SFS error on Pentair MasterTemp 250 and coil replacement

Ukiwis

Well-known member
Jul 22, 2018
60
California
My Pentair MasterTemp 250 stops heating and is giving an SFS error.

I have replaced both the thermister and the Flue Stack Sensor but have the same issue.

The heater fires and exhaust temp slowly climbs to 480F then shuts off.

I placed a warranty claim and provided all this information and the service Co indicates that I need a new heater, due to "Checmical Damage". I haven't heard from the warranty Co yet but I believe the wording is specific wording this way so that the claim will be denied. My pool has been serviced 2X week sicne I've owned the property so I doub't it's due to any chemical issue (more likely age related) so if declined I'll be pressing for more information on that. In my opinion, the service Co is just being lazy and I'm fairly certain that this could be resolved without complete replacement.

Anyway, the manual leads me to "Check Heat Exchanger Coil for leaks, liming, soot, or low flow"
1607100820381.png

If I'm unable to get resolution through the warranty Co I plan to open the thing up for a look. If there's evidence of "Chemical Damage" I will probably have a go at this:

Has anyone attempted this and is it relatively simple?
Does the kit include everything that would need to be replaced?
My concern would be that I replace it and introduce some leak due to some seal that I should have replaced at the same time.

TIA
KIWI
 

cowboycasey

Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
4,819
Fletcher, OK
I do not have one so I have not done this.. It looks like you can do it with no issue just your time... most companies want to replace the complete system and it would cost them to much to take it apart and fix..
 
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setsailsoon

Gold Supporter
LifeTime Supporter
TFP Guide
Oct 25, 2015
3,805
Stuart/FL
Pool Size
12800
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-30 Plus
I agree with Casey the only way to repair if you have this issue is DIY. Repair service will cost as much or more than a new heater. The tube bundle alone is the most expensive part in the heater usually close to $1000. It comes with the o-rings for the manifold seal but I don't think it includes the insulation pads.

I've completely disassembled a Jandy version of this heater which is almost identical inside. Requirements are you need to be competent to do gas plumbing work and work with 240 v electrical. Was not hard at all to do though. Just need to be patient and organized with the stuff you remove. Take photos of all electrical before you remove connectors. Same for the air hoses that connect to the blower housing. There's one on the bottom that can be accidentally disconnected and you don't realize it.

Before yo do this I'd confirm water is indeed in the firebox. There are other things that can cause an apparent SFS error. Remove the igniter and use a piece of 1/4" dowel rod as a dip-stick. It should show water if you have this issue and it will be pretty rusty as the video shows if you've had the problem any amount of time.

If you have chemical damage it will be very apparent with tube ends badly corroded inside the manifold. Sadly, weekly maintenance from a pool service rarely prevents since many of them have no idea how to really balance. Even if they know about the chemistry they can only afford to come weekly which means they have to "over treat" and your pool is out of balance to start or at the end of their weekly cycle.

Chris
 

JamesW

TFP Expert
Mar 2, 2011
22,127
Do you have chemistry records?

What is the highest CSI that you have had?

You can try descaling the heat exchanger by pumping descaling solution through the heat exchanger. Remove the thermal regulator before using the descaling solution.


If descaling doesn't help, the heat exchanger might be sooted and you can take it out and clean it.

You can verify the gas pressure going to the heater to help diagnose sooting if that's the problem.

You can remove one of the bottom manifold bolts to see if the heat exchanger is leaking.

If the heat exchanger is leaking, the combustion chamber will fill with water and water will come out when you remove one of the bottom manifold bolts.

If no water comes out, the heat exchanger probably does not need to be replaced.
 
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swamprat69

Well-known member
Mar 30, 2019
374
Las Vegas, NV
I assume that you are talking about a "Home warranty Co." that covers your pool equipment. The service company that was sent out by the "Home warranty Co." is supposed to diagnose the problem with your heater and exactly what has caused this problem. There are many things that can cause an "SFS" error. Reduced flow of combustion byproducts through the heater due to physical restriction of flow through the heat exchanger or or reduced air flow from the blower due to a weak blower capacitor or failing motor bearings. Reduced water flow through through the heat exchanger for various reasons. Reduced flow of combustion byproducts through the heat exchanger due to standing water in the combustion chamber from a leaking heat exchanger. Inability of heat exchanger to transfer heat due to a thermal barrier caused by scaling of the inner surface of the heat exchanger. I am not sure exactly what has been done so far to by the Service Co. to either eliminate or pinpoint the cause of the problem, but it sounds as if they are saying that the problem is either a leaking or scaled heat exchanger due to water chemistry without opening up either the combustion chamber or the heat exchanger??? Both of these can be proven by physical observation. Are they arriving at this conclusion simply by supposed elimination of other possibilities and are their elimination of other possibilities valid through standard diagnostic procedures. It sounds as if they are putting the onus on you to disprove their diagnosis rather than actually proving their diagnosis. Caveat: Many service Co. technicians are not capable of correctly troubleshooting and diagnosing problems with a heater/system and are geared towards selling replacement equipment rather than repairing an existing heater/system.
 
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Ukiwis

Well-known member
Jul 22, 2018
60
California
So, the service Company is telling ORHP that the issue is "chemical damage due to a missing check valve". They also state that the "heat exchanger is leaking badly and a new heater is required. They were here for about 7 mins.

So...
  1. can someone determine that the heat exchanger is leaking in such a short period of time.
  2. Is there something wrong with my setup and is a check valve needed on the heater? It looks like water goes through the heater whether or not it is turned on so I have no clue if there is anything wrong.

    1607454377418.png
TIA
KIWI
 

Ukiwis

Well-known member
Jul 22, 2018
60
California
No tab feeder. Here's a pic of the whole system.

I'm told by a local pool store that Pentair Heaters don't require the check valve.

I actually got it opened the thing up and determined that it hasn't been leaking....at least not much. There's some salt/copper deposits but it's bone dry. Their report says it is "leaking heavily"...what a bunch of shysters!

1607485524905.png

ORHP are getting a second opinion and I'm hoping it'll be covered. I have not reassembled so we'll see how that goes. Wish me luck!

KIWI
 

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JamesW

TFP Expert
Mar 2, 2011
22,127
I don't see any need for a check valve.

I don't see any evidence of the heater leaking.

I would suspect that the internal bypass might be bad or the heat exchanger might be scaled.

You can check the internal bypass by removing the thermal regulator and looking up in the hole for the plunger part. You can see the spring part by looking in the heater inlet.

Verify that the thermal regulator is ok.


 
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Ukiwis

Well-known member
Jul 22, 2018
60
California
UPDATE: The 2nd service provider said Pentair heaters DO NOT require a check valve unless a salt cell is present (It is not). He also said there is no evidence of the Heat Exchange leaking. ORHP have updated the status to: Authorized - Service Provider returning to complete job.

UPDATE2: By the time service provider 2 came around I had disasembled the heater, to inspect further. I figured it was going to be denied and and the repair was on me. After I learned they were sending someone for a second look I was not able to reassemble the heater so although they reported the above, they couldn't diagnose the issue. I now need to reassemble the heater so they can complete their diagnosis. #FUN
 
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