Plate and frame heat exchangers have a considerably higher heat transfer per cubic inch since the surface area is so much higher. The problem is that they are more prone to clogs and harder to clean. The freshwater side won't generally clog unless it is contaminated by oil or rust, or you use Dec-cool and let it get really old and gummy. On the other hand, the raw water side is very likely to clog with all types of sea life. In a typical tube style heat exchanger cleaning the tubes meant keeping a dowle rod on board to ram out the gunk. With a plate and frame heat exchanger replacing them is the best option.
Since they are so small maybe consider a 3-way valve on both ends of a pair of heat exchangers in parallel. If one fouls then a quick switch of the two valves would place the other heat exchanger in service. Of course a properly sized raw water strainer can keep you from fouling the heat exchanger. I believe most of the as built strainers are sized with holes smaller than the tube ID - mine is. The plate and frame heat exchangers have very small passages so you'd need to account for that with the strainer. Smaller holes in the strainer means more head loss so you have to use a larger strainer, especially as it starts to clog. There is no such thing as a free lunch. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD Nov 14, 2025 09:22:51 Della Barba, Joe via CnC-List <[email protected]>: > Those flat-plate heat exchangers don’t seem to be intended for salt water or > engines, but they are so much smaller and cheaper I could just buy two and > carry a spare. Are you using electric pumps or the mechanical one? > > > */Joe Della Barba/* > */DCSI/* > */410-966-7255/* > > > > > *From:* Neil Gallagher via CnC-List <[email protected]> > *Sent:* Thursday, November 13, 2025 5:20 PM > *To:* CnClist <[email protected]> > *Cc:* Neil Gallagher <[email protected]> > *Subject:* Stus-List Fwd: Re: [EXTERNAL] Re: Long Term Reports on a few > things: > > > Joe > Here's the tank I used, the same place has the cap and fittings. > https://www.speedwaymotors.com/Speedway-Aluminum-Radiator-Coolant-Overflow-Expansion-Tank-8AN,1840.html > > I put an external Indigo thermostat after the manifold outlet and blocked the > bypass flow on the side of the engine so all the water flows from the pump > thru the block. I use a 160deg thermostat, although you can get 180deg. The > only issue I've run into is that there's so much grit in my engine block even > after I blew it all out with compressed air (40 yrs with raw water cooling > does that, as you found out) that I'd get some under the plate of the > thermostat valve itself which then wouldn't open and the engine would heat > up. I put a strainer upstream of it and that's worked for the last 5 years > or so with no issue, runs right at 160. > > I did not put a zinc in anywhere in the raw water side, the heat exchanger is > stainless, just has bronze brazing between the plates. > > Neil Gallagher > Weatherly, 35-1 > Glen Cove, NY > > > On 11/13/2025 1:15 PM, Della Barba, Joe via CnC-List wrote: > What are you using for an expansion tank? What temps were you running? Did > you add a zinc? > Thanks! > > */Joe Della Barba/* > Coquina > > *From:* Neil Gallagher via CnC-List <[email protected]> > *Sent:* Thursday, November 13, 2025 11:49 AM > *To:* Della Barba, Joe via CnC-List <[email protected]> > *Cc:* Neil Gallagher <[email protected]> > *Subject:* [EXTERNAL] Stus-List Re: Long Term Reports on a few things: > > Joe, > > FWIW I have used this heat exchanger since I put FWC on my A-4. They're so > cheap I consider it a throw-away. First one lasted about 10 years and was > still fine but the copper was getting a little green. I'm on 5 years of the > second. Plenty of cooling capacity. > > https://www.vevor.com/plate-heat-exchanger-c_10378/heat-exchanger-brazed-plate-heat-exchanger-30-plate-heat-exchanger-for-heating-p_010268730644 > > > Neil Gallagher > Weatherly, 35-1 > Glen Cove, NY > > On 11/13/2025 10:58 AM, Della Barba, Joe via CnC-List wrote: > 1. The PVC hawsepipe fix: When the previous owner back in 1973 or maybe the > factory cut the hole through the deck for the anchor chain, whomever did it > did NOT SEAL IT AT ALL. Believe it or not the balsa sort of held up, > apparently being open to air let it dry back out mostly. I got some PVC pipe, > maybe 3 inches, and cut the deck hole a bit bigger so the pipe fit a little > loosely but not much. I cut the pipe to stick through the deck below about ½” > or maybe a bit less. I sealed around the bottom with butyl and then poured > epoxy around the pipe from the top to fill in the tiny gap and seal the > balsa. This was a few years ago and has worked perfectly 😊 I was afraid the > epoxy would not stick to the pipe, but it did and the pipe keeps the chain > from eating away at the deck and compromising the seal. > 2. Using liquid rubber to seal my forward hatch: This I would rate so-so. My > hatches are totally original from 73 and tend to leak around the screw holes > and sela between the glass and the frame. A combination of liquid rubber and > some Creeping Crack Cure makes them watertight, but it does not last. Adding > a touch more is a yearly thing now. It is still a cheap cure vs. a new hatch, > but it is not a one-and-done. I still can’t complain too much, no 52 year-old > Lewmar hatch will even be intact. If I ever do get new hatches, I will be > avoiding the low-end Lewmars, they seem to leak starting at age 2 or 3 from > all I read online. The higher-end versions seem well worth it. > 3. AGM Batteries: No one seems to make lead-acid cells of any version > whatsoever that are as good as the gel batteries I could get around 1990. My > 2 year-old Odyssey thin-plate is doing OK, but not nearly as good as my gel > from back in the day was at age 7. I am going lithium, the savings on > chiropractor bills alone will be worth it! > 4. Fresh Water Cooling – I decided my old engine didn’t need it, the extra > heat and hoses all over did not seem worth it. Joke was on me, last December > the salt water ate through and the engine was no more. Now I have a new (to > me) engine with a Moyer rebuild and sleeved cylinders I will be adding FWC. > The engine will probably outlive me, but I do need to hunt down a bigger heat > exchanger. > 5. Solar: I have had a 50 watt panel for many years. It has literally paid > for itself in gas not used to charge batteries. For a long time I would be at > anchor for 2 weeks straight while the kids were at sailing camp, so there was > no reason to run the engine except charging. It was not enough to keep up > totally, but I went from daily charging to once every 3 days or so. I plan to > fix up more panels. > > */Joe Della Barba/* > Coquina > C&C 35 MK I > > > November is the time of the year when my Internet bills come in. It's also > the time when you can show your appreciation of this list and the C&C Photo > Album. Please help by making a small contribution using PayPal at: > https://www.paypal.com/paypalme/stumurray All contributions are greatly > appreciated. > > > November is the time of the year when my Internet bills come in. It's also > the time when you can show your appreciation of this list and the C&C Photo > Album. Please help by making a small contribution using PayPal at: > https://www.paypal.com/paypalme/stumurray All contributions are greatly > appreciated. > >
November is the time of the year when my Internet bills come in. It's also the time when you can show your appreciation of this list and the C&C Photo Album. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
