Spa/ Pool Heater Cycling.. Need Ideas

[quinnstefanie]

Hello, I am new to this group and a new pool owner as I just bought a house. My kids were very excited about the hot tub in this new house and sadly it is not operating correctly.

The pool has a Pentair MiniMax 400. This is an old model heater. This heater only has one service light and it does not tell you what the error is like newer models.

After heating for 10 minutes or so, it begins to cycle with service light coming on and off. As you can imagine, the cycling makes it take hours to heat the spa. It cycles about every five minutes.

What I have already tried:

1). Put in new high limit switches. Also tried bypassing them. Did not correct the issue.

2). Changed the thermastor with a new one. Did not correct the issue.

3). Installed a new thermal regulator. Did not correct the issue.

4). Bypassed the pressure switch. Did not correct the issue.

5). Tested heating just the pool rather than spa to see if there was some issue with the spa. Problem occurred just the same heating pool versus heating spa.

At this point, I am all out of ideas. I thought the the above would have fixed it. What other sensors Or switches are there that would cause the service light to come on intermittently??

Brandon

 

[ajw22]

Welcome to TFP.

Short cycling is often caused by low water flow.

What type and model filter do you have?

What is the PSI of your filter?

When did you last clean your filter?

 

[quinnstefanie]

Filter is Pentair FNS Plus.

Pressure on filter is showing around 10 right now. It was reduced a lot after backwashed.

I backwashed the filter about a month ago and added the DE. I just bought the house. I have not actually had the filter cleaned yet.

 

[ajw22]

Did you replace this flow valve?

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[ajw22]

Pressure on filter is showing around 10 right now.

At what pump RPM? What model pump do you have?

 

[quinnstefanie]

Did you replace this flow valve?

Pacfab Minimax Plus 400 heater is short cycling

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Hi I am brand new to the forum, but looking forward to the wealth of knowledge here. I live in Phoenix and bought a house with a large (~40,000 gal) pool + spa + water feature. Recently I have been having trouble with my Pentair Minimax 400 short cycling. I pulled the flow valve today and...

www.troublefreepool.com

Yes. I did replace that part. I don’t think the old one was bad but replaced it anyway. Did not fix the problem. I will get you the pump model in a moment.

 

[ajw22]

Attached is the MiniMax Plus Service Manual. See page 30.

Also attached is the MiniMax Installation Manual.

 

[quinnstefanie]

At what pump RPM? What model pump do you have?

It is a Pentair superflo High performance pump

Not sure where to find the RPMs. It is 2 hp.

 

[ajw22]

You have a singe speed pump running at 3450 RPMS.

10 PSI is low for a Pentair FNS DE filter with a SS 2 HP pump.

Post pics of your equipment pad.

When did this problem begin?

When did the heater last work properly?

 

[quinnstefanie]

The problem has persisted since I bought the house several months ago and first try the heater. It could be new or possibly been this way for years. Don’t have a relationship with the previous homeowner.

Right now at the 10 psi, I am only running the pool and spa returns. I believe the psi goes up some when running the spa drain and cleaner. However, it stays below 20.

 

[ajw22]

The arrow points to a valve that diverts water from your filter and heater to a cleaner line.

What type of cleaner do you have connected to this cleaner line?

You should close this line by turning the handle 90 degrees to the right so that all water flow goes through your filter and heater.

Do that and tell me what your filter PSI becomes and if the heater works better.

 

[1poolman1]

The problem has persisted since I bought the house several months ago and first try the heater. It could be new or possibly been this way for years. Don’t have a relationship with the previous homeowner.

Right now at the 10 psi, I am only running the pool and spa returns. I believe the psi goes up some when running the spa drain and cleaner. However, it stays below 20.

Is this a propane heater? If so, is your tanks at least 50% full? What else is on that gas line? It appears that the supply splits, though can't really see behind the leaves in the picture. MiniMax heaters were extremely sensitive to low gas pressure and can have the issue you describe. Have you cleaned the flame-sense rod?

 

[quinnstefanie]

The arrow points to a valve that diverts water from your filter and heater to a cleaner line.

What type of cleaner do you have connected to this cleaner line?

You should close this line by turning the handle 90 degrees to the right so that all water flow goes through your filter and heater.

Do that and tell me what your filter PSI becomes and if the heater works better.

View attachment 467305

I will give it a try. Please standby. It seems like I may have tried the heater with the cleaner closed but maybe not. I will try.

It is a Polaris vacuum cleaner.

 

[ajw22]

Show me pics of the way your valves are when in SPA mode.

 

[quinnstefanie]

Show me pics of the way your valves are when in SPA mode.

Here is spa mode with the cleaner off. I am trying it now to see if it cycles.

 

[quinnstefanie]

Is this a propane heater? If so, is your tanks at least 50% full? What else is on that gas line? It appears that the supply splits, though can't really see behind the leaves in the picture. MiniMax heaters were extremely sensitive to low gas pressure and can have the issue you describe. Have you cleaned the flame-sense rod?

It is all natural gas. It is high pressure.

 

[quinnstefanie]

It is all natural gas. It is high pressure.

Where is the flame rod? That is an interesting idea. Have not addressed that yet.

 

[ajw22]

Here is spa mode with the cleaner off. I am trying it now to see if it cycles.

What is your filter PSI when the valves are set for the spa with the cleaner off?

 

[1poolman1]

It is all natural gas. It is high pressure.

That regulator steps the pressure down to less than .5psig (10" water column). Do the following first.

Where is the flame rod? That is an interesting idea. Have not addressed that yet.

Looks like this, has a single wire running to it. Don't use sandpaper. Literally a newer dollar bill works great.

 

[quinnstefanie]

Here is spa mode with the cleaner off. I am trying it now to see if it cycles.

It is still cycling with the cleaner valve off. See pic with service light that just popped up. psi shows 20 in spa mode.