Problem with heater

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Brandon Penland

Member
Apr 18, 2023
22
Charlotte, NC
I have a mini max plus 400 heater that has been around for about about 20 years.

I was having problems with it and recently replaced the flame sensor/fire sparker mechanism, and it has been working great ever since until today.

Today, I was heating the pool and it was heating fine until it wasn’t. I came back to the heater and the service light was on and I could hear a constant clicking noise where it was trying to fire.

I can see that the spark is working and I see a small flame to start the heater. It is almost like it is not giving out the gas so it will not ignite

Does anyone out there have any ideas to help me out of how to fix this. I would love to get my pool heated for tomorrow. Again, it just keeps sparking constantly but will not start.

Any help is appreciated.

The picture is the old part that I replaced with a new one already.
 

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You could have infant mortality of the flame sensor you replaced. Check the connections to it and clean it with a rolled up dollar bill.

Otherwise you need to check the static and dynamic gas pressures with a manometer and see if you have a gas pressure or gas valve problem.

Let’s see if @swamprat69 is around .
 
Thanks for the advice and info.

I do not own a manometer, but I am thinking it is probably the valve because it was running fine for about three hours and then just switched over to clicking with no gas. Seems like the gas pressure would not of changed sporadically (Just a theory).

I will try to mess with the flame sensor and clean it but is very very new and looks clean.

Is there a way to clean or repair a valve without replacement. Also, I checked all three connections, pilot, proving, and main. They are all show electrical current when I turn heater on.
 
Gas valves should not be tinkered with or repaired. They should only be replaced.

Do you have a proper sediment trap on your heater gas line? You could have sediment clogging the gas line or valve. You could have a gas meter problem.
 
I’m not sure what to look for with the sediment trap, but I’m guessing this drop-down pipe could be set to catch sediment.

I also just tried cleaning all the electrical connections. It did not fix the problem.
 

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Your heater does not look like it has been cleaned and operation checked by a qualified technician in a while. This can effect its operation in various ways. Let me know if this assumption is not correct. The valve that you are showing is not a replacement for the valve that is shown in your first photo if it is the original valve that the heater came with. The 7th digit (a letter) in the model number is the opening characteristic of the gas valve. K = slow opening and M= standard opening. You should only replace a gas with one that has the same opening characteristics as the original as that was how the heater was certified.
 
Brandon Penland said:
I’m not sure what to look for with the sediment trap, but I’m guessing this drop-down pipe could be set to catch sediment.

I also just tried cleaning all the electrical connections. It did not fix the problem.
Click to expand...
Your sediment trap is not correctly done so that the gas makes a 90 degree turn while any sediment drops into the trap.

Your gas line will blow sediment directly into the gas valve and clog it.

1711897252255.png
 
swamprat69 said:
Your heater does not look like it has been cleaned and operation checked by a qualified technician in a while. This can effect its operation in various ways. Let me know if this assumption is not correct. The valve that you are showing is not a replacement for the valve that is shown in your first photo if it is the original valve that the heater came with. The 7th digit (a letter) in the model number is the opening characteristic of the gas valve. K = slow opening and M= standard opening. You should only replace a gas with one that has the same opening characteristics as the original as that was how the heater was certified.
Click to expand...
I was able to get a crossover sheet from Honeywell attached and I believe this references the correct universal part and a couple competitor parts that also crossover. I assume that I would be safe to replace it with the univerasal or competitor?

Having my sediment trap in the wrong place would explain how over time the valve could get damaged.

I really haven’t had it serviced, just been fixing it myself as I actually like to learn this stuff. Last resort, I will eventually have everything replaced once I get the money lined up.

My logic here is since I’m seeing the Pilot flame, seeing electrical current, showing up in all three terminals, and hearing the clicking sound that it is trying to get gas, it is probably the valve. Would this logic be likely or is there something else I should consider?
 

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Both K and H in the 7th digit designate a slow opening gas valve, You could go with a competitors valve that crosses to your original honeywell valve model number, but the physical pilot and electrical connections may require you to make some adaptations. Page 2 shows model specifications
 

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It is entirely possible that the problem is not with the gas valve, so I would first try to get a qualified technician to do a throrough clean and check on the heater. I know that this can be difficult as most HVAC techncians won't work on pool heaters and most technicians that do work on pool heaters have minimal training in gas heaters.
 
I see you have a regulator on the gas line between the sediment trap and the heater. The sediment could have clogged the regulator and never got into the gas valve. That regulator could have failed.

Goes back to why you need to put a manometer on the gas valve and see if the heater is getting proper static and dynamic gas pressure.
 
ajw22 said:
I see you have a regulator on the gas line between the sediment trap and the heater. The sediment could have clogged the regulator and never got into the gas valve. That regulator could have failed.

Goes back to why you need to put a manometer on the gas valve and see if the heater is getting proper static and dynamic gas pressure.
Click to expand...
Good advice. I’ll pick up a manometer before I buy the valve. Do you know the ideal measurement? I think I see on the picture that it needs to be between three and five.
 
Brandon Penland said:
Good advice. I’ll pick up a manometer before I buy the valve. Do you know the ideal measurement? I think I see on the picture that it needs to be between three and five.
Click to expand...

It is in the manual which is attached to this post...

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OK. Just checking in with update. I got a hold of a manometer. I tested the inlet side and it read 8. I tested the outlet side with the heater turned on. Nothing but clicking, I can see piolet flame, and the outlet side is reading 0 on manometer. My deduction from this test is that the gas pressure is fine, no clogs in the line. It seems like the valve is just not opening.

(I am seeing volts of electricity showing up on my voltmeter at all electrical connections when heater is turned on. )

Now that I’ve run this test. Let me know if anyone sees any other variables, or if it is just time to replace the valve. I went ahead and grabbed a valve that I on standby is the universal replacement on Honeywell crossover guide.

Thanks again for everyone’s help.

Brandon
 
Thanks for everyone’s help. I had success today. I replaced the valve and now it works.

The old valve did indeed have alot of debris in it looking through the outlet when I removed it. I’m sure that has built up over many, many years. Checked all my joints with soapy water to ensure there are no leaks.

Thanks for everyone’s advice. It helped a lot.

While I had all the pipes out, I cleaned the burners , got all the carbon debris off of them and the cleaned the water pipes that they heat up.

Interesting, the heater now seems to run more quietly, I don’t know if the new valve is set lower with gas pressure or if it is just from the cleaning that I did. The flame still looks solid, and they are blue. It just seems like the heater used to have a low roaring sound, now, it is pretty much quiet. Any thoughts?
 
Brandon Penland said:
It just seems like the heater used to have a low roaring sound, now, it is pretty much quiet. Any thoughts?
Click to expand...

The heater was talking to you and no one was listening.

Sounds like you have it working well now with a strong blue flame.
 

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