest of the cheapest spas, and they "cool" the motor with spa water so that the motor waste heat isn't wasted but instead goes into heating the spa water along with the friction heat. That's obviously not the case there, but that's still not saying it still couldn't be friction heated.

 

[manfacro]

Re: Hot Tub or maybe it’s a Spa questions

I think it could be a "Friction Heater", a quick Google search pulls up a device that looks almost exactly like the red piece that is on the output of the pump...which is leaking a bit so off to Lowes to get a pipe wrench. Can't turn it by hand, but it looks like it has a few more threads to go.

The White/Black is the lighting, it metered to 13.5VAC.

The temperature is rising, its gone up 3 degrees in the past 10min. So I think this whole friction thing is the case. I know nothing about the tub other than me digging into it, looking up part numbers or asking about it here. Its very likely it a "Cheap Tub", the previous home owners didn't leave any documentation.


My new concern is the jets like to run forever. If I plug it in, and then immediately set the temp to below where it is now, they will cycle off. If I raise the set temp they will go on and stay on, even if I lower the set temp again. I'm guessing there is some kind of duty cycle thing it has to complete, the user manual for the VL200 doesn't seem to match up fully to what I have.

 

[Oly]

So how is the friction heater working out? Any thoughts?
I'm curious if these systems work as advertised.

 

[manfacro]

So how is the friction heater working out? Any thoughts?
I'm curious if these systems work as advertised.

So in about 2 days it went from 76 to 100 f for 160gal. From what I can tell other hot tubs with heaters normally have a scondary pump that circulates the heat and to do normal filtering. My tub only has one, one speed pump, so everything is bubbling when it’s heating and filtering... and by that logic it’s heating while filtering. I’ve been playing with the filter times because it’s creeped up to 101-102 just during its normal cleaning cycle.

Honestly, I’m not 100% sure how the water is actually getting warm, but it does seem to be working.

 

[jseyfert3]

Yup, friction heat. Rub your hands together fast. They get hot. Same thing happens with water.

Yes, as it filters or bubbles it'll best. That's why I said friction heaters seem only to be found on cheap spas. They save the cost of a heater, but you loose ability to control well. No heat without jets, not jets without heat.

 

[Oly]

So in about 2 days it went from 76 to 100 f for 160gal.

Well done, you have a nice soaking tub.
I was looking and temps in Davenport with highs in the 70s and lows in the 50s, that's not bad. I am curious how this system compares in energy use with heater models. I also wonder how this system would work further north with much lower temps.