Calorifier woes

[Cloudinspector]

I recently replaced our leaking twin coil calorifier with an almost identical one. Everything works fine except I can't get the water from the engine to flow through the coil. I've bled the system several times via the skin tank and the drain/bleed valves in the coil loop shown in the pics. I've also disconnected the push fit pipes from the calorifier to check if there's water in them which there is. I'm at a complete loss as to what the problem may be. Any ideas folks?

 

 

[mark99]

The flow will be/should be controlled via a thermostat on the engine. It takes a lot of heat/time on mine before the thermo opens on engine and allows flow into calorifier. I've not got it to open unless out running the engine hardish.

Edited October 24, 2015 by mark99

[Tony Brooks]

The flow will be/should be controlled via a thermostat on the engine. It takes a lot of heat/time on mine before the thermo opens on engine and allows flow into calorifier. I've not got it to open unless out running the engine hardish.

 

That very much depends upon your engine an dis by no means universal. I suspect more boats have the calorifier plumbed to the engine side of the thermostat than the skin tank side. IT makes for more reliable circulation. A few engine makes have an additional thermostat controlling the flow to the calorifier so we need to know the make and model of the engine and where the "hot out of the engine" connection is fitted.

 

To expand a little. Most engines use the cab heater connection to feed the calorifier and if that were on the radiator side of the thermostat it would take ages to get the windscreen defrosted.

[ditchcrawler]

Have you tried flowing water through the coil or blowing through it in case its blocked by something.

[Cloudinspector]

Engine is a Gardner 2LW and the hot in comes off the by pass loop, the 15 MM. pipe with short rubber hose in pic below.

The coil isn't blocked as I've disconnected the push fit connections from the calorifier and water is flowing out.

The new tank is almost identical and I've not altered anything other than re-route some of the push fit piping.

 

[Boredrider]

Our 2LW is similarly fed from the bypass loop, but I don't have that "T" junction that is in the picture. Where does the vertical pipe go to that runs downwards off the "T"?

[OldGoat]

It looks to me like a "simple" air lock - especially as your calorifier link is a higher resistance that the main flow.

I had the same problem with my horrid-little-industrial-engine, rather than your highly polished piece of British Engineering (!). Even with a header tank in the loop it steadfastly refused to circulate....

 

My solution - which might help was to bleed the loop at the engine end and while running introduced some pressure from the header tank end - blowing heartily through the filler. That got it flowing and it's been fine since then.

 

 

If you don't get a better solution - give it a go!

[Cloudinspector]

Our 2LW is similarly fed from the bypass loop, but I don't have that "T" junction that is in the picture. Where does the vertical pipe go to that runs downwards off the "T"?

The vertical pipe is the bypass return to the water pump

[Tiggs]

The new tank is almost identical and I've not altered anything other than re-route some of the push fit piping.

 

Maybe this is the issue then; does this make the heating loop more restrictive?

 

 

 

or maybe you need a slight restriction in the main flow just before the off take to get some pressure to force the water around your heating loop.

Edited October 24, 2015 by Tiggs

[Cloudinspector]

It looks to me like a "simple" air lock - especially as your calorifier link is a higher resistance that the main flow.

I had the same problem with my horrid-little-industrial-engine, rather than your highly polished piece of British Engineering (!). Even with a header tank in the loop it steadfastly refused to circulate....

 

My solution - which might help was to bleed the loop at the engine end and while running introduced some pressure from the header tank end - blowing heartily through the filler. That got it flowing and it's been fine since then.

 

 

If you don't get a better solution - give it a go!

Really it can only be an airlock but I've tried everything and can't get it to budge. I'll give your method a whirl.

[Tony Brooks]

The vertical pipe is the bypass return to the water pump

 

Is there any rubber hose in that return? If so clamping it so the full pump flow has to go via the calorifier might blow the air out. I suspect that f it was mine a valve would have been fitted into it. I seem too easy for flow to bypass the calorifier, especially at low engine speeds.

[Boredrider]

The vertical pipe is the bypass return to the water pump

I've just looked at ours. The bypass out goes straight to the calorifier circuit, with the return teed into the skin tank return before the oil cooler. So Tony's suggestion of a valve or restriction in that vertical pipe down to the pump is right on the money.

[Cloudinspector]

 

Is there any rubber hose in that return? If so clamping it so the full pump flow has to go via the calorifier might blow the air out. I suspect that f it was mine a valve would have been fitted into it. I seem too easy for flow to bypass the calorifier, especially at low engine speeds.

Unfortunately not. Your suggestion to fit a valve may be the answer.

[Tony Brooks]

The bypass circuit is designed to keep water circulating through the engine so any hotspots are cooled while the thermostat is shut. If the calorifier circuit can never be turned off then a long as the calorifier return ends at the same point as the existing bypass then I have no idea what the bypass is for. At the moment it seems ideal for shorting out the calorifier circuit. I suspect if this were mine a large pair of grips might get applied to the bypass pipe. If there are any compression fittings how about stuffing a small cork into the pipe at the fitting?

 

Also worth noting that there are two types of bypass thermostat. The photo seems to indicate it requires an earlier type with the bypass "valve" being a band around the outside of the thermostat. Modern bypass stats have an extra disk on the bottom to close the bypass port. They are not interchangeable but a non-bypass stat would fit that housing I think.

 

If you tried bleeding the calorifier with a hot engine the bypass stat would have more or less closed the bypass port so try again with the engine revving but cold.

[bottle]

You have had the experts view but now a novices thought...

 

Water will take the path of least resistance.

 

 

The vertical pipe is the bypass return to the water pump

 

Maybe a re-route would do it.

 

I know you said the new one is similar to the old but perhaps the internal coil is different, longer, slightly more restrictive.

 

Only thoughts and can be totally disregarded.

[Tony Brooks]

You have had the experts view but now a novices thought...

 

Water will take the path of least resistance.

 

 

Maybe a re-route would do it.

 

I know you said the new one is similar to the old but perhaps the internal coil is different, longer, slightly more restrictive.

 

Only thoughts and can be totally disregarded.

 

 

100% Agree

[cereal tiller]

I recently replaced our leaking twin coil calorifier with an almost identical one. Everything works fine except I can't get the water from the engine to flow through the coil. I've bled the system several times via the skin tank and the drain/bleed valves in the coil loop shown in the pics. I've also disconnected the push fit pipes from the calorifier to check if there's water in them which there is. I'm at a complete loss as to what the problem may be. Any ideas folks?

 

 

Had the same problem when adding a second Calorifier ,the water was reticent to prime when dealing with a total of 3 heating coils

 

Installed a little pump originally designed for solar hot water circulation,it draws 12 watts and is energised by the engine switch ,so off when engine stopped and continuous running when engine on.

 

No air locking since installation 2 years ago.

 

Think it came from Solar Projects

 

CT

[Cloudinspector]

The bypass circuit is designed to keep water circulating through the engine so any hotspots are cooled while the thermostat is shut. If the calorifier circuit can never be turned off then a long as the calorifier return ends at the same point as the existing bypass then I have no idea what the bypass is for. At the moment it seems ideal for shorting out the calorifier circuit. I suspect if this were mine a large pair of grips might get applied to the bypass pipe. If there are any compression fittings how about stuffing a small cork into the pipe at the fitting?

 

Also worth noting that there are two types of bypass thermostat. The photo seems to indicate it requires an earlier type with the bypass "valve" being a band around the outside of the thermostat. Modern bypass stats have an extra disk on the bottom to close the bypass port. They are not interchangeable but a non-bypass stat would fit that housing I think.

 

If you tried bleeding the calorifier with a hot engine the bypass stat would have more or less closed the bypass port so try again with the engine revving but cold.

I've had a good read of the Gardner manual and as I understand it the bypass circuit is designed to aid quicker warm up by returning the water into the engine water jacket. I'll try bleeding when the engine is cold and if that doesn't work fitting a valve to isolate the bypass circuit manually is probably the next step.

[mark99]

Just spent many hours with mooring neighbour trying to cure an airlock on neighbours 3LW engine/skinT/calorifier.

 

Ended up connecting mains water to skin tank bleed to blast out air from circuit. Ran out of time/light to see if it's cured it.

 

Lesson - getting air lock out can be problematic.

 

ETA engine thermostat removed.

Edited October 24, 2015 by mark99

[IDS]

Are the isolating valves on the 15 mm pipe 'Full bore' or do they introduce a restriction? Many domestic valves are restrictive and used on outlets.

[ditchcrawler]

My calorifier is higher than the engine and the way I bleed it is to fill the system with coolant, run the engine up to temperature so the coolant expands and is at I think 15psi I then open the bleed at the highest point and wosh.

[Cloudinspector]

Just spent many hours with mooring neighbour trying to cure an airlock on neighbours 3LW engine/skinT/calorifier.

 

Ended up connecting mains water to skin tank bleed to blast out air from circuit. Ran out of time/light to see if it's cured it.

 

Lesson - getting air lock out can be problematic.

 

ETA engine thermostat removed.

I have considered moving to a water point and connecting a hose to the top valve on the coil loop and standing a bucket under the bottom one, thereby forcing any air out

[Tony Brooks]

I've had a good read of the Gardner manual and as I understand it the bypass circuit is designed to aid quicker warm up by returning the water into the engine water jacket. I'll try bleeding when the engine is cold and if that doesn't work fitting a valve to isolate the bypass circuit manually is probably the next step.

 

Forgetting the calorifier circuit for a moment. If you want the fastest warm up then trapping the water in the engine so it can not circulate through an external pipe will do the job. However that would leave some areas of water getting far hotter than the others so the hot areas may boil simply because there is no or insufficient circulation. This is overcome by fitting a bypass. Those of us who had Minis know all about the bypass hose. On other engines its a small port between the water jacket in the head and the inlet side of the water pump. On those engines the bypass can have no effect on the speed of warm up. In fact I would suggest the longer and more metallic any external bypass pipes are the slower the warm up.

 

When cab heaters or calorifiers are involved they too will slow the warm up UNLESS their supply pipe is fitted with its own thermostat. However even then as the calorifier thermostat needs to open at a lower temperature than the main stat it will still give to a very minor degree a slower warm up. To give the fastest warm up the calorifier supply would nee to be on the skin tank/radiator side of the engine thermostat but then we get into the sort of problem the OP seems to be suffering from in that the skin tank with its large pipes may form an easier path then the calorifier so coolant tend so bypass the calorifier.

 

In short I think the manual's explanation is just wrong on that point. Probably misunderstandings between the technical author and the engineers. However I do not think it makes much difference to the problem, especially as we have another Gardiner owner seems not to have the bypass pipe with the calorifier circuit acting as the bypass. A valve is certainly a good idea but if it were mine the bypass circuit would be blocked. The vast majority of engines fitted with calorifiers I would suggest in effect use the calorifier circuit as a bypass and accept a slower warm up of the engine but a faster warm up of the calorifier.

[nb Innisfree]

Going back to basics it perhaps needs to be understood that the original reason for bypass circuits was due to engines being designed with thermostats in the first place, a faster warm up is just a byproduct.

[mark99]

Air bubbles came out of our "purge" yesterday under mains pressure for nearly 10 minutes. (The mains water was being expelled via two hoses connected to the system - each end underwater and we watched via side hatch).