Author Topic: WS90 Heater repair  (Read 1311 times)

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Offline Autofill

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WS90 Heater repair
« on: November 04, 2024, 11:33:38 PM »
I noticied this winter my heater was not turning on when the temps dropped below 5oC, and even down to -7oC when I confirmed there was a problem because my battery was not reporting the usual 0.8 amp draw when the heater turns on (more about my heater power system here https://www.wxforum.net/index.php?topic=43135.msg448456)

My device is from the Kickstarter program, so its almost 3 years old but I contacted Ecowitt anyways.

The heater system is quite simple, and based on a thermostated switch. This switch, which is normally open, if shorted, will turn on the heater like so (see red wire):

 [ You are not allowed to view attachments ]

and you can see the heater plate warm up (actually almost went to 50oC)

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Ecowitt sent me the part, and i removed the old one and soldered in the new one. The part is "JUC31F- 0oC H" more about the part here:

https://www.calcoelectric.com/images/pdfs_thermostats/juc31.pdf

you can see its a simple bimetallic snap-click thermostat mechanism. Supposedly, its rated to 100,000 cycles at 5VDC. I have not done the math, but this thing works hard in cold climates, it turns on and off, probabably every few minutes (depending on the temp), for 3 to 5 months of the year, here.

Long story shory, after I soldered in the new part, here:

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my heater is now back to being functional.

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Cheers


« Last Edit: November 05, 2024, 11:10:31 AM by Autofill »
Ecowitt WH2320-E
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Offline Autofill

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Re: WS90 Heater repair
« Reply #1 on: November 05, 2024, 10:43:24 AM »
I was doing some math here to determine if this was pre-mature failure of the switch or just a maintanenace item.

Take this for example, last night, the temperature was around 0oC, and it turned on AND off about 80 times (or 40 x 2 = 80) in an 8 hr time span:

 [ You are not allowed to view attachments ]

so 80 times in 8 hrs means 240 snaps per day. Winters here are 4 to 5 months, 24/7, so lets say 5 months or 152 days (basically, Nov, Dec, Jan, Feb and March)

152 days x 240 = 36,000 clicks in one winter (give or take)

so after 2.5 winters, it would have clicked on/off about 90,000 times, which is pretty close to the 100,000 times for the life of this part (and this is assuming average temp of 0oC in Winter, but its colder than that).

Ok, looks like I'll be doing this every 2 to 3 years based on this back of the envelope math.

« Last Edit: November 05, 2024, 11:40:00 AM by Autofill »
Ecowitt WH2320-E
Ecowitt HP2551-C (SOLD - replaced with Home Assistant Fully Kiosk FireTab HD10)
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Ecowitt GW1100
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Ecowitt WH32B
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Ecowitt WH41 (Honeywell-based USB/Supercap modified)
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Ecowitt WH55 (x4)
Ecowitt WH45
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Ecowitt LDS01
Ecowitt Wittboy running on 12VDC  solar power

Offline henry

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Re: WS90 Heater repair
« Reply #2 on: November 09, 2024, 05:35:16 AM »
The later design switched to a thermister controlled MOSFET switch, and this cycle of 10,000 life time issue should be gone with the later batches.

Offline Dirk27

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Re: WS90 Heater repair
« Reply #3 on: November 10, 2024, 02:28:55 PM »
The later design switched to a thermister controlled MOSFET switch, and this cycle of 10,000 life time issue should be gone with the later batches.
Do all HW 3.0 versions already have that MOSFET switch?
 
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Offline Gyvate

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Re: WS90 Heater repair
« Reply #4 on: November 10, 2024, 02:58:30 PM »
The later design switched to a thermister controlled MOSFET switch, and this cycle of 10,000 life time issue should be gone with the later batches.
Do all HW 3.0 versions already have that MOSFET switch?
 
as stated by Ecowitt, yes - the older switch was with the beta-test version only as the original post in combination with the reply#2 says. So the latest WS90 models with the slope definitely have that MOSFET switch - already earlier ones had.
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Offline Autofill

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Re: WS90 Heater repair
« Reply #5 on: November 10, 2024, 06:56:05 PM »
The later design switched to a thermister controlled MOSFET switch, and this cycle of 10,000 life time issue should be gone with the later batches.

Thank you Henry! I'm going to assume that it won't be as simple as replacing this chip with the new mosfet chip sounds like there's some logic with the mosfet, plus I believe mosfets are three prong not two.
Ecowitt WH2320-E
Ecowitt HP2551-C (SOLD - replaced with Home Assistant Fully Kiosk FireTab HD10)
Ecowitt GW1000
Ecowitt GW1100
Ecowitt WH69E
Ecowitt WH32B
Ecowitt WH57 (x3)
Ecowitt WH51 (x6)
Ecowitt WH41
Ecowitt WH41 (Honeywell-based USB/Supercap modified)
Ecowitt WH31 (x8)
Ecowitt WH55 (x4)
Ecowitt WH45
Ecowitt WN34S (x2)
Ecowitt WN35
Ecowitt LDS01
Ecowitt Wittboy running on 12VDC  solar power

Offline Autofill

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Re: WS90 Heater repair
« Reply #6 on: February 04, 2025, 11:34:00 AM »
I've noticed something with the new chip, when it gets really cold, like colder than -24oC, the heater stays on permanatly, i.e. it does not switch on and off every 1 minute or so. This should greatly increase the life of the chip.
Ecowitt WH2320-E
Ecowitt HP2551-C (SOLD - replaced with Home Assistant Fully Kiosk FireTab HD10)
Ecowitt GW1000
Ecowitt GW1100
Ecowitt WH69E
Ecowitt WH32B
Ecowitt WH57 (x3)
Ecowitt WH51 (x6)
Ecowitt WH41
Ecowitt WH41 (Honeywell-based USB/Supercap modified)
Ecowitt WH31 (x8)
Ecowitt WH55 (x4)
Ecowitt WH45
Ecowitt WN34S (x2)
Ecowitt WN35
Ecowitt LDS01
Ecowitt Wittboy running on 12VDC  solar power