YarnMaster
SupporterHad some time in the shed this weekend so decided to do something about an issue I have and have heard others on AULRO complain about.
Heater lever set to "cold' & blower fan 'off' - driving along with hot air coming into the cab. Our 130 runs no A/C so it is particularly noticeable when doing long runs. It is amazing to feel how much air flow runs up the glass, hot air flow at that!
Sooo, some Al offcuts, and old MIG liner, some 1.0mm hard drawn 316 wire a few screws and some tinkering resulted in this modified vent.
Push / pull cable runs inline with factory heater box control. So when cabin lever is pushed to hot, flap on guard opens. Slide control to cold and flap closes. Havent tested it on a long run yet but no air leaking so far with flap closed. Overall should help to keep cabin temps down a bit on longer runs.
Next stage this arvo is I plan on converting the windscreen/footwell controller to be a hand throttle. We only ever run the heater onto the glass (and very rarely at that) and using the existing controller will be a very neat setup.
Photos give an idea of the vent.
Steve
Wizard
I presume you are trying to get more air into your heating/cooling duct by 'ram air effect'. I am not trying to be a white ant, but ram air effect only works at speads greater than Mach 0.3 (ie you would need to be travelling as speeds greater than 400 kph). Your modified vent may in fact reduce the airflow making your problem worse. But maybe I have misread what you are trying to achieve.
Cheers
KarlB
Swaggie
No - the opposite - I read that he is trying to shut off airflow when on the cold setting.Originally Posted by KarlB
Btw - any fluid dynamics calcs to back up your assertion?
Master
Clearly Karl, clearly you didn't read the post, no he is not after a ram air effect. Quite the opposite, he is after a NO air effect.
As such, his mod is quite good.
Steve
YarnMaster
SupporterKarl,
As mentioned above, the mods purpose is to prevent air into the heater box and this works very well.
But despite your assertion that when open less air will enter when open at sub Mach 0.3 I beg to differ!
At 80kph (a touch less than M0.3) with the vent open and blower off feels equivalent to blower fan setting 1 whilst stationary. Soooo either my defender bends the space time continuum to achieve mach 0.3 or/ the speedo is a touch out and my flogged out 300tdi is punching above its weight!
Being the shallow person that I am, any landy experiements I try and fail on will never get posted up here! There are quite a few of them
Steve
Swaggie
Steve,
As an aside, how is the heater water valve controlled on a 110?
On a county (combined heater/AC unit) it is vacuum controlled, and opens up to let hot water through whenever you shut down and lose vacuum. So if doing stop-start driving, the AC is fighting the heater. I have seen people fit a manual tap to turn off the hot water in summer
Wizard
Eek! No! I gave up physics as soon as a I could. And fluid dynamics is almost a black art (like metalurgy). However, a good starting point might be http://www.paladinmicro.com/documents/RamAirMyth.pdf. Alternatively just Google "ram air effect".
Cheers
KarlB
Wizard
Yes, I didn't read properly but that is not unusual for me! So, as I read it a second time, the issue is that with the the air vent 'normally close', air still comes in so blocking the entrance solves this. Then a very neat solution.
Cheers
KarlB
Swaggie
He is arguing something slightly different - and his logic is flawed - I note a lack of maths in his rant.
Like most things, fluid mechanics is a continuum, rather than discrete in nature. You can get changes in pressure and/or flow rate without compressing air.
If his argument were true, bonnet scoops over intercoolers would have no airflow unless there was a fan underneath or you were travelling at mach 0.3 or above.
YarnMaster
SupporterBen,
On a 300tdi there is no tap in the heater circuit. Full flow from thermo housing through the heater matrix and back into the head.
A tap was another option I had contemplated however I wondered if doing that to a 300 designed with full flow may create some other head cooling issue. Probably not considering people block the heaters off in discos with dead heater matrixes?
Besides doing it this way gets rid of the poxy plastic cover piece. But it will be interesting to see how the blower motor holds up in the wet (when I actually use the heater to defog the glass) time will tell.
S
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