The Pymeter PY-20TH Guide: How to Program It (And Stop the Beeping)

Pymeter PY-20TH Controller: Mastering Temperature & Humidity Science for Reptiles, Plants & Fungi

So you bought the Pymeter PY-20TH (ASIN B08SXWSPZJ). You probably saw it was cheaper than an Inkbird and, as the [资料] reviews confirm, it’s a dual-outlet workhorse for your “gourmet mushrooms,” “reptile” enclosure, or greenhouse.

And now you’re here. Because, as user Michael D. (4-star review) puts it, “the instructions are almost mandatory - but are written very poorly.”

You’ve come to the right place. Welcome to the “real” manual. As your mentor who has been through this, I’m going to explain the confusing logic and, most importantly, how to stop that infernal beeping.

The Core Concept: You Have Two Separate Controllers

First, stop thinking of this as one device. It’s two independent on/off switches that happen to share a sensor. * OUTLET 1: Controls Temperature (Heat or Cool). * OUTLET 2: Controls Humidity (Humidify or Dehumidify).

The “confusing” part is that you don’t set a single “target.” You set the ON-point and the OFF-point. This is called hysteresis, and it’s brilliant. It prevents your gear from rapidly switching on/off, which would burn it out.

The logic is simple. Think about your goal: * Are you ADDING something (Heat / Humidity)? * Are you REMOVING something (Cooling / Dehumidifying)?

This one question determines your settings.

Lesson 1: Programming Temperature (Outlet 1)

This outlet uses two settings: * 1tN = Outlet 1 “ON” Temperature * 1tF = Outlet 1 “OFF” Temperature

Goal A: HEATING (You are ADDING heat)

Your goal is to turn the heater ON at a low temp and OFF at a high temp.
Logic: 1tN must be LOWER than 1tF * Example Setup: You want to keep your reptile enclosure between 78°F and 82°F.
* Set 1tN = 78.0 (When temp drops to 78, heater turns ON)
* Set 1tF = 82.0 (When temp rises to 82, heater turns OFF)

Goal B: COOLING (You are REMOVING heat)

Your goal is to turn the cooler (fan/fridge) ON at a high temp and OFF at a low temp.
Logic: 1tN must be HIGHER than 1tF * Example Setup: You want to cool a greenhouse when it gets too hot, keeping it between 80°F and 85°F.
* Set 1tN = 85.0 (When temp rises to 85, cooler turns ON)
* Set 1tF = 80.0 (When temp drops to 80, cooler turns OFF)

Lesson 2: Programming Humidity (Outlet 2)

This outlet uses the exact same logic, just with different names: * 2hn = Outlet 2 “ON” Humidity * 2hF = Outlet 2 “OFF” Humidity

Goal A: HUMIDIFYING (You are ADDING humidity)

Your goal is to turn the humidifier ON at a low humidity and OFF at a high humidity.
Logic: 2hn must be LOWER than 2hF * Example Setup: You’re a “mycology fruiting” user (like Jeremy B. in the [资料]) and need to keep your tent between 90% and 95% RH.
* Set 2hn = 90.0 (When humidity drops to 90%, humidifier turns ON)
* Set 2hF = 95.0 (When humidity rises to 95%, humidifier turns OFF)

Goal B: DEHUMIDIFYING (You are REMOVING humidity)

Your goal is to turn the dehumidifier ON at a high humidity and OFF at a low humidity.
Logic: 2hn must be HIGHER than 2hF * Example Setup: You want to keep a curing room between 55% and 65% RH.
* Set 2hn = 65.0 (When humidity rises to 65%, dehumidifier turns ON)
* Set 2hF = 55.0 (When humidity drops to 55%, dehumidifier turns OFF)

Mentor Pro-Tips: Fixing the “Junk” Reviews

Okay, now for the real reason you’re here. You’ve set it up, but it’s beeping, or it’s just plain broken.

Pro-Tip #1: How to Stop the High-Humidity Beeping

This is the #1 complaint. You’re running a mushroom tent at 92% humidity, and the controller is screaming at you. User Jeremy B. notes his old Rainbird had this “irritating habit,” and user Michael D. came here to write a 1-star review about it.

The Problem: The default High Humidity Alarm (h_H) is set to 99%. But as Michael D. discovered, “As soon as the humidity goes above 89.9% you will hear a continuous beep.” (This is likely a firmware bug, where the alarm triggers 10% below the setpoint).

The Solution (from user Michael D.):
1. Press SET for 3 seconds to enter the menu.
2. Keep pressing SET to cycle past the 1tN, 1tF, 2hn, 2hF settings.
3. Stop at h_L (Low Humidity Alarm). Press SET again.
4. Stop at h_H (High Humidity Alarm).
5. Set the h_H value to be equal to your h_L value.
6. Example: By default, h_L is 10. Change h_H from 99 down to 10.0.
7. Press SAV. The beeping will stop. Forever.

The “Nuclear” Solution (from user Honest Opinion):
If that doesn’t work, do what this 5-star user did: “I didn’t bother to figure out alarm settings, and just removed the speaker inside… I desoldered it… and it won’t beep EVER now.” (A true prosumer fix!)

Pro-Tip #2: Understanding the “EEE” Error

Several users (Janelle W., scott h.) report the humidity sensor “stopped working,” “is always on EEEE,” or “crapped out.”

The Problem: “EEE” is an error code meaning the sensor is out of range or has failed. As Janelle W. was told by the seller, there is an “issue with the product” in “high-humidity environments.” User scott h. confirms: “The humidity sensor is always on EEEE… humidity sensor is way too inaccurate and sensitive to actually use.”

The Solution (The Hard Truth): This controller’s sensor (ASIN B08SXWSPZJ) seems to fail when placed directly in a 99-100% humidity environment. You must protect the sensor. Try to place the sensor probe just outside the main misting stream, or in a spot where it reads the ambient air of the tent, not where it gets directly sprayed by your humidifier. If it fails, you must contact the seller for a replacement.

Pro-Tip #3: Don’t Burn Out Your Controller

User Baba Pi (3-star review) “had one burn out using Portable AC.”

The Problem: This controller is rated for a TOTAL of 1200 watts. A portable AC unit can easily draw more than this. A powerful heater (1000W) and a humidifier (200W) running at the same time will also exceed this.

The Solution: Check the wattage of your appliances. If your total load is over 1200W, you cannot use this device. It’s a fire hazard. Also, for compressors (like in an AC or fridge), use the P7 (Power-On Delay) setting to 3-5 minutes to protect the compressor.

The Verdict

This is a $30 controller that does the job of a $60+ Inkbird. It’s a bargain. Its “terrible manual” and “annoying beep” are the price you pay. But now, with this guide, you have the knowledge to bypass those flaws and turn this “junk” (as user scott h. said) into a 5-star “charm” (as user Jason A. said).