I am looking at the various scenarios of fan control for the radiator and adding additional pusher fans. I wonder how people have them wired and what the thought on when to cut in? With ignition control heat soak can occur after engine switch off and temperatures exceed the thermostat cut in.
1. My thoughts are I would like to have the puller fan hot wired not ignition controlled and thermostatically controlled 95c cut in on cast iron block. Should this be lower temperature for ali heads on iron block? Pusher fans manual controlled. Three relays used for the fans.
2.Pusher fans on manual switch or thermostatic controlled?
3.Puller fan on ignition switch and pusher fans hot wired on thermostat control.
I have seen a two relay switch control unit which can be set for cut in for a/c control which would be my manual over ride switch.
how about a timed relay that operates after the ignition is turned off that leaves the fan running for a certain time, maybe even wired in with the thermostat switch so only works when the engine is over a certain temperature?
So, my pusher fans are basically non-operational. I did wire them in to a dashboard toggle switch, but one of them that seems a bit stiffer to turn kept blowing the fuse, so I don't use them.
The big sucker fan that does all the work is controlled by one of these:
https://www.demon-tweeks.com/davies-craig-digital-thematic-ewp-fan-switch-2012892/?sku=DCP0448&istCompanyId=a2904180-3a7d-4e56-b876-cf81c9512180&istFeedId=6fbc4b04-fd28-4ce1-8513-835c8f118690&istItemId=pxltarmrx&istBid=t&gclid=Cj0KCQjw0tKiBhC6ARIsAAOXutnty0yyUdAH1QFCACZ2tiMEfsTAL8sb4nFaTxKToT9ZmDGG2HixEE8aAotQEALw_wcB&gclsrc=aw.ds
This unit has 2 speeds, the faster one kicks in after 10s.
Its not authentic, but then a sucker fan isn't authentic either. However, I like using it becaise it takes 5s to dial in a new cut in temperature as the seasons change - I use a higher cut in temp in the winter compared to the summer which just helps temper thermal run-away on a hot day in a traffic jam. It also tells me whats happening temp wire on the top hose where I have the sensor installed.
The fan switches off when I remove the ignition key....which is when I open the bonnet if its hot. I don't see much point in blowing hot air over a hot engine, or trying to cool the now static water in the rad after switch off.
Tony,
Like the timer idea with a thermostat control after switch off. I know one of my local guys wants me to wire it in for him.
Kevin W,
That is the same digital controller I was looking at installing. Seems to be a nice solution to control one or two fans. I was thinking of a two temperature thermostat but my fan is in a shroud in my Dax which works very efficient at pulling the temperature down. I have no shroud in the Crendon yet but will be looking to install one. I don't think the pushers will do much so might no even wire them.
Quote from: JON1D on May 05, 2023, 06:06 PMTony,
Like the timer idea with a thermostat control after switch off. I know one of my local guys wants me to wire it in for him.
Kevin W,
That is the same digital controller I was looking at installing. Seems to be a nice solution to control one or two fans. I was thinking of a two temperature thermostat but my fan is in a shroud in my Dax which works very efficient at pulling the temperature down. I have no shroud in the Crendon yet but will be looking to install one. I don't think the pushers will do much so might no even wire them.
Be interested to see how well a shroud works, as none on mine either
If you're concerned about heat soak, you may want to consider on EWP. They are much more efficient at keeping an engine at temperature and can be set to keep running after switch off. They work in conjunction with an electric fan to control temps.
I have twin speed puller fans with a good shroud, these are controlled by a two temperature thermal switch that is
located in the top hose and two good relays with decent terminals .
All of this has an independent override switch that I use when the engine is switched off, it's just what I do, it
may not be nessary but it gives me a choice.
As for the Davies Craig switch, that may be of interest to me due to it having adjustable temp settings.
Would also like to emphasise using decent wiring/connectors, I have soldered most of mine due to considerable
current draw and a good battery is also in order if you run the fans for a good few minutes after stopping the engine.
Chris.
I know this is overkill, but here it is if anyone is interested:
(https://i.imgur.com/gwAwTI0.jpg)
I have 2 puller fans and wanted them to come in at different temperatures giving me two stage fan cooling as per a couple of my more modern cars. I also have an override switch on the dash. The dash switch feed runs off the switched ignition feed and therefore if the fans are in manual mode they will go off when the ignition is switched off. The temperature sensors are mounted in the hot part of the radiator side tanks, this cct is permanently live and will therefore keep the fans on even with the ignition off if the water temp is still too high. Note that you need 2 relays for the switched fan supply or you will simply link the two temp controlled relays causing them both to work at the same time defeating the object. I may also fit an EWP on a timer as per Simon's comment if its required but I think this should be enough as it is.
Its obviously more complicated than some solutions but I had decided on the functionality that I wanted so this is the result.
Interesting set up James. Having a single puller I could use FAN 1 as puller and Fan 2 as Pushers with two relays to feed each pusher. Looking at dual thermostat sensor but an adjustable is far better .
Quote from: JON1D on May 07, 2023, 06:29 PMInteresting set up James. Having a single puller I could use FAN 1 as puller and Fan 2 as Pushers with two relays to feed each pusher. Looking at dual thermostat sensor but an adjustable is far better .
Yes you could use this exactly as you describe. I can't entirely agree on the adjustable sensor being better though, I had one....... It was temperamental, and often needed to be messed with as the rheostat sometimes worked and sometimes did not meaning that when you really needed it, on occasion there was no fan working, which lead to several boil overs. With 2 fixed sensors working at different temps and effectively 2 separate cct's then you should always have one of the 2 fans working and even if that's the one at the higher switching temp it should still save you, that's why I did this. But that's all down to individual experience I guess
Not much to add other than my set up sounds very similar to what Chris describes, two 11" puller fans, independent relays, radiator mounted temp switch with 2 on 2 off settings giving sequential operation, dash mounted override which I use in stop start traffic to keep the temperature down.
As we speak, I'm fitting a new radiator and swapping the two 11" fans for one 16" with a shroud. Ill put the 11" fans on the for sale section.
Quote from: JamesB on May 09, 2023, 05:44 PMYes you could use this exactly as you describe. I can't entirely agree on the adjustable sensor being better though, I had one....... It was temperamental, and often needed to be messed with as the rheostat sometimes worked and sometimes did not meaning that when you really needed it, on occasion there was no fan working, which lead to several boil overs. With 2 fixed sensors working at different temps and effectively 2 separate cct's then you should always have one of the 2 fans working and even if that's the one at the higher switching temp it should still save you, that's why I did this. But that's all down to individual experience I guess
The Davis Craig system is digital - no analog rheostat. Seems to work pretty well for 1000 miles....so far