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Adding Pump to Heater


hunter77ah

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Hey Crew,

I installed a heater this winter.  As numerous people have indicated, it works great when the boat is running, but not so much when it isn't.  Before cutting into the system, wanted to see if the crew had any thoughts on my intended setup.  

Planning to add 2 "T" barbs between the engine block and the heater core.  Before the T on the return line, I want to add the pump.  If this works as I think it should, unless the pump is running, the water should bypass the core and return to the block.  If the pump is running, it will pull the warm water through the exchanger.  If the boat is off, the pump should recirculate the hot water through the Ts.   A picture link is below.  I can't get it to post here for some reason and let my membership lapse...

Thoughts?  While I want hotter air through the heater, I really do not want an engine block overheat situation.  Thanks in advance!

 

https://imgur.com/a/7oY2NiW

Edited by hunter77ah
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granddaddy55
2 hours ago, hunter77ah said:

Hey Crew,

I installed a heater this winter.  As numerous people have indicated, it works great when the boat is running, but not so much when it isn't.  Before cutting into the system, wanted to see if the crew had any thoughts on my intended setup.  

Planning to add 2 "T" barbs between the engine block and the heater core.  Before the T on the return line, I want to add the pump.  If this works as I think it should, unless the pump is running, the water should bypass the core and return to the block.  If the pump is running, it will pull the warm water through the exchanger.  If the boat is off, the pump should recirculate the hot water through the Ts.   A picture link is below.  I can't get it to post here for some reason and let my membership lapse...

Thoughts?  While I want hotter air through the heater, I really do not want an engine block overheat situation.  Thanks in advance!

 

https://imgur.com/a/7oY2NiW

the fact that the pump isn't allowing exchange of free flow doesn't mean you need to plumb for that.  run exactly  what you diagrammed snd flip switch on once a day.

Assuming you want heat at key off?, you could do a Y pipe and easier install snd achieve heat at idle

what you diagrammed is all you need

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I'm confused by what you're trying to achieve. Adding a pump won't make the water hotter so you won't get hotter air. Pump on using residual engine heat will only work for a short time (guessing a couple of minutes). 

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Just now, uk_exile said:

I'm confused by what you're trying to achieve. Adding a pump won't make the water hotter so you won't get hotter air. Pump on using residual engine heat will only work for a short time (guessing a couple of minutes). 

At lower RPMs, there isn't enough pressure to move sufficient water through the exchanger.  The circulation pump helps pull the warm water through.  I'm trying to add the pump without having to turn it on all of the time.  I only want it to turn on when I turn the heater blower on.  My concern is that I am not exactly sure how the 409 internal plumbing works and I don't want to block a cooling line with an inline pump. 

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granddaddy55

is this partial closed cooling?  if open cooled then it doesn't matter as ypipe closes off return at water pump snd routes it to y pipe barb. and since it is a nominal return it doesn't matter  

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The heater loop is an integral part of the cooling system on the Monsoon 409.  If the flow from the "heater out" to the "heater in" on the engine is interrupted it can cause the cooling system to over heat.  Usually, if the heater plumbing is more than about 40 inches total length a circulation pump is often required to allow the cooling system to flow properly.  I haven't seen a heater plumbing set up like that before, so I don't know if will work or not.

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granddaddy55

then you have nothing to worry about with  no flow to return unless heater switch setting is on

running pump to heater fan control/circuit i assume?, any worries run it with vents closed but thats unnecessary

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Putting a one-way valve in your bypass hose will keep the pump from just circulating cool water around the heater loop.

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I added a booster pump to the return line from the heater core. This pulls water through the core and pushes it back into the circ pump. Water flows through whether or not the pump is on. With the pump on and engine off, I get constant heat for a good 10 minutes or so. 

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granddaddy55
On 7/13/2021 at 9:39 AM, UWSkier said:

I added a booster pump to the return line from the heater core. This pulls water through the core and pushes it back into the circ pump. Water flows through whether or not the pump is on. With the pump on and engine off, I get constant heat for a good 10 minutes or so. 

why is this bypass flow necessary on an open cooled system where the flow is nominal at best at idle ?

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31 minutes ago, granddaddy55 said:

why is this bypass flow necessary on an open cooled system where the flow is nominal at best at idle ?

@csleaver already answered that question.  The engine is designed to have that flow in order to circulate the hot water properly and keep the temperature correct.

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granddaddy55
24 minutes ago, justgary said:

@csleaver already answered that question.  The engine is designed to have that flow in order to circulate the hot water properly and keep the temperature correct.

he though it was a closed cool heater, the poster immediately responded to the prev post that it was an open cooled heater which is def not critical to the cooling of an open cooled system evidenced by two things   :

1 , no heater installed, what then??

2, install a y pipe on a heater install snd you block off the return to water pump housing just like i did with mine

what is the diff on a 5.7 vs 6.2 open cooled???

i have a friend with the pump on s 5.7 iride with no bypass plumbing and i have the ypipe on my 5.7

Edited by granddaddy55
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The Monsoon 409 uses the GM L96 6.0L engine which has what is often referred to as a reverse flow cooling system.  That is why it uses an air purge tube connected to both cylinder heads.  The small u-shaped hose on the heater loop allows the coolant to flow properly through the system.  It doesn't really matter if it has a closed system with coolant or and open system with sea water, the proper flow is important in this type of system which is very different from the 5.7L GM engine cooling system.

I would personally never consider using an open sea water cooling setup with the L96, but Indmar and Pleasurecraft Crusader have plenty of them out there.

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granddaddy55
14 hours ago, csleaver said:

The Monsoon 409 uses the GM L96 6.0L engine which has what is often referred to as a reverse flow cooling system.  That is why it uses an air purge tube connected to both cylinder heads.  The small u-shaped hose on the heater loop allows the coolant to flow properly through the system.  It doesn't really matter if it has a closed system with coolant or and open system with sea water, the proper flow is important in this type of system which is very different from the 5.7L GM engine cooling system.

I would personally never consider using an open sea water cooling setup with the L96, but Indmar and Pleasurecraft Crusader have plenty of them out there.

so all of these boats have the heater option. ?

the poster installed his heater. so a heater loop was already on his boat i assume.

then he simply needs to tee off of that and back in and its already routed before his heater install where he would have seen it?

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3 hours ago, granddaddy55 said:

so all of these boats have the heater option. ?

the poster installed his heater. so a heater loop was already on his boat i assume.

then he simply needs to tee off of that and back in and its already routed before his heater install where he would have seen it?

The original question, as I understood it, not about how to install the heater, it was that if he puts a pump in the circuit to give him good flow with the engine off, will it harm the engine to run it when the pump is off?  The answer to that question is probably yes, it will harm the engine. 

The next question is what about putting a bypass in the line before the pump so that circulation is never blocked?  My answer is that I would be concerned that the pump will circulate cool water around the closest loop and maybe not draw enough hot water to get good heat.  A one-way valve installed in the bypass would make sure that the pump could only draw hot water from the engine, yet still allow the bypass to work correctly when the heater pump is off.

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