water heater hook up

[pullark]

Hi,
I have a 1989 Catalina 30 with Universal M25XP motor. I would like to install a water heater and am hoping someone can advise on the installation. I'm wondering if I should use thermostat bypass connection method or take hoses off heat exchanger. What is the preferred method? What are pro and cons with each option. Not sure how the hook up off the HE works...a schematic would be helpful.
Also have heard that air locks can cause problems in the system. How does one bleed off any trapped air?
Thanks in advance.

 

[Old Skool Neil]

Your comments and concerns are spot on which tells me when you are done you'll have a well thought out and reliable system.

I went through this last winter and although our engines are different the water heater loop principles are similar. As in my case the water heater is often mounted higher than the engine necessitating the addition of a header tank. Note that this is different from an overflow recovery bottle. The header tank is mounted at the highest point in the system and if at all possible the hoses running to it should be oriented in an uphill fashion. This will automatically bleed any trapped air.

My installation has the water heater under the V berth and although pretty close, I was not able to fully route the hoses uphill resulting in a small air trap at the top of the heat exchanger. I installed a 1/8" radiator drain valve at the trap (circled in the pic) that bleeds the air pocket within seconds.

You may also see in the attached drawing that my coolant is circulated with an electric pump. The typical Atomic 4 coolant pump is driven by a supplemental pulley on the front of the engine and on our C-30's there is simply no room there. With the electric pump I can circulate the coolant and bleed the system without running the engine, an unexpected side benefit. And as the drawing shows, I color coded my cooling system hoses.

 

[Stu Jackson]

Most OEM installations take it off the thermostat housing for M25 series engines. Bleeding is called "Burping" and the simple trick is to get the air out of the system by assuring that it is full: reply #6 here: http://c34.org/bbs/index.php/topic,4518.0.html

With your engine, you might be interested in some of these Critical Upgrades:

http://c34.org/bbs/index.php/topic,5078.0.html

Maine Sail has also installed a coolant system air release right on top of his thermostat housing.

Just some options for you.