So, the plan is to use the waste heat from the Dometic fridge overnight to keep the water in the tank warm enough to use in the morning. In its job of heating the ammonia solution to cool the inside of the fridge, the Dometic puts at least 50oC of heat out the flue pipe - wasted heat!
Click on the image to see it full size.
Auxilliary Water Heater - Part 3The final step was to place a newer version of the copper heat coil, with tighter coils, around the corrugated upper flue flex pipe.
|
|
---|---|
The new tighter coil in place |
This coil has about 11 wraps and fits tightly against the corrugated upper flexible flue pipe, just above the brass ferrule. It is insulated with fiberglass and aluminum tape. Further fiberglass insulation was added around the copper tube up to the foam rubber insulation. |
Heat Test Graph 6 |
This 48 hour test, used only the Dometic fridge to heat the water in the storage tank. Water temperature reached 23.5oC, almost 6 degrees above ambient, not quite as hot as previous versions.
This version of heat coil did not rob the ammonia boiler tube of its heat, so the fridge stayed as cool as normal - about 18-20 degrees Celsius below ambient.
|
Heat Test Graph 7 |
This really is the last graph! As a continuation of the above graph, the engine was started and the van taken for a drive. The water heat reached about 37oC, the water circulation pump was turned off. When the water temperature decreased to about 33oC the pump was turned on again. This kept the water at just under 33 degrees for 9 hours (until hour 12) when eveything was shut off. The fridge temperature did rise to 1oC above zero, but the ambient was now over 20 degrees Celsius, so a differential of 18 to 19 degrees was maintained. So it would seem that the Dometic water heater can maintain a full tank of water at an acceptable 33 degrees Celsius for 9 hours, while the fridge did not suffer a loss of efficiency as in the earlier tests. A 10 day road trip in June tested the latest setup. It did work as tested. A slightly higher water temperature would have been nice, but this new setup did greatly please my travelling companion!
|
As a footnote the indicator lights on the stove panel represent the following non-linear degree of fullness:
RED light = about 4 litres left, although not all may be useable,
ORANGE light = about 8 litres above the RED light, (12 litres total)
GREEN light = about 27 litres above the ORANGE light, (about 43 litres total).
Back to Home Page. |
---|
Copyright © 2018
F. Griffiths
To contact us, please type the following into your email address
griffco AT griffco DOT ca
to avoid automated email spammers.