The Naiad Voyages

Mark Austen

2016.11.18 - The Hampshire Heater

I was delighted to receive the Hampshire Heater early this morning, so I postponed my planned tasks for the day and started work around the heater. To me it is a fantastic heater, small, lightweight, shiny and looks wonderful and it is going to look magnificent in Naiad. The designer and maker of these heaters rates them at 3kWh. The marine rule of thumb is 15 x Volume to heat in cubic feet = required heater output in BTU (British Thermal Units). Now a cubic metre is 35.3 ft3 and 1kWh = 3412.14 BTU. Doing the required maths gives:

Volume to heat in cubic metres / 6.44 = required heater output in kWh.

Or, if you like your volumes in cubic feet and your output in kWh then:

Volume to heat in cubic feet / 3412 = required heater output in kWh.

Why all the maths? Well, it's interesting, I'm an engineer remember and it means that I can see how much space will be heated by 3kWh. The answer being 19m3 or 682ft3. that would be a cube 2.67m per side or 8' 9.6" per side. That is about twice the volume of Naiad's cabin so she is going to be toasty warm when the heater is going!


Here is the heater on the kitchen worktop.

I put a wine bottle alongside so you can see the size. it weighs just 6kg or 13lb. the heater that is, not the bottle.

The first thing I need to do is to find out how hot it gets as this will determine how and where I mount it. I screwed it to two pieces of timber and used cramps to clamp those to a third timber which also formed two supports to prevent it falling over forwards and then used two more cramps to form supports to stop it falling over backwards.

Now the thing about lighting solid fuel heaters is that until you get the air in the flue and the flue itself warm, the heater will not draw properly and the fuel will either take ages to light and be very smokey in the process or not light at all. Warming the air in the flue is key. This is the solution. It is a piece of ceramic wool.

Having put the correct amount of fuel in the heater to get it started, a quarter full in the case of the Hampshire Heater, you put a small amount of alcohol or meths on the ceramic wool, place it at the bottom of the flue and light it. then replace the lid. You should hear a faint roar as the air starts flowing up the flue.

Then you light the heater as described in the manual. Once the fuel has lit properly, take off the lid, remove the ceramic wool and put it somewhere safe for next time, fill the fire chamber with the correct amount of fuel then replace and secure the lid.

Works every time.

You will need these, a pair of good leather gloves. I use these for blacksmith work and when I'm cooking over an open fire.

And before I get taken to task for lighting a charcoal fire in my workshop, this is what is less than five feet away.

The charcoal I have has been stored in the workshop and is a little damp so it smokes a bit until it gets going.

This shows the lint burning off as described in the manual. It stinks so I'm glad I did thing before putting the heater in the cabin.

So, how hot does it get? 131 Celsius at the bottom of the fire chamber.

A little cooler at 123 Celsius about halfway up.

Cooler still near the top at 119 Celsius.

Much cooler on the side of the lid which is not surprising as it is double skinned.

This is about 12" up the flue.

Another 6" up the flue.

The temperatures were taken with the air inlet fully open and about 20 minutes after lighting. later on these temperature became higher by abut 20 Celsius as the heater settled down. Then I wound the air control down to about 1mm only open and I'll leave it like that for an hour or so before checking the temperatures again.

The ambient temperature in the workshop is about 6 Celsius and you can tell the difference in the corners where the heater is working despite the workshop being ten times the volume of space for which this heater was designed.

The galley dismantled as I need to rebuild it differently to allow for the heater to be installed. Just as well I didn't use any epoxy here!

Now, lunchtime!