Why only Luke warm water?

[CFarr]

Edit: Solved. See last post.
The boat was taken round to her new berth today after 18 months ashore.
Flat calm so motored all the way, about 6 hours.
On turning on the hot taps the water was found to be only Luke warm instead of piping hot as it was before she got lifted out.

Any ideas?

I haven't a plumbers brain so no idea where to start.
When the tanks were refilled we did have a problem with a pipe to the hot water tank leaking but once this was nipped up everything seemed ok.
It is a very large tank but I'd have thought 6 hours would have heated it sufficiently.

Many thanks for looking.

 

[PlankWalker]

My first thought would be a possible air lock in the hose from engine to calorifier.
Try removing the filler cap and moving the hose around to encourage the air upwards.

Plank

 

[VicS]

Air lock, as suggested, Was the engine cooling system drained and refilled? Presumed to be indirectly cooled ... is that right?

Blockage

engine thermostat stuck open, does the engine reach its normal operating temperature?

 

[CFarr]

Thank you Plank
When we filled the normal tanks the water pump pumped water through to the hot water tank and does appear to have filled it. Would this be the case if there was an air lock?

EDIT: Vic, yes, drained by yard. We simply filled through the deck filler and then switched on the water pump.

 

[Puggy]

Air lock, as suggested, Was the engine cooling system drained and refilled? Presumed to be indirectly cooled ... is that right?

Blockage

engine thermostat stuck open, does the engine reach its normal operating temperature?

Yes +1 to VicS' suggestions. I would check the temperature of the hoses between the calorifier and the engine and see if they are hot, if not either a blockage or engine not reaching temperature. If the thermostat is stuck open, it will over cool. Is the engine reaching normal operating temperature??

Finally, last thought. Some systems have a hot/cold water mixer plumbed into the hot side of things to prevent the water being scalding. Maybe this has got turned to maximum and is mixing in lots of cold?

Puggy

 

[CFarr]

Thanks guys. I'll pass suggestions on to the crew to check today if they can.
I'm currently 7 hours away from boat so tricky to answer queries quickly.

I'm guessing the engine did get up to temp ok. They reported that it ran beautifully yesterday.
I don't remember there being a temp gauge though.

 

[sarabande]

Sometimes the pressure relief valve on a calorifier can leak and get rid of all your precious hot water. So...

Is the fresh water tank as full as you would expect it to be ?

and

Did anyone notice if the bilge pumps were working overtime yesterday ?

 

[Chalker]

It's not the fresh water from the pump through the.calorifier to the tap.
It's the engine cooling water through the calorifier that needs to be bled of air.
The engine hot water heats the tank freh water in the calorifer/ hot water tank without mixing the two.

 

[CFarr]

It's not the fresh water from the pump through the.calorifier to the tap.
It's the engine cooling water through the calorifier that needs to be bled of air.
The engine hot water heats the tank freh water in the calorifer/ hot water tank without mixing the two.

Aha, thanks. I said plumbing wasn't my thing

 

[VicS]

EDIT: Vic, yes, drained by yard. We simply filled through the deck filler and then switched on the water pump.

I was thinking of an airlock in the engine cooling system, if that has been drained and refilled., more specifically in the the connections to and from the calorifier or the calorifier itself.

I'm guessing the engine did get up to temp ok. They reported that it ran beautifully yesterday.
I don't remember there being a temp gauge though.

Check by some means or other. By feel if no gauge and no infra red gadget

 

[vyv_cox]

A way of clearing an airlock in the calorifier hoses is to run the engine at a fast tickover and squeeze closed the hose that takes coolant from the engine to the heat exchanger, using a mole wrench. This diverts all the flow from the pump to the calorifier hoses. Shouldn't need more than 10 seconds, if that doesn't clear it repeat a few times but don't leave the mole on too long or the engine just might run too hot.

 

[duncan99210]

The one time I had this problem, I found that the engine coolant level was low. Topped it up and the hot water was fine.

 

[neale]

Another possibility is that during its time on the hard, someone has knocked one of the valves to the calorifier and it is partially shut. That's if it has got them of course.

 

[CFarr]

Well that was an easy fix - when the problem was discovered.
I went through the various solutions and possibilities highlighted here when I wS up at the boat this Easter weekend but couldn't solve it.
A chap came over to have a look and puzzled alongside me.
On going through the various fittings he said 'and I think this is the temperature control to the tank - oh, it's turned all the way to cold'
someone at the yard must have turned it when draining/winterising because it was red hot last season.
At least I now know more than I did before so thanks again all who contributed.

Anyway, very happy bunnies now

 

[macd]

Revelation 3:15
Luke: I know your deeds, that you are neither cold nor hot. I wish you were either one or the other!


Vyv's suggestion is probably more practical, but calorifiers sometimes respond to prayer when all else fails.
Of course you might have meant luke-warm

PS: a most thoughtful edit to your opening post, CFarr. What a very good idea.