Cooling system modification... Opinions sought...

[Black Country Lee]

I'm overhauling the cooling system on Tara as it takes hours to get any hot water through the calorifier...

 

The blue lines are the existing system which has an open bridge connection prior to the engine (bit daft IMO) so I'm thinking of an isolating valve here (or simply removing it entirely). It also has no thermostat fitted so takes an age to get warm enough to heat the HWS to a satisfactory temperature, does any think the thermostat (X) is in the correct place? I thought here as it would negate the need to have a bypass fitted (or run the calorifier off said bypass) to feed the HWS first before the return to the skin tank??

 

Lee.

 

ETA:- Perhaps the bridge should stay with a closure but going to the skin tank side of the thermostat just in case the calorifier ever gets drained down?

Edited November 1, 2014 by Black Country Lee

[smileypete]

Normally the calorifier is installed to a heater take-off on the engine block/head, any reason why this can't be done?

 

cheers, Pete.

~smpt~

[RLWP]

Remind me - which engine do you have?

 

Richard

[Black Country Lee]

Normally the calorifier is installed to a heater take-off on the engine block/head, any reason why this can't be done?

 

cheers, Pete.

~smpt~

 

It's a single cylinder Kingfisher engine, it has one inlet and one outlet, no heater take-off unfortunately.

 

Remind me - which engine do you have?

 

Richard

 

As above Richard. There are pipes everywhere that is how I ended up confusing myself lol. Let me add some description to a photo and I'll add it to clarify my confusion.

 

Lee.

[Black Country Lee]

 

Sorry about the angle lol

 

Lee.

[smileypete]

Ah OK.

 

Might be worth having a look at a 'bypass thermostat' available from kit car suppliers and for some production cars eg certain Rovers IIRC.

 

http://www.carbuildersolutions.com/uk/by-pass-thermostat-80-deg

 

 

In your case the flow would come from the skin tank return pipe, and the bypass would be teed into the skin tank feed pipe. The calorifer could then utilise some of the bypass flow, so it's heated before the thermostat opens.

 

For a small engine it could well be worth using a solar rated thermostatic valve (TMV) to itself bypass the calorifer until the engine reaches 65°C, to stop the engine being overcooled (note: not all TMV go up to 65°C, many only go to about 45°C so choose carefully!), eg:

 

http://www.ebay.co.uk/itm/Caleffi-thermostatic-mixing-valve-TMV-22mm-/231372497505

 

The hot side of the TMV would be teed into the calorifer feed, the cold side of the TMV would be fed from the calorifer return, and the output of the TMV would now be the calorifer return.

 

While the engine is below 65°C the TMV would take water from the hot side, bypassing the calorifer and preventing engine overcooling, then as the temp rises the TMV would take some water from the cold side, allowing the calorifer to be heated. Clear as mud?

 

Basically the TMV itself acts as an additional lower temperature bypass thermostat for the calorifier (even more confused? )

 

cheers, Pete.

~smpt~

Edited November 1, 2014 by smileypete

[Black Country Lee]

Anyone up near the Waterfront is welcome to pop along to shake their heads and tut loudly as I'm doing this, there'll be no charge

 

Lee.

Ah OK.

 

Might be worth having a look at a 'bypass thermostat' available from kit car suppliers and for some production cars eg certain Rovers IIRC.

 

http://www.carbuildersolutions.com/uk/by-pass-thermostat-80-deg

 

 

In your case the flow would come from the skin tank return pipe, and the bypass would be teed into the skin tank feed pipe. The calorifer could then utilise some of the bypass flow, so it's heated before the thermostat opens.

 

For a small engine it could well be worth using a solar rated thermostatic valve (TMV) to bypass the calorifer until the engine reaches 65°C, to stop the engine being overcooled.

 

cheers, Pete.

~smpt~

 

I've picked up an 72 deg/C thermostat for a LR TD5...

 

 

Single pipe to skin tank, bypass to Caloifier inlet, 3rd pipe to the hot side of the engine if my brain is working lol

[smileypete]

Anyone up near the Waterfront is welcome to pop along to shake their heads and tut loudly as I'm doing this, there'll be no charge

 

Lee.

 

I've picked up an 72 deg/C thermostat for a LR TD5...

 

 

Single pipe to skin tank, bypass to Caloifier inlet, 3rd pipe to the hot side of the engine if my brain is working lol

 

Looks good, I would say label end to skin tank return, opposite end return back to engine, 'dog leg' to calorifer return, calorifer feed is teed into skin tank flow between engine and skin tank.

 

I also edited my post above and added a bit about using a TMV to prevent engine overcooling.

 

Maybe draw and post a revised layout piccy if in any doubt.

 

cheers, Pete.

~smpt~

Edited November 1, 2014 by smileypete

[Black Country Lee]

 

Looks good, label end to skin tank return, opposite end return back to engine, 'dog leg' to calorifer return, calorifer feed is teed into skin tank flow between engine and skin tank.

 

I also edited my post above and added a bit about using a TMV to prevent engine overcooling.

 

Maybe draw and post a revised layout piccy if in any doubt.

 

cheers, Pete.

~smpt~

Opposite pipe to label to hot or cold side of the engine ?

 

Lee.

[smileypete]

Opposite pipe to label to hot or cold side of the engine ?

 

Lee.

 

Sorry, to cold side/water pump inlet.

 

This is why diagrams are handy I s'pose.

 

cheers, Pete.

~smpt~

Edited November 1, 2014 by smileypete

[Dalslandia]

 

Sorry about the angle lol

 

Lee.

 

I see the gearbox, But where is the Engine? Is that hiding behind the 40X25 U beam?

[Scholar Gypsy]

Just out of interest, what powers the water pump? I assume electric, as the drive belt just goes to the alternator ?

 

In the diagram above, presumably the thermostat opens only when the water coming back from the calorifier gets hot. Is there a risk of the engine getting too hot in the meantime?

[Dalslandia]

looks like the drive shaft from engine goes throe the top of gearbox, and drive the water pump, then the prop shaft comes out below

Edited November 1, 2014 by Dalslandia

[Tony Brooks]

KIS. Do what I did on my Bukh. Hot out pipe to calorifier, cooler calorifier return to skin tank and skin tank back to engine so the calorifier is in serine with the skin tank. This has worked well for me but you need to make sure the calorifier coil is 22mm/1" and use suitably large hoses to ensure there is still sufficient coolant flow. Thsi will delay the water heating until the engine thermostat starts to open.

[Black Country Lee]

Yes water pump is driven by the primary gearbox shaft. After much annoyance I've sort of joey rigged it as Tony Brooks has it but I need to pick up a bit more hosing lol

[smileypete]

One drawback with the calorifier inline with skin tank, is that the hotter the calorifier gets the more heat lost thru the skin tank.

 

So to get the calorifier heated to 80% it'll take about twice as long, but to get it to shower temperature ~40°Cish will only take around 60% longer (according to my dodgy maths - someone like Nick Norman may work it out better. )

 

cheers, Pete.

~smpt~

Edited November 2, 2014 by smileypete

[Tony Brooks]

The engine thermostat controls the running temperature not the heat sink (calorifier & skin tank) so although less flow goes through eh calorifier on partial thermostat openings it will still be pretty much at running temperature.

 

As the calorifier is before the skin tank it can take all the heat from the water that it wants. The cooler water is then passed to the skin tank.

[smileypete]

Maybe, it can only take heat up to what the contents of the calorifier are.

 

Say the the coolant is 70°C, the river/canal is 10°C, (60°C less than coolant) the calorifer is 50°C (20°C less than coolant), then the calorifer can only remove about a third of the heat, the other two thirds is 'lost' to the skin tank.

 

Only really an issue if wanting the calorifier to heat as quickly as poss, eg while moored up charging the batts.

 

cheers, Pete.

~smpt~

[Tony Brooks]

Agreed but where ever the calorifier is plumbed as it comes up to temperature it will waste/dump heat via the skin tank so from my own experience there is little difference in hot water warm up between my boat and one with a "conventional" calorifier circuit. I am happy to trade that small difference for a simple system.

[smileypete]

If the calorifer is in the bypass circuit, or a heater takeoff, any hot water from the calorifier coil will go back to the engine so no heat is lost to the skin tank until the main thermostat opens.

 

To get the best out of it, just means a £20-30 blending valve and extra tee in the calorifier feed, not that complicated surely.

 

But like I say, it's only needed for getting the calorifier hot as quick as poss with limited engine running. But as a benefit it means the route between engine and skin tank isn't restricted by a calorifier coil.

 

cheers, Pete.

~smpt~

Edited November 2, 2014 by smileypete