Hot water

Tim R. · Oct 1, 2009

Who did the work?

Is your expansion tank mounted above the level of the water heater? Does it have any coolant in it?

Have your properly bled you fresh water cooling system?

Bob V · Oct 1, 2009

bleed it

If you diid not do anything with your domestic water system the problem is in the new hoses to the heater. If you have cold water coming out of the tap with ONLY your hot faucett turned on, this verifies that your domestic system is working.

Find the highest fitting and loosen the hose clamps. Pull the hose far enough off for it to leak and if it doesn't leak you have found the bubble or at least one of them. If it leaks air or a combination of air and coolant just wait until the air is gone and you have cleared that bubble. Their could be other bubbles in other high spots depending on how your system is plumbed. You may need to run the engine while doing this to provide pressure to push out the bubble.

It's a good time to have a lot of old towels laid out to catch the mess before it runs everywhere. Don't forget to top up your engine coolant afterwards.

Stu Jackson · Oct 1, 2009

Are you running the engine under load? If you're just wasting time at the dock in idle, you won't get hot water.

Otherwise, you need to "burp" the hot water loop from the engine to the heater. Take one end off, usually at the thermostat housing, get a hand pump and suck on it, putting the water back in the manifold.

You simply need to assure yourself that the hose is full of water with no air.

Oddly enough, if you've run the engine for 45 minutes and it hasn't overheated, it sounds like you don't have a problem, other than running under load.

It would help if you told us what engine.

See reply #6 here for a Universal M25-series engine: http://c34.org/bbs/index.php/topic,4518.0.html

RichH · Oct 1, 2009

If the top of your 'water heater' is HIGHER than the level of the 'radiator cap', then you need to be sure that there is not an 'air bubble' in the top of the water heater engine coil.

The easiest way for repetitive 'burping' is to place a tee in the 'highest' section of hose in the system; attach a small 'cock valve' that will allow purging of any entrapped air. Opening the cock valve when the engine is running will expel any 'air bubble'.

If the water heater and its delivery/return hose is lower than the level of the 'radiator cap' ... then the system will automatically purge the air (if the cooling system has a 'reservoir tank').

Stu Jackson · Oct 1, 2009

RichH said:
If the water heater and its delivery/return hose is lower than the level of the 'radiator cap' ... then the system will automatically purge the air (if the cooling system has a 'reservoir tank').

Rich, with all due respect, at least for our M25 series engines, that statement is incorrect, for just about every Catalina made, where the hot water heaters are lower than the engine. Know for sure about the C30, 34 & 36. That's why I provided the link that I did in my earlier reply. Unless the loop is burped properly, as detailed in the link, the engine WILL overheat. Period. It is much easier to burp it properly than it is to watch the engine temperature hit 200 and try to open the petcock on the top of the thermostat housing while gunning the engine and spraying coolant all over the engine compartment. I did it the hard way in 1998 to 2000 and have learned and used the easy way ever since.

Other engines MAY be different, but he still hasn't told us what engine he has...:dance:

Stu Jackson · Oct 1, 2009

Dream Chaser said:
Question is what is the best way to correct this? Thanks for any and all help

Answer: get the stupid mechanic back to fix it!

If you trust him to ever touch your boat again, that is. You let him get away without checking this? This is another reason I recommend that folks work on their own boats.

Here's an example of some work that took me a full day, but I got it done, and done right and never did it before, but I know it was done right. And I burped the engien after this, which is what led me to write the burping article, too: http://c34.org/bbs/index.php/topic,3769.0.html

For those who claim "I dunno anything about electrical," or any other boating subject for that matter, I strongly urge you to start reading. There is so much out there, and you can either buy or library a book, or find it online.

I recognize that some folks don't have the time, can't make the time, or like our classmates in school some folks just don't get math & science, while I never "got" art. That said, I still believe that knowing your systems on YOUR boat and being able to troubleshoot and repair them is an important and very basic safety issue. No one says you need to know everything or be Mr. Toolman, but you can learn the basics to be able to work on the systems you have on your boat. It's wires and connections, or pumps and connections, or rigging and connections, and YOUR safety if things don't work. Much of it is actually simpler than the stuff we have in our homes. So, consider buying a simple book about boat electricity and other boat systems and read it every once in a while, and sooner or later some of it will get through.

I didn't know any of this stuff when I bought our boat in 1998. I started reading and DOING, how else ya gonna learn?

RichH · Oct 1, 2009

Stu Jackson said:
Rich, with all due respect, at least for our M25 series engines, that statement is incorrect, for just about every Catalina made, where the hot water heaters are lower than the engine. Know for sure about the C30, 34 & 36. That's why I provided the link that I did in my earlier reply. Unless the loop is burped properly, as detailed in the link, the engine WILL overheat. Period. It is much easier to burp it properly than it is to watch the engine temperature hit 200 and try to open the petcock on the top of the thermostat housing while gunning the engine and spraying coolant all over the engine compartment. I did it the hard way in 1998 to 2000 and have learned and used the easy way ever since.

Other engines MAY be different, but he still hasn't told us what engine he has...:dance:

Stu .... his orginal post:
"After running for 45 minutes I still do not have hot water from the faucet. Engine temp is good so I'm thinking that I have an air lock. Question is what is the best way to correct this?"

......... that post seemed to me to clearly state that his engine is NOT overheating ...

I'll refer back to my immediate previous post as a most probable cause.
Second most probable cause would be a large air bubble in the top of the potable water side of the tank ... and all he has to do is 'burp' the thermal/pressure relief valve to purge that side of the HW system.

That his engine temp is good would mean the engine is within proper operating temperatures ... that he doesnt have hot water but flow, means there is a heat transfer anomaly ... and trapped air bubbles (on either side of the HW heater) can cause heat transfer anomalies. :dance:

;-)

Stu Jackson · Oct 1, 2009

Yup, I agree.