Coolant System Heater Hose Length

[DougR]

Originally Posted by Dsanduril

Yes, the limit is only based on overflowing the expansion tank because of the additional volume of total coolant circuit.

Only limit from the other side will be how much flow you get through the circuit and I haven't seen any numbers in that regard from Volvo. Eventually, with enough hose you just won't get the heat transfer you want (but as Nate notes this shouldn't affect the engine if using the aux. takeoffs).

One other minor item, Volvo does recommend moving (remote mounting) the expansion tank if the auxiliary users are above the expansion tank. The cap to the expansion tank is not sealed and if the users are above the tank they can drain by gravity when not in use.

All of the expansion tank caps on the D1-13 thru D2-75 are sealed pressure caps, and the recommendation to raise the expansion tank if the heater is above the engine is not because the system will gravity drain, but because otherwise there is the possibility of an air lock in the system when filling.

IN the case of the D2-55, as stated, if the volume of the external circuit exceeds 1.7 qt., an additional expansion tank should be fitted. 1.7 qts. of fluid is the equivalent of about 27' of 5/8" hose, so that's a pretty good run of hose before another tank is required.

V.P. offers an auxiliary expansion tank kit for the D2-55 engine which taps into the standard aluminum tank, but it's easy to source this after market as well.

DougR

[Dsanduril]

Originally Posted by DougR

All of the expansion tank caps on the D1-13 thru D2-75 are sealed pressure caps, and the recommendation to raise the expansion tank if the heater is above the engine is not because the system will gravity drain, but because otherwise there is the possibility of an air lock in the system when filling.

Why I keep coming back to CF even with frustration on some of the topics - I learn things (and especially when it's things I should have known). Thanks.

[smac999]

Liky 2 things to cosider. Both different.

Total amount of coolant volume. The more you have. The longer the engine Will take to get up to operating temp. Running cold is not great.

Total heat removal. The more heaters added. At some point the engine may never reach proper operating temp. CUsing extra wear and extra fuel to run it.

These are both diff. One heater 100’ away or 10 rads in a 10’ circle each has a diff problem.

[ramblinrod]

Originally Posted by MJH

Last year I installed a small REAL heater in the salon for the Admiral prior to going to Alaska; it does a good job of heating and she likes it. It is the hydronic type using the diesel engine freshwater coolant, similar to a car/truck heater. I had to extend the total coolant hose only about six feet. Overall, the cost was very reasonable compared to installing other type of heaters. Of course, the engine has to be running to get the heat but many legs going north often have to be motored anyway.

This installation has made me wonder on how to determine what the upper limit of the total hose length can be before negatively affecting the engine...I've given some thought to installing a second heater in another compartment.

Thanks.

~ ~ _/) ~ ~ MJH

In a closed system you don’t have to worry about lift, and head loss is limited to flow resistance. You would need to get the pump curve and calculate the total resistance resistance curve based on the CV of the hose times length and of all fittings.

[MJH]

DougR,


A couple years before the REAL heater was installed, 30' of new hose to/from the water heather in the stern was completed; that should now make the total hose length about 36'. Again, I see no ill affect at this time.


~ ~ _/) ~ ~ MJH

[Cheechako]

I don't think you will have a problem with most reasonable lengths of hose.
I had a boat with a heater like that though and with the fan on, it would cool the engine coolant so much that after maybe 10 minutes the heater air became cold because the heater coolant was cold!!
So I don't know if two heaters will do that to you or not.