Fitting a Calorifiers

[Ribtecer]

Fitting a Calorifier

Hi Helpful Chaps

When I bought my boat last year it came with a brand new calorifiers all nicely boxed up and ready to be fitted.

Now the time has come to fit it I have been looking at the way others have plumbed them in in and around our boatyard, and now I am confused.

I need to know if it is best practise to connect the heating water to the fresh or salt side of the engine, the engine is a Mercedes OM636 does anyone on here know this particular engine exactly, if so where does the connection go?

Very grateful for any guidance to this very necessary job - isn't it dear!!!

Many thanks

Toby

 

[Tranona]

It goes in the fresh water side, so you need to look on the cylinder block or head for two blanked off take off points (one for feed and the other return). Don't know exactly where they are on your engine so you may need to see an installation on the same engine in another boat or find somebody who knows their way round the engine.

 

[MrCramp]

I have the same OM636 engine and do intend to fit a calorifier soon . I think the feed comes from a blanck-off near to the temperature sender, and the return goes into the back of the header tank, near to the elbow for exhaust water.

 

[Alpha22]

I have the same OM636 engine and do intend to fit a calorifier soon . I think the feed comes from a blanck-off near to the temperature sender, and the return goes into the back of the header tank, near to the elbow for exhaust water.

I have done some limited work on an Ocean 30 fitted with those beasts and that sounds like what I remember.

 

[TradewindSailor]

You'll need to consider where the expansion tank is placed and make sure that there are no air locks in the hoses. The expansion tank doesn't need to be above the calorifier, but if it isn't the calorifier will become a potential airlock and you will have to crack off a hose when the engine is running to let the air out.

Your engine installation manual will probably have instructions on at what height the expansion tank is mounted, the maximum length of the heater hose, and the max height of the calorifier is above the engine.

 

[vyv_cox]

You'll need to consider where the expansion tank is placed and make sure that there are no air locks in the hoses. The expansion tank doesn't need to be above the calorifier, but if it isn't the calorifier will become a potential airlock and you will have to crack off a hose when the engine is running to let the air out.

Your engine installation manual will probably have instructions on at what height the expansion tank is mounted, the maximum length of the heater hose, and the max height of the calorifier is above the engine.

I have never seen a calorifier installation with an expansion tank, and I have seen lots. A calorifier on an indirectly cooled yacht engine is just like the heater on a car - they don't have expansion tanks either.

The calorifier on my motor sailer is about 1.5 metres above the engine. It has no expansion tank nor header tank at calorifier height. I installed a central heating air bleed valve at the highest point to bleed air out when first filling the system, since when it has remained closed and the calorifier works fine. An additional in-line pump is installed because I was afraid that the pump on the ancient BMC engine would not deliver due to excessive system resistance.

 

[pampas]

Where did you fit the return pipe to the BMC? Have found the h/w blank on the block but the return baffles me, thanks.
Gordon

 

[brians]

Calorifier

I have never seen a calorifier installation with an expansion tank, and I have seen lots. A calorifier on an indirectly cooled yacht engine is just like the heater on a car - they don't have expansion tanks either.

The calorifier on my motor sailer is about 1.5 metres above the engine. It has no expansion tank nor header tank at calorifier height. I installed a central heating air bleed valve at the highest point to bleed air out when first filling the system, since when it has remained closed and the calorifier works fine. An additional in-line pump is installed because I was afraid that the pump on the ancient BMC engine would not deliver due to excessive system resistance.

How do you deal with expansion of hot water and the water discharge (dripping) from the PRV? This is the biggest problem I have with mine. I do not have an expansion tank either.

 

[TradewindSailor]

I have never seen a calorifier installation with an expansion tank, and I have seen lots. A calorifier on an indirectly cooled yacht engine is just like the heater on a car - they don't have expansion tanks either.

The calorifier on my motor sailer is about 1.5 metres above the engine. It has no expansion tank nor header tank at calorifier height. I installed a central heating air bleed valve at the highest point to bleed air out when first filling the system, since when it has remained closed and the calorifier works fine. An additional in-line pump is installed because I was afraid that the pump on the ancient BMC engine would not deliver due to excessive system resistance.

Vyv .... you have no expansion tank in the fresh water cooling circuit? It only need to be somewhere in that circuit to work .... but I can't believe you haven't got one. The problem is position. If the filler cap is below the top of the calorifier the coolant will flow out when the cap is released.

 

[vyv_cox]

How do you deal with expansion of hot water and the water discharge (dripping) from the PRV? This is the biggest problem I have with mine. I do not have an expansion tank either.

I think you are talking about the domestic water (heated) side of the calorifier whereas the discussion is about the engine coolant circuit (heating). In your case there are two or three possibilities. The PRV may be leaking because it is not seating correctly. This happens over time when salts accumulate on the seat. The PRV set pressure may be too low compared with the shut-off pressure of your pump. You should be able to compare the two and ensure that the PRV pressure is a few psi above the pump cutoff. Adding an accumulator to the fresh water side may contain the small pressure increase when the water heats up but this is the most expensive option. It does improve the flow from the pump though, unless you have one of the new pumps that is said not to need one.

 

[vyv_cox]

Where did you fit the return pipe to the BMC? Have found the h/w blank on the block but the return baffles me, thanks.
Gordon

Mine is the 2.2 diesel. The hot take-off is on the top of the cylinder head at the aft end, a vertical blanking plug. I believe the 2.5 is different. The return goes to a blank on, or just below, the thermostat housing.

 

[pampas]

yes you are correct, but the blank is fwd. end cannot find the return. I have thought of putting a valved tee in the jacket drain plug, thanks for the info on your set up.

 

[vyv_cox]

I have thought of putting a valved tee in the jacket drain plug, thanks for the info on your set up.

That's how it is done on the Bukh 20. The drain tap is removed and a hose tail substituted for the return from the calorifier coil. Means you have to remove the hose to drain the block, but not something you do every day.