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Super heaters for miniature loco, Garratt

Garratt

Joined: 1-01-80

Topics: 2

Replies: 0

Posted: Sat 10th Jan 2015, 4:55am
Super heaters for miniature loco, Garratt

I am building 2.1/2 to the inch Garratt and I have had a number of people who have been trying to talk me out of having super heaters,SO what the pro for or againts having super heaters?????
Arthur Boyd
 

Replies To This Post

MikeH

Joined: 1-01-92

Topics: 1

Replies: 3

Posted: Wed 4th Mar 2015, 10:05pm

I'm surprised this hasn't opened an old can of worms. The superheat/no superheat debate has been long, loud, frequent and sometimes acrimonious. For them, in my view, economy and a drier exhaust, against - added complication and the need for occasional renewal. Forget the attempts at thermodynamic analysis that have sometimes appeared in the model engineering press. There was one in the 'Model Engineer' some years ago that fell at the first hurdle: the author started his analysis from the assumption that the steam leaving the boiler was dry saturated, i.e. no water carry over whatsoever.

For what it's worth, given the length of both steam and exhaust pipes on a Garratt, I'd fit superheaters - radiant ones that reach out of the superheater flue over the fire. They must, however, be from stainless steel. I use 316 grade for weldability and service life. I run for the public and have one or other of my two locos in steam about 220 days a year, often both locos. The superheaters last several years. We put one loco back into service last summer after firebox renewal. It was tight to get it ready before the school holidays and we didn't refit the superheater elements as they needed new flanges making and fitting. Suffice to say that they will be refitted for this season.

Mike Henderson
 
 
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