Hose replacement to HW heater w/ Hose Flix

[Ron Hill]

Craig : With the AGE of our boats it's a constant maintenance challenge!! 
Today one thing (water heater hoses), next propane hose?, exhaust hose? etc.?  You can't let it get ahead of you!! 
My 1st Mate said that if the USCG ever calls and asks "What kind of a boat are you"? she 'll answer a "Work Boat"!!   

[crieders]

Mike, how did you get the heater out? Did you have to tear the trim off the door or is it screwed in? I thought about going with a larger capacity isotherm; round tank

[Stu Jackson]

Cliff, one has always been required to remove the door trim to remove and replace the hot water heater.  Assure that what you buy has the appropriate hose connections (front or rear) depending on how you hoses are positioned.  I suggest you consider adding small extensions of hose from wherever your hose connections are with a simple butt connector to the hoses to the engine (see my story above), which will make it easier to connect those hose if necessary.

[Mike and Joanne Stimmler]

Normally you do have to remove the door trim to get the water heater out but I understand it's a tight fit, so I don't know if a larger capacity heater would fit. When I replaced mine, I also replaced the sink, fawcet and fresh water pump along with all hoses and clamps so I was able to drop mine in from the top. I've never had a problem with running out of hot water. The recovery is pretty quick on these heaters.

Good Luck,
Mike

[Craig Illman]

Cliff -

Another way to extend effective capacity is to install a tempering valve to mix cold in with the 160+ deg. hot water to get 120 deg. output. They're available at: http://www.pexsupply.com/Categories.asp?cID=329&brandid=

Craig

[Stu  7/20/11 - that link didn't work, try this one:  http://www.pexsupply.com/pex/control/search?SEARCH_STRING=tempering]

[Stu Jackson]

Craig, that's one way to do it, and a lot of C36 boats have that.  My understanding is that it has caused more problems than it solves most likely due to lack of understanding of the concept.

Speaking of concepts, here's one about hot water:  We installed a 180F thermostat after a recent experience documented on the board here some time ago.  I was planning to switch back to a 160F, but after using the boat for awhile with the hotter hot water, I realized that perhaps we're using LESS hot water with it being so much hotter from the 180F heat transfer.  When we want "tempered" (mix of hot and cold) water, we're using LESS hot water from the limited six gallon heater capacity.  Although we're rarely run out of hot water any given evening, even washing all the dishes, it may not be that much of a difference, but the heat transfer math does work.

[Ron Hill]

Guys : As I understand a thermostat the temperature # is when it opens.  This means that it'll heat the coolant to that set temperature and then open so a 160 will open faster than a 180.  Then the warm coolant will flow thru the water heater exchanging its heat with the water in the water heater.  Once the thermostat temperature is reached the thermostate stays open until the engine is shut off.

I'd guess that after about 20 minutes of running the engine the hot water temperature for both the 160 and 180 thermostats should be about the same in temperate outside/ocean water conditions?? 
If you run into the situation where the thermostate stays partially closed (colder conditions) the coolant will be hotter and the same for the water in the hot water heater.  But then the engine is also running hotter.   

[Craig Illman]

Ron - I think if the coolant in my engine is registering 180 degrees, my hot water is going to approach that as well. I think that's pretty dangerous at the sink or shower, so I added the tempering valve earlier this fall. We'll see next season how well it works out. Stu - I did a search on the C36 site and didn't find any references or matches to "tempering" or "mixing".

Craig

[Stu Jackson]

Craig, I don't think they have yet "named" it the way you have -- it's just been an ongoing "conversation" about "what's that danged valve for" type of thing.  If I stumble across an example, I'll link it here.  Just something that's been in the C36 Tech Notes in Mainsheet for years and years and occasionally on their MB.

[Tom Soko]

Stu and Craig,
I think you are talking about two different things.  The reference in the C36 messages to a mixing valve in the plumbing has nothing to do with restricting the temp of the domestic hot water.  In earlier C36's there was a gate valve (installed at the factory) and a bunch of extra hoses which could be adjusted to completely or partially restrict the coolant flow to the WH.  I've never been able to get a good reason for its existance.  After checking with several sources (Universal dealer, mechanics, etc.), I removed it from my boat.  It greatly simplified the plumbing around the engine.  I believe what you would be looking for, Craig, is something that controls the output (domestic hot water) from the WH, and not the input (coolant).  Hope this helps.

[Craig Illman]

Tom - Yes, that's what I installed, a valve that blends cold water in with the very hot from the tank regulated to predictable temperature. The tempering valve works just like the thermostat on the engine, but is adjustable within a range of 120-160 degrees.

Craig

[Stu Jackson]

Thanks, Tom, the input side was what I was referring to.  I never saw any reason for it either, complicated a simple two pipe source to and return from the heater.  As I recall, it was never documented.

[Ron Hill]

Guys : I've always thought that's what knobs on the faucet were for!!!!!   

[John Langford]

I am interested in the possibilty of replacing my 160 degree M35B engine thermostat with a 180 degree thermostat. It would appear that Stu and possibly others have done this with the M25. I have never understood why the engine is run at 160 degrees since I understand that you get more efficient operation at higher temperatures (obviously up to a limit). The Perkins on my 320 ran happily at 192 degrees. Does anyone know why Universal maintains that 160 degrees is the right temperature? Has anyone done the swap on a M35B?

[Jon Schneider]

I can't tell you what calculations and risk-assessments went through the engineers' minds at Universal, but I think you have to ask yourself just how much more "efficient" could your engine get by operating 20 degrees higher and what are the risks.  These are tiny engines that consume minute amounts of fuel.  What if you achieved a 5% gain in fuel consumption (I actually doubt any little fix could achieve a 5% gain)?  If you run it 100 hours per year, you might save two gallons of fuel (doubtful it would be that much, but let's look at the high side).  $7.00.  Okay, so you've gained a beer at the yacht club bar.  You've achieved that at the cost of having a 20 degree cushion to prevent catastrophic failure and damage if something goes wrong.  That's probably an extra minute or two to notice the issue and do something about it.  $7.00/year isn't worth it to me, not to mention that we've got tens of thousands (probably many more) engines "happily" running at 160 degrees over decades and very few running hotter with a long track record.  Do you really want to become a guinea pig for $7.00?