Mastertemp 400 heater problem

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jsoto58

Member
May 2, 2024
12
Houston
I am new to the board. Lots of great information sharing going on.

I have a Mastertemp 400 NA Standard. Install 2014
I am getting the same conditions as Farmoci. The blower comes on, I can hear the gas valve open (smell gas) and it does not fire. It does this 3x and shuts down. My igniter shows 53 ohms so I know that is good. I know my AFS is good. I have good water flow. Fenwal blinks 3x for Ignition lockout. My grounds have no corrosion. I have jumpered out the AGS, HLS but same results. I also pulled the bottom bolt on the manifold to see if there was any water in the can. Nice & dry.

Can I pull the Igniter out of the chamber to see if it is heating? with the gas turned off. If I pull the connector off the igniter can I test the voltage there? I have a 240V system. It was running about a month ago.

How do you test S1 & S2? do I need alligator clips? I have a True RMS multimeter with the straight pins.

Any help would be appreciated.
 
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jsoto58 said:
Yes, I am thinking it might be the gas pressure or the Fenwal, but why would the gas pressure change?
Click to expand...

I had my gas meter fail.

Gas valve gets clogged by sediment in gas line.

You have a properly installed sediment trap in your gas line?

Show us pics of your heater gas line connection.

What is the CFM of your gas meter?
 
jsoto58 said:
Yes, I am thinking it might be the gas pressure or the Fenwal, but why would the gas pressure change?
Click to expand...
It's possible that your underground gas line is leaking. Do you smell gas anywhere along the buried run from the gas meter to the pool heater?

I ran into this issue. When we bought our house, it had a rusted out Teledyne Laars pool heater that hadn't worked in nearly a decade. Gas line to the heater had been left shut off at the meter. We replaced the heater with a new Jandy JXI400 after we moved in, and reused the old gas line (I don't recall if the pool company pressure tested the gas line).

The heater worked for a couple of months. We then started smelling gas in the backyard, and a few weeks later the heater stopped firing with a "check ignition steps" error.

After working with several plumbers and even reaching out to the original owners of our house who put in the pool, we discovered the following:
-The gas was leaking at a location ~100 ft from the gas meter. Buried gas poly pipe typically comes in 100 ft lengths.
-The wrong type of poly pipe coupler was used at the poly pipe junction. It was allowing gas to leak out, but was also allowing groundwater to leak in.
-Once a slug of groundwater filled the lowest spot in the gas line, it blocked enough gas flow so that the heater wouldn't fire.

We had to replace the buried coupler and then use an air compressor to blow the slug of water out of the gas line. Has been working fine since.
 
Your gas service is undersized. You have a 250CFM gas meter trying to feed a heater that requires 400CFM.

Your heater gets insufficient gas and runs lean or not at all.

Contact your gas company and request an upgrade in gas service. Most gas companies do the upgrade at no charge.
 
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gkw4815 said:
It's possible that your underground gas line is leaking. Do you smell gas anywhere along the buried run from the gas meter to the pool heater?

I ran into this issue. When we bought our house, it had a rusted out Teledyne Laars pool heater that hadn't worked in nearly a decade. Gas line to the heater had been left shut off at the meter. We replaced the heater with a new Jandy JXI400 after we moved in, and reused the old gas line (I don't recall if the pool company pressure tested the gas line).

The heater worked for a couple of months. We then started smelling gas in the backyard, and a few weeks later the heater stopped firing with a "check ignition steps" error.

After working with several plumbers and even reaching out to the original owners of our house who put in the pool, we discovered the following:
-The gas was leaking at a location ~100 ft from the gas meter. Buried gas poly pipe typically comes in 100 ft lengths.
-The wrong type of poly pipe coupler was used at the poly pipe junction. It was allowing gas to leak out, but was also allowing groundwater to leak in.
-Once a slug of groundwater filled the lowest spot in the gas line, it blocked enough gas flow so that the heater wouldn't fire.

We had to replace the buried coupler and then use an air compressor to blow the slug of water out of the gas line. Has been working fine since.
Click to expand...
the meter is located about 5' from the heater. We don't smell gas at the meter or heater when not running.
 
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jsoto58 said:
Ok, but the heater ran fine a few months ago and we don't have any issues in the house (we have gas dryer, two tankless water heaters, gas furnaces....)

I will call my gas company for an upgrade.
Click to expand...

The gas appliances in your home only need a few tens of CFMs. If you added up all appliances together, they probably wouldn’t needs more than 150CFM or so. A 400kBTU heater is a monster draw on your supply. While the heater may have been “working” in the past, it was probably doing so very inefficiently. Once you contact the gas company, you need to give them a full list of ALL gas appliances and their need. Then the meter needs to be sized to be able supply everything on the list. It’s not uncommon for a pool and house gas meter to be rated close to 1000 CFM (1 MBTU).
 
jsoto58 said:
My email from Centerpoint Gas says that I need my heater to be regulated. What exactly does this mean?
Click to expand...

What is the size of the gas line to the heater and the length?

If the gas line is too small for low pressure then they upgrade the gas line to high pressure and put regulators by the devices to lower it back down.

1715027793440.png
 
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If you have 1" gas line 5' long you should be fine.

If gas company needs to upgrade your service to high pressure they can put one regulator after meter and before the house to lower pressure for all the gas equipment in the house.
 
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