TrailManor Owner's Forum - View Single Post - Fridge - optimize Heat Exchanger temp by using a Thermostat for Fan Control

**rickst29** · 07-14-2013, 05:46 PM

Answering my own question: According to a page in "ehow", the Norcold's Heat Exchanger (the radiator-like thingy at the top of the upper panel) works best if the temperature is held to less than 85-90 F. I presume that figure is meant for the area on the left side of the unit (facing the Fridge backside from completely outside) - and isn't meant to recommend that you "prematurely" cool down the hot pipe which isn't bonded to most of the fins - the pipe along the rear from the right side heater stack.

So, the exhaust fans (the TM-provided exhaust fan which pulls from the top to the bottom, through flex tubing, and/or your own added-in fan blowing straight out from the upper panel) should probably turn on somewhere within this temperature range, and probably turn off when temps at the Heat Exchanger are below 80F. There is probably a cheap 12V thermostat which would be adequate for this, but because I'm already familiar with the JLD-7100 temp controller, I'll waste a little more money and buy another one of those: http://www.lightobject.com/JLD7100-D...oller-P66.aspx. Using Farhenheit settings, I'll try starting from SV=0085 (desired temperature), HY= 0005 (variability for On/Off control around SV), and (of course) rd = 1 (cooling mode, not heating).

The TM exhaust fan sounds like jet engine; I have added an extremely quiet computer fan to the left side of the removable panel (the side opposite the heater stack) - and used "FlexFix" flex duct tape to tape it on the inside surface, and to seal up all the other gaps in the rest of the left side. (That's "UL 181-B", not everyday "Duct Tape"). It has extremely good heat resistance, the glue doesn't smear around, the tape doesn't slip, and it's vibration-proof. Big box hardware stores all have it.
My fan is this one: http://www.newegg.com/Product/Produc...82E16835426016 It moves just 37 CFM, but that's quite adequate for this application - and you can barely hear it when standing outside, leaned over, with your ear right next to the panel.

I'll report on results when the TM is next out of the garage, and I have finished the installation.

07-14-2013, 05:46 PM	#1
rickst29 yes, they hunt lions. Join Date: Aug 2005 Location: Reno, NV Posts: 1,318	Fridge - optimize Heat Exchanger temp by using a Thermostat for Fan Control Answering my own question: According to a page in "ehow", the Norcold's Heat Exchanger (the radiator-like thingy at the top of the upper panel) works best if the temperature is held to less than 85-90 F. I presume that figure is meant for the area on the left side of the unit (facing the Fridge backside from completely outside) - and isn't meant to recommend that you "prematurely" cool down the hot pipe which isn't bonded to most of the fins - the pipe along the rear from the right side heater stack. So, the exhaust fans (the TM-provided exhaust fan which pulls from the top to the bottom, through flex tubing, and/or your own added-in fan blowing straight out from the upper panel) should probably turn on somewhere within this temperature range, and probably turn off when temps at the Heat Exchanger are below 80F. There is probably a cheap 12V thermostat which would be adequate for this, but because I'm already familiar with the JLD-7100 temp controller, I'll waste a little more money and buy another one of those: http://www.lightobject.com/JLD7100-D...oller-P66.aspx. Using Farhenheit settings, I'll try starting from SV=0085 (desired temperature), HY= 0005 (variability for On/Off control around SV), and (of course) rd = 1 (cooling mode, not heating). The TM exhaust fan sounds like jet engine; I have added an extremely quiet computer fan to the left side of the removable panel (the side opposite the heater stack) - and used "FlexFix" flex duct tape to tape it on the inside surface, and to seal up all the other gaps in the rest of the left side. (That's "UL 181-B", not everyday "Duct Tape"). It has extremely good heat resistance, the glue doesn't smear around, the tape doesn't slip, and it's vibration-proof. Big box hardware stores all have it. My fan is this one: http://www.newegg.com/Product/Produc...82E16835426016 It moves just 37 CFM, but that's quite adequate for this application - and you can barely hear it when standing outside, leaned over, with your ear right next to the panel. I'll report on results when the TM is next out of the garage, and I have finished the installation. __________________ TM='06 2619 w/5K axle, 15" Maxxis "E" tires. Plumbing protector. 630 watts solar. 450AH LiFePO4 batteries, 3500 watt inverter. CR-1110 E-F/S fridge (compressor). TV = 2007 4runner sport, with a 36 volt "power boost".