Heater knob temperature malfunction


Old 05-01-04, 07:12 PM
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Heater knob temperature malfunction

This may potentially be an easy question for an expert, here it goes:
Got an old hot tub (~7 years) installed, wired, everything works fine EXCEPT:
The Heater portion is controlled with a round knob that has numbers from 1-10 on it. When I fill the tub with the garden hose (around 68 degrees?) and then turn the heater knob, it does not start to "kick-in" until it is set to number 5ish. I left it on at 10 for a few hours, but the max. temperature it got was around 90 degrees, then the heater turned itself off.
My theory: there is some sort of temperature measuring thing inside the heater that is lazy (broken?). Is there a fix to this?
Any help greatly appreciated

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Old 05-02-04, 10:02 AM
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Hello: fridolin

Very likely the thermostat is defective. Also very likely the prior owner had the same problem. Also likelt any pool & spa dealer in the area would have a replacement part.

The local dealers are listed in the phone book. They may also be best able to help with problem solving, have access to a repair manual or repair information and or know where to obtain such, etc.

Part replacement should not pose any problems. Be sure electric power to unit is turned off. Assuming the heater is electric or not. Not mentioned which type of heater the unit has...gas or electric.....???????

For more detailed information read the recent postings within this forum. The questions already asked describe like or similarly related problem descriptions as your question. Those prior postings and all the replies offered within them contain almost all the required information needed.

Additional Help and Suggestions:
Read the manufacturers online web site for problem possibilities, solving methods, disassembly, reassembly methods, repair procedures, pictorials, downloadable repair manuals, etc which may be available online.

Search the manufacturers web site for a downloadable version of the owners or service manual. The file will be a pdf file opened with Adobe, which also needs to be downloaded first but worth having once obtained.

Do an online search for the model by brand name or use a search engine web site like goggle etc. This web site also has help info. All of which can be found in the banner above at the top of this page.

Check back on your question several more times. Other members posting replies in this forum topic may offer you additional advice, ideas, suggestions, test and or repair methods.

Use the reply button to add additional information or questions. Using this method moves the topic back up to the top of the list automatically.

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Old 05-02-04, 12:04 PM
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great info - appreciate it very much! The heater is electric, i took it apart and am in the process of taking the thermostat out. as it turns out, i noticed that the timer has a "made in west germany" sign on it, dating this thing back at least 15 years! that may also be the reason that i couldn't find anything online on the manufacturer. it says "RC Diversified 2" on it...

I'll see if I find the replacement thermostat.

Old 05-02-04, 01:29 PM
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problem solved!

After taking the thermostat off, it was impossible to find the exact model online (probably due to the above mentioned age...). However, I found that the thermostat has a tiny adjustment screw, that allows the dial to "kick-in" at the correct temperature. I believe this has solved the problem, without any purchases.

Thanx again,

Old 05-02-04, 04:18 PM
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Hello: F

The problem may seem resolved but may not be. But I do hope so.

The tiny screw is most likely but not assuredly, a calibration screw. Which means the way the thermostat is adjusted to a measured and accurate temp. Once the sensing element losses some of it's internal vapor charge, the calibration reacts to that change.

Thus it may be a good idea to start taking daily water temp readings, in an effort to note which the temp is and if it holds steady. May hold for a few days and than change again.

Repeating the change in the same directions. Either constantly increasing or decreasing depending upon how the elements vapor charge functions on the internal thermostats baffles.

Yes, baffles, like those of the musical instrument of an accordian. The vapor either pushes into the baffle expanding it or the pressure decreases and allows the baffles to collapse some.

Each movement either makes or breakes a set of contact points which either pass electirc curent or do not. Simple type theremostat. Other are slightly more complex but operate on the same principle.

Just thought you would like to know....

If the above is the case, hope is not lost. Any generic, like or similar spa thermostat can be adapted. All that is done is the sensing element is inserted into the incoming water line via a small adapter.

The adapter is inserted into a small hole drilled into the return water line. The adapter is inserted into a pre drill size hole and tightened in place. The sensing element inserted into the adapter hole and closed in place.

Water tight seal....Problem solved....

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