Bleeding Calorifier Loop?

[Dockhead]

I have had a lot of trouble with my calorifier loop. The problem is apparently that it gets airlocked because of a high place between the engine and the calorifier. From time to time over the years, I have tried to get rid of the air by taking the hoses off and filling them with a funnel, and trying to hold the coolant in while I get the hoses re-attached. Sometimes it sort of worked.

Now I'm going to be installing a bus heater to get some space heating out of the engine waste heat, and there will be two high spots. It looks a little like this:




What is the right way to deal with this? I saw in the blog of someone on here how he put in a "t" connector at his own high spot, with a hose led higher, with a cap on the end. He would unscrew the cap and pour in coolant, I guess -- right?

Or how best to do it? Maybe instead of something like that, you just need a small bleed valve at the high spot like on a radiator in a home hydronic system? Just start the engine and open the bleed valve until coolant comes out?

Or what do you knowledgeable folks recommend?

[donradcliffe]

better to add coolant at the high spot than bleed it--by definition you can't add coolant at any lower spot to force air out of the highest spot.

[DeepFrz]

This is from Beta Marine's website.

Hot water heater system

If you are going to fit a hot water heater (calorifier) and let the coolant from the closed circuit of the engine heat the water for you, It is essential to get the plumbing correct so that you don't have an overheat problem with your engine. Keep the supply and return lines between the engine and hot water heater as short as possible and avoid any big loops or dips in the hose. Remember that you fill the coolant at the cap that is on top of the manifold that is on the engine. This must be the highest point of the cooling system because you cannot pour water uphill. If the shape of the boat forces you to mount the hot water heater above the engine, then you need to follow the drawing (link below) to ensure that your cooling system works correctly.

Edit: Some engine manufacturers require a coolant pump in the calorifier/heater cct.

[Dockhead]

Originally Posted by DeepFrz

This is from Beta Marine's website.



Edit: Some engine manufacturers require a coolant pump in the calorifier/heater cct.

Hmm, that's very useful. Thanks.

So they require an actual header tank at the highest point.

And no word about what to do when you have two high points

[sailorchic34]

Another option would be to tee in a manual or automatic air vent at the high point or points. Oddly used all the time in building hydronic systems. Something like this.

Automatic Air Vent – Model 97 | Xylem Applied Water Systems - United States

A manual valve would work too but you may need to bleed the loop every time you check the coolant level. An automatic ball float unit does that simply.

Putting a header tank high works too, but if you can't, then a 1/4" (5-6 mm) automatic air vent would do the trick.

[Dave852]

Of course with the header tank you can check the coolant level... Think about doing that from the cap that is not at the highest point.


Sent from my iPad using Cruisers Sailing Forum

[ggray]

Originally Posted by sailorchic34

Another option would be to tee in a manual or automatic air vent at the high point or points. Oddly used all the time in building hydronic systems. Something like this.

Automatic Air Vent – Model 97 | Xylem Applied Water Systems - United States

A manual valve would work too but you may need to bleed the loop every time you check the coolant level. An automatic ball float unit does that simply.

Putting a header tank high works too, but if you can't, then a 1/4" (5-6 mm) automatic air vent would do the trick.

That looks like a good idea.

I've thought about this situation a good bit because while my water heater is about the same height at the motor, the hoses loop up at least 2 feet above them. When I installed the WH, I made sure to fill the water circuit completely by filling from one end until coolant came out the other end.

Never had a problem from the arrangement, but since hearing of potential problems from others, I did look seriously into these headers tanks. However I never followed through to do anything.

So these valves let air but no coolant out, and let nothing in?. That sounds great!

[Dockhead]

Originally Posted by donradcliffe

better to add coolant at the high spot than bleed it--by definition you can't add coolant at any lower spot to force air out of the highest spot.

You can if the system is operating and pressurized.

[Dockhead]

Originally Posted by sailorchic34

Another option would be to tee in a manual or automatic air vent at the high point or points. Oddly used all the time in building hydronic systems. Something like this.

Automatic Air Vent – Model 97 | Xylem Applied Water Systems - United States

A manual valve would work too but you may need to bleed the loop every time you check the coolant level. An automatic ball float unit does that simply.

Putting a header tank high works too, but if you can't, then a 1/4" (5-6 mm) automatic air vent would do the trick.

My first reaction was skepticism -- temperature and of an engine's main fresh water cooling circuit versus home hydronic heating? But I see from your link that they are rated for 150 psi -- 10 bar IIRC -- and 240 degrees F. That might be a hot tip (so to speak!).

[Blue Stocking]

The on-line Operator Manual for the Westerbeke W46 has a very good illustration for this situation.

[Dockhead]

Originally Posted by Blue Stocking

The on-line Operator Manual for the Westerbeke W46 has a very good illustration for this situation.

Fantastically useful, thanks!!





From here: http://www.westerbeke.com/operator%2...6_oper_man.pdf


Salient point:

"If any portion of the engine cooling water circuit to or from the
heater rises above the engine's own pressure cap, then the pressurized
remote expansion tank must be installed in the circuit to become the
highest point. The tank kit part number is 24177. Install the remote
expansion tank in a convenient location such as a sail locker for ease
of checking fresh water coolant level."



It looks from all of this like my system is fundamentally wrong and unworkable.

I might be able to eliminate the first loop by re-routing the hoses, but there's no way to get around the fact that the bus heater would be higher than the radiator cap, and that there is no continuous rise from calorifier to engine .


With re-routed hoses like this:





There will be a high point at the bus heater without, however, a continuous rise to the engine. I guess I could put in a header tank right there at the bus heater, and take off the radiator cap on the engine until it starts to overflow, then further maintain the coolant level from the bus heater.

Or maybe I could get away with it? The standard header tank is higher than the engine -- about at the level of the bus heater. Maybe it will work ok if I just get the air out?

[sailorchic34]

I would just put a air vent at the bus heater and call it good. It's whats done on high rise buildings all the time. Yes it will easily handle engine temperatures.

I might put the bus heater on the discharge side of the clorifier, as the temperature required in the clorifier is higher then the discharge air temperature of the bus heater. Put the bus heater first and when its running its going to take a while to heat the clorifier.

[sailorchic34]

Originally Posted by ggray

That looks like a good idea.

I've thought about this situation a good bit because while my water heater is about the same height at the motor, the hoses loop up at least 2 feet above them. When I installed the WH, I made sure to fill the water circuit completely by filling from one end until coolant came out the other end.

Never had a problem from the arrangement, but since hearing of potential problems from others, I did look seriously into these headers tanks. However I never followed through to do anything.

So these valves let air but no coolant out, and let nothing in?. That sounds great!

Exactly, only air out, no water. Very common problem in high rise hydronics.

[DeepFrz]

Exactly, only air out, no water. Very common problem in high rise hydronics.

sailorchic34;
Of course high rise apartments are relatively stable (except maybe in CA or other earthquake prone regions). Do you see any problem with it on a sailboat bouncing around at sea?

[sailorchic34]

Originally Posted by DeepFrz

sailorchic34;
Of course high rise apartments are relatively stable (except maybe in CA or other earthquake prone regions). Do you see any problem with it on a sailboat bouncing around at sea?

Not really, it generally would not be effected by movement.