Water flow in an MC-8

[JackConrad]

     I have a question about the water flow in our MC-8.  We have removed the OEM heater core and plan to connect a circulating pump to the 2 pipes that used to connect to the heater core.  I want to make sure the pump we are adding pumps in the same direction that the water pump on the engine does. One of the OEM pipes is on the passenger side of the bus in the OEM heater core compartment (in front of front baggage bay) and appears to come from the temperature control valve that is installed on the side of the center tunnel (this valve has already been "gutted" to insure maximum water flow). The other pipe is on the driver's side of the OEM heater core compartment.  Thanks in advance, Jack

[gumpy]

Driver's side was supply. Should come into the center of the engine compartment above tranny.
Passenger side (valve) was return. Came into engine compartment and routed down below a/c compressor.

[JackConrad]

Thanks Craig, that's what I needed.  Jack

[JohnEd]

Jack,

If you install the pump in the front of the coach your pump will have to lift the water and suck on the line resistance to move the water.  I would suggest that the pump be mounted near the engine and be allowed to "push" the water thru the system.  With all the actions such as "gutting" the thermostat and such, it would seem that you have had heating problems for awhile.  While I have never done this I have pondered the procedure:  Isolate the front system.  Blow out the lines and heat exchanger for the heater/defroster.  Recharge the front system with water and CLR.  Use the aux pump you are going to install anyway and circulate that cleaning mix that will clean the lines and radiator/heat exchanger.  I would reinstall a good thermo for the front after cleaning the system.

Does that sound like a good way to improve the functioning of the defroster and heater to you?  The core in the front has to be funky after all these years.

John

[JackConrad]

Jack,
    If you install the pump in the front of the coach your pump will have to lift the water and suck on the line resistance to move the water.  I would suggest that the pump be mounted near the engine and be allowed to "push" the water thru the system.  With all the actions such as "gutting" the thermostat and such, it would seem that you have had heating problems for awhile.  While I have never done this I have pondered the procedure:  Isolate the front system.  Blow out the lines and heat exchanger for the heater/defroster.  Recharge the front system with water and CLR.  Use the aux pump you are going to install anyway and circulate that cleaning mix that will clean the lines and radiator/heat exchanger.  I would reinstall a good thermo for the front after cleaning the system.
   Does that sound like a good way to improve the functioning of the defroster and heater to you?  The core in the front has to be funky after all these years.
John

    Actually, we have never had heating problems (of course we rarely tavel in temps below 40-50 degrees).  We removed the OEM heater core years ago, but kept the defroster which works great.  The reason for the pump is to circulate the engine coolant through a heat exchanger that has the other side connected to our ProHeat. This will allow preheating our engine. I had planned to install the circulating pump near the heat exchanger. We hope to also be able to extract heat from the engine coolant when using our ProHeat and the engine is running (using the aux. pump to supplement the engine coolant pump. 
   The temperature control valve was gutted years ago at the same time we removed the OEM heater core because we removed all the temp control sensors and switches. The defroster has a manual shut-off valve next to the driver's seat that isaccessible even when driving.  Jack

[gumpy]

Jack,
This should work just fine for you.  I've done the same thing with my Aquahot, except that I ran 3/4" copper through the tunnel from the center bay to the engine compartment before I reinstalled my floor. I put a march pump on it for engine preheat off the Aquahot.
When traveling, I heat the aquahot off the engine simply by the flow through the engine with the engine water pump. I don't turn on the march pump at all when driving. Within 100 miles, my aquahot is hot. Not sure how hot. I know it's not 185 because when I turn on the aquahot master switch, the burner kicks on, but it only runs a few minutes, so I think it's getting heated to about 160* or so. Also, I just flow the engine coolant through the march pump when driving. There's not enough resistance through the pump to be a problem.
Note that I would not be able to heat the coach in this manner, as the tiny heat exchanger in the aquahot simply won't supply enough heat for that, but when I get where I'm going, I have hot domestic water.

craig

[Ednj]

Jack,

I'm in the process of gathering the parts to do the same thing.
So far I got the Flat plate heat exchanger and a Taco pump w/flanges.
In the Proheat/ Webasto installation manual, they show where to tie into the heads for engine preheat and proper circulation,
Might be a bit easier.

[JackConrad]

Jack,
   I’m in the process of gathering the parts to do the same thing.
So far I got the Flat plate heat exchanger and a Taco pump w/flanges.
In the Proheat/ Webasto installation manual, they show where to tie into the heads for engine preheat and proper circulation,
Might be a bit easier.

Ed,
   Might have been easier, if my proheat and heat exchanger were closer to the engine. I installed my ProHeat in the middle bay and the heat exchanger is in the front bay near the (removed) OEM heater core.  I really doubt that we will use this to preheat the engine more than a few times a year. We also have a block heater for the engine. I was more concerned about extracting heat from the engine for the ProHeat when driving.  If the temps start to get too cold, time to start the bus and head south LOL  Jack

[JohnEd]

Jack,

I have asked this question before and I don't think I got an answer.  Why not splice in the proheat circuit to the engine coolant?  All eth gly mix I think.  I would think that that would make all of your Proheat features available while underway.  I saw one that had the Webasto and engine connected and he had basically a choice as to whether to heat with one or the other and the W heated the engine when needed.  A coach builder told me the best way to cool a gen was to use the engine coolant and rad.  He was simply amazed that some people would balk at that upgrade when they were having him install a sound proof genny box.  Amazed!

Still curious,

john

[Iver]

Hi Jack,
    I took Craig's advice and added a secondary volume of water for my Hurricane heater.  I bought a marine electric (120v.) hot water tank, (around 6 gal.), with an engine heat exchanger built in.  This gives me more water circulation through the baseboard heaters in the coach.
    I built a supply manifold and a return manifold and installed them in place of the original large heater core. One loop goes into the marine water tank and out to the return manifold.  I plan on another loop to circulate through my propane water heater and maybe a third loop to a separate heater for the co-pilot.
    Just in the trial stages so far but the engine heat circulates very well through the marine tank just from the engine water pump.

    So while I'm on shore power,  I turn on the electric heat in the marine tank, then start my Hurricane circulation pump which moves water through the baseboard heat.  Then when driving, the engine heat keeps the marine tank hot which also give me heat in the coach.   I should only have to use the Hurricane furnace when parked in very cold weather.

   This marine tank is normally used to heat potable water but I have it plumbed into the Hurricane system to give me a "poor mans" Aqua Hot.
       Iver.

   

[JackConrad]

Jack,
I have asked this question before and I don't think I got an answer.  Why not splice in the proheat circuit to the engine coolant?  Still curious,
john

Just a personal choice. I wanted to keep the systems isolated so a failure in one system would not affect the others.

Iver,
   We had to add a tank also to get enough volume to prevent the ProHeat from "short cycling"   Jack