steam blower or electric?

is the gauge OK?

What happens if you open the regulator?

where is the snifting valve connected to?

Sorry – I only asked as you said it was blowing hard.

Fire – begin with wood or charcoal soaked in paraffin and then feed coal quite quickly. make certain the whole grate is covered and there are no holes in the fire.

Two areas to investigate – firstly if the gauge is reading zero it is either not making steam or the passage to a fully working gauge may be blocked and secondly is the fire burning brightly or not? If not check ashpan and grate.

If this is your first loco you could possibly do with someone else there to observe and advise as you light up – are you a member of a club?.

Edited By Nick Clarke 3 on 04/07/2019 20:57:05

If it is fitted to the superheater water can come over if the is over full and the regulator is open (unlikely from what you have said) or from condensation – but in a modern high superheat boiler design makes this unlikely to be more than a few drops if there is a fire lit – steam is more likely than water.

You have puzzled me too. Can't offer any other suggestions, sorry, but when you do find a solution please come back here as I am now close to being as curious as you to find out the cause.

Rather dumb question, but is it possible that it's caused by the Columbia design's rather exposed cylinders and valvegear? How long have you run for before concluding that there's too much wet coming from the snifters?

Edited By Mark Rand on 05/07/2019 00:54:27

I know almost nothing about small boilers in practice, but seems to me there are only two possibilities:

1. The boiler is developing pressure but the gauge or pipework leading to it is faulty. However, ff the boiler was pressurised I would expect working the regulator, whistle, etc to emit steam. In the worst case, the safety valve should lift. (From what's been said I don't think a faulty gauge is likely to be the problem, but take care. )
2. Not enough heat available to convert water to steam. At atmospheric pressure it takes about 400kJ of energy to raise 1kg of water to boiling point. Thereafter, it takes a lot more energy to convert boiling water to steam, another 2400kJ to evaporate 1kg of boiling water, about 6 times. Two possibilities:
   1. In the limited space available, the fuel can't make enough heat. Welsh steam coal is famously good, other coals and barbeque briquettes etc may struggle. Wood is likely hopeless. This is assuming that the fire is getting enough air; too little will choke the flame.
   2. The boiler and everything attached to it are acting like a central heating radiator and losing heat faster than the fire can make it. Try temporarily insulating the boiler and anything connected to it by wrapping the whole in several layers of Aluminium kitchen foil or a fireproof blanket. Another possibility is the blower is too powerful. Too much air forced through the fire will cool the output and reduce the time available for heat to transfer from gas to the tubes. Try reducing the blast a bit. On full-size leaving the fire-door open cools the fire, I don't know if the effect is greater or smaller on a model.

Quite likely a number of factors are at play making the problem hard to diagnose: a combination of low heat-value fuel, too much blowing and an insufficiently insulated boiler perhaps. Fix one or two and the engine might burst into life.

If not tried already, you could give the boiler a head start by filling it with boiling water immediately before firing. If that works, it means heat loss / insufficient heat from the fire is definitely the issue.

Sounds like the snifting valve is leaking slightly. My guess is that's not the problem. If the valve, or anything else, were leaking badly enough to stop pressure rising I'd expect to see a lot of steam vapour coming out of it. As that's not happening, you either have a completely sealed boiler (aka a bomb), or the water inside isn't getting enough heat.

Dave

Terry –

Just had a look at the Columbia drawings and I have to agree with Clive's suggestions. The ashpan is very shallow indeed and the four holes in the front corners may not allow sufficient air through to the front of the fire. I addition the thermic syphon comes very close to the grate at the front of the firebox and as such may allow a hole to develop in the fire around there.

The snifting valve is pointing downwards at the bottom of a pipe from the hot header and without sufficient pressure in the system to hold it tight should leak steam if anything, but it could be water, even with the radiant superheaters the full length of the firebox.

As regards the regulator this appears to be the most complex I have ever seen drawn for a model locomotive – a twin poppet valve arrangement operated by cams. I would certainly be wanting to check that it sealed tight.

Terry,

It may be priming if it's never been steamed before which would explain the water, but not the lack of pressure, unless the dissolving flux has allowed a tube to leak into the firebox since the hydraulic test.