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Removing Red Dot heater

May 16, 2015
42
C&C 37 128 Portland
Hey all:
As I complete installation of a new diesel heater, I'm thinking about removing the original bus heater (Red Dot). This runs off hot coolant from the engine and might be a good secondary (engine running) if it worked. As it is, the hose connection leaks and the fan needs replacing--not really worth the effort, and I prefer to be rid of the extra leak potential. If you've removed a unit like this, any advice? Believe I need to install a bypass coolant hose at the engine and plan to use a section of the existing heater hose. Engine is a Yanmar 3H 27. Feedback?
 
Feb 11, 2017
121
former Tartan 30 New London, CT area
I removed a similar unit from a Perkins 6-354. I didn't run a bypass. Just plugged the source and return ports. This was NOT in my T30!
 
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Dec 15, 2020
8
Swan 40 Seattle
I used to be chief eng. at RedDot. Your heater is just like a hot water tank in that it circulates the coolant from your engine. If you want to remove it just plug the inlet and outlet connections from the engine.
 
May 16, 2015
42
C&C 37 128 Portland
Perfect, thanks SS. I’m headed to boat tomorrow to see if the ports are threaded and find the appropriate plug. What is typically used?
 
Dec 15, 2020
8
Swan 40 Seattle
Probably 3/4 in tapered pipe plugs. Remove your hose nipples and match the thread. Don't force things. Use a little teflon thread sealing tape.
 
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CarlN

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Jan 4, 2009
577
Ketch 55 Bristol, RI
Whatever you do, when you are done don't forget to bleed the engine coolant to clear it of any air bubbles.
 
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Apr 8, 2010
1,604
Ericson Yachts Olson 34 28400 Portland OR
We have used a Heatercraft "coolant circuit" heater for almost 20 years. Wonderful when transiting the WA coast up or down. Almost never much wind so we're usually motoring. Given that your electrical and hose routing is already in place, I would just replace the hoses and the heater. While it's only useful when the engine is running, that tends to be often in the Pacific NW.
Ours was plumbed in series with the hot water tank coil.
Anyhow, just my .02.....

Small world: we are just finishing up the install of a diesel forced air heater, as well. Looking forward to having heating choices.
 
May 16, 2015
42
C&C 37 128 Portland
Yes, I do understand the benefit of keeping it, especially for those windless motors in the cold. We're counting on using our new heater, but having an alternative source is wise. Need to test it with power. PO cut the wires to the fan motor--not sure why.

Small world: we are just finishing up the install of a diesel forced air heater, as well. Looking forward to having heating choices.
Which diesel heater did you get and where installed on your boat? I've mounted ours in the lazaret, takes up precious space--one of those tradeoffs.
 
Apr 5, 2009
1,564
Catalina '88 C30 tr/bs Oak Harbor, WA
I have seen many suggestions to just plug the lines but that is not correct. You can bypass it by replacing the heater with a nipple but cannot plug it.
In order for the red-dot to work it must be in the "cooling circuit". that means that coolant flows through it. If you plug the lines you break the circuit and the coolant in that circuit no longer flows. That is a bad thing.
It would have been plumbed into either than thermostat by-pass circuit or the primary coolant circuit.
  • If it is in the former, the thermostat will likely not open until after the engine block is overheated because without the by-pass circuit, the coolant is not circulated through the t-stat housing.
  • If it is the latter you will overheat the engine when the thermostat opens because the coolant will not flow through the heat exchanger.
 
May 16, 2015
42
C&C 37 128 Portland
Hayden, maintaining the circuit was my original understanding.By nipple I assume an appropriate hose installed outport-inport. Makes sense to me.
 
Apr 8, 2010
1,604
Ericson Yachts Olson 34 28400 Portland OR
Yes, I do understand the benefit of keeping it, especially for those windless motors in the cold. We're counting on using our new heater, but having an alternative source is wise. Need to test it with power. PO cut the wires to the fan motor--not sure why.
Which diesel heater did you get and where installed on your boat? I've mounted ours in the lazaret, takes up precious space--one of those tradeoffs.
I have tried to research the 'major players' (Webasto, Espar, and Wallace) in this field, at least among the technicians that I know. Nowadays there does not seem to be any one that is demonstrably better or worse... and since our installer is very familiar with Espar, that's what we went with.

This will mount in the lazaret and also have an ABS-mandated outside air intake. Also we put in a separate smaller fuel tank which will let us burn Kerosine if we wish to. You are sure right about space tradeoffs...!
Oh boy.
Everything you add to a boat is somewhat like the old "squares" puzzle game we played as kids where you keep moving the little tiles around to get the letters to line up a certain way. :)
Lucky also that we have an unused breaker on the main DC panel that I have been "saving" for this project.
 
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Apr 5, 2009
1,564
Catalina '88 C30 tr/bs Oak Harbor, WA
Hayden, maintaining the circuit was my original understanding.By nipple I assume an appropriate hose installed outport-inport. Makes sense to me.
What you want to do is connect the two hoses that go into the red dot to each other with a suitable connector. Cut off a bit of the hose and take it with you to your local hardware store and get the correct size. You can remove as much hose as you like as long as you join the two ends back together. If you have a water heater that is connected to your engine, it is more than likely in the same coolant loop as the red dot.
 
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May 16, 2015
42
C&C 37 128 Portland
Resolved. I even found the fiberglass cutout and taped back in place. I'll be looking for a replacement bus heater down the line.5F1266A8-72C4-4498-AF50-D244542AF36E.jpeg
 
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Apr 5, 2009
1,564
Catalina '88 C30 tr/bs Oak Harbor, WA
Good job. You will still need to make sure that you get that hose purged. You get air in the line when you open it up and if that gets trapped, you will not get proper cooling.
 
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