Chinese Diesel Heater - Workshop Install

I needed heat in my single-garage workshop but did not want to use an electric heater. I wanted to use a cheap (under £100 on eBay) Chinese Diesel Heater (intended for heating large vehicles such as camper vans).

There are dozens of videos on YouTube showing various installations in workshops, but none were mounted outside the workshop, and many were quite Heath Robinson.

I wanted an external, boxed, mounting to:

1. Reduce the high sound levels from the burner/fan/pump.
2. Keep the diesel out of my workshop, due to its smell.
3. Get a straightforward layout for the components.

The heater was mounted on the external wall of my garage, a half-brick was removed to allow the hot air duct to enter directly into the workshop. I chose to mount the diesel tank in an adjacent shed, alongside the heater.

This Instructable is not a step-by-step 'how-to' (as mentioned there are dozens of these), more an overview of what I did, in case it is of use to someone else.

I gleaned much information from a brilliant series of Australian videos.

I have also posted a video, based mainly on this Instructable.

Having watched the series of videos linked to above, when I bought my heater, I looked carefully for one marketed as having

• an output of 5kW
• photos which showed a 'straight-through' exhaust silencer (as opposed to one with a kinked or bendy path)
• a small-diameter hard-nylon fuel supply pipe (not a 6mm diameter, floppy, soft plastic pipe)
• an LCD control panel
• a four-way remote control (on, off, up and down)
• a fuel filter

On receipt, the fuel pipe was soft and floppy! I purchased a length of suitable pipe from eBay. In all other respects, the heater was great (and worked brilliantly first-time) and was delivered quickly.

eBay purchases (March 2021)

The heater was listed as "12V 5000W Air Diesel Heater LCD Display Display 2KW-5KW for Car Truck Motor-Home" Sold by connectingrodeclub. Not sure of the location, but it came in a few days. £82

I ordered a power supply "DC12V Top Quality LED Transformer Driver Power Supply LED Strip Lights MR16/CCTV" (150W 12.5A). Sold by electricalsone located in Coventry UK. £14

The nylon pipe was listed as "NYLON TUBE METRIC PNEUMATIC Air Line Flexible Hose AIR FUEL - HIGH QUALITY" (4mmx2.5mm BNTM04/025). Sold by fletcher3691 located in Chelmsford UK. £1.60

This step is just an opportunity to show numerous close-up photographs of the build and note down a few details (many gleaned from the videos referred to in the introduction).

• The exhaust pipe can eject water vapour, so I have tried to avoid a water-trap by making it fall steadily.
• I shortened the exhaust pipe, as it was too long and very inflexible. This caused a problem, because the original had smooth unions formed at each end - this was impossible to replicate on the end that I had cut. I had to insert a small piece of steel tube to join the pipe to the silencer.
• The silencer has a drip-hole in the bottom, which can drip onto the ground in my installation.
• The power supply must be able to provide at least 10A at 12V. The glow plug takes a large current (8A?) and the fan/etc takes 2.5A. I believe that many installations have low-voltage error problems due to poor batteries or lack of current capacity. I chose a 12.5A supply.
• Keeping the red and black power supply cables as short as possible has got to be a good thing, due to the large current demand noted above.
• One draw-back of using a mains-powered supply is what happens if there is a power-cut when the heater is operating. The suggestion is that the residual heat in the unit will mean that it will destroy itself by overheating/melting if there is no power to run the cooling fan. I think this suggestion is likely to be true! As I never have power-cuts, the likelihood of having one when the heater is running seems remote - I hope!
• I mounted the pump at an angle of 30° - 40° with the output end uppermost.
• All of the wiring looms were too long for my layout, so I cropped them and used connector blocks. The colour-codes on the two wires to the pump were identical, so I guess that it does not matter which is which, but I was careful to mark one wire to retain the existing polarity.
• On the photos of the final installation, you can see a length of open aluminium channel (just below the power supply). The plastic fuel line is supported by this. It is intended to make sure that the plastic pipe is protected from any heat radiated by the exhaust silencer. In reality, nothing gets very hot inside the enclosure.
• The heater I purchased came with a "Tee" for the 80mm diameter air pipe. I wanted to keep the enclosure as narrow as possible and used it as an elbow, by cutting off one arm and plugging the cut arm with a plywood circle. This can be seen on the left of the heater. It is hard to bend the 80mm diameter 'flexible' pipe into a tight bend.
• I was not sure whether I wanted to re-circulate the air from the inside of the workshop, hence the large hole cut in the backboard to the right of the heater, which I will use if needed in the future. In fact, I 3D printed a grill and placed it on the side of the enclosure to provide fresh air for both the workshop supply and the burner supply.

It was convenient for me, to mount the 10litre fuel tank in the wooden shed, next to the heater. Some images of the installation can be seen above. A few notes:

• The heater came with a dip-tube, which could be mounted onto an existing diesel tank. I did not use this.
• The supplied tank did not have a fuel-union fitted (one was supplied). I drilled a hole in the side of the tank (as near the bottom as possible - but above the bottom to stop debris entering the fuel line). I then poked a stiff wire in through the hole and out of the top of the tank, fitted the union onto the wire and tied a knot in the wire, then pulled the union through the tank and out of the drilled hole, then put the nut on and tightened it up. I pulled the wire back out through the tank.
• I wanted to fit an on/off valve and purchased one locally.
• To protect the fuel supply pipe from damage, I threaded it through some hose pipe to get it out of the shed and into the heater-box. I 3d printed some fittings, to support the pipe where it left the shed, entered the enclosure and touched the brickwork.
• The black clips for the 6mm pipe were 3d printed.
• The tank has a tiny vent-hole in the fuel cap.
• Both the tank and the heater are mounted at about the same height above the ground. The pump can pull the diesel up-hill but it was convenient for me to have them at about the same height. To prime the system, I just opened the tap, disconnected the fuel supply pipe from filter and as the diesel flowed out, I connected it back onto the filter. I had already tested the heater, so did not have to repeat the initial pump-priming operation.

I have only run the heater a few times, so far. It powered up without any hassle and produces large quantities of very hot air. I will have to wait for next winter to fully test its effectiveness, but I am very confident. The last cosmetic tweaks inside the workshop, still need to be done.

Outside, it is very noisy indeed for the first 10 minutes of operation (and when ever it is running flat-out). This is a combination of fan-noise and combustion-noise. I am very pleased that I have mounted it outside (rather than inside my workshop). As it reaches the target temperature, the noise level reduces considerably. The noise level inside is fine - there is quite a rushing of air from the 80mm pipe which delivers the hot air into my workshop - but it is not much more intrusive than an electric fan-heater would be.

I can set a target temperature (the LCD controller has a built-in thermometer to measure the room temperature) and the heater slows down considerably, once the target temperature has been reached. Alternatively, I can control the rate at which the diesel is delivered to the burner - say 2 pulses of fuel every second (each pulse delivers 0.02ml of fuel).

At 2 pulses per second, the heater would use 0.14 litres of fuel per hour. A 10 litre tank would last about 70 hours. In the winter, I guess that I might use it for a couple of hours a day - so maybe 10 litres of diesel a month???

Condensation worries
My workshop includes a small lathe and I am worried about condensation forming on a cold-soaked lump of iron. I have no doubt that the heater could easily reach a comfortable temperature in a few minutes from 0°C, but this might risk condensation forming on the lathe. (Hot air holds much more water vapour - when it touches cold-soaked metal, the condensation will form). One reason for fitting the heater is the hope that the the long-term, consistent, ambient temperature in the workshop can be increased in winter from a few degrees C to something nearer 10°C - 15°C. Whether this can be done without consuming lots of diesel, remains to be seen. One strategy I will try, is to 'hide' a filament bulb somewhere on the body of the lathe and run it permanently during the winter. I wonder whether a 10W or 20W bulb would raise the temperature of the iron just enough to ward-off condensation when I enter the workshop and power-up the heater. A 20W bulb would transfer about ½kWh of electricity each day (costing around 8p per day in the UK - 2021). I will find out whether this would have any actual effect!

I worried about rain entering the enclosure and getting into the mains power supply. The case is designed to avoid that, with a sloping 'roof' intended to guide the rain away from the wall (and hence the back panel of the box). I have also put a 'rail' screwed to the wall above the sloping roof as shown in the photograph.

I'm pretty happy with the arrangement. We have has a huge amount of heavy rain in the UK and the inside of the unit is bone-dry (so far).

More Details

This page will grow to answer questions as necessary.

Contents:

1) Box dimensions

2) Possible air contamination

1) Box Dimensions

There have been several queries about the dimensions of the box. The Sketchup diagrams show my original design, but when I laid things out, I needed some additional width, hence the basic box is now 670mm x 480mm x 150mm.

You can see that the roof slopes down a few cm, so the front open face of the box is only 430mm or so high.

The hinged door is 720mm wide which gives 25mm overlap on each side to help keep any rain out.

2) Possible air contamination

It has been suggested that there is a marginal possibility of the exhaust silencer splitting, or one of the exhaust clamps working loose and permitting the exhaust pipe to come adrift. Were this to happen, the exhaust from the heater could fill the box and find its way into the air destined to be heated and pumped into the room.

I have added a short length of 70mm pipe to make sure that the air which is to be heated-up is drawn from OUTSIDE the box, so any potential for exhaust air contamination from inside the box entering the room is removed. This is a very sensible modification to the design.