[SOLVED Again] MasterTemp 400 Igniting Momentarily, No Diagnostic Codes

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H

huggablejunk

Bronze Supporter
Nov 14, 2017
33
Marietta, GA
This may be related to my previous issue, but I'm at wits end trying to figure out what could be my issue now.

SOLVED: MasterTemp 400 Service Heater Light

Hi there, I have a 4-year of Mastertemp 400. Recently, we discover a family of mice were living in the heater and had urinated all over the control boards internally. The heater would turn on, the blow would turn on, and then the heater would fail to light and eventually light of the...
www.troublefreepool.com www.troublefreepool.com

For the past few weeks I can not get my heater to stay lit for more than a second.
When I got to the EasyTouch Panel and turn on the heater for the SPA, everything starts up normally.
The heater and blower turn about 20 seconds later, the gas valve flips with a noticeable click, the gas ignites, the exhaust pipe rumbles for about a second because its burning fuel, momentary heat, then no more rumble as if the flame is extinguished. The heater try agains, exact same thing happens, 3 more times, then finally the Service Heater light comes on.

From my last post, I knew how to dig into the heater immediately to check for diagnostic LEDs.
I am receiving absolutely zero diagnostic LEDs on the back of the control board and the Fenwal Ignition Board doesn't have any blinking lights (like it did last time).
The EasyTouch reports no issues and there are no diagnostics codes on the startup of the heater.
It appears as if everything is working, but in fact it doesn't stay lit.

Is there a silent failure on one of the sensors somewhere?
What in the world could be causing this? Nothing has changed with my setup outside of winter arriving and the pool/spa cycling through frost protection when its below 36 degrees.
No mice this time either, all mouse proofed, all the wires look great.

From my previous maintenance about 3 months ago:
  • Replaced Fenwal Ignition Control Board
  • Verified grounds are clean and in good working order
  • Replaced the Hot Surface Ignitor
  • Replaced High Limit Switch
  • Replaced Thermal Regular and Thermsistor (Just verified regulator looks and works good)

Thanks for any troubleshooting advice.
I have no idea what to do next, there isn't an obvious sensor issue that the heater is reporting.
 
I think I see your MO here ;)
Going to have to buy a True-RMS multimeter.

I was outside fiddling with it today and eventually I did get an error code from the Fenwal: 3 Flashes Ignition Lockout.
I cleaned the grounded contacts again and tried a combo of the wires on the grounding box but nothing seemed to fix it.

Since I just replaced the Fenwal in October 2019, is it possible the board went bad?
Think its worth trying to replace it and return the new board if the same thing happens?
It worked initially for a few months and then recently with no noticeable damage anywhere it just starts not being able to ignite.

In the back of my head I keep thinking that I have a combustion chamber leak. The unit is only 4 years old and I didn't have notice any kind of rusting of damage to the outside of the boiler by the mice. Am I wrong to think this?


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I would start by bench testing all the components ... yeah again. The HSI would be a good place to start. Also check the solenoids on the valve. If there are no error codes except for an ignition lock out on the Fenwal, I bet the board is fine and something else if preventing ignition. You say it ignites for a few seconds? or is it just the blower coming on.
 
Three flashes indicates no flame current being sensed.

Get a good true-rms meter that can measure dc microamps and see what the flame current is.

You can remove one of the bottom manifold bolts to see if water comes out, which would indicate a heat exchanger leak.
 
@setsailsoon had problems with the flame current on his heater. Maybe Chris will have some ideas based on what he found.
 
Hug,

I had the exact same frustration after a lightning strike. As James said you have a flame-sense issue. I have the exact same Fenwel module. The flame sense circuit is extremely reliable and sensitive. I found that testing for the flame sense signal is easy if you have the right equipment but if not it's easier just to assume you have a good signal with a new module. If this assumption is correct your problem is one of the following (so long as you hear the flame ignite and briefly feel heat from the exhaust):
  1. Corrosion in the grounding circuit
  2. Broken or corroded current sensing wire
  3. Interference in the ground signal
You can fix these as follows:
  1. Take the blower flange bolt loose and strip a wire with a longish strip ( 1inch or so) then slide it into the gap between the flange and the flame tube, Connect this to the yellow ground wires that are ganged inside the control panel (usually next to the Fenwel). Then restart the unit and see if this works. This will ensure you have a good ground connection to the Fenwel which is required to measure the tiny signal.
  2. Sounds like you've had potential issues like this from your rat problem in the past. So double-check the wire by replacing it.
  3. If the power supply wire insulation to the unit is compromised you can have leakage to the ground circuit that is very small so the unit will actually work but the ground has sufficient interference that it prevents the flame sense circuit inside the Fenwel from working. This can cause the Fenwel test pin readings to indicate a bad module but it isn't bad it's your power supply quality. To test this simply rig up a temporary parallel supply wire. I used a piece of romex wire I had laying around in the garage. Run it to a different breaker if possible. This is a test wire only, don't leave it in place due to the obvious hazard. If your unit runs this way then just re-pull new supply wires
An aside on testing the flame sense signal: If you don't have the RMS meter that James describes you can just test for voltage on the two test pins to confirm if you have flame sense. Voltage is an indirect indication but easier to do with typical DIY equipment. But it's still very difficult to measure unless you make up some pin wires to clip your voltmeter to. Or you can order some insulated micro clips for the test. The reading should be 3-8 volts and this corresponds to the millionth's of an amp signal your flame sense signal should reading. If you try to check this be very careful since you can easily short the 24 vac circuit which can blow the transformer before the 2 amp fuse blows.... really aggravating! On my unit the fuse was incorrect so my transformer did a great job of protecting it ($87!).

You'll read a lot about potential problems with the igniter location. Your heater is very similar to mine and there's no adjustment to this. It works fine if you have a new igniter installed properly. It's almost impossible to do it wrong. Since you have a new igniter and new Fenwel they are almost certainly not the problem unless you got the Fenwel from a cheap eBay site. I did get one bad one from a cheap source then switched to an authorized reseller.

I hope this helps.

Chris
 

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Here is a status update on where I landed. I tried all that stuff in that document and none of it worked.

So, I called my pool company and they came out and determined that I have zero gas-flow at the pool heater. There is another thread in this forum that has something similar where the guy chased down the problem for months and it ended up being a gas regulator issue.

The pool company went back to the meter and showed me that when the flipped the valve you had a sudden woosh of gas from the pressure built up but then the sustained pressure was very low. Apparently its not low enough to not run my hot water heater or fire pit or furnaces, but its low enough at the pool heater that you can't even smell gas coming out and I understand that the MasterTemps need higher pressure. This is why you can smell a bit of gas when you try to ignite first after sitting overnight but then there isn't enough sustained pressure.

So they recommended that I call the gas company and have my meter replaced.
They pool company indicated that they might need to put on a regulator on the line but I didn't need one for the past 4 years.
Gas company can't make it out for a few weeks due the quarantine.

So the real question, is it common to have gas meter issues?
The gas meter was installed by the gas company 4 years ago when we put the pool in.

I also really wish there was a way to install a pressure meter on the gas line so this is something thats easily diagnosable in the future.
 
huggablejunk said:
Here is a status update on where I landed. I tried all that stuff in that document and none of it worked.

So, I called my pool company and they came out and determined that I have zero gas-flow at the pool heater. There is another thread in this forum that has something similar where the guy chased down the problem for months and it ended up being a gas regulator issue.

The pool company went back to the meter and showed me that when the flipped the valve you had a sudden woosh of gas from the pressure built up but then the sustained pressure was very low. Apparently its not low enough to not run my hot water heater or fire pit or furnaces, but its low enough at the pool heater that you can't even smell gas coming out and I understand that the MasterTemps need higher pressure. This is why you can smell a bit of gas when you try to ignite first after sitting overnight but then there isn't enough sustained pressure.

So they recommended that I call the gas company and have my meter replaced.
They pool company indicated that they might need to put on a regulator on the line but I didn't need one for the past 4 years.
Gas company can't make it out for a few weeks due the quarantine.

So the real question, is it common to have gas meter issues?
The gas meter was installed by the gas company 4 years ago when we put the pool in.

I also really wish there was a way to install a pressure meter on the gas line so this is something thats easily diagnosable in the future.
Click to expand...

I remember the thread you're talking about. Validates the old adage to "try the simple stuff first!" Seems to me that many if not most gas meters supply enough to handle a house and a pool heater. But there are some exceptions and most seem to be on older houses. It's not hard to figure out. Just look at the btu/hr for each component. Add them all up and compare that to the meter capacity. Use 1000 btu per cubic foot and add 20% to account for efficiency. Even if you're close or a little over meter capacity you should be OK since meter capacity is at delivery conditions that are above the heater minimum requirements.

You can have the gas plumber install a tee with a small small connection for a manometer that will measure your supply pressure under load. Just be sure to re-install the plug and leak check it with bubble fluid. If you've got plenty of pressure you may have a plugged screen on the gas valve inside the heater or it may be failing. This is very rare though.

Chris
 
When we installed the pool 4 years ago, we called the gas company and installed a larger meter. This meter feeds the house with furnaces and hot water as well as fire pit and grill hookup in addition to the heater. I have no regulator on the line and I didn't need one for the past 4 years, I have literally have had zero problems with the heater. Then along comes the mouse that wrecks the Fenwal and grounds and now this, coincidental?

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huggablejunk said:
o the real question, is it common to have gas meter issues?
The gas meter was installed by the gas company 4 years ago when we put the pool in.

I also really wish there was a way to install a pressure meter on the gas line so this is something thats easily diagnosable in the future.
Click to expand...
H,
No gas meters rarely fail. There are huge liabilities and that drives residential meter standards to very high quality components. Your meter is rated at 400 cu ft/hr with only .5 in water column pressure drop. That should easily run your heater. Try this. Turn off all gas appliances and turn your hot water heater to standby. Then run the pool heater from it's local panel. Does it run? If so then start each appliance and see if the pool heater fails. I doubt it will. Your heater ran for years with this same setup, right?

Looking at your photo the easiest way to hook up a manometer is at the debris trap in your piping on the gas line into the heater. Remove the cap that is facing down and install an adapter to reduce down to a barbed fitting that will attach to the line. You can get a cheap digital manometer for about $25 from Amazon. Or you can rig a home made one up yourself with tubing, water, and some water dye. I've done it both ways and they both work well. If your not comfortable and/or trained on gas plumbing get a gas plumber to help you. It should be under a couple hundred $.

Hope this helps.

Chris
 
There's a test port directly on the gas valve in the heater.

Is there a shut off valve near the gas meter?

How far is the heater from the gas valve?

Get a good true-rms meter that can measure dc microamps and see what the flame current is when the heater lights.

You can remove one of the bottom manifold bolts to see if water comes out, which would indicate a heat exchanger leak.
 
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The pool technician opened the gas connection at the heater (you can see it in the picture) and nothing was coming out, no pressure, no smell, nothing. The heater is probably 60-70ft from the gas meter. There is a small test port on the main line for the pool heater gas line by the gas meter and this is what the guy opened up to show there is very little pressure coming out, there is nothing behind that except the high pressure gas line. He even opened up the gas valve with everything connected inside the heater and nothing was coming out. I was astounded when he opened the black gas line before it goes into the heater and nothing was coming out.

The only conclusion here was that the gas main isn't metering the high pressure line correctly?

I just went back out to the gas main turned on the line for the pool heater and removed the drip leg of the gas pipe. Found it full of water, turn on the ball valve for gas and absolutely nothing coming out. Attached is a photo of the gas meter, the back pipe with the valve closed goes to the pool heater. You can see its directly into the gas meter. When the guy opened up the little screw just blow the ball valve here very little pressure was coming out.


IMG_8682.JPG
 
It might be a bad ball valve.

If the line is higher pressure, there should be a regulator near the heater to step down the pressure.

If the line is lower pressure, then it's too small.

So, something seems off.
 
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If you don't get flow at the heater and don't smell gas there's definitely no gas at the heater. As James asked did you leave the valve at the gas main closed on purpose?

You should have no water in this system.. Natural gas is dehydrated before it goes into their main trunk line. It's dryer than a popcorn f*rt. Has anything else been done at your house or close by like a hydro-test of the system? It doesn't take much water column to block the flow of gas even if your meter is brand new. Are you having any problems with any other gas appliances?

Chris
 
Ok so I'm posting another photo to help clarify.

The blue arrow is coming from the street into the meter.

The yellow arrow is the branch going to the pool heater (open now). The orange pipe/arrow is connected to the same pipe with yellow valve but the orange branch controls my fire pit and gas stove and these are working fine. So I'm getting some flow just not enough to power the heater at this point. This has been the exact setup for the past 4 years where the pool heater worked, nothing has been modified.

Obviously when I tested by removing the drip leg and opening the local ball valve at the heater, I made sure the valves were opened and I'm getting absolutely nothing at the other end.



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