Horizontal boiler

Recently I saw 2 horizontal boilers in an antique centre. Approx 3 x 6". They are mounted on a thin sheet rectangle with a "fire hole". Top of boiler has wooden cladding. I presume that they are designed for a meths or gas boiler. Several bushes are fitted, one of the boilers has a pressure gauge and water level indicator. I assume that they are a part completed project. Priced at £75 each - would this seem a reasonable price? (I know not an easy question to answer unseen)
There are a few (5 from memory) vertical tubes running up into the boiler. Am I correct in assuming that these direct hot air up into the boiler and will pass out through the chimney? This was the bit I was curious about - is this a standard design? Next time I am their, will will look more closely. Details may not be exactly correct as I am relying on my memory from a quick look.
Thanks
Keith

That would be a most unusual arrangement, vertical fire-tubes in a horizontal boiler. They'd need a smokebox along the the top of the shell; perhaps with the chimney in the centre, but from what you say this is not the case here.

Are they actually fire-tubes, or in fact a form of thermic syphon, so full of water in use? That is quite common on small horizontal boilers made for gas or liquid-fuel, with the burner heating the entire length of the shell.

As for value... I could not say but it would depend heavily on their condition, and evident signs of good workmanship would be a start.

It'd be worth asking if the shop also has any model engines etc, that look as if intended to accompany these boilers; or at least came from the same seller..

From the description, it is one design that I have never seen.

Once again a photo is worth a 1000 words in describing it for a sensible answer.

Sounds more like water tubes sticking out he bottom of the drum. Google Stuart 500 Model Boiler and have a look at a few examples showing the water tubes.

these used to be common in the boating world. They are designed for short duration-high output used in straight running steam boats.

Did get a second quick look today. Does look like a marine boiler that I found online.

For example **LINK**

Vertical fire tubes go into a rectangular smoke box and chimney (both missing on one).
Thanks for all of the comments - this site always has helpful comments. Will try and have more time to speak to the staff next time.