Calorifier sprung a leak

[Jen-in-Wellies]

2 hours ago, ivan&alice said:

One last question - how does the system "know" when the water is up to 85 degrees and to start using the skin tanks for cooling?

Most engines, there are two water circuits. A small bore one, which can go to the calorifier, and a large bore one, going to the skin tank. Out from the top of the engine and returned to the water pump. The large bore, skin tank circuit has a thermostat that acts as a valve that opens at a set temperature, 60 to 85C, depending on the engine and this keeps the water coming from the top of the engine to the calorifier at around this temperature, once the engine has heated up to its normal working temperature. From cold, the thermostat is closed, so no coolant flows to the skin tank and the engine heats up quickly. There are variations in how it is done of course.

[Chewbacka]

If you have a crack and want to stop it growing then you should drill a little hole at both tips of the crack - say 3mm.  Cracks propagate as the stress concentrates at the ends but if you drill a little hole it gives a much bigger radius to reduce the peak stress.  Solder alone which is very soft will block the hole but longer term will not stop the crack getting longer.  However if you drill a hole you do then have a hole to seal up.

Anyway see how your repair works, get an expansion tank to reduce stress and if it holds until you get a new tank, that’ll be good.  If it splits some more try the little holes.  Good luck.

Edited November 17, 2019 by Chewbacka

[WotEver]

Two questions asked by the OP that don’t appear to have been answered on my quick skim through the thread...

 

PRV in this context is Pressure Relief Valve, not pressure reducing valve. 
 

The ‘hot water tank’ itself is what is commonly referred to as the calorifier. 

[WotEver]

13 hours ago, WotEver said:

PRV in this context is Pressure Relief Valve, not pressure reducing valve. 

And two pretty obvious (?) points...

 

1. The pressure of the PRV should be higher than the cut-out pressure of the pump. 
 

2. The maximum pressure of the calorifier should be higher than the PRV.