Controlling and affecting proper operating temp

[Sony2000]

I would like an opinion on adding a ball valve to the exiting raw water from my Atomic. I made the decision to reinstall the motor without the thermostat, and the water pump has a new higher volume cam. Such a system is without control,, so a partially closed ball valve, as in the picture, would add a little pressure to quickly fill the block , contol temperature of the motor, and I can see the setting fairly easy from the cockpit. What are the nays?

[Marian Claire]

Sony: I used that set up for a year or so. It worked fine for controlling temp and gave me the ability to get the engine to a good operating temp. It does create head pressure for the pump and may cause more stuff to settle out in the engine due to slower flow. But neither of those is that big of a deal. I then switched to the recirculating loop and I feel it is a better set up. Dan S/V Marian Claire
Edit: Sorry I should have added that I have a early A-4 so do not have the by-pass, T-stat housing or temp sensor in the head like the late model. Thanks for the reminder Dave.

[Dave Neptune]

Important!!

Sony, don't run without a t'stat UNLESS you are using a restriction (valve) in the bypass line. You need to be assured that the water is actually going through the block and not just cooling the area around the housing where the sensor is. Also be sure your diverter inside is still functional,
I have run without one for over 26 years now and no troubles at all. Actually I never have used a t'stat in my engine since I have owned it. I removed it when I "un-siezed" my engine when I bought the boat. I did however have to replace 1 exhaust valve at that time.

Dave Neptune

[hanleyclifford]

I would like an opinion on adding a ball valve to the exiting raw water from my Atomic. I made the decision to reinstall the motor without the thermostat, and the water pump has a new higher volume cam. Such a system is without control,, so a partially closed ball valve, as in the picture, would add a little pressure to quickly fill the block , contol temperature of the motor, and I can see the setting fairly easy from the cockpit. What are the nays?

This is not a good idea. As has been suggested it will slow down flow in the block - this will cause sediment build up and put unnecessary strain on the pump. Better to go with a bypass loop with shut off valve.

[Marian Claire]

Sony: Would you give use a description of your present cooling system. Dan S/V Marian Claire

[ndutton]

Okay youse guys,

Since you're of a mind to maximize the coolant flow, how do you propose to do it?

[Marian Claire]

I think that the recirculating loop allows for 100% flow thru the engine 100% of the time. I will describe the set up I have. It is a FWC system. The RW loop is the normal set up. 100% RW inters the thru hull to pump to HX to wet/dry and out the transom. The FW loop, 100% AF enters the pump 100% goes in the side of the block, remember early block and head so no by-pass, thru the block and head then to manifold. 100% comes out of the manifold and then I have a T, now I do not know the exact % but in theory 50% goes left and 50% goes right. The right hand line goes to the HX and is cooled and returns to the pump. The left hand line, the recirculating loop, passes thru a ball valve and then returns to the pump. In reality due to the ball valve being half closed the % is probable more like 75% to HX and 25% recirculated but it varies as I adjust the ball valve. So the engine has 100% all the time. No T-stat to slow it down. No by-pass to divert some of the coolant. The FW side of the HX is not getting 100% all the time but I do not see that as a problem.
To me what this does is allows you to control the temp of the coolant entering the block and therefor the operating temp without restricting or by-passing. And that should make for less of a difference in temp of the entrance coolant to the exit coolant and maybe more uniform temps thru the block. I will try and get some actual temps when I get back to the boat. But just from feeling the different lines and reading the two thermometers I have I would say the coolant exiting the manifold is at 140 to 150 F. The mixed coolant entering the pump is warm to the touch so say 110 F???? By adjusting the valve I can change the mix ratio and therefor its temp so the temp of the water the boat is in or how hard I am pushing the A-4 can be accommodated.

I ran a similar set up when I was RWC and ran it for hundreds of hrs. I have only been running the FWC set up for a few hrs. We must also remember that it was my head that cracked but I really do not think this set up was the reason for that. Dan S/V Marian Claire

[Kelly]

I think that the recirculating loop allows for 100% flow thru the engine 100% of the time. I will describe the set up I have. It is a FWC system. The RW loop is the normal set up. 100% RW inters the thru hull to pump to HX to wet/dry and out the transom. The FW loop, 100% AF enters the pump 100% goes in the side of the block, remember early block and head so no by-pass, thru the block and head then to manifold. 100% comes out of the manifold and then I have a T, now I do not know the exact % but in theory 50% goes left and 50% goes right. The right hand line goes to the HX and is cooled and returns to the pump. The left hand line, the recirculating loop, passes thru a ball valve and then returns to the pump.

I'll pipe up to add another data point. My FWC setup is exactly as described here but installed on a late-model block. I've removed the "T" entering the cooling side plate and have removed the thermostat from the housing in the head and blocked off the bypass port. The coolant now leaves the pump, enters the block, is circulated through the head, crosses over to the manifold (using the lower opening on the manifold as the inlet) and exits the manifold through a "Dole" thermostat housing, sans thermostat. One side continues on to the heat exchanger while the other side is the ball valve-controlled recirculating loop heading directly back to the pump (Johnson electric).

I've just finished installing a new dual-pass heat exchanger and need to see what coolant temperatures I now get as I'm trying to correct long-term overly hot running temperatures. Depending on how testing turns out, I may re-install my Dole thermostat as I sure would prefer having automatic water temperature control rather than having to fuss with the ball valve.

To be continued...

[Sony2000]

Sony: Would you give use a description of your present cooling system. Dan S/V Marian Claire

Dan, my system is raw water in, splits as usual on the side of the block, then from T housing to the exhaust manifold. With the ball valve, post manifold, I can add a little back pressure to the system. (good) Then direct to mixing with the exhaust gases.

[Marian Claire]

Sony: If you close the by-pass forcing all the water thru the block and add the ball valve between the manifold and the wet/dry then you will have essentially what I ran for awhile. As stated it worked well but I think the recirc loop is a better system if you choose to not run a T-stat. Access to the ball valve is needed for either system but it is not like you have to adjust it every 5 minutes. A little experimentation will give you a good setting. Dan S/V Marian Claire

[ndutton]

Earlier in this thread there was a discussion over the effect of coolant flow rates where I offered a reduced flow of hot coolant through an exchanger could result in increased heat exchange and resultant lower output temp of the coolant. The suggestion was met with lengthy posts in complete disagreement.

I was OK with that and felt continued haranguing (is that a word?) over it was not good for the forum in general plus I'd developed an overall feeling I was posting way too much anyway. This is the Moyer forum, not the ndutton forum.

Still, it bothered me. I felt as strongly about my position as the others felt about theirs so I went a-lookin'. Attached is an excerpt of a study published by a professional engineer in the geothermal industry. The only variable in the two examples is the flow rate in the hot side of the exchanger, highlighted by red arrows. The resultant output temperatures are highlighted as well.

Please note that this is exchanger dynamic only, not the complete system.

[positron]

Hi Neil-

You shouldn't apologize for continuing this topic- this is what the winter months were made for! I think I have a pretty good idea how heat exchangers work, but I am still puzzling through how to set up a bypass valve so I can remove my thermostat… As Red Green says, we're all in this together.

Yup, this is what is supposed to happen. Some of the hot water (or antifreeze in an A4) spent more time in the HX so it got cooled down more. Another way of saying this is that by cutting the flow in half, the volume of antifreeze that was cooled also got cut in half. The temp dropped about 5 degrees, but only half of the antifreeze volume got cooled. So overall less heat is getting pulled from the entire volume of antifreeze.

The problem is that the tester had the luxury of a benchtop system that could maintain a constant input temperature to the HX. For an A4 mounted inside a boat, if you try this the temperature of the antifreeze and of the engine will rise. The same principle is happening inside the engine- a smaller volume of antifreeze will undergo a larger temperature change, only this time the engine outputs antifreeze with a warmer temperature that becomes the HX input, also with a warmer temp. So overall the engine passed less heat into the antifreeze.

[hanleyclifford]

Lose the "T" fitting at the water jacket side plate, plug the hole in the thermostat housing and then install a diverter valve off the manifold output fitting. Divert flow to coolant pump input side.

[Administrator]

Thanks very much for posting that report, Neil.

Nothing like hard data to steer a conversation in the proper direction!

Bill

[edwardc]

.. plus I'd developed an overall feeling I was posting way too much anyway. This is the Moyer forum, not the ndutton forum...

Please don't stop! Your posts are among the most interesting and informative.

Still, it bothered me. I felt as strongly about my position as the others felt about theirs so I went a-lookin'. Attached is an excerpt of a study published by a professional engineer in the geothermal industry. The only variable in the two examples is the flow rate in the hot side of the exchanger, highlighted by red arrows. The resultant output temperatures are highlighted as well.

Please note that this is exchanger dynamic only, not the complete system.

I looked over the numbers and am in complete agreement with them. Slower flow lowers the output temperature. But again, lets's not confuse temperature with heat energy. They are not the same thing.

Heat energy is often measured in BTUs (British Thermal Units). A BTU is the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. So lets look at the numbers in the paper's two cases. (sorry Hanley, but I promise, no differential equations )

In the first case, the hot side cools from 135 to 117.83 (a drop of 17.17 degrees) at a flow rate of 8 gallons/minute.
A gallon of water weighs 8 pounds, so 8 gals/min equals 64 pounds/minute.
So, 64 pounds/min times 17.17 degrees equals a heat transfer rate of 1098.88 BTU/min.

In the second case, the temperature goes from 135 to 112.82 ( a drop of 22.18 degrees), and the flow rate is 4 gal/min.
4 gal/min x 8 lb/gal = 32 lbs/min.
So this time we have 32 lbs/min x 22.18 degrees equals a heat transfer rate of 709.76 BTU/min

The second case removes considerably less heat energy per unit of time from the hot side, even though the exit temperature is lower.