MasterTemp 400 Service Heater Light On Heater Cycling

[ajw22]

To get that heater running I think you need to go after the corrosion. That means unbolting everything and cleaning the corrosion off down to the bare metal. Then see how much meat you really have left on some pieces.

If you disassemble it all and clean it up either it will work or you will know you need to replace the heater. What is your time worth?

 

[-Ed]

Where is the flame sensor located?

 

[ajw22]

Where is the flame sensor located?

Some heaters use a flame sense rod. The Pentair MasterTemp and Sta-Rite heaters use the igniter as part of the flame sense circuit.

Thus corrosion around the igniter can affect the flame sensing.

 

[-Ed]

It seems to be a flame current issue, which can be due to a weak flame or a defect in the flame sensing circuit.

The corrosion has probably interfered with the flame circuit path.

It looks like the corrosion is bad enough that getting a good flame current path will be difficult.

A weak flame can be due to low gas pressure due to a gas line problem or maybe a defective gas valve.

You can check the gas pressure to see if it is in range.

A poor flame can also be caused by other issues.

Is the combustion chamber corroded completely through anywhere?

The combustion chamber is solid. The corrosion on the lid is superficial and could be removed. We seem to have narrowed this down to an issue with the flame sensor circuitry. Since I am understanding that the igniter is part of the flame sensing circuit, and I've just replaced the igniter, would it make sense to remove that and re-seat it?

If there are any more suggestions I'm open to try. It's the end of the pool season here and I didn't want to put this away broken. If I have to replace it then it's had a good life as it is only 15 years young.

 

[JamesW]

After the gas valve opens, the HSI (Hot Surface Ignitor) will switch to a sensing mode to monitor the flame.

When the HSI switches to flame sensing mode, it is looking for a microamp current in the 1 to 10 microamp range (1.0 to 10 µA).

If the flame sensor does not read at least 1.0 microamps, the Fenwal controller will shut down power to the gas valve.

 

[-Ed]

I did a bit of exploration with a screwdriver and found that the cover for the heater, 42001-0214S, as you suspected, is toast. Thank you for your help in this matter. Pictures were very helpful for getting to the bottom of the problem as you know! I did check on the part and it's no longer available. So that makes the decision a bit easier.

Next up is to search the blog for information on which new heater shall replace this unit. This heater works will with the Pentair control center, and it did last 15 plus years. Will any unit connect to the control center or are Pentair the only ones? Are there new options that are of value? Should I pay for making my control center work via WiFi?

All new to me!

 

[ajw22]

Will any unit connect to the control center or are Pentair the only ones? Are there new options that are of value? Should I pay for making my control center work via WiFi?

What control center do you have?

In general all pool heaters work with pool controllers using the "firemans switch" 2 wire connection.

Heater Control with Automation - Further Reading

www.troublefreepool.com

Some new heaters can also connect using RS-485 comm link to a controller that supports the link.

15 years is a great run for a MasterTemp heater. I would just get another one. There are no other heaters that are better then a MasterTemp.

 

[-Ed]

What control center do you have?

In general all pool heaters work with pool controllers using the "firemans switch" 2 wire connection.

Heater Control with Automation - Further Reading

www.troublefreepool.com

Some new heaters can also connect using RS-485 comm link to a controller that supports the link.

15 years is a great run for a MasterTemp heater. I would just get another one. There are no other heaters that are better then a MasterTemp.

I am using an EasyTouch 8. It's also vintage 2007. I have the EasyTouch Wireless Control Panel but when the mother board in the panel went bad and I replaced it the Wireless Control would no longer communicate with it.

 

[ajw22]

I am using an EasyTouch 8. It's also vintage 2007.

So all pool heaters with a 2 wire fireman's switch control will work with your EasyTouch.

If you get a new MasterTemp heater it will be a "connected" version with RS-485 controls. But you will need to continue to use the Fireman's Switch with your ET system.

I have the EasyTouch Wireless Control Panel but when the mother board in the panel went bad and I replaced it the Wireless Control would no longer communicate with it.

@Jimrahbe or @ogdento is best to help you with the wireless control panel.