No thermostat?

[RobJ]

Tom, I think you are trying to agree with Larry but your comment conflicts with that. Larry says his feet would heat up more quickly, you say the feet would have a lower temp. Maybe yall mean heat up quicker but have a lower temp??? In this example you sort of want the feet to heat up to take the heat away from the coals... Maybe try the finger over a candle trick. I'm sure my hand heats up quicker if I hold my finger over the flame for 2 seconds than quickly going over it quickly for a total of 2 seconds(see that blister)

Aren't AC systems designed to move air over the coils at a certains speed. Move the air to fast and it doesn't pick up the cold from the coils.

Funny how everything can be explained away with some sort of science. But cars and trucks still have a thermostat in them. That tell me something.

I'll let the scientist take over from here...know one? :d

 

[JSharp]

<to slow coolant down so that it spends enough time in radiator to effectively transfer liquid heat to air>

is not valid. The amount of heat removed by the air passing through the radiator is directly related to the temperature of the water in the radiator. If you slow down the flow in the radiator, you will decrease the temperature in the radiator, and you will remove less heat.

If GM taught this concept, they had poor engineers. I can believe that.

There may be reasons to keep constrictions (open thermostats) in the line. Primarily, the pump was designed with that restriction. The reason is just not this one.

Chris

Exactly. Removing the thermostat will cause many water pumps to cavitate thus reducing flow through the system.

I'm not sure how the whole "water moving too fast through the system" myth got started. I've never seen a case in industrial cooling where increasing flow didn't increase cooling...

 

[Tom_Veatch]

Tom, I think you are trying to agree with Larry but your comment conflicts with that. ...

It is quite true that each slow trip through the coals transfers more heat than each fast trip and Larry's feet reach a higher temperature on the slow trips than they do on the fast trips.

But if he runs twice as fast, he can make twice as many trips in a given period of time. Due to the physics of heat transfer, each fast trip will transfer more than half as much heat as each slow trip. The end result is that a given number of slow trips will transfer less heat than twice that number of fast trips. In either case, I expect Larry will pick up a few blisters unless he runs really fast.

If you are interested in the math, DAGS "Newton's Law of Cooling" and you'll find the basic differential equations that describe the physics. They are derived from the principle that the rate of conductive heat transfer between two bodies is proportional to the difference in temperature between the bodies.

 

[Egon]

differential equations

Now what might those be?? Or was that the time class was cut to play some pool!

 

[larso1]

About many import tractors not having a T-stat, that is the case with my Japanese grey-market Iseki TS-1610-F. Did not come with one, has no provision for one, and there is no restrictor in the cooling system. However, the USA model Bolens G-194 which is almost identical to mine, same sheet metal, same Isuzu motor, does have one. It's a separate bolted on casting at the outlet from the block that conatains the T-stat and also by-passes a small amount around the radiator through a small separate line. So to me, that indicates they may not be particularly necessary unless you live in cold climates and don't want to wait a long time for the motor to heat up. I don't think it's very cold in Japan during the early and late crop seasons when they're being used there.

The tiny bubbles being talked about are actually steam, produced on the back side of the pump's impeller in a zone of low pressure, created by the spinning impeller, AKA cavitation. If you pulled a sufficient vacuum on the radiator with 70-deg.F. water in it, it would all flash to steam. When the water bursts into steam bubbles on the surface of the impeller, pitting and a reduction of material thickness of the impeller blades is what results, and over time the impeller needs to be replaced. Normally, higher system pressure (via the radiator pressure cap) eliminates this effect of cavitation on the pump when the water temp is high.

On the liquid flowing too fast thru the system, as has been mentioned above, liquid turbulance increases as the velocity increases and actually makes heat transfer more efficient. It eliminates or reduces the skin effect (a resistance to heat flow, common in a laminar flow situation) on the interior surface of the radiator tubes. In heating boilers, some have spiral inserts in the water tubes called, surprisingly, "turbulators" that enhance liquid turbulance and thus heat transfer. The liquid going thru the radiator may not lose as much heat in one pass when the flow rate (velocity) is increased, but it will make more passes thru it in a given time and should all average out. Or, I could be wrong....just show me;o)

Bill

 

[Soundguy]

I didn't mean to imply that you may be mistaken about the part you were looing at.. what I was getting at was, Is it possible the unit could have originally been thermosyphon.. and then been upgraded to the water pump. If so.. I'd think that'd be why it may not have a provision for a thermostat. Just a guess on my part.

Soundguy

Nope that is DEFINITELY a water pump. But it is curious as the Hoye parts manual does not show a thermostat anywhere. Guess some rumors are right. I wonder how they planned on getting the thing to normal temp in the winter? cover the rad I suppose, but they you need a gauge so that you know when it is time to open it a bit.

Hoye has a sale on the pumps right now for $116.
Mike

 

[Soundguy]

That statement is sufficently vauge as to nearly rener it void. I can show you many OEM presurized cooling systems with air space inthe top tank.

Also.. any time you have a pump and fluid.. you can get cavitation.. if you can get cavitation.. you can have bubbles in a fluid... it's a simple vapor pressur issue.. ( cavitation pinholes in diesel sleaves aren't cause by entrained air.. but rather by micro bubbles forming and then imploding ont he sleave surface causing pitting... the vibration / expansion / contraction from the cyl is what changes the local vapor pressure properties of the coolant around the sleaves. Thus the various addatives to prevent cavitation and electrolysis.. etc.. )

Soundguy

There is no air to form bubbles in a properly filled, closed cooling system. Heat transfer from the coolant to the metal surface of the tube in the radiator - the longer it stays in contact with this cooler surface, the more heat is transfered away from the coolant. Same thing with the heat transfer from the iron cylinder wall to the coolant. Pour a cup of water in a hot skillet for 5 seconds or for 15 seconds - which one will produce hotter water? It's pretty basic. In the case of removing a thermostat in an engine, some systems can handle it better than others, depending on alot of factors, but in most automotive engines you will definitely see some sort of increase in operating temp. at higher rpms, some to the point of overheating especially if the radiator isn't 100% clean or a soft lower hose trying to suck shut etc. etc. It's still a good idea to gut a bad thermostat as opposed to removing it completely to get you by until a replacement can be installed.

 

[Soundguy]

No, it is not true. The YM2220, which is definitely a Japanese rather than an U.S. model, does have a thermostat. Or at least the one I own does.

(And as other's have indicated, physics is no respector of national origin. Physical principles are the same regardless of the language printed on the warning decals.)

Most of the grey models under the 2000 were sans water pump... there are exceptions..

Soundguy

 

[Soundguy]

Lets consider boundary layers, rate of heat transfer for ambient conditions, laminar or turbulent fluid flow and its impact on rate of heat transfer to fluid mass per given unit of time!

Might as well throw in open channel flow when looking at the top rad hose as well..

Soundguy

 

[Egon]

Bill, did you turn on a light switch and put some illumination on the topic???

Are there not some types of graphs that show the fluid state versus pressure versus temperature???

Do you wish a v-notched weir or just a plain old square gate one Soundguy?? Probably could not see it just looking at the top radiator hose!