Hi All - first time posting. I really appreciate all the posts that have helped me over the last few years. I'm posting as I have not seen this problem yet so I've started a new thread. The pool heater was shutting down after a few minutes and restarting and repeating until lockout. Generally no codes, sometimes AFS on the board. All signs pointed to the ground or the igniter flame sensing to the Fenwall. I added the ground under the flame holder and a second above. The problem still persisted. I went to change the igniter and found the area around the igniter cracked and melted. Previously I had cleaned the coils (taking the HX out for full descaling). When doing so I could see the lid was a bit warped so I straightened it and it was flat and no damage around the igniter was seen. That was a few months ago. Now under inspection, I think adding the ground wire, coupled with a missing gasket on the ignitor caused the hot burner gas to escape and melted the lid in that area. Last week I replaced the lid, the two upper insulation pads and the ignitor with OEM parts. The previous hard insulation was in good shape but the soft fiberglass was not around the ignitor hole. Replaced both in hopes it would keep the heat away. All back assembled I smiled and fired it up. First problem. The heater is located in an indoor mechanical room. It filled with smoke and set off the alarms. I shut it all down and figured maybe it's the oil from the manufacturer burning off the new lid. Waited a day and tried again. Less smoke, at first. Then, I looked at the cover where the flame holder gaskets are and saw it warping away from the blower plate. The sheet metal lid was allowing a gap in the gasket and smoky hot air was escaping. I shut it down again as I feel there may be too much heat in the burner or something else that is not good. FWIW I didn't use any RTV on the gaskets. From a design point, it seems the distance between the bolts is too great causing the heat to warp the the lid cover to warp the extent it opened an air gap (< 1/16"). Should I have put RTV around the flange or on the gaskets? Should I be concerned there is too much heat getting to the lid and not use the heater? I did not reinstall the ground wire yet because I wanted the best seal I could get with the new lid. That good seal lasted under a minute until the warping happened. Thoughts?
Melted Lid on Mastertemp 200 Indoor Mechanical Room
- Thread starter Matt2337
- Start date
Heat inside the combustion chamber is usually at 2000f. The heater was designed to handle that if it is vented properly.
SFS is telling you the exhaust is too hot most of the time. AFS means the blower is not moving enough air. Check your venting and the amount of air that is allowed into the room.
Looks to be a 200K BTU unit (250?). That needs two openings of at least 200 sq. in. One within 12" of the floor and the other within 12" of the ceiling. For a 250 the number is 250 sq. in. each.
When things start melting/warping in a pool heater it is almost always a venting issue. Check for a birds'/rodents' nest at the far end of the exhaust pipe.
Last edited:
Thank you for taking the time to respond! I checked the vent and it’s clear and has not recently changed. No blockage and 4 inch diameter. Been the same for years. The problem can’t be fresh air because the room is open to the outside air during the testing. I agree it seems like the heat is not getting out. The exhaust gas barely gets to 200f before the cover is extremely hot. I’ll measure with my IR and let you know more accurately. Just seems that the insulation would stop the heat from quickly getting to the igniter and the blower plate. I’m wondering if the fan speed is now too slow? Can I check the operation with a digital manometer? Also does the flame holder need to be replaced even if it seems clean and appears in good shape? The heat has already caused the white igniter gasket to brown. Not sure it’s the high heat or just the manufacturing oils in the lid seeping into the gasket. Photos added are after a few minutes of operation then shutdown with no codes on board or fenwall. The brown oily burned marks are on brand new shiny clean parts just minutes before. I’m at a loss. Hoping it’s the blower speed but no afs issues.
Attachments
while I was taking IR measurements of the top cover in the dark room it started to glow red hot. I'll take the exhaust off and try again, but it's a clear. However it's about 6 feet of a vertical run and then another 25 feet horizontal to exit the side of the house between floor joists. Is this typically too long? It appears to be within range from the installation manual.