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Rick in Michigan

Tiger river Bengal warm but not hot

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I have a used tiger river Bengal hot tub with a IQ2020 controller. Has worked great until a couple weeks ago. No changes were made between working and not. Water temperature will not get more than 80-85F. I'm in Michigan so it's cold out. No flashing lights. Ready light not on. LIM ok light is on. Heater on light is off. I am getting 240v at the heater terminals. Circulation pump is not running. I get 0v at the terminals for the pump. Made a pig tail and plugged the pump into 120v direct and the pump runs fine. At a loss here. Is it the main circuit board? 

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If the "heater on" light is not on, you're correct, the PCB is not giving the signal to energize the heater.  Try a new control thermistor (temp sensor).  They're usually sold in pairs, as the hgigh limit thermistor is right next to the control thermistor in the heater, they're different thread sizes, but since you're doing one you may want to go ahead and do the other.  They're around 20-25 bucks each IIRC

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I also have a Tiger River Bengal with IQ2020 control board- with a heater control issue. After  applying power, the power indicator turns on, then the circulator pump kicks in. After about a minute the power & ready indicators start flashing.

Everthing had  been running fine for a  few weeks after I got it filled again ( I winterize it every fall &  bring it up in May). The circulator pump went out, so I replaced it. It has good flow- there are plenty of bubbles from the bottom drain with the circulator running ( &ozonator on). Shortly after that the heater stopped & behaving as described above ( flashing power & ready indicators). Heater is fine, measures 10 ohms, but the HTR ON LED on the board does not turn on.  The LIM THERM (thermistor) LED indicator above HTR ON  is solid green.

Both thermistors measure 10k ohms with the temperature at 76 degrees, so I believe they are also good. The pressure switch reads 0 ohms. From what I've read, it should read 0 ohms. Is there anything else I can check?

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i removed the filters as suggested but the issue remains. I removed the ozone venturi tube & replaced it with a straight 3/4" pipe. The venturi tube was clean- no buildup.  Ran it without the ozonator & filters. 

How does the pressure switch circuit work? Is it a contact closure? I don't measure any voltage on either terminal of its connector on the board. I'd expect it to have a weak pullup  for the controller to sense it. 

Does anyone have a schematic of the IQ2020 controller board?

Thanks for your response.

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@castletonia might. 

The symptom is typical of an overheat condition or faulty thermistor. Since they test good, I would check the flow. Alot of bubbles is a good indicator, but not foolproof. When the lights start flashing does the heater feel hot to the touch? Test the thermistors before you start it and again immediately after the lights start flashing.

Post some pics of the equipment area and circuit board.

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Thanks @RDspaguy. Attached are some pictures. Its been in the upper 90s here in Maryland this past week, so the spa temperature is in the 90s without the heater running. I've got the setpoint @104F. Both thermistors measure approximately 6.7k- when pulled out of circuit - which is about right for 94F. In circuit, they both measure approximately 2.33V. The voltage on the thermistor comes up a few seconds after i powerup & stays at that level - it doesn't change after the lights flash. The power indicator comes on right away, then about 30 seconds later the power & ready indicators start flashing. I can hear the circulator pump kick in within a few seconds after power on & lots of bubbles coming up thru the footwell port.

The control unplugged RED LED flashes on powerup, then stays off . The green LIM OK LED stays on. I never see the HTR ON LED turn on.

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Pics of equipment area? I need to see the plumbing for the heater and circ pump to see what you have. Especially the circ pump suction side pipes.

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If you have 240v at h1 and h2 and no heat, the heater is no good. Without the heater on led lit you should not have power to H1 H2 at the relay board. Assuming you meant 240v at the line in from circuit breaker. The pressure switch in heater is not closing you can get new heater or jump pressure switch at IQbox connection.

Edited by tjr
more info

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12 hours ago, tjr said:

If you have 240v at h1 and h2 and no heat, the heater is no good. Without the heater on led lit you should not have power to H1 H2 at the relay board. Assuming you meant 240v at the line in from circuit breaker. The pressure switch in heater is not closing you can get new heater or jump pressure switch at IQbox connection.

 

On 6/10/2020 at 8:20 PM, Dave D said:

Heater is fine, measures 10 ohms,

Flashing ready and power lights indicate a thermistor fault, usually caused by low flow.

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If the power and ready lights are flashing together the pressure switch is not working . If the power light is flashing the hilimit thermistor is bad or water is too hot. If the ready light is flashing the tstat thermistor is the problem. Jump the pressure switch and spa will start heating. Since the pressure switch is built into the heater it is not serviceable and heater will need to be replaced if you remove jumper at pressure switch pins on IQ box.

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IMG_20200723_203311865.thumb.jpg.f1638247d92a3d63751c81b710b92ce9.jpg

 

Attached is a picture of the equipment area.The suction side of the circulation pump has a check valve. I can see it closed when the pump is off, then flow inward when the pump kicks in.

The pressure switch itself measures 0 ohms. I tried shorting the pressure switch connection on the board, but no change. Both thermistors measure approximately 6.7k with the temperature at 94F.  

Thanks for your input.

IMG_20200723_202348811.thumb.jpg.bb476398cf943e66037ccff326e6e98c.jpg

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Dave I just realized that we have two different hot tubs.  With the limit ok lit and tstat good, the board should  send power to heater and the heater led should light up. Is the summer timer on? If not then you may have an issue with main circuit board and or control panel.

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That's what I was looking for. You should be able to remove that check valve and replace it with a short piece of 1/2" pipe. You can pinch off the hoses on either side with some needlenose vice grips, or just be quick about it so you don't have to drain it. I have seen those be an issue a few times. Worth a shot.

Also, how long has that tee on the circ pump output been in there? The original was a 90* elbow with a barb, which will flow much better than that tee setup. I would at least turn the tee so the small hose is coming off horizontally. In fact, try pinching it off, it's just an air bleeder, to increase flow through the heater and see if it works. Again, you can pinch off the hoses while you work.

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I replaced the check valve with a straight 3/4" CPVC pipe & used vice grips to pinch off the air bleed on the circ pump output- see attached pic. The tee on the pump output has always been there. 

Still it behaves the same. Does the controller look for a specific difference  between the inlet & outlet thermistors to determine if the flow is good enough to turn on the heater?

The in-circuit voltage readings are very close, but not exactly the same.

Thanks,

Dave

IMG_20200728_191701740_HDR[1].jpg

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Sort of, a low flow condition will cause the temp to rise too much too fast which will trigger an error. Unfortunately these controls do not have a great error display, relying on led lights rather than a code on the controller. 

We are running out of options other than a faulty board. I am very reluctant to recommend a new board as they are expensive and problems are rare. But if a flow issue can't be identified and the thermistors are good there's not much left. What were the thermistor readings? You said they were close, how close?

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Sorry for not responding sooner, I was away last week.

With the  water temperature at 87F, the thermistor connected to LIM Therm measures 7.97k. The thermistor connected to REQ Therm measures 8.02k- so it looks like a difference of approximately 50 ohms.

I also measured the voltage with the thermistors plugged in & the board powered on. Lim Therm is 2.525V & Req Therm is 2.520V- so it appears to be a difference of 5mV.

Thanks,

Dave

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On 7/21/2020 at 11:40 PM, RDspaguy said:

When the lights start flashing does the heater feel hot to the touch? Test the thermistors before you start it and again immediately after the lights start flashing.

If there is a flow issue the heater will get hot, it will not if flow is good. Testing the resistance of the sensors before you start it and again when it faults will give more precise results than your hand. You should also check voltage to the heater to verify that it is turning on briefly at start-up.

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