Calorifier.Difference from bog standard domestic hot water tank ?

[oldgit]

Thanks all.

Thanks to all who replied.Although there appear to be to be a four unions on tank cannot see anything which looks remotely like a couple of unused heater coil connections.
Am going to assume it is a domestic tank and swap the thing for puka calorifier.

 

[All The Gear No Idea]

Thanks to all who replied.Although there appear to be to be a four unions on tank cannot see anything which looks remotely like a couple of unused heater coil connections.
Am going to assume it is a domestic tank and swap the thing for puka calorifier.

The two unions on the side of the tank will be for the heating coil. Check out where the attached pipes connected to for confirmation.

 

[John100156]

Chaps,

There are various types of calorifiers/cylinders for use in the home and on boats: direct/indirect heated, unpressurised/pressurised cylinders. You must specifiy which type you require; typically on boats they will be indirect and pressurised.

Indirect means the hot water used to heat the cyclinder (termed primary hot water) is seperate from the hot water stored in the cylinder (secondary hot water) serving the taps.

If the primary heating coil is not used or connected to the engine circuit the cylinders are normally heated via an electric immersion heater with thermostat and high temperature cut off located under the of the heater.

If you select a typical un-pressurised domestic calorifer/cyliner, the secondary storage side is usually manufactured to work only at atmospheric pressure, the secondary pipework includes an open vent that runs up over the cold water tank, if you use this type of cylinder on a boat, you run a very high risk it could leak or even burst. You may get away with it, but I would certainly not recommend it, always ask for a mains fed or pressurised cylinder.

So lets assume yours is an indirect/pressurised: They have various connections, typically seondary hot water feeding taps leaves the cyclinder at the very top, cold water enters at the bottom. There are usually two other pipework connections for the primary heating circuit hot water. If unused, they could be left open as water in the cyclinder does not enter them, so you can check them on your cylinder by removing any caps/plugs and they should of course be dry.

On a boat or pressurised system the accumulator or expansion vessel provides two useful functions, it cushions the pressure in the secondary system reducing the frequency of pump starts (when only a small amount of hot water is drawn off), it also provides a space that water can expand into when heated, if not the pressure in the seondary system would build up to a level that would activate the pressure relief valve which should also be installed to or very close to the calorfier. Just imagine, when the cylinder/system is first filled the pump will pump it up to pressure and with all taps vented then shut off, you have say 50L of water in a fixed volume system, that will expand when it is heated from sat 10C to 55C building up the pressure!

Added to the good advice already given by others you should now understand all that you need!

 

[Heckler]

In that case, I'd check the thermostat and the cooling system.

Why?
In the case of the MD22, Volvo advise that the thermostat starts to open at approx 80 plus deg and is fully open at 98 deg C. On the MD2030 and 40 they refer to it as an over pressure system and again the thermostat starts to open at 82 deg and is fully open at 95 deg C.
They both have automotive type pressurised caps on the top of the coolant vessel which has an air gap to allow for expansion. The caps are to allow for overpressure in the system (as advised by VP) The over pressure has the effect of stopping the coolant turning to steam as the temp goes over 100 deg C and allows the engine to operate at a more efficient temp.
If you are inferring that marine engines dont operate at such temps then I suggest you take a look at some of the more modern marine engine specs, from that you would then learn to be a little bit cautious when removing pressurised caps on indirect cooled engines.
Stu

 

[pappaecho]

I am assuming that the tank has either 22mm or 28mm heat exchange coil inside it. The burst pressure of such pipework will be in the order of 40-50 bar, well beyond anything which your engine cooling system can muster

 

[pvb]

Why?
In the case of the MD22, Volvo advise that the thermostat starts to open at approx 80 plus deg and is fully open at 98 deg C. On the MD2030 and 40 they refer to it as an over pressure system and again the thermostat starts to open at 82 deg and is fully open at 95 deg C.
They both have automotive type pressurised caps on the top of the coolant vessel which has an air gap to allow for expansion. The caps are to allow for overpressure in the system (as advised by VP) The over pressure has the effect of stopping the coolant turning to steam as the temp goes over 100 deg C and allows the engine to operate at a more efficient temp.
If you are inferring that marine engines dont operate at such temps then I suggest you take a look at some of the more modern marine engine specs, from that you would then learn to be a little bit cautious when removing pressurised caps on indirect cooled engines.
Stu

As you're quoting from Volvo Penta literature, I'm sure you're also aware that VP state that the "normal operating temperature" of the MD2010/20/30/40 is 75-90C, and that the normal operating temperature of the MD22 is 75-95C. Whilst, in extreme operating conditions, temperatures can rise above these normal ranges, extended operation at higher temperatures isn't recommended.

 

[pappaecho]

Having now go a computer which will display images, there appears to be an "in" and "out" towards the bottom of the tank, with white pipes connected. One has a grey connector and the other chrome. These are the connections to the heat exchange coil. If the installation has worked OK for period of time using the immersion heater, then connecting the indirect coil will not cause a problem. The question therefore is what are the two white pipes connected to?
I would carefully trace them back to the engine connection. On my P33, the port Ford Mermaid engine pumps water to the coil and back, using the existing water pump. The starboard engine is not connected, and it would appear that they have just simply "broken into" the circuit on the port engine, on the outlet side of the water pump. The system wrks very well

 

[TrueBlue]

Thanks to all who replied.Although there appear to be to be a four unions on tank cannot see anything which looks remotely like a couple of unused heater coil connections.
Am going to assume it is a domestic tank and swap the thing for pukka calorifier.

Revisiting this thread, and not noticing who the OP was, not that that has anything to do with it - I wonder whether your cylinder is indeed a marine type tank anyway.

The possible giveaway for me is that it has an immersion heater at the bottom, and that implies to me that arrangement could only have a small heater installed. Domestic cylinders have a heater in the top, else one is limited to about 1.5Kw - which is the maximum size I've seen on marine units.

My current tank - from ASAP - is in the same format as yours, so the shape is no indication. The location of the overpressure valve has thrown me, it's usual to have them in the top, teed of the hot water takeoff (it makes it easier to clean / vent the unit by turning the knob on the valve).

Domestic units don't have pressure release valves built in - unless they are intended to work under pressure.

The lump on the bottom of your tank could be for a drain off tap, but that is usually incorporated into the cold feed. Looky here

Something seems wrong with your system - if th engine has never been used to heat the water. Could the coil be damaged (in which case game over) or not connected properly?

It possibly needs more investigation before you junk it.

Indeed it's been there for some time and hasn't blown up, so may be a marine or high pressure domestic unit.

 

[Bobobolinsky]

Diesels don't run at 100c if everything is working well, The tank as fitted is a commercial hot water tank as supplied by the oil heating company (Refleks, discarded as flues were too big) any way they are supplied for fishing boats etc by one of their UK agents

 

[oldgit]

All is revealed

Just thought of something else,only ever bothered to check starboard engine regards no connection to cylinder.Doh.....


OOPS.Have just checked other engine.It is a proper calorifier and is connected to the "other" engine.
Found the connections,turned on the isolation valves and hey presto......hot water.

Lesson learnt....use Mk1 eyeball as it can save you a lot of work and expence.
My "new" second hand calorifier from EBAY will no doubt be turning up soon to add to my discomfort..
Anyone want to by a cheap tank.