Pentair Pool Heater makes a loud bang (backfire?) when it ignites.

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RJS3

RJS3

0
Apr 28, 2008
14
Upstate NY
I have a Pentair 200 pool heater on Natural gas. I had turned this heater on when I first opened the pool and it fired up well. Then I decided to power wash it as I was cleaning my deck. Bad idea. I killed the membrane pad. So I vacuumed and cleaned out the inside of the heater (with some forced air) and replaced the membrane pad, now that a button was not working. After everything was done, I cranked it up. The membrane pad worked great. But as soon as the valve opened and the ignitor fired, I got a loud bang that sounds like a backfire. It kept banging over and over again until I finally turned it off. Here is a link if you want to hear/see what I mean. <
>. I ordered a new igniter just to see if that might be the issue. I pulled the old igniter out and it pretty much crumbled in my hands, though that might have been my fault for touching it. I have had this heater for 10 years and never had a problem with anything. The gas flow should be fine, but I haven't tested it. I have a call into Pentair, but does anyone have any suggestions?
 
As I said, only time I've seen that is with water in the line. Gas flow gets interrupted and then clears rapidly. To test:
Close the gas cock. Pull the cap. Turn gas on. If there is water you will hear a gurgling sound, may get a few drips. Only takes about 10 seconds, don't go longer and no smoking. Let the gas dissipate for a minute before reassembling. Natural gas will rise. If this is propane it is better to have an experienced tech work on it.
 
1poolman1 said:
As I said, only time I've seen that is with water in the line. Gas flow gets interrupted and then clears rapidly. To test:
Close the gas cock. Pull the cap. Turn gas on. If there is water you will hear a gurgling sound, may get a few drips. Only takes about 10 seconds, don't go longer and no smoking. Let the gas dissipate for a minute before reassembling. Natural gas will rise. If this is propane it is better to have an experienced tech work on it.
Click to expand...
I saw a vid on this very thing. Its worth a try. The Pentair person I talked to suggested that there might be something wrong with the Thermal Regulator. But I'm going to do the gas test first.
 
So here is an update to this issue. At the suggestion of @1poolman1 I checked the gas line for water (don't smoke :)), and all looked good. The cap to the gas trap looked brand new, gas flowed out normally and I could not detect any gurgling sounds or water dripping or anything out of the ordinary.

Following the Pentair tech advice, I checked the Termal Regulator as well. I pulled it out and tested it under hot and cold running water. It worked flawlessly. I reinstalled it. The new ignitor came. I installed that. (FYI: The Pentair tech told me I probably didn't need an ignitor because when they go, they don't light at all. And this one is lighting as was the old one.

So after everything was back together, I tested it. Same issue happened. Heater turns on, the valve opens, the ignitor lights, and there is a bang and it does not stay lit. Now that I am a bit more used to this and not thinking it is going to blow up, I did pay closer attention to the blower when it did this, and I noticed that the air orifice/intake blew off when the bang happened. Here is another short vid illustrating this: <
>.

The fan is spinning freely so I doubt there is an issue with the fan or housing. But I am wondering now about the AFS or tubing in and out of the AFS. Not getting an error code, but I wonder if that is the problem. Any thoughts?
 
The Pentair burners are in a sealed burner pot and the only exits are the exhaust fan and the air intake.

You have an air/gas mixture problem in the burners and when the mixture explodes the pressure can only be released through the exhaust and air intakes. That is why you see the air intake being blown off.

Let's check some basics...

What voltage is the heater connected to 120V or 240V?

Show us a pic of the voltage plug in the heater.

full
 
As soon as the venturi blows off the fan the heater will shut off. I've never seen that happen, but have seen them clogged with rodent nests which stops the air flow through it. Guessing you have made sure the securing screw is tight. This is different from your first video that had a series of pops. Why was the vent screen off the exhaust in the first video?
 
I'll address @1poolman1 first. The vent screen is off because I wanted to see if the coils inside and if the chamber was filled with Crud/water. I put my iPhone in an shot some video just to make sure that there wasn't water or anything inside the chamber. Best I can tell, the chamber is good. Both videos have the pop or bang. The first one it happens multiple times. The second video, the bang is not as clear, but it's there and there is only one bang. So initially it was lighting several times in a row with a backfire each time. Now it just does one. I have seen the screen backed up with nest too. It is clean, but I am wondering about the clear hose coming from the AFS back to the (whatever it goes into). I'm going to check for any hose cloggings tomorrow. But I think they are clear.

I'm thinking @ajw22 might be on to something with air/gas mixture. That makes sense to me as a typical way a backfire occurs. I can post a pic tomorrow, but it does have the 120 plug in it. I will say that after the first year I had it, I had a mouse in there and needed to tape some of the wires. But I'll post a pic when its light out.

Thank so much for the help. This site rocks.
 

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attached is a pic of the electrical. It has the 120 plug and the wires seem in good shape. There are a couple of electrical tape repairs I had to make when a mouse nested in their one winter. I am curious about how to deal with a potential air/gas adjustment @ajw22 IMG_4800.JPG
 
I know you are trying to get the heater running but those electrical tape repairs on heater wiring is not proper and you have major corrosion around grounds that will cause operational problems.

I think it is time to put down the tools and shop for a new heater. This one will never be safe.
 
@ajw22, I hear you on the job. I did clean up the grounds, and the electrical tape was some added sheathing when a mouse chewed on the wire some years ago. I re-did a couple of the connectors and the electrical tape is gone now. There were no breaks. Anyway, I'm not quite ready to throw in the towel. The replacement cost is steep with a kid in college.

I'm thinking I might try to pull the fan and just check it more closely as @Poolbreh suggests. It's a pain to pull the fan, but it might be worth it and it would give me a chance to inspect the heat exchanger a bit. The fan is spinning freely, but there could be a blockage somewhere. The AFS seems to be fine, as best I can tell. I am getting a fair amount of suction on the air intake, but I am not sure what it should be.

If anyone has any other thoughts, I am happy to give it a try.
 
My next suggestion was going to be to inspect the burner. I've never heard or seen rodents in the combustion chamber, but maybe. Also, look for a cracked burner. That would allow too much gas into the chamber and cause explosive ignition. Again, never seen it in a Max-E-Therm/ MasterTemp.
 
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RJS3 said:
I'll address @1poolman1 first. The vent screen is off because I wanted to see if the coils inside and if the chamber was filled with Crud/water. I put my iPhone in an shot some video just to make sure that there wasn't water or anything inside the chamber. Best I can tell, the chamber is good. Both videos have the pop or bang. The first one it happens multiple times. The second video, the bang is not as clear, but it's there and there is only one bang. So initially it was lighting several times in a row with a backfire each time. Now it just does one. I have seen the screen backed up with nest too. It is clean, but I am wondering about the clear hose coming from the AFS back to the (whatever it goes into). I'm going to check for any hose cloggings tomorrow. But I think they are clear.

I'm thinking @ajw22 might be on to something with air/gas mixture. That makes sense to me as a typical way a backfire occurs. I can post a pic tomorrow, but it does have the 120 plug in it. I will say that after the first year I had it, I had a mouse in there and needed to tape some of the wires. But I'll post a pic when its light out.

Thank so much for the help. This site rocks.
Click to expand...
Your right

Its a “time to engage” or “light” based upon air gas mixture. For my 206A now how to fix that ??

RE heaters 206A
NOTE banging noise from a 206A gas heater that would be the sping in the heater core of the bypass line Or header. its a large screw Cap and once that is replaced (30$ eBay) the banging noise stops.

NOTE: The first thing to check normally is sooting on the coils
to check for sooting . take off the hood cover then with a flashlight in the bottom looking up and out..
if you see the coils in the normal Layout then its fine. If they are full the light will not come thru them..

Raypack has the worlds best tech support for any company. i swear they are so willing to hel….

Now im not sure yet how to fix the mix-air gas issue but i know what it is… and we have 9 of them heaters so im glad in 20 years not once did this happen. (It was an explosion for sure) loud as heck… and worse i could not turn it off so i was worried It would re light…
 
Thanks @Pdxonthego1. I’ve had to put this on hold for a bit as my son just got married, but I’ll be tearing into this shortly. Not sure how the 206a compares to the pentair or if there is a similar “sping in the heater core of the bypass line” but it’s with checking out. I’m also wondering if it’s related to the gas valve. But I’m going to pop open the can and check the coils first.
 

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