|
|
Hot water
Oct 20, 2017 7:43:05 GMT
via mobile
Post by lollygagger on Oct 20, 2017 7:43:05 GMT
It wouldn't be unusual for me to be missing something obvious.
Old boat - water heated by engine or 240v immersion. Once heated it stays piping hot. 12 hours later it would still be too hot to keep your hands in.
New boat - water heated by engine, 240v immersion or Webasto central heating. Once heated it goes cold really quickly. Piping hot last night is barely discernable from the cold this morning.
WTF is going on and if anyone has had the same experience with central heating (I assume it's something to do with this), what can I do to keep the water hot?
|
|
|
|
Post by tonyb on Oct 20, 2017 7:57:46 GMT
Thermo gravity circulation from calorifier back to the engine where it is cooled.
Potential solutions.
1. Try swapping the upper and lower engine coil connections on the calorifier.
2. Make sure there is a horizontal run away from the calorifier on both engine pipes before any upward bend, say about a foot or more.
3. Fit a swan neck in the top pipe from engine to calorifier but make sure you fit a bleed point at the top.
4. Fit a flap type non-return valve in the supply pipe from engine to the calorifier
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 20, 2017 8:19:26 GMT
I don't know that much but does the orientation (horizontal v vertical) make a difference? For some reason I think the horizontal ones stay warmer longer but might be wrong on that.
|
|
|
|
Post by tonyb on Oct 20, 2017 8:28:45 GMT
Not in my experience as long a sthey are plumbed and orientated correctly. If not horizontals can be worse because air gets trapped at the top reducing the effective capacity.
|
|
|
|
Hot water
Oct 20, 2017 9:00:33 GMT
via mobile
Post by lollygagger on Oct 20, 2017 9:00:33 GMT
I don't know that much but does the orientation (horizontal v vertical) make a difference? For some reason I think the horizontal ones stay warmer longer but might be wrong on that. Both boats have horizontal type so not in this case. |
|
|
|
Hot water
Oct 20, 2017 9:08:15 GMT
via mobile
Post by lollygagger on Oct 20, 2017 9:08:15 GMT
Thermo gravity circulation from calorifier back to the engine where it is cooled. Potential solutions. 1. Try swapping the upper and lower engine coil connections on the calorifier. 2. Make sure there is a horizontal run away from the calorifier on both engine pipes before any upward bend, say about a foot or more. 3. Fit a swan neck in the top pipe from engine to calorifier but make sure you fit a bleed point at the top. 4. Fit a flap type non-return valve in the supply pipe from engine to the calorifier You think engine rather than the rads? I ask as both boats are plumbed into the engine cooling. New boat engine and heating coils supply pipes run horizontally at floor level then up to feed into top and return from bottom connections. Next time the water is hot I'll have a feel of me pipes (ooer missus). Like the flap valve idea. I was almost temped to fit a manual valve but wouldn't be good to forget then run the engine. Maybe a solenoid valve triggered from the alternator light wire if it does prove to be the engine coil sapping the heat? |
|
|
|
Hot water
Oct 20, 2017 9:10:29 GMT
via mobile
Post by lollygagger on Oct 20, 2017 9:10:29 GMT
Or if it's the rads, solenoid valve triggered by the webasto? Not sure where I'd pick up a signal for that but there will be a way.
|
|
|
|
Post by tonyb on Oct 20, 2017 10:34:51 GMT
Thermo gravity circulation from calorifier back to the engine where it is cooled. Potential solutions. 1. Try swapping the upper and lower engine coil connections on the calorifier. 2. Make sure there is a horizontal run away from the calorifier on both engine pipes before any upward bend, say about a foot or more. 3. Fit a swan neck in the top pipe from engine to calorifier but make sure you fit a bleed point at the top. 4. Fit a flap type non-return valve in the supply pipe from engine to the calorifier You think engine rather than the rads? I ask as both boats are plumbed into the engine cooling. New boat engine and heating coils supply pipes run horizontally at floor level then up to feed into top and return from bottom connections. Next time the water is hot I'll have a feel of me pipes (ooer missus). Like the flap valve idea. I was almost temped to fit a manual valve but wouldn't be good to forget then run the engine. Maybe a solenoid valve triggered from the alternator light wire if it does prove to be the engine coil sapping the heat? In that case it might well be the rads, especially if eh top pipe runs upwards away from the calorifier. the engine should!! be adequately cooled without the calorifier, if you did forget to turn a manual valve on the only problem would be no hot water. |
|
|
|
Hot water
Oct 21, 2017 6:56:39 GMT
via mobile
Post by lollygagger on Oct 21, 2017 6:56:39 GMT
You think engine rather than the rads? I ask as both boats are plumbed into the engine cooling. New boat engine and heating coils supply pipes run horizontally at floor level then up to feed into top and return from bottom connections. Next time the water is hot I'll have a feel of me pipes (ooer missus). Like the flap valve idea. I was almost temped to fit a manual valve but wouldn't be good to forget then run the engine. Maybe a solenoid valve triggered from the alternator light wire if it does prove to be the engine coil sapping the heat? In that case it might well be the rads, especially if eh top pipe runs upwards away from the calorifier. the engine should!! be adequately cooled without the calorifier, if you did forget to turn a manual valve on the only problem would be no hot water. Showing my ignorance there, I assumed the coil was in series rather than parallel. |
|
|
|
Post by tonyb on Oct 21, 2017 7:08:04 GMT
In that case it might well be the rads, especially if eh top pipe runs upwards away from the calorifier. the engine should!! be adequately cooled without the calorifier, if you did forget to turn a manual valve on the only problem would be no hot water. Showing my ignorance there, I assumed the coil was in series rather than parallel. Not too sure exactly what you mean but both "coils" are normally totally separate, otherwise when the engine coolant comes up to pressure it would blow water out of the central heating header tank. In a horizontal calorifier the "coils" might be some other shape like a zigzag or in some cases a sort of double walled, open ended cylinder with the coolant running between the two walls. A simple coil like those used in a vertical calorifier may make it very difficult to get all the air out. On a horizontal calorifier I would expect you to have the central heating inlet and the outlet at one end and the engine ones at the other but who knows? They may both be at the same end. |
|
|
|
Hot water
Oct 21, 2017 7:33:07 GMT
via mobile
Post by lollygagger on Oct 21, 2017 7:33:07 GMT
Showing my ignorance there, I assumed the coil was in series rather than parallel. Not too sure exactly what you mean but both "coils" are normally totally separate, otherwise when the engine coolant comes up to pressure it would blow water out of the central heating header tank. In a horizontal calorifier the "coils" might be some other shape like a zigzag or in some cases a sort of double walled, open ended cylinder with the coolant running between the two walls. A simple coil like those used in a vertical calorifier may make it very difficult to get all the air out. On a horizontal calorifier I would expect you to have the central heating inlet and the outlet at one end and the engine ones at the other but who knows? They may both be at the same end. Ah, I meant engine supplied calorifier coil in series with the engine cooling skin tank(s). Thinking about the central heating plumbing, that coil is parallel plumbed into flow and return like another radiator so yes probably the engine coolant coil is plumbed similarly into the engine coolant flow and return. At the calorifier each coil in/out is on separate ends with feed being the "top" connections to both coils (or zigzags). |
|
|
|
Post by tonyb on Oct 21, 2017 9:10:02 GMT
Apart from the need to lengthen one pipe and lose a bit of the other there is no reason not to try swapping the engine in and out over, it sometimes works.
It so happens that my calorifier is in series with the skin tank because mine used to be a direct raw water cooled engine but this is highly unusual and I made sure the coil ID and hose/pipe IDs were sufficient for the cooling flow.
Typically the take off for the calorifier is on the engine side of the cooling thermostat and is returned into the cold feed to the water pump. There may in some cases be an extra calorifier thermostat at the take off point to ensure the engine warms up before robbing heat for the calorifier but in my view that’s overkill and unnecessary complication - an arguable point. Far fewer boats take the calorifier feed from the skin tank side of the engine thermostat but this risks the skin tank "short circuiting" the calorifier. In all cases the calorifier is in parallel with the skin tank.
|
|
|
|
Hot water
Oct 21, 2017 9:30:27 GMT
via mobile
Post by lollygagger on Oct 21, 2017 9:30:27 GMT
Apart from the need to lengthen one pipe and lose a bit of the other there is no reason not to try swapping the engine in and out over, it sometimes works. It so happens that my calorifier is in series with the skin tank because mine used to be a direct raw water cooled engine but this is highly unusual and I made sure the coil ID and hose/pipe IDs were sufficient for the cooling flow. Typically the take off for the calorifier is on the engine side of the cooling thermostat and is returned into the cold feed to the water pump. There may in some cases be an extra calorifier thermostat at the take off point to ensure the engine warms up before robbing heat for the calorifier but in my view that’s overkill and unnecessary complication - an arguable point. Far fewer boats take the calorifier feed from the skin tank side of the engine thermostat but this risks the skin tank "short circuiting" the calorifier. In all cases the calorifier is in parallel with the skin tank. Whichever way mine is plumbed, I'll try switching the pipes, IIRC the pipes convert from flexible to plastic just inside the engine compartment and the connections are adjacent. Or thinking more practically those pipes are low level so I'll add a valve/tap to the upper calorifier connection if it is parallel as you predict. 👍 |
|
|
|
Hot water
Nov 17, 2017 8:54:33 GMT
via mobile
Post by lollygagger on Nov 17, 2017 8:54:33 GMT
Update.
I added valves to the engine fed coil circuit which is indeed parallel with the engine cooling.
It hasn't made any difference, probably because it had (has) a ruddy great air lock - barely lost any coolant fitting the valves. Also noticed the "coolant" looked more like water to me!
I've also followed the pipes for the webasto fed coil which dip down to the bottom of the boat within a few feet of the calorifier which should prevent the thermal effect?
Next thing for heat loss - pipe lagging session.
But now I have another job which is to change the engine coolant and refill with the correct ratio of coolant/water. I have two options I think.
1. Get all the old out and replace. Difficult as skin tank pipes are 1m + solid steel up to a high level and tank is below engine relatively so I'd have to pump out the tank.
2. If there's a way of perhaps measuring the existing coolant specific gravity I could guestimate the total volume, and calculate how much coolant to add. Can this even be done? Perhaps with a battery or wine making floaty thing?
|
|
|
|
Post by Mr Stabby on Nov 17, 2017 9:00:42 GMT
|
|
