Whats the difference?

[marty]

Just trying to understand the difference, are some the same just have different names? thanks!

hi limit switch
pressure switch
flow switch
vacuum switch
thermocouple

I have a pent air mity max nt that's giving us trouble.
Is this and all pool heaters the same as heater in home that have a pilot light and are all "millivolt" right?

 

[Charlie_R]

All the items you mention are different, when it comes to a heat producing appliance.

High limit switch -- Overtemp switch. turns off the gas if the temp in the combustion chamber goes too high.

Pressure switch -- can be used for gas pressure or water pressure, depending on where it is.

Flow switch -- ensures there is water flowing through the heat exchanger.

Vacuum switch -- Not sure where this is in the heater, so don't know what it's for.

Thermocouple -- If your heater has a pilot light, sends a millivolt signal to the main valve allowing the main burner to light when heat is called for.

Not all pool heaters have all of these, some have more, some have less. NOT the same as a home heater or furnace, or even a tankless domestic water heater.

 

[Charlie_R]

Edit:

You didn't say you have a forced draft heater. The vacuum switch makes sure there is air flowing through the combustion tubes before the main valve is allowed to open when lighting.

 

[marty]

Thanks Charlie, I don't know if I have a forced draft heater, how can I tell? I got a Eo4 code on our mintmax nt, I searched and seems its a fan sensor issue... is that the sensor right up front that has the ceramic body that you are not supposed to touch ?

Is a fan sensor easy/cheap to replace?

I read about using a "jumping wire" to bypass, is that process for some other switch?

 

[Charlie_R]

I'm not sure where the fan sensor would be, but I think if you try the "bypass wire" you could risk fire or explosion. Please don't do it.

I'm only going on what I've learned from working with HVAC people in the past. That is the only reason I had a clue about what those items were and what they do.

Best bet would be to contact tech support for your heater. They would be better equipped to guide you through troubleshooting your heater.

What I said about lubing the fan motor may cure the problem, though. If the fan sensor isn't getting enough air past it from the fan running at normal speed, you might get that error code.