Max-E-Therm 400 heat turning off after a few seconds

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grunky_peep

Gold Supporter
May 26, 2020
143
Sacramento, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
So I'm in the Sacramento and we just received 6" of rain over the weekend. Ever since, my heater will light (I hear the large boom and it rumbles the house), stays on for 3-5 seconds, and then it goes out. This repeats 3 times before it shuts itself off and the "Service Heater" LED lights up. Putting my hand by the exhaust, I can feel the heat for those 3-5 seconds, then it goes back to air temperature. Not sure if water from our downpour got into the enclosure somehow? It's worked just fine for the past 18 months we've owned the house, and just started having this issue after our weekend rain.

Is there anything easy I can check before paying someone to come look at it? I've never opened it up before, so this is brand new territory for me.
 
JamesW said:

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com
Click to expand...
Thanks. Reading this, it sounds like the flame sensor is being wonky. I can hear the gas start and the burner ignites, but then shuts off after a few seconds like it didn’t detect a flame.

Anyway, I tried it later in the day and it actually ignited. I let it run for 15 mins or so and the spa warmed up. It went out once or twice, but was able to reignite and keep warming the spa.

So I’m guessing the flame sensor got wet from the rain somehow, and just took some time to dry out? I’ll try it later today to see if it can run longer without having to reignite.

This will be one $2500 repair/replacement I’ll be glad to avoid :)
 
Just a follow up.

Used the spa without issue a couple nights ago. Heater kicked on and stayed on without having to re-ignite. Guessing some water just got inside the enclosure? Not sure.
 
Old thread of mine, but this is happening again after we have gotten hammered with rain for a few weeks straight now. Sometimes it'll heat 10' or so, then start the shutoff/3 retry cycle.
This time I opened up the egg just to check things out since my kids really wanted to go in the spa this weekend. I found the igniter and have a consistent 61 Ohms across it, so I don't think there's anything particularly wrong with it. I didn't unscrew it due to the weird location, so I couldn't visually check it out.

There was this switch that where the terminals were filled with water. The terminals labeled TH/TR were filled with water as well. I tried blowing it out with canned air to dry it out, but it was still moist afterward. Not sure if that would be the issue, but I'm guessing water in a switch never helps. The gas supply pipe is in the bottom of this pic and feeding into the switch:
99C73EE1-B57D-455E-AE50-CA63FF68D20E.jpeg
 
Check for water in the combustion chamber by removing a bottom bolt on the manifold.

If water comes out, the combustion chamber has water in it, which is usually due to a leak in the heat exchanger.

1673982491231.png
 

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JamesW said:
Check for water in the combustion chamber by removing a bottom bolt on the manifold.

If water comes out, the combustion chamber has water in it, which is usually due to a leak in the heat exchanger.

View attachment 469507
Click to expand...


Thanks! I'll definitely check these out. The heater fired up last night and brought the spa to temperature without any ignition retries or other issues, so I feel like there's definitely water somewhere that dries out after a couple days. Next time it happens I'll check for water in the combustion chamber.
 
I have had a similar issue with a maxetherm after heavy rains. It was replaced with mastertemp so I never discovered the remedy. My thought was maybe the water that was getting in and sitting ontop of the combustion chamber(which was always wet after heavy rain) was disrupting the ground, causing the flame rectification dc reading to be inaccurate.
 
grunky_peep said:
Old thread of mine, but this is happening again after we have gotten hammered with rain for a few weeks straight now. Sometimes it'll heat 10' or so, then start the shutoff/3 retry cycle.
This time I opened up the egg just to check things out since my kids really wanted to go in the spa this weekend. I found the igniter and have a consistent 61 Ohms across it, so I don't think there's anything particularly wrong with it. I didn't unscrew it due to the weird location, so I couldn't visually check it out.

There was this switch that where the terminals were filled with water. The terminals labeled TH/TR were filled with water as well. I tried blowing it out with canned air to dry it out, but it was still moist afterward. Not sure if that would be the issue, but I'm guessing water in a switch never helps. The gas supply pipe is in the bottom of this pic and feeding into the switch:
View attachment 469505
Click to expand...
You should seriously consider replacing that gas valve. Anytime a gas valve is exposed to that much water it can be compromised. If it fails closed, no problem because no flame. The issue is that they can fail open which will mean the heater won't shut down when it is supposed to.

Every heater school I ever attended warned against putting a corroded gas valve back into service.
 
1poolman1 said:
You should seriously consider replacing that gas valve. Anytime a gas valve is exposed to that much water it can be compromised. If it fails closed, no problem because no flame. The issue is that they can fail open which will mean the heater won't shut down when it is supposed to.

Every heater school I ever attended warned against putting a corroded gas valve back into service.
Click to expand...

This is probably a very good idea. I've got no idea how old the heater is, but I had to pay a nice bag of money to replace basically everything but the heater and filter egg when I moved in almost 3 years ago now. I'd put my money on them not maintaining anything that well. Is this something I can DIY (don't think I'd take on messing with anything gas-related) or a part I can buy? Or does it have to go through a pool service pro?

Side note: I see you are in Sacramento as well!
 
grunky_peep said:
This is probably a very good idea. I've got no idea how old the heater is, but I had to pay a nice bag of money to replace basically everything but the heater and filter egg when I moved in almost 3 years ago now. I'd put my money on them not maintaining anything that well. Is this something I can DIY (don't think I'd take on messing with anything gas-related) or a part I can buy? Or does it have to go through a pool service pro?

Side note: I see you are in Sacramento as well!
Click to expand...
If you're not comfortable with replacing gas-related parts it would be good to hire a pro, yes.
If you want to DIY, here's the best price you will find:
bestpoolshop.com

Max-E-Therm MasterTemp Heater Gas Control Valve 42001-0051S

Buy Max-E-Therm MasterTemp Heater Gas Control Valve 42001-0051S for the best price and Free Shipping.
bestpoolshop.com bestpoolshop.com
 
Following up again with different symptoms since I'm now seeing the issue seen by a few people here. It's been dry for a while now, but the ignition isn't happening at all now.
Also because I've read a ton about this heater since, and did a bunch of testing yesterday that I'm now comfortable doing. It is the a 2011 non-connected version.

- No error LEDs underside the control board
- 3 blinking LEDs on Fenwal (ignition lockout)
- AFS correctly closing the circuit when air flow is present. Open circuit when no airflow.
- 60 Ohms across the igniter
- No water when taking the bottom manifold bolts off
- No normal hiss at my gas meter when it's on

When I turn the spa on, the AFS clicks, I think the gas valve clicks? But I'm no longer hearing any 'squeak' of a valve opening, and I don't smell any gas, and definitely no rumble of ignition. After 3 tries, the Fenwall throws the cutoff LEDs.
So yeah, @1poolman1 , I do think the gas valve is faulty, possibly from all of the water. I don't feel comfortable making gas connections myself, so I am having a pool service tech come out to diagnose and replace it, if it is indeed the issue. Unless it's a simple "screw gas inlet into new valve, and connect the air lines" 15-minute job, because I'm sure I'll get overcharged for the part and probably a few hundred of labor at the minimum.

The other possibility is the gas supply line is obstructed somehow, but it's been completely fine until this week. Only leaving this as a possibility after reading this thread:

Sta-Rite Max-E-Therm Will Not Light No Error Codes

Suddently our pool heater stopped lighting. I had a decent pool guy come out and he told me he thinks, isn't sure, that it's the blower because there are no error codes and he changed out the igniter. Sigh. So I found that hard to believe so started on my own investigation (Electrical...
www.troublefreepool.com www.troublefreepool.com

I do think it's the valve though, and went ahead and ordered from the link you dropped above. Seemed to be the cheapest from browsing around.

Is there a better way to protect it from the water?
 
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grunky_peep said:
Following up again with different symptoms since I'm now seeing the issue seen by a few people here. It's been dry for a while now, but the ignition isn't happening at all now.
Also because I've read a ton about this heater since, and did a bunch of testing yesterday that I'm now comfortable doing. It is the a 2011 non-connected version.

- No error LEDs underside the control board
- 3 blinking LEDs on Fenwal (ignition lockout)
- AFS correctly closing the circuit when air flow is present. Open circuit when no airflow.
- 60 Ohms across the igniter
- No water when taking the bottom manifold bolts off
- No normal hiss at my gas meter when it's on

When I turn the spa on, the AFS clicks, I think the gas valve clicks? But I'm no longer hearing any 'squeak' of a valve opening, and I don't smell any gas, and definitely no rumble of ignition. After 3 tries, the Fenwall throws the cutoff LEDs.
So yeah, @1poolman1 , I do think the gas valve is faulty, possibly from all of the water. I don't feel comfortable making gas connections myself, so I am having a pool service tech come out to diagnose and replace it, if it is indeed the issue. Unless it's a simple "screw gas inlet into new valve, and connect the air lines" 15-minute job, because I'm sure I'll get overcharged for the part and probably a few hundred of labor at the minimum.

The other possibility is the gas supply line is obstructed somehow, but it's been completely fine until this week. Only leaving this as a possibility after reading this thread:

Sta-Rite Max-E-Therm Will Not Light No Error Codes

Suddently our pool heater stopped lighting. I had a decent pool guy come out and he told me he thinks, isn't sure, that it's the blower because there are no error codes and he changed out the igniter. Sigh. So I found that hard to believe so started on my own investigation (Electrical...
www.troublefreepool.com www.troublefreepool.com

I do think it's the valve though, and went ahead and ordered from the link you dropped above. Seemed to be the cheapest from browsing around.

Is there a better way to protect it from the water?
Click to expand...
The StaRites are fairly well protected from water, but have to be open enough to allow the combustion blower to get the proper amount of air. Heavy, wind-driven rain can sometimes get in, a heater under an eave that doesn't have a gutter or one that is clogged can cause the issue. I saw one that was under a tree and, even though the limbs were sufficiently high above the heater, there was enough water that would run off the tree that it would get into the shell. It would pour almost like a shower right onto the heater. Happened to an older Laars once as well, ruining that heater.
 
1poolman1 said:
The StaRites are fairly well protected from water, but have to be open enough to allow the combustion blower to get the proper amount of air. Heavy, wind-driven rain can sometimes get in, a heater under an eave that doesn't have a gutter or one that is clogged can cause the issue. I saw one that was under a tree and, even though the limbs were sufficiently high above the heater, there was enough water that would run off the tree that it would get into the shell. It would pour almost like a shower right onto the heater. Happened to an older Laars once as well, ruining that heater.
Click to expand...
Good to know. We do have partially clogged gutters, and the rain flows down that wall when it rains really hard, so that might be contributing. I can definitely see how wind would blow it in the upper vents and get into the switch though. Since it looks like you're in Sac as well, as you know, we've definitely gotten a few really windy storms this year. :)

Well, I paid $30 to upgrade the shipping. Hopefully the gas valve gets here quickly. I can't seem to find any video tutorials on how to replace the valve. You wouldn't happen to have one handy, would you? If not, I'll just pay the pool guy to install it.
 
grunky_peep said:
Good to know. We do have partially clogged gutters, and the rain flows down that wall when it rains really hard, so that might be contributing. I can definitely see how wind would blow it in the upper vents and get into the switch though. Since it looks like you're in Sac as well, as you know, we've definitely gotten a few really windy storms this year. :)

Well, I paid $30 to upgrade the shipping. Hopefully the gas valve gets here quickly. I can't seem to find any video tutorials on how to replace the valve. You wouldn't happen to have one handy, would you? If not, I'll just pay the pool guy to install it.
Click to expand...
Quite literally the gas line is removed, valve is un-screwed and then the new one screwed on, and gas line replaced. Sometimes, on those heaters, the water connections have to be removed to get clearance to move the gas line without disturbing it more than necessary. But, if you're not comfortable working with gas plumbing, let a pro do it. You'd need a couple of pipe wrenches, pipe dope, a large Channel Lock pliers (sometimes) at the very least. Care must be taken with the valve as it has an aluminum body that can be damaged.
 
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Ok, am now 99% certain it’s a bad valve. Followed the troubleshooting flow chart in the manual and also ended up on replace the gas valve. I’m reading 26VAC across the valve terminals during the ignition try.
IMG_8214.jpeg

IMG_8213.jpeg

IMG_8215.jpeg
 

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