MARZ Posted November 13, 2018 Report Share Posted November 13, 2018 Is there an upgrade or replacement to the existing cabin heat box for a 67 F? Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted November 13, 2018 Report Share Posted November 13, 2018 (edited) I don’t know of an upgrade, but they are relatively easy to adjust if you’re having a problem. My F is a 68, so could be different... I live 69 miles from Canada (where I heard it gets real cold) and fly all winter in temps around 0-10 f at altitude. Sometimes I wear a light jacket but the heater works pretty good. Flapper valve adjustment is key to get good heat in winter and none in summer. Back seat passengers will be cooler for sure. Door and baggage door seals are real important to cut real cold drafts. Also, rich of peak is noticeably warmer... whats going on with your heater? Edited November 13, 2018 by Ragsf15e Quote Link to comment Share on other sites More sharing options...
carusoam Posted November 14, 2018 Report Share Posted November 14, 2018 Slide valves are the old system, flapper valve was the upgrade... rubber compoments go bad or missing around the flapper... Making what you have work is the low cost solution... LOP at 12,000’ doesn’t provide much heat at all, so there isn’t heat to deliver to the cabin.... A leaky cabin makes the minimum heat available get lost... What do you have? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
takair Posted November 14, 2018 Report Share Posted November 14, 2018 I'm curious, wouldn't 25 ROP and 25 LOP put out the same heat for the heater? Same temperature... Quote Link to comment Share on other sites More sharing options...
MARZ Posted November 15, 2018 Author Report Share Posted November 15, 2018 Probably just needs some TLC - I've not had much use for it in Texas - and last time I did try to "crack" it for a little heat I got a LOT of heat - tried to shut it off but no Joy. I know it's the flap version with the heat in and another short hose hanging for the heat out. Just thought there might be something out there that had a more robust and positive shut off. Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted November 15, 2018 Report Share Posted November 15, 2018 Not that I know of. You found the finicky part though... getting it on and (more importantly in Texas) off requires some adjusting and tinkering of the flapper with the cowl off. Getting a medium heat setting is more a function of full heat directed down with the vent fins and then open the cabin vents a little to mix to the right temp. It ain’t as good as a modern car... but better than running my old truck with the heat full on and the windows open. Quote Link to comment Share on other sites More sharing options...
Shiny moose Posted November 15, 2018 Report Share Posted November 15, 2018 The heat on my 67F works great, and so can yours. make sure your flapper valve is opening completely(all the way up when heat on, also all the way aft when off, check for seal condition), I used baffle material to make a new seal take the hoses off and check for full movement , check that someone didn’t put the scat hoses on incorrectly, check the front scat tube from front side of muffler heat schroud to front of baffle has not fallen off or deteriorated or a big hole, check all tubes for holes or chushed. Hint: because no rear seat heat vent. During winter travel when wife in back seat I take a 2.5 inch X 3 ft scat tube along, after gear up and in normal climb i place tube infront of heat vent and lay between seats so part of the heat is blowing to the back seat. Sometimes she asked to turn heat down ! Without it she’s cold Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted November 15, 2018 Report Share Posted November 15, 2018 11 hours ago, takair said: I'm curious, wouldn't 25 ROP and 25 LOP put out the same heat for the heater? Same temperature... My guess would be less combustion happening in the exhaust system. This for the same reason EGT's go up when you switch from "both" to either "L" or "R" mag. Puts a bit more unburned fuel into the exhaust, where it ignites. 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted November 15, 2018 Report Share Posted November 15, 2018 Great question, Rob! Had to think about that one for a bit... ROP has a fair amount of excess fuel still burning when the exhaust valve opens... but Oxygen is limited... LOP has a tendency to be done burning... before the exhaust valve... and is fuel limited... Peak is Peak... and 25°F LOP or ROP, is still 25° off peak... Even though the exhaust streams have different components of excess air or 100LL in them, and the heat capacities of each chemical would have them carrying different amounts of heat, at the same temperatures... I think the important part of the statement is where the heat was being produced... @12k’... At this high altitude, with an NA engine, the MP is pretty low, the matching FF is low, the heat generated is just low, LOP or ROP. And... the outside temps are awfully cold at 12k’ in winter, in NJ... And... the wind blowing by @150kts is cooling the cabin as fast as possible through heat transfer through the windows and walls.... And my M20C wasn’t air tight so there was some convection cooling going on as well... Check that all the hoses coming from the air mixing box are connected and going to the proper location... if they are original, get some motivation going to swap out for new hoses... one hose goes to the back right... one goes to the back left.... If the gates in the cockpit, don’t close properly most of the heat will dump in front of the co-pilot... then the pilot... My C had a broken gate, the copilot got all the heat... I didn’t know where to find a replacement... (pre-MS days) Since heating season also comes with CO alertness... to get the maximum amount of heat to the cabin, it takes knowing how well your heat muff is doing... the muff is the sheet metal wrapped around the muffler... check the hoses that go in and out of the muff... make sure they are working properly...if it is inspected during annual be looking at the health of the muffler while you are there.... PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
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