Minimax 400 with PowerMax "Scortching"?

[mjohnson003]

OK - this one has me a little worried.

We have a pool that is about 24 years old. We use a Purex Triton Minimax 400 with the PowerMax hood that vents to the outside of our pool shed.
The heater seems to be working fine, but now that it is turning cold, it is running long hours to keep the water warm.

The issue is, on the top of the heater, near where the vent pipe comes out, there are now scortch marks. The PowerMax is running when the heater is on just fine, and we've never seen these types of marks before (or even noticed that top of the heater was excessively hot). They started about 2-3 weeks ago, but seem to have gotten worse in the last week.

Any idea what might be causing this? I don't want to burn down our shed.... What should I be checking?
Pic of heater and the scortch marks on top are included.

 

[setsailsoon]

I would check the vent pipe and vent top for obstruction.

 

[swamprat69]

That looks like soot ( from incomplete combustion ). May have been from partially blocked flue, but if you have spillage that low in the flue pipe I would check both the flue and the heat exchanger. Also need to check the burners for rusting/partial blockage. Has the heater had any regular cleaning/maintenance?

 

[Pool Clown]

Is your shed properly ventilated? Especially with a power vent, there needs to be plenty of air getting INTO the shed from the outside.

 

[JamesW]

How long has it been installed like this?

Has anything changed recently?

How much total ventilation surface area is available for providing fresh air?

How old is the heater?

You should turn the heater off until you can have it professionally checked.

 

[mjohnson003]

Thanks for the quick replies everyone!
In answer to your questions:
1) Checked the vent pipe and did not see any obstructions
2) Heater gets cleaned/maintained every spring, but will check burners again.
3) Shed is ventilated with multiple 2x2 vents. Nothing is obstructing them
4) It has been installed like that since 1999, with no changes since to the installation/configuration or shed
5) Heater is original (1999). It has had the heat exchanger replaced due to rusting through about 5 years ago.
I guess I'll call the LPS and have them take a look. The only other items of note are that it has been very cold lately, and the system is running long hours to keep pipes from freezing - so the heater has also been running longer than usual.

 

[swamprat69]

Soot/carbon can only be formed as a byproduct of incomplete combustion. Soot on the top panel of the heater is a sign of a problem with the seal of the B-Vent at the heater and inadequate flow through the vent pipe. Both the incomplete combustion problem and the seal problem should be addressed and both of these problems can be the result of multiple different causes. Spillage at the top of the heater is worrisome as this can only happen if the flow of flue gas through the vent is not normal ( can be caused by several things i.e. wind, height of stack above shed roof etc. ). These problems and causes should all be diagnosed/addressed by the company servicing the heater.