Murso Squirrel Back boiler leak

[Slim]

I note that everyone is talking about a steel back boiler. It may be cast iron. I know for an absolute fact that mine is. I fitted it into the stove about 20 years ago. 

 

 

Edited March 18, 2020 by Slim

[Ex Brummie]

On ‎18‎/‎03‎/‎2020 at 17:08, BEngo said:

The fairly thin welded boiler in a Squirrel is a wholly different thing to the substantial cast iron lump in an  Aga or Rayburn.   

 

 

N

The boiler in my Squirrel was cast iron, and considerably thicker than the side and top. Dry sand can be easily poured into the top connection, and can be stirred about quite easily with a flexible rod. It need not be packed tight, and can readily be topped up after a week or two when cruising will help it settle.

[Tracy D'arth]

Early Squirrel boilers were glass lined cast steel.

Later are fabricated stainless steel. Seen plenty used with no water or sand in and working OK.

 

I would try a large can of radweld in the expansion tank first before spending £1000+ on a new boiler.

[Higgs]

5 minutes ago, Tracy D'arth said:

Early Squirrel boilers were glass lined cast steel.

Later are fabricated stainless steel. Seen plenty used with no water or sand in and working OK.

 

I would try a large can of radweld in the expansion tank first before spending £1000+ on a new boiler.

 

Part of the reason to have sand in the boiler would be to improve the fire's ability to contain the heat in the space inside the fire. And, also to control the transfer of heat to the plates of the boiler. To keep it within a reasonable range. However, never cap both outlets of an empty boiler, as it could cause the boiler to fail quite dramatically, due to heat expansion of the air inside the boiler, causing an over pressurisation of the boiler structure. 

 

 

[MtB]

12 hours ago, Higgs said:

 

Part of the reason to have sand in the boiler would be to improve the fire's ability to contain the heat in the space inside the fire. And, also to control the transfer of heat to the plates of the boiler. To keep it within a reasonable range. However, never cap both outlets of an empty boiler, as it could cause the boiler to fail quite dramatically, due to heat expansion of the air inside the boiler, causing an over pressurisation of the boiler structure. 

 

 

 

A right load of old claptrap, in my opinion.

 

 

 

[BEngo]

Easy enough to calculate the possible pressure rise.  Assuming you start at 0 deg C (273 Kelvin)  and the  normal air  pressure of 1 bar then at 273 C the pressure will be 2 bar,  at 546 C it will be three bar and at 819 C the pressure will be 4 bar, and so on in 273 C steps, if I have my gas laws right.   This ignores any expansion of the boiler and the change in gamma/specific heat with temperature.

 

At 819 C  the boiler will be nearly red hot and the material will probably be losing strength.  I can only guess at how things might develop from there but the stove itself is also going to be hot, damn hot as someone once said.

N