Pentair MasterTemp 250 Heater Natural Gas 460732

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bru

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Jun 26, 2013
11
Hello,

Long time lurker, first time poster.

I have a MasterTemp 250 NGas heater that's been giving me some headaches lately. Last year prior to closing it was 'bumping' and rattling. This spring I've replaced the thermal regulator and the manifold bypass valve (thanks to posts on this site). I believe the 'bumping' is gone, however, there still appears to be some rattling. I had the heater on today, but at some point it quit heating but it kept running. I noticed the 'heating' light was flashing. I also noticed the 'AFS' light briefly came on once but did not stay on, nor did I see it a second time.

To me the rattling seems to be coming from the 'combination gas control valve'. There appears to be a switch on the side closest the opening with 2 wires going to it, maybe a breaker of some type, this seems to float back and forth. The part is attached along with red arrow pointing to switch I am speaking about.



Any insight?


Thanks,
Bruce
 

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Yes, you can hear it with all panels on and from a 15ft distance. I suppose it could be something else causing the rattling/clicking. However, it is not as loud by the front access panel as it is at the back panel with both panels removed.

Bruce
 
I would get a gas person out and have them check to make sure your pressures are right. Not sure why the AFS light would come on unless there is an issue with the blower motor or the air tubes.
 
Thanks for your feedback Paul!

Is it a typical symptom of the valve to rattle?

Do you think I'm barking up the wrong tree and the rattle I hear is not on the valve but elsewhere?

I should mention the rattle appears after the unit comes up to temp or at some point later - it does not happen at startup.
 
Just a quick note. I looked into the blower and saw some insulation. I pulled it out, noticed a turd, so i unscrewed the star nuts and took the cover off to pull the remainder of insulation out and make sure it was clean. I removed the top of the unit to look down into the hole the fan feeds into. There is yellow insulation in there. Before I pull it out I'm trying to understand if this is supposed to be there?
 
Well I pulled the insulation out. Does not feel like it should be there. However, there appears more down in there.

Looking for additional comments/tips.

Should I pull the blower assembly off or should I just put a shop vac on it instead. How far down can the insulation be?
 

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Yes it looked like typical yellow house insulation.

Here's a picture of where i found it. This is a picture of my blower with the face off looking down into the combustion chamber.

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On the bottom of the MaterTemps is usually a pad of insulation of which the can sits on. Do you see it on the bottom between the can and the plastic bottom enclosure?
 
Hi btu. I've worked on the Master Temp and it's predecessor the Maxi Therm. There should be no insulation down in the ignition chamber itself. There is a gasket that the blower sits on but it is white. The calling card of rats and mice is yellow insulation from usually house attics. That being said, I've only seen insulation and debris once down in the combustion cone. It took forever to figure it out. Basically the plastic vent cover over the blower intake was broken so that's how they got in. I shop vacuumed it out.
 
Sorry for the late reply and follow-up.

First thanks for the replies and help.

OldPoolMan I pulled all the insulation out, however, there still appeared to be some grunge down there so I pulled the blower off entirely. I then removed the cone, it looked like a lint trap so I cleaned off with an old tooth brush and shop vac and air. With the blower off I was able to vac out the chamber much better too. I put it all back together and the heater works much better, it's heating much quicker and no longer popping.

It did have the plastic guard in place to keep mice out however the center hole looks big enough to allow mice in, I bought some small wire mesh which I will cut to place around the plastic guard as extra protection to keep the mice out.


Again thanks for all your help.

Bruce
 
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