MasterTemp 400 Igniting Momentarily, No Diagnostic Codes

huggablejunk

Bronze Supporter
Nov 14, 2017
20
Marietta, GA
@setsailsoon
I was also thinking maybe water go into the line somehow?
The drip leg at the heater had about 3 inches of water in it, it surprised me honestly.
So I wonder if I have water blockage somewhere?

We haven't noticed any other appliances being affected: Hot water heater, furnaces, fire pit, and natural gas fireplace and and natural gas connected grill all work fine. But they are on a different leg of that pipe.

Anyway for me to try and blow out that pipe is that something I can ask the company to do?
 

Rocco

Well-known member
Dec 23, 2012
235
Manassas Park, VA
When I have experience similar issues it is normally a dirty burner assembly which is where the gas comes out and is burned. The burner assembly has a bunch of tiny holes and if the holes are blocked there is no enough gas flow to sustain the flame. So it lights and then goes out shortly thereafter.
This assumes that you are actually getting sufficient flow to your heater.

If you can I recommend removing the burner assembly and checking and cleaning if needed.
 

setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
2,122
Stuart/FL
Anyway for me to try and blow out that pipe is that something I can ask the company to do?
Yes, you can blow it out with air pressure. Or you can get a gas plumber to do it. If you don't have knowledge the gas code or aren't comfortable get a gas plumber to do it for you. If you have water in the line and the others are working I suspect a leak and the line will very likely need to be replaced. Most building departments will require a 24 hr pressure test above 25 psi before you put it back in service. The gas plumber can run a test line above ground to your heater to confirm if that's the problem. He should not under any circumstances leave it in place for obvious safety issues. If you're comfortable you can do the same thing but you can't do this if you don't know how to properly pressure and leak test it. It's not worth a couple hundred $ to risk fire and or explosion. If this proves out get a gas plumber to replace the line and do it properly.

Hope this helps!

Chris
 

mguzzy

Well-known member
Jul 8, 2015
925
OV, CA
I was the guy that figured after months that it was the regulator side of the gas valve. And one of the things I did in the leading up to that was checking the gas lines for a blockage. I blew and sucked them out with a shop vac. I had the gas company out on something else and they checked the line for pressure at the meter and they said it was good. That put my focus back on the heater. .. so just keep going and through a process of elimination you'll get it! Just make sure you post back your ultimate solution for prosperity sake.
 

swamprat69

Well-known member
Mar 30, 2019
108
Las Vegas, NV
Natural Gas is normally dried to a water vapor density that corresponds to a dew point of -40 degrees F. Water should not condense in your gas line until the temperature falls below that point! Are the Pool, Heater and buried gas lines to outdoor equipment all 4 years old? Who installed the gas lines to the heater and outdoor equipment? A drip/dirt leg should not fill up with water and is usually an indication of a leak in a buried pipe. Gas valves that have been exposed to flooding or excessive internal moisture need to be trashed. If you have a leak in a buried pipe, it will have to be replaced and may have effected other parts of your gas distribution system. If buried piping was not installed correctly and/or has a leak, blowing it out is not a solution. Wait and see what your gas supplier recommends when they are able to send someone out. It is not worth your exposure to adverse/dangerous effects to try to DIY repair.
 

huggablejunk

Bronze Supporter
Nov 14, 2017
20
Marietta, GA
Thank you everyone for the great advice, I knew not to mess around with the natural gas so I called a plumber and my natural gas company.

The gas company inspected the meter and the lines and indicated there were no leaks or degradations in the line, even with a pressure test. The gas company upgraded my street valve and my house for good measure and the gas supply has never been better to every appliance. The couldn't figure out why I wasn't getting gas out to the heater and suggested that the line might have been pinched somewhere (only 4 years old and I had my doubts). Gas line is about 70ft run from the meter under earth and some concrete. The plumber was going to return the next day after the natural gas company had done their due diligence. On a hunch after finding water in that drip leg, I decided to shut the gas off totally to the back yard as it was on a separate valve from the house. So I opened up the drip leg to find no more water in there and connected my shop vac to the line. Within about 20 seconds I heard a huge glug of water (about a cup) come through and into the shop vac and then no more water, held it on there for a while to make sure nothing else was there. Made sure the shut offs were in place at the heater and then turned the gas back on, went back to the heater and BAM, an absolutely ton of gas was coming out the line at the heater as it should have been.

We had ALOT of driving rain for the past 70 days in the south and I'm wondering if water worked it's way from the heater exhaust somehow or if a malfunctioning heater shoved water back in the line?

In any case, I reconnected the heater and it fired up on the first try. Turned it off and on a few more times and it ignited with no issue every time. So I put the spa on and left it to heat. Came back an hour later to find the spa at full temp but the Service Heater light was on (NOOO!). So I opened the heater and looked at the Fenwal and it was flashing two lights. At this point, I decided to try the new grounding wire fix where you attach the wired to the blower top and below the blower as diagrammed by Pentair. First try after I connected the new ground wire, it fired and stay on, and over the next hour as it called for heat it would turn on with no issues. Just as we're about done the dreaded Service Heater light comes on again, even with the new ground fix. At this point, I shut everything off and called it a night. I canceled the plumber because he was already out once and identified the same no-gas issue there wasn't any else he was going to do for me outside of suggest running a new gas line which I don't need. Also I checked the drip leg several more times for water and its all bone dry.

I knew I was going to have a beautiful day in the south today so I had programmed the Easy Touch to turn the heat on for the pool. I woke up to the pool and the heater running perfectly. The pool heater ran all day flawlessly heating the pool to about 90 degrees. Once the pool reached the 90 degree mark, the heater turned off as expected. When it turned on again to keep the temperature up, the Service Heater light comes on with the same Fenwal 2 Flashes, no call for heat (no other sensor lights on the heater control panel) I suspect that if I leave it off for the night and it starts again tomorrow it will ignite and run fine from a cold (dry?) start.

So now I'm kind of back to where I was in November. The heater has gas, the igniter works great, and after a period of drying out or non-use it fires up first time every time. But after it gets to temperature it doesn't want to re-ignite, or if it does, its not reliable, even with a new ground fix. My pool company was waiting for me to figure out the gas issue before they returned but I am literally at a loss for what else this could be so I'll be calling them back over the next week. The heater and all of it's sensors clearly work and they can run for 12 hours+, but they don't want to reignite reliably after the system has been running for an extended period of time.

I think the worst part of all of this is I'll probably never have piece of mind that MasterTemp 400k will be reliable, but conversely I never had a single problem with it for the first 4 years of its life.

So guys.... any other special tricks up your sleeve?
 

JamesW

TFP Expert
Mar 2, 2011
17,419
Two flashes means that it's detecting a flame current when the heater is off.

The Flame rectification current is in the microamp range.

One millionth of an amp is tiny and you can get a random current that can interfere with the flame rectification signal.

Test the flame current with the heater off and report back what you get.


 
Last edited:

setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
2,122
Stuart/FL
Hug,

Very interesting. When I was troubleshooting my flame rectification problems the only way I was able to get two flashing lights on the Fenwal was when I jumped the gas valve open with 24 vac during the 7 second period the gas valve was opened. This kept the flame going to confirm the gas valve was operating properly. Each time I did this the unit would shut down at intermittent times but it always shut down and had 2 flashes at the Fenwal light. It should have run this way 'till my pool reached temperature. As James indicated this was my clue that I had some kind of interference in the grounding. So I rigged up a temporary power supply from a separate breaker using spare romex that I had laying around the garage. Voilla! In my case lightning had damaged the insulation on the hot wire and was causing intermittent leakage to ground. Not enough to cause the unit to trip a breaker but plenty enough to make flame sense detection at the millionth of an amp level unreliable. I replaced the original wires in the conduit and the unit has worked reliably every since... the jumper is easy and pretty quick. Just disconnect the power to the heater and replace the connections with the jumper. Might be worth a try.

Chris
 

mguzzy

Well-known member
Jul 8, 2015
925
OV, CA
Whoa Nelly! So.. wait a minute. Not so fast. I realize we are onto the next issue and its so cool you were able to flush your line with a shop vac.. Luckily I found nothing in mine when I "aired" out my lines. But if yours was filled with a blob of water I would be concerned where it came from? It may come back again. Does your plumber have the ability to scope the line? At a minimum I would inspect your drip trap on a regular basis. If there is something else I missed, I would be happy to stand corrected.
 
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setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
2,122
Stuart/FL
Mguzzy's right there should be no way for water to get into the gas line from the heater. It can't get there from rain through the heater exhaust. That would fill up the firebox but not get to the gas line. Did you pressure test that section of line? The only way I can think of is the line pressure went to zero and ground water seeped in through a leak.