Thanks Trevor , will do so .
Dave , I hope you receive this .
Kind regards
Chris de Wet
P O Box 472 , Ifafi , 0260 , South Africa .
Telephone 012 - 3398071 ( office ) 012 - 2591129 ( home ) Cell 0839989744
Fax 012 - 3398118
One '56 TR 3 with o/d and one '64 Spitfire 4 ( Mk 1 )
Two Heralds and three early Spitfires without o/d for sale in order to
finance the restoration of the TR 3 .
-----Original Message-----
From: Trevor Jordan [mailto:tjordan@bigpond.net.au]
Sent: Thursday, September 07, 2000 2:21 PM
To: Chris De Wet
Subject: RE: One more electric fan conversion question
Chris
I am not on the Spit list, so you might want to forward this reply to Dave
Chu.
An adjustable switch and a manual override are not essential
(although I have an override switch and indicator light on my car),
but it is necessary to make sure that the thermostat and the thermal
switch operate properly together.
When you install an electric fan, you end up with two temperature
controls. The thermostat controls the temperature at speed (the fan
should be off) and the thermal switch controls the temperature when
stationary. In stop/start traffic the temperature will move between
those two values.
The thermal switch temperature has to be higher than the thermostat
temperature for it to work properly, otherwise the fan will be on
most of the time as Chris DeStaffany mentioned below and the whole
exercise is self-defeating.
(The other complicating factor is hysteresis; the thermal switch (and
to some extent the thermostat) will exhibit hysteresis which is a
band of temperatures in which a switch will be stable in either
state. For example, the thermal switch may not close until 85C but
not open again until the temperature drops to 80C. The switch will
be open as the temperature rises to 85C and remain closed as the
temperature drops back to 80C, so it can be either open or closed
between 80 and 85C.)
I have found that the best practical method of setting up an electric
fan is to put both the thermostat and the thermal switch in a pot of
water and bring it to the boil. A buzzer should be connected to the
thermal switch, but the operation of the thermostat is easily
visible. Make sure that the thermostat is fully open before the
thermal switch closes. Then turn off the heat and make sure as it
cools that the thermal switch opens before the thermostat closes. If
not, then you will need to change one or the other until they operate
correctly. You do not need to measure the actual temperatures unless
you are really interested.
If you are using an adjustable thermal switch, you can use this
technique to set the adjustment. Alternatively, you can do it in the
car by adjusting the thermal switch so that there is a clear increase
in the temperature between highway running and stationary.
Regards, Trevor Jordan
74 TR6 CF29281U
The information contained in this e-mail including any attachments is
privileged and/or confidential. If you are not the intended recipient
please reply immediately and delete this message. Please do not make use of
it, nor disclose it's contents in any way. Thank you.
|