Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 25-09-2016, 15:05   #16
Registered User

Join Date: Sep 2016
Location: Chesapeake southern new jersey
Boat: Eastward ho 24
Posts: 72
Re: Md7a fresh water conversion heat exchanger sizeing help

Cool thanks for all the input. I'll post the build as I get into it probably not till winter is here though...one last thing is your exchanger copper nickel type (cupronickel) or the straight copper? I think I'm gonna go with the copper nickel for longevity.
__________________

__________________
Eastward ho 24 is offline   Reply With Quote
Old 25-09-2016, 16:28   #17
Registered User

Join Date: Oct 2011
Posts: 2,216
Re: Md7a fresh water conversion heat exchanger sizeing help

Before a fire wiped out my shop, I had a freshwater cooled MD7A. I had to go way back in my emails to find photos from when I bought it. This was a Sendure system. The drive pulley went on the end of the camshaft where the hand crank usually goes and the pump mounted to the front of the exhaust manifold. The heat exchanger (about 12 inches high) mounted vertically on the side of the heat exchanger (near the front). It really didnt add to the overall dimensions of the engine. If you modify your engine, I would keep all of the parts needed (including the lower temp thermostat ) to change it back in case you loose a starter and need the hand crank. If you PM me your email, I will send you the photo. Grant.
__________________

__________________
gjordan is offline   Reply With Quote
Old 25-09-2016, 16:34   #18
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 15,544
Re: Md7a fresh water conversion heat exchanger sizeing help

Quote:
Originally Posted by Eastward ho 24 View Post
Cool thanks for all the input. I'll post the build as I get into it probably not till winter is here though...one last thing is your exchanger copper nickel type (cupronickel) or the straight copper? I think I'm gonna go with the copper nickel for longevity.
How do I tell which metal it is made of?

It takes plain zinc anode. The metal, when polished, looks gold rather than red, it oxidizes in the air very fast - if you polish it now, you can't paint it tomorrow.

It does not resemble an electric wire grade copper. It is much lighter shade and feels harder too.

Martec is a Swedish company (?) I think. They probably used the better metal then for the application.

b.
__________________
barnakiel is offline   Reply With Quote
Old 25-09-2016, 16:58   #19
Registered User

Join Date: Sep 2016
Location: Chesapeake southern new jersey
Boat: Eastward ho 24
Posts: 72
Re: Md7a fresh water conversion heat exchanger sizeing help

Copper nickel is copper with nickel alloy added. ( from what I've read I'm no expert) still looks like regular copper but it's suited for saltwater use. And copper is not. Most of the quotes I've gotten from the manufacturers were for copper I had to specifically ask for copper nickel even then some said they only made them in copper. Usually if there's the same exchanger and ones "saltwater" rated then you are safe to assume it's copper nickel. I got a few quotes that the exchanger was rated as "salt water" upon further investigation it was regular copper, so I'd say you'd need to ask the manufacturer. Other means I couldn't tell you how to tell. I could only assume the copper lines on the md7a to and from the pump are copper nickel, mine have been there since 1977. From what I understand copper is not suitable and quickly corrodes. And remember copper is ok from the coolant side but in the exchanger its exposed to the raw water on one side. I don't know how long regular copper would stand up to the test. So if my assumption is correct you could look at your md7a lines and use that as a reference but I'm sure that's not good enough but it's a start.
__________________
Eastward ho 24 is offline   Reply With Quote
Old 25-09-2016, 17:05   #20
Registered User

Join Date: Sep 2016
Location: Chesapeake southern new jersey
Boat: Eastward ho 24
Posts: 72
Re: Md7a fresh water conversion heat exchanger sizeing help

Gjordan, thank you, however I'm using the piggy back pump so I won't need a pulley or pump, but if it's not too much to ask I could use a reference as to what the bracket looks like and its location. I'm gonna try to fabricate a bracket and I've been concerned about elevations of the exchanger. I'd like to just mount the exchanger in my lazarette and run a little extra tube so I could quick check often. I'm not sure if the extra 2 or 3 foot of tubeing would affect the pumps capacity negatively. Am I possibly over thinking this?
__________________
Eastward ho 24 is offline   Reply With Quote
Old 25-09-2016, 19:46   #21
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 15,544
Re: Md7a fresh water conversion heat exchanger sizeing help

The tubes will run nearly horizontal thus there is very little extra pressure per ft of the tube. Some friction, but no head. Also the tubes (if rubber) are bigger diameter than the connectors on the pumps and on the exchanger, hence again little or no pressure added.

I can't tell about a piggyback pump but the electric Bosch has well in excess of any possible pressure drop - remember sweet water is in a closed circuit system - so the pressurized water goes back to the same pump but from the opposite direction. Hence, like in a power recovery pump, the pressure of the returning water helps the pump. I may be wrong but I think there is no pressure loss here.

I do not think there is any worry brewing here.

The cap of our exchanger is slightly above the engine's oil cap level. So that you can open the exchanger any time it is cold and visually check the level. You can also run the sweet water pump and visually check the flow then. The expansion tank is in the locker adjacent to the engine.

If you say copper is too vulnerable then our exchanger can only be the more noble metal - it is as a minimum 20 years old and internally pristine. Outwardly it is like new, except the very bottom part where it has the salt water connections, the anode and the back plate. A riddle, but I can live with it. Maybe one day I will discover why too.

Bueno. Have a fine day, I am off to my bunk now.

Cheers,
b.
__________________

__________________
barnakiel is offline   Reply With Quote
Reply

Tags
heat exchanger, size, water

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SeaEra conversion kit - fresh water AND raw water enovillo Plumbing Systems and Fixtures 3 28-06-2014 16:17
Which Heat Conductive Material to Boost My Exhaust Heat Exchanger? Exhaust Shanaly Plumbing Systems and Fixtures 4 05-07-2013 04:58
Raw-water to fresh-water cooling conversion Catamount Engines and Propulsion Systems 31 06-05-2012 08:29
Heat Exchanger Conversion to Water Tank prae Plumbing Systems and Fixtures 4 20-10-2010 21:17
Heat Exchanger Conversion clausont Engines and Propulsion Systems 15 21-02-2008 18:57


Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 21:59.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.