Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Mini-Boiler Heating Problem

Otsfarm
Otsfarm Member Posts: 2
in THE MAIN WALL
I have an EMB-W-90 mini-boiler for my in-floor heating. The output water temperature is only about 65 degrees. I checked the 205° hi-limit manual reset and it is not tripped. The green LED on the circuit board is full on indicating the Stage 1 electric element is on. It appears that the Stage 2 element is not turning on. What would cause this problem?

Comments

  • GroundUp
    GroundUp Member Posts: 2,122
    Open the panel and look at the back side of the control board. There should be 2 red LEDs in there labeled 1STG and 2STG signifying which elements are powered. What is the inlet temp to the boiler when the outlet is 65? If you have a multimeter available, test the input and output of the relays on the bottom left of the boiler; there should be 24v in and 240V out to the elements. I had of these with a failed board that had similar symptoms and would never energize the 1STG LED, and despite the 2STG LED being on, there was no power to any of the elements. I swapped the board and it was all better. The W-9 is an old boiler already, how long has it been in service?
  • Otsfarm
    Otsfarm Member Posts: 2
    Thank you. I will check out your suggestions. I don't know the inlet temperature but it's not much lower than the output temp. The boiler was installed in 2005. Where can I get a new board if I need one?
  • GroundUp
    GroundUp Member Posts: 2,122
    You can call Electro tomorrow and talk to tech support about it, parts are readily available and they may even choose to warranty whatever the issue is. I doubt it's the board unless it's in a wet environment, but may very well be something as simple as a bad element at 15 years old. Testing with the multimeter will narrow down where the power stops and tell you what's wrong

Categories