Moyer heat exchanger emptying

[ArtJ]

How full should the Moyer heat exchanger reservoir tank stay `normally?


My new heat exchanger has been refilled several times and is currently
nearly 2/3 empty. I believe the loss is going to the plastic overflow bottle.
I resealed the fitting on it with 5200 a couple weeks ago. Maybe it did not
seal correctly

I am thinking that the overflow plastic bottle is setting up a siphon and
I am thinking of temporarily removing the hose and simply letting overflow
go directly into the bilge. I have seen stains from the area of the overflow
so I know some antifreeze was going there and leaking out.

I am limited as to where I can place the plastic bottle. Currently it is
a about 3 ft outboard of the heat exchanger and at the appox. same
height. It can't be placed closer to center line as it would wet switch
panels. I wonder when boat heels if I siphon is being set up

There are no other leaks that I can find .

Comments and suggestions appreciated.

Art

[hanleyclifford]

Art - My overflow bottle is over a foot above the exchangers. I believe the bottle must be the highest component in the system. Regards, Hanley

[ArtJ]

Thanks Hanley

I will see if I can mount it a little higher.

I will also experiment with having no overflow plastic bottle and see if
less antifreeze is lost.

What is normal level in your reservoir? ( you may have mentioned this in
another posting)

[ArtJ]

Another possibility might be if the plastic bottle is totally sealed, top and
bottom, then if a siphon setup, it would only be effective until plastic bottle
totally filled, then when engine cooled,and boat righted or tacked antifreeze simply would flow back into reservoir , assuming
boat is "on the level" and seals are water tight ? (probably not totally feasible)

[ndutton]

Art,

If you're actually losing coolant it's definitely going somewhere. If it were simply going to the plastic recovery bottle, the bottle would be full. If the bottle is overflowing, the coolant would be in the bilge. Your post suggests neither.

You did say the exchanger was new. Is here any chance air in the system is burping itself to the exchanger, like from a water heater loop? If so, your falling coolant level should stabilize over time.

So, do you have a water heater? Is it or its connecting hoses above or below the heat exchanger fill cap? Do the hoses run in a continuous uphill path to the exchanger or is it more like a roller coaster path?

[rigspelt]

Art, I think the idea is that the heat exchanger should be full when cold, to avoid air bubbles circulating in the closed antifreeze system. When warm, expansion causes antifreeze to back up into the reservoir.

When I was installing our FWC system, I found these tips:

From Don at MMI: The very top of the fill neck of the heat exchanger itself should be an inch or so above the highest point in the engine's cooling system, simply to avoid water spilling out of the exchanger when you remove the fill cap.

From Tom at Indigo: The overflow bottle can be plus/minus one foot relative to the top of the heat exchanger.

I placed the reservoir so its bottom is just above the heat exchanger.

I filled the heat exchanger to the top and put the cap on. What I am not sure about is whether to add more antifreeze to the reservoir so there is always antifreeze in the reservoir. I can't find low-high marks on the plastic reservoir. Maybe I should add more antifreeze to the reservoir so there is about an inch in it and see what happens. Would be easier to check antifreeze level and top up antifreeze using the reservoir than by waiting for the engine to cool and removing the pressure cap on the heat exchanger. But if I do that, then when I remove the pressure cap for some reason, antifreeze will spill out of the heat exchanger.

[ndutton]

This recent thread might be of help, specifically posts 86 through 95.

http://www.moyermarine.com/forums/sh...?t=4016&page=2

Also, I would avoid mounting the recovery bottle above the exchanger reservoir. With the bottle above, opening the exchanger cap would gravity drain the bottle contents and potentially overflow the exchanger resulting in a coolant mess.

The coolant in the recovery bottle is drawn into the exchanger reservoir as it cools and develops a negative pressure gradient so a gravity flow mounting position is unnecessary.

[ArtJ]

Originally Posted by ndutton

Art,

If you're actually losing coolant it's definitely going somewhere. If it were simply going to the plastic recovery bottle, the bottle would be full. If the bottle is overflowing, the coolant would be in the bilge. Your post suggests neither.

You did say the exchanger was new. Is here any chance air in the system is burping itself to the exchanger, like from a water heater loop? If so, your falling coolant level should stabilize over time.

So, do you have a water heater? Is it or its connecting hoses above or below the heat exchanger fill cap? Do the hoses run in a continuous uphill path to the exchanger or is it more like a roller coaster path?

I have actually seen the stains from the coolant leaking from the plastic bottle That is why I recently sealed it with 5200. I see the coolant in the
bilge.
The Plastic bottle's bottom fitting didn't
really seal well was partially stripped. It may still be leaking.

More details of the cooling system are a newlly installed oil cooler from
Indigo, also a early style indigo mixing valve is installed.

[hanleyclifford]

Neil is right about opening the fill cap and spilling antifreeze via a drawdown from the the overflow tank. However, this is the price I don't mind paying in order to keep the system free of air pockets. If you want to get fancy, put a small shut off valve between cap and overflow tank - then very little antifreeze will be lost.

[ArtJ]

Originally Posted by ndutton

This recent thread might be of help, specifically posts 86 through 95.

http://www.moyermarine.com/forums/sh...?t=4016&page=2

Also, I would avoid mounting the recovery bottle above the exchanger reservoir. With the bottle above, opening the exchanger cap would gravity drain the bottle contents and potentially overflow the exchanger resulting in a coolant mess.

The coolant in the recovery bottle is drawn into the exchanger reservoir as it cools and develops a negative pressure gradient so a gravity flow mounting position is unnecessary.

Neil
The bottle is mounted probably a foot more or less above the
Heat exchange reservoir. The plastic line goes down near the
bottom of the engine( this is a tartan 34c with the engine mounted
in the centroid of theboat cabin partially down in the keel.
The plastic line then travels outboard thru battery compartment and then
thru a bulk head into the electrical console where it the bottle is mounted
outboard about 3 feet from exchanger and less than a foot above it.
I used this exchanger last fall without indigo regulator and oil heater.
At the time I could mount bottle somewhat lower than heat exchanger
inside battery compartment. Because of adding more batteries I had
to relocate inside electrical console (away from components for sure)

I have bleed the regulator per Indigo instructions. Again this is the
style of mixing valve Tom sold 10 years ago, which I never installed till last
fall.

Thanks

Art
PS I take it you bottom line is to mount it at the same level as reservoir

[ArtJ]

IF mounted at the same level, isn't a siphon setup when boat heels? Especially since bottle is 3 ft outboad of exchanger?

[hanleyclifford]

To get back to the questions in your original post. Yes, the exchanger should always be chock full of antifreeze. Yes, the overflow bottle should always have antifreeze in it but NOT be full. The overflow line under the bottle should always be full of antifreeze and must not leak. The only way I know to accomplish this is to mount the over flow tank at the high point of the system and make sure the line going from the overflow tank to the exchanger runs downhill without any uphill deviations. This configuration will allow the system to "burp" especially if you have heaters or other remote accessories. It is true that automobile systems have overflow tanks at the same level as radiator caps and do rely on pressure gradient to maintain a tight, full, air free system. If you can make that work for you, so much the better. Of course as you have already pointed out, sailboats heel and (hopefully) autos do not.

[rigspelt]

Originally Posted by ArtJ

PS I take it your bottom line is to mount it at the same level as reservoir

Neil and Art, thanks for getting me to revisit this again. I really struggled with trying to figure out where to mount the exchanger and reservoir when I upgraded to FWC. Hanley, we posted simultaneously, and I revised this post given your thoughts. You favour option A for a boat, Neil favours option B. I'd like to make B work, but for now I have A.

I like the idea of mounting the reservoir so the bottom of the reservoir is below the top of the heat exchanger pressure cap. Maybe some day I'll move the heat exchanger down and inboard on the bulkhead, which will give me room to mount the reservoir lower so that I can remove the heat exchanger pressure cap without spilling antifreeze, but allow me to watch the antifreeze level through the translucent wall of the reservoir, and top up via the reservoir not the pressure cap. This will free up space and shorten the hose runs too. But, as Hanley points out, this has disadvantages, and maybe I'll leave this as they are.

I made up this little drawing to give us a frame of reference for this recurring discussion about where to mount the heat exchanger and reservoir.

[hanleyclifford]

Rigspelt - That system looks fine assuming the levels shown are the cold positions. Just make sure the level in the plastic tank is above the cap on the exchanger.

[hanleyclifford]

Rigspelt - Option "A" is superior to "B".

[ndutton]

Art,
I don't think the overflow reservoir location has anything to do with your original question, that being disappearance of 2/3 of the coolant in the heat exchanger. The overflow system will work in either of Rigsy's drawings but one of them is a little more user friendly than the other. The coolant is not returned to the exchanger by gravity so the lower mounting works fine. I acknowledge that you've seen evidence of the reservoir leaking and with that leak, any coolant in the reservoir will find it's way out but your posts suggest this evidence is minor, no where near the magnitude I would expect.

Rigs,
Add to one of your drawings a coolant loop for a water heater with the heater mounted slightly higher than the engine and/or the feed and return hoses routed a little higher (typical for a sailboat installation). That'll show the problem of trapped air, and plenty of it, when filling the coolant system. With use, the trapped air will eventually work its way out and when it does, coolant will take the place of the air reducing the level in the exchanger or header tank (see next paragraph).

The thread I referenced discusses the addition of a 'header' tank in such an installation (distinctly different from an overflow recovery tank). The header tank is mounted at the highest point in the system (water heater and coolant loop included), not just higher than the engine. The header tank gets the pressure cap and the overflow recovery system.

IF mounted at the same level, isn't a siphon setup when boat heels? Especially since bottle is 3 ft outboad of exchanger?

Nah, pressure cap eliminates any possible siphon.

[hanleyclifford]

The header tank is an excellent suggestion in that it makes it possible to "burp" the ENTIRE antifreeze system, as Neil indicated. I accomplish the same thing by means of a "riser" from the top of the pump intake. The riser also carries the pressure cap. The key is getting above the rest of the system with the pressure cap.

[ArtJ]

Neil I am not what you mean by a header tank. Could you please describe this ?

I have seen a large stain leading from overflow on the side of the hull.
This suggests a large flow, not a trickle.

My overflow is higher and OUTBOARD by 3 ft. of the exchanger tank.

That is why I think a siphon is a possibility, even with the engine off.

If the tanks are mounted near each other, both would stay relatively
close vertically when the boat heels. Unfortunately, I do not have
room to do this. I know that Tom Stevens on his t34c has the overflow bottle
mounted in the battery compartment, which would make it lower.

I am going to remove hose and see if no tank improves loss of coolant.

Art

[ArtJ]

Couple of afterthoughts:

The original universal factory fresh water cooling small exchanger that
I had up till mid summer last year lost a little water, maybe a quart or
so after a 8 hr run. It mounted right over the manifold. It also had
no recovery bottle. But it never was a big problem


Secondly, my problem might still be the leaky poor quality threading
at bottom of plastic tank, even though I 5200'd it maybe it didn't cure
or got antifreeze in the way. I.E antifreeze flows into bottle, drips out
and can't go back in. over a few hours running or sailing, tank goes
down and after 5 or 6 hours of running is only 1/3 full.

Thirdly, mounting it outboard as I have may be contributing to the problem

[ArtJ]

Another thought- As I mentioned earlier, I have installed Tom steven's
earlier style mixing valve. Could this setup put the system under greater
pressure and possibly exhasborate (sp?) the coolant loss ?

[Administrator]

My overflow is higher and OUTBOARD by 3 ft. of the exchanger tank.

Hmmm. Outboard.... Is it still higher when you're heeling under sail?

Bill

[ArtJ]

Hi Bill

it may not be above. I mounted it as high as I could.

[Concord]

If the overflow is connected to the reservoir thru a pressure cap it should not matter where you locate the tank. The pressure cap should prevent syphoning. The overflow in cars is always lower than the highest point in the system. I once had a motorcycle where the overflow was mounted in the lower couling under the engine. The critical thing is that the reservoir and the interconnecting tubing be leak free. When the fluid heats up it expands and the pressure cap allows the extra fluid to go to the overflow reservoir. Once the fluid has expanded the cap should close to prevent syphoning.

If I had to guess I would say your pressure cap is not working right. I think it would be worth a call in to Don to discuss. If it is not a pressure cap then I would consider putting 2 small spring checks in the line to the reservoir. One to allow flow to the reservoir with a 10 lb spring and one to allow fluid back with a 1-2 lb spring.

[ndutton]

Originally Posted by ArtJ

Neil I am not sure what you mean by a header tank. Could you please describe this ?

It is imperative that the fill point, with a pressure relief cap, is the highest component in the FW side of the cooling system. As a ridiculous example, imagine filling a car radiator from the bottom. Further, it's best for the pressure relief cap to relieve air before fluid. It's the heated air that expands and displaces coolant, the more air burped out, the less displacement. The highest point is where the air collects and therefore where the cap should be to do the most good.

Moyer's heat exchanger has its own fill point and pressure cap but many others do not. The Perkins 4-107 I had on my previous boat had the heat exchanger mounted at the rear of the block below the level of the head and had no filler, only 4 ports: raw water in/out and coolant in/out. So how do you fill a system like that?

Enter the header tank concept. The header tank is simply a reservoir mounted higher that the rest of the entire cooling system (preferably higher than all ancillary components too like the water heater and its plumbing) where the system can be opened for filling and trapped air collects. It's at this point that the pressure cap belongs. It can be mounted on the engine or remotely.

OK, now on to the pressure cap function as it pertains to the coolant overflow recovery system. A coolant recovery type pressure cap allows flow to and from the coolant recovery bottle under two very different circumstances:

Flow to the bottle occurs when the cooling system positive pressure exceeds the cap pressure rating, somewhere around 10 - 15 psi. This pressure is due to heat. Until that pressure is reached, the cap is sealed (this is why there's no siphoning regardless of where the bottle is mounted). When it opens, air and/or coolant (whatever is at the level of the cap at the time) is vented to the recovery bottle where it's held.

Flow from the bottle occurs when the system cools down. Upon cooling the system develops a vacuum. It takes very little vacuum to open the cap and when it does, the contents of the recovery bottle are drawn back into the cooling system.

So the pressure cap opens with two influences: high positive pressure or very low vacuum. Which way the coolant flows is determined by the pressure gradient.

The point of all this is to hopefully describe the difference between the two components. The header tank is part of the pressurized system, the recovery bottle is not.

And Art, if you remove the overflow hose, whatever the pressure cap releases will be spewed all over the place.

Sorry for the poor pics but they show a low heat exchanger and a header tank. The heat exchanger is the green thingy on the backside of the engine. No recovery system in the pics.

[ArtJ]

Thanks for the highly informative and impressively detailed response!

Perhaps I should get the pressure cap tested, though it is new.

Also, if I have a small leak at bottom of plastic bottle, I assume that once
the main reservoir gets down to a happy pressure point, it will not allow
any more flow to plastic bottle even though it never returns due to leak ? I wonder what amount of expansion
space this would occur at? half full? or will it continue to deplete system?



Thanks very much !


Art