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Old 04-03-2016, 14:08   #1
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Header Tank Question

I have had problems with my engine coolant calorifier loop over the years, as the hoses get airlocked -- there are spots where they are higher than the engine.

At the same time, I've been licking my lips thinking about using that waste heat for other purposes. In our climate we need heat year round, and also for drying out the boat.

Maybe I'll kill two birds and one stone, and install a radiator in my after heads. It would be very simple to do since one wall of the heads is also a wall of my engine room. I could mount the rad (or a towel rail) on this wall, hoses through the wall, and it would be a cinch to plumb it into the loop.

And this will be higher than everything, so a good place to get rid of the air.

So here's the question -- do I have to have a header tank here? Remember this is engine coolant , which makes me slightly nervous.

Or can I just have a bleed valve, like on radiators in homes?

I guess I'm going to need some kind of a booster pump, but that will also improve circulation through the calorifier, so not a bad thing to spend a little money on.

Thoughts?
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Old 04-03-2016, 14:31   #2
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Re: Header Tank Question

Dunno IF you need a header tank but it would make things easier for future trouble shooting IMO. Yes more initial cost but a better outcome - again IMO.
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Old 04-03-2016, 14:37   #3
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Re: Header Tank Question

Like this?

Cabin Heater - c34.org

There has been discussion about this in the past, and the good advice was to install an automatic air vent, used in HVAC heating systems. Does the job without manual intervention.

From an engineering perspective, this is a CLOSED system, meaning the only resistance the coolant pump on the engine sees is the piping and fitting friction loss. Friction loss through a bus heater is small, but always good to check. Unless your new heater will be very far away from the engine, it usually is not required to add either another pump ('cuz the engine coolant pump should do and there is no heat available when the engine is off) or a header tank, 'cuz if you have one for the main manifold that works as the expansion tank for the entire system.

Good idea, good luck.
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Old 04-03-2016, 14:45   #4
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Re: Header Tank Question

Vehicle header tank would work, header tank and radiator caps are also pressure relief valves.
A decently planned installation will avoid air locks easily enough.

A pump would be useful if the system also uses a heat source other than the engine.
Saves having to use massive gravity-circulation size pipes.
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Old 04-03-2016, 16:07   #5
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Re: Header Tank Question

A small circulation pump is probably necessary. With a pump and bleed ports or air ejectors you should be fine. You might need an expansion tank.

I winter in coastal Oregon. Snow about 2-3 days a year. Night freezing or below about 20 days a year. I have a hydronic system that has a diesel fired basement style boiler at its' heart. Originally it ran at about 15psi/250F (about 1.05 kg/cm - 151C). It was installed when diesel was $.25/gallon. I kept the same pressure but reset temp to 180F (112C) about engine running temp. I also went to forced air marine heaters in place of the baseboard radiators and sped up heating a cold boat and cut diesel use about 30%.
I plumbed in my mains - Detroit Diesels - into the main circulation lines. The engine circulation pump circulates engine water between the boiler and engine fine. The boiler pump circulates when heat is demanded. I also have a pellet stove with a coil that also heats the boiler. It has a 12 volt solar panel circulation pump.
I use automatic air ejectors, a hydronic expansion tank, and have 5 heat zones. I have no air problems. The engine header tanks have the same 15psi as the boiler. The boiler pump probably solves the air problem. Plumbing is up and down. The oil burner isn't used when other heating is available. Various valves isolate the system parts when necessary. When draining the system and refilling, it takes a couple hours for all the air to leave.

A side benefit, I can preheat my engines before start in cold weather.
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Old 04-03-2016, 18:38   #6
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Re: Header Tank Question

Heads or Head?
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Old 05-03-2016, 10:35   #7
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Re: Header Tank Question

Quote:
Originally Posted by StuM View Post
Heads or Head?
Sorry, I've been over here so long that I've fallen into UK usage versus Yank usage, although I am a Yank by birth. U.K. nautical usage, also, seems more logical to me, so I haven't really resisted this.

U.S. "head" = U.K. "heads" or "heads compartment", and in the U.K. you NEVER call a toilet -- the fixture -- a "head". The "heads" is the room not the fixture.

Likewise with a lot of nautical terms. For example, "line" as a nautical-sounding or pseudo-nautical-sounding synonym for "rope" really grates on me now -- sounds lubberly to my ears. In fact I think a case can be made that this is just wrong, and not a question of U.S. vs. U.K. usage. Over here, "line" is a rope applied to a specific function, never cordage as such, which is classified as "small stuff", "rope", or "cable" depending on size.
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Old 05-03-2016, 13:19   #8
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Re: Header Tank Question

Hi Dockhead,

I've mentioned the automatic air bleeders before in discussions about hydronic heating systems. They are very prevalent in our boiler installs in Alaska. They also work great on engine coolant loops which are basically the same as a boiler loop. [hot antifreeze, etc.]

I use the same small, cheap, automatic air bleeders used in home boiler heating systems. [The Taco and Watts brand at the above link are very good from my experience. Sorry- a quick search did not reveal them on Amazon UK, but I bet you can find them locally...]

Typically I'll install a T at the top of each hydronic core, and install the air bleeder in the highest port of the T. [i.e., Where the coolant return line to the engine exits the core.] Where possible, I install a small ball valve between the T and the air bleeder to facilitate isolating the bleeder for maintenance/replacement...

As you already know, air bleeders need to be installed at a high point in each coolant loop.


Enjoy all that heat.

Cheers!

Bill
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Old 05-03-2016, 13:51   #9
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Re: Header Tank Question

Quote:
Originally Posted by Dockhead View Post
I have had problems with my engine coolant calorifier loop over the years, as the hoses get airlocked -- there are spots where they are higher than the engine.

At the same time, I've been licking my lips thinking about using that waste heat for other purposes. In our climate we need heat year round, and also for drying out the boat.

Maybe I'll kill two birds and one stone, and install a radiator in my after heads. It would be very simple to do since one wall of the heads is also a wall of my engine room. I could mount the rad (or a towel rail) on this wall, hoses through the wall, and it would be a cinch to plumb it into the loop.

And this will be higher than everything, so a good place to get rid of the air.

So here's the question -- do I have to have a header tank here? Remember this is engine coolant , which makes me slightly nervous.

Or can I just have a bleed valve, like on radiators in homes?

I guess I'm going to need some kind of a booster pump, but that will also improve circulation through the calorifier, so not a bad thing to spend a little money on.

Thoughts?
You don't need a header tank if you can allow for coolant expansion above highest level of coolant in the engine. (Cylinder head and thermostat)

If you have hose routing above the highest coolant passages in the engine, or any high loops, then you need bleeds at the high points. Where do you route them? To a high mounted header or expansion tank. Bleeds should be no more than 1mm or 0.0040".

If you can reroute your hot water hoses so you dont need bleeds then you can avoid the bleeds. I personally wouldn't add any of the home domestic type bleeds. That stuff is junk and has no place in a boat. They will also dump coolant.

Don't add schrader type bleeds. Just an orifice and then tubes to the header tank. It will be self bleeding. You dont need the added complexity of electric cooling pumps if the pressure drop theough your heater bypass circuit is reasonable. Air rises in coolant so dont fight the laws of physics.

If you route them to a see through header tank you can see when the air is bled. You'll have a tiny stream of coolant. Volkswagen golf coolant header tanks are ideal.

The above is how we design motorsport cooling systems. We reroute the flow so the cool coolant first enters the heads. Bleeds are required to ensure no air pockets can form. Normal cooling system routing is the opposite. The little bleed hole in the thermostat acts as a bleed for this exact purpose in a normal cooling system.

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Old 05-03-2016, 13:54   #10
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Re: Header Tank Question

Our boat came with the water heater plumbed into the raw water line between the engine and exhaust elbow. Worked great until the aluminum connector broke off and tried to sink us.
I've been looking at the Quick Sigmar unit with the SS tank and exchanger.
If I can figure how to get the old one out without destroying the boat.
Till then we'll just use a teapot.
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Old 05-03-2016, 16:02   #11
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Re: Header Tank Question

Quote:
Originally Posted by wrwakefield View Post
Hi Dockhead,

I've mentioned the automatic air bleeders before in discussions about hydronic heating systems. They are very prevalent in our boiler installs in Alaska. They also work great on engine coolant loops which are basically the same as a boiler loop. [hot antifreeze, etc.]

I use the same small, cheap, automatic air bleeders used in home boiler heating systems. [The Taco and Watts brand at the above link are very good from my experience. Sorry- a quick search did not reveal them on Amazon UK, but I bet you can find them locally...]

Typically I'll install a T at the top of each hydronic core, and install the air bleeder in the highest port of the T. [i.e., Where the coolant return line to the engine exits the core.] Where possible, I install a small ball valve between the T and the air bleeder to facilitate isolating the bleeder for maintenance/replacement...

As you already know, air bleeders need to be installed at a high point in each coolant loop.


Enjoy all that heat.

Cheers!

Bill
Hi Bill: Thanks for that -- I remember your having mentioned them and have been looking at them. The idea of them is excellent.

Do you think they are reliable enough for engine coolant loops? Unlike the case with a home system, if they blow out, it can be life threatening.

If there's any significant risk of that, then I'd prefer to do some kind of manual bleeding screw.
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