Look for a slot approximately 2" x 6" at the back of the fireplace that passes beneath the back boiler.
This must be free of ash blockages.
There will be a damper in the flue, just above the fire. If its a slider type, move it to the left and hot gases will pass from the fire and around the boiler before going up the chimney...you can get a vacuum cleaner pipe in there, down the back of the boiler to clean it out if you don't mind getting dirty!
Another type is the butterfly damper...these have a lever mounted in the fireplace somewhere, and it does the same thing. Either way, you need to allow hot gases around the back of the boiler before you'll get much hot water.
John
P.S At this point, I have to say that I am the easiest person in the world to fall for a wind up
Thanks Burnerman, this really wasn't a wind up, I've recently moved into a cottage in the Scottish Highlands that has the coal fire and I've never used one before. I have cleaned out the vent at the bottom and adjusted the damper and this has had a positive result. I can have a soak in the bath at last! Thank you once again, your advice is greatly appreciated. The girlfriend no longer wants to kill me!
burnerman is right about the damper and the back passage round the boiler - but from experience you can get a reasaonable result from piling the coal up @ the back sloping to the front of the grate . We hardly ever used the back of the boiler - it`s also about timing - a fierce burning flamed fire wont give the same heat to the boiler as a settled bed of glowing embers
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local