Air in calorifier

[captain flint]

A couple of years back I had to replace my calorifier. The new one is the same size as the old one, but the hot water doesn't last nearly as long. This makes me think it's not full. 

 

Which would make sense. It lies on its side, so the inlets and outlets are  positioned considerably lower than the top of the tank, and it was installed empty. 

 

I'm wondering if there's any straightforward  way to bleed it? I can't think how you'd do it. 

 

Also if there's some way this could have been avoided in the first place I would be curious to hear about it. Of course, if we had filled it on end, and installed it full, that would have done it. But I'm guessing that it would be a heck of a job, even with a winch, as it sits in the engine bay on the counterpane. But maybe I'm wrong about that. 

[Tony Brooks]

5 minutes ago, captain flint said:

A couple of years back I had to replace my calorifier. The new one is the same size as the old one, but the hot water doesn't last nearly as long. This makes me think it's not full. 

 

Which would make sense. It lies on its side, so the inlets and outlets are  positioned considerably lower than the top of the tank, and it was installed empty. 

 

I'm wondering if there's any straightforward  way to bleed it? I can't think how you'd do it. 

 

Also if there's some way this could have been avoided in the first place I would be curious to hear about it. Of course, if we had filled it on end, and installed it full, that would have done it. But I'm guessing that it would be a heck of a job, even with a winch, as it sits in the engine bay on the counterpane. But maybe I'm wrong about that. 

 

I think it needs twisting on is cradle so the hot out is as close to the top as possible. I am assuming this is a horizontal calorifier, rather than a vertical one fitted on is side. Sounds like incorrect fitting to me, without any photos to see if it is a horizontal one.

[captain flint]

Thanks Tony. Makes sense. Not on board right now, will have a gander later, might  post a photo

[alan_fincher]

I think unless you are very lucky, you will not successfully heat as much water in a horizontal calorifier as in a vertical one.

That said, I agree with Tony that "rotational adjustment" of an horizontal one might well improve its performance.

[Russ T]

Did either of them have a thermostatic mixing valve fitted? If the old one did, and the new one didn’t, wouldn't the water last longer?!

[captain flint]

17 hours ago, Rod Stewart said:

Did either of them have a thermostatic mixing valve fitted? If the old one did, and the new one didn’t, wouldn't the water last longer?!

I have no idea at all!

[Ex Brummie]

Pictures of the installation will tell a full story. If it is a vertical one laid horizontal and the vertical configuration has been retained, with take off from the top connection, you will have 1/2 a cylinder of water that is never used. The remedy is to feed the 'top' of the cylinder and take from the normal feed connection ensuring the cylinder is oriented to make sure that is at the high side.

[plato]

On a surejust horizontal cylinder the outlet is at the top already. 
I’ve recently fitted a horizontal twincoil one and definitely not getting as much water as the vertical one on my previous boat. 
Also it airlocked and has been an absolute pig to bleed it, despite trying all sorts of ways to do it. 
spoke to surejust about it and their response was “get a plumber to do it” 

 

[Ex Brummie]

There will be a small air bubble in the top of the cylinder and it is designed to be there. It is a common feature on domestic mains pressure cylinders.

If you are talking about the coils being bled, then if then they can ba filled manually before fitting the engine hoses.

[ditchcrawler]

2 hours ago, Ex Brummie said:

There will be a small air bubble in the top of the cylinder and it is designed to be there. It is a common feature on domestic mains pressure cylinders.

 

Designed to be there? in that case how do you replace it when the air has finally been absorbed into the water. With a domestic one there is a valve arrangement to do that, also the boat one should have an expansion vessel to do what the air cap dose in the domestic one 

[Ex Brummie]

There is no doubt the  design does not really allow for it to be bled .

[ditchcrawler]

10 hours ago, Ex Brummie said:

There is no doubt the  design does not really allow for it to be bled .

Very true, I wonder if the hot take off point goes to the top inside like a snorkel ?

3 minutes ago, ditchcrawler said:

Very true, I wonder if the hot take off point goes to the top inside like a snorkel ?

It doesn't look like you could put it up side down but the hot takeoff is not that close to the top edge

[Tony Brooks]

40 minutes ago, ditchcrawler said:

It doesn't look like you could put it up side down but the hot takeoff is not that close to the top edge

 

But there will, presumably, be a certain thickness of insulation, plus the outer case, so the out connection is probably a lot closer to the top of the inner calorifier cylinder than it looks. Anyone had one apart who could tell us?

[ditchcrawler]

20 minutes ago, Tony Brooks said:

 

But there will, presumably, be a certain thickness of insulation, plus the outer case, so the out connection is probably a lot closer to the top of the inner calorifier cylinder than it looks. Anyone had one apart who could tell us?

I would love to know as well