Pentair MasterTemp 400 Igniting but only cold water in pool and spa returns

mdemsnx2

New member
Jan 14, 2021
2
San Clemente CA, 92672
Just replaced an old MasterTemp 400 with a brand new one. Easy install, didn't change any plumbing, electrical, or gas connections. It fires up and ignites without any problem no error codes or leds light up. The water returns to the pool and spa have good flow, but the water is cold. Any thoughts?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
22,131
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Welcome to TFP.

If the heater is running then the BTUs of heat can only be going into the water. If the BTUs were not going into the water the heater safeties would overheat and shut it down.

How long did you let the heater run for?

What is the water temp of your pool and the air temp?

Post pics of your heater and equipment and valves.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,252
Bedford, TX
x2,

I agree with Allen.. The heater can't be running and not heat the water.

Is this the first time using the heater?

Is this a standalone heater or is it being controlled by an automation system..

Thanks,

Jim R.