Removing Hot Water Heater from Engine Cooling Circuit

[Dreaming]

Hello!

I am the new owner of Catalina 310 Hull #31 S/V "Harmony". Due to a drip in the plumbing for the Transom shower that was left unattended for years the hot water heater has become exceptionally corroded.

In preparation for its replacement and because I am afraid of it failing I would like to remove it from my Universal M25XPB Cooling circuit. I know that having a hot water heater hooked up to the engine is basically an optional add on so would I just remove the hoses on the engine side? Or Would I connect the hoses or run a short hose between the two valves?

As you can tell, I'm not all that experienced with working on engines but the owners manual only tells you how to hook up a water heater, not disconnect one.

Any and all help is appreciated. Thanks!

 

[Claude L.-Auger]

You might want to install another heat exchanger tank for hot water one of these days so I would simply disconnect the 2 hoses at the tank and install a by-pass from one to the other. Get a double ended brass hose-barb at your local hardware store and insert both ends into the hoses. Double clamp earch hose on the barb and you should be good to go. Start engine and check for leaks. Or you can remove the 2 hoses at the engine and run a short piece of hose from the outlet to the inlet creating the same loop that your system presently has, only shorter. The final way is to remove the hoses and the fittings and put plugs where the fittings are. Good luck.

 

[weinie]

Once you get air in the system, you will have to burp it to get it out. Run the engine with the coolant cap off and rev it a few times. After that, put the cap back on and run the engine long enough so that it gets to normal operating temp and make sure it stays there for several minutes longer. If you start overheating, you still have air in the system and you need to burp it some more. You might also have to add more 50/50 coolant if you spilled a lot of it when you cut the hose. (Which will probably happen, so have a bucket nearby to put under the ends of the hoses while your work). Then again, it might be a good opportunity to change all the coolant with new.

I dont think you can plug the fittings like the previous poster said. It is one continuous loop.

If you add a new heater later on, you really have to be sure to burp it good. You may even find you have to prime the hoses by filling them with coolant using a funnel and quickly connecting them together to minimize the trapped air.

 

[Stu Jackson]

The heater is "run" from hose extensions that begin from underneath the thermostat housing and above the coolant circulating pump on the front of the engine.

Then the hoses run to the heater connections.

Your BEST BET is to disconnect the hoses at the engine end, rather than the heater end, primarily because the ones at the engine are a LOT closer together.

You'll need about 6 to 8 inche3s of 3/8" heater hose. Simply disconnect the two hoses from the engine (3/8" engine to 5/8" heater) and install the 3/8" bet6ween those two connections.

PS - I think you'd be wise to replace the heater. I just did. It's nice to have hot water when you're cruising.

PPS - Burping simply means filling up the hose(s) from the engine to the heater. Like this: Engine Overheating 101 - How to Burp Your Engine (Reply #6) http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462 Simple.

Good luck.

 

[Duke]

FWIW: Sometimes it helps to physically trace the hoses between the connecting points and draw a simple picture of what you see. It may help you visualize how the system works and what it would take to bypass the water heater.

 

[rpwillia]

Not an exact picture

I can get one next time I am at my boat, but here is a picture of the kit. The Tee and the Check Valve (brass thing in the middle) go on the outlet on the left side. The switch valve (brass thing on the bottom) goes on the inlet on the right and the hose connect the valve on the inlet to the Tee on the outlet which is after the check valve directly attached to the outlet fitting.

 

[gpd955]

Don't have anything to add since you've been given wise direction. Just wanted to say welcome to the SBO and C-310 families.

 

[paulj]

M going outy key board is


My key board is going out............can not use some keys




aulj :troll:

 

[Dreaming]

The heater is "run" from hose extensions that begin from underneath the thermostat housing and above the coolant circulating pump on the front of the engine.

Then the hoses run to the heater connections.

Your BEST BET is to disconnect the hoses at the engine end, rather than the heater end, primarily because the ones at the engine are a LOT closer together.

You'll need about 6 to 8 inche3s of 3/8" heater hose. Simply disconnect the two hoses from the engine (3/8" engine to 5/8" heater) and install the 3/8" bet6ween those two connections.
.

Perfect. Thank you so much this is really helpful.

I can get one next time I am at my boat, but here is a picture of the kit. The Tee and the Check Valve (brass thing in the middle) go on the outlet on the left side. The switch valve (brass thing on the bottom) goes on the inlet on the right and the hose connect the valve on the inlet to the Tee on the outlet which is after the check valve directly attached to the outlet fitting.

Thank you! Where can I get one of those? So that *after* I replace the water heater I can hook one of those up?

So, I didn't get to it this weekend. I wanted to get a good look at what I was dealing with first and take pictures. I can only get to the boat on the weekends currently.

I honestly think plugs can work because from the literature it sounds like the engine can run with the outlets to the heater plugged up as the water heater is just an add on. But what do I know, so I think Im gonna just hook up a hose between the outlets on the engine and get rid of the nasty old hoses anyways.

Then after replacing Im gonna hook up the bypass kit as shown by Paulj and Rpwillia.

Here are some pictures of what Im working with. Now you can see why I want to bypass. The corrosion on the Water heater is a result of years and years of an unchecked leak from the transom shower plumbing.

I managed to fix the leak in about an hour and a half (Coulda been done in twenty minutes but I'm still new at this stuff). I just can't believe the PO (And the charter fleet it was in) Let such a small thing wreak so much havoc.

 

[rpwillia]

Anywhere

I got my Camco kit at an RV store for about $15-20 dollars. West Marine also has them (same part #) for about $38 as I recall.

 

[Stu Jackson]

1. I honestly think plugs can work because from the literature it sounds like the engine can run with the outlets to the heater plugged up as the water heater is just an add on.

2. But what do I know, so I think Im gonna just hook up a hose between the outlets on the engine and get rid of the nasty old hoses anyways.

1. Noooooo. Don't plug them, use the hose or else your engine will overheat. Big time. The hose connections I mentioned are NECESSARY for the coolant pumped circuit to work at all. Please, read your engine manual.

2. Now you know, and why.

 

[Long Story]

OMG looking at the photos I can see why your hot water heater might be leaking... I have never seen one in that condition..

 

[JK_Boston_Catalina310]

You can get the bypass kits from Amazon for $18 (http://www.amazon.com/Camco-35983-Q...81&sr=8-2&keywords=rv+water+heater+bypass+kit)

You can temporarily bypass the water heater from the coolant loop in a total of 1 minute. See the attached photo.

Good luck. That water heater is in rough shape and should be "fun" to get out of there.

Jesse