Live Steam

If you want to run live steam on an existing layout, you will probably need to beef up the electrics; the usual stuff for the standard 12v 'Trad' system is far too light - typically maximum capacity of an amp. The Hornby live steamer uses up to 6 or 7amps. If this high current causes a large voltage drop between controller and track, control of the loco will be lost.
You need to approach it in the DCC style - busbars under the baseboard feeding the track at regular intervals. I used 1 sq mm wire for my layout feeding each baseboard section - about 800mm long on each section; this works quite well. Baseboard sections are linked with 10A capacity plugs and sockets to prevent these overheating.

Have fun - the live steam is great!
Regards,
John Webb

Bearing in mind that the Hornby live steamers are electrically 'fired' the only by-product is a small quantity of steam. Your loft should cope with this - mine does. I'd agree with Jeff (Gwent rail) if you were trying to run larger gauge spirit or solid fuel-fired live steamers indoors where you do have the extra 'products of combustion' to contend with. (Although I'd disagree about Chubb extinguishers!!)

You don't say if your layout is set-track or flexi-track. If set-track, and therefore more fishplates/rail joiners present, you do need to ensure these are gripping firmly to the adjacent piece of track.
I've used flexi-track and have soldered all fishplate joins to ensure continuity - I've also bypassed the wiring in the points (both PECO and Hornby) to avoid these carrying the heavy current other than for the short time the loco is passing over them. By observing these precautions I've not had any trouble so far with track joints overheating.
Regards,
John Webb

Brian - the Hornby 'boiler' takes 25ml (5 teaspoons) of distilled water. This take about half-an hour to be dispersed into my loft. I suspect more water vapour gets through the tiles and soffit vents when it rains than is put out by the live steamer, so I'm not worried by it.

The larger steam models will put more into the atmosphere, of course, and this may be of greater concern.

The biggest drawback is that the live steamer follows prototypical practice in making the track dirty through dropped oil and water (we are at least spared cinders and ash!) and particularly to keep the 'trad' 12v locos running after a live steaming session the track will require more frequent cleaning, as will rolling-stock wheels.

For scoobyandy's information: the forum on "0, G and larger Scales. Garden and Live steam" has a number of topics covering the Hornby live steamer already (including some info on my small layout).

Regards,
John Webb