yours is set right so the coment wasnt for you it was for the poster saying the air is best taken from inside of the building then goes through the burner then out
I guess that the expelled exhaust gasses are not hot enough to melt the casting housing exhaust spigot as the heat exchanger cooling holds the temp safely well below that ( 230 oC seems to ring a bell ) If it gets too hot the 230 oC maximum the heater goes into auto shut down , I suspect that the casing metals melt at around 660 oC plus . None of the stripped down heaters I've seen on a dozen or more Your Tube videos have had any melting take place .
Yes I know of the balanced flue & heat exchanger systems and did consider doing just as you suggest as I have the old balanced flue system from a previous oil fired boiler ( it's where the stainless steel 75 mm tube came from that comes in through the wall . I considered it too much hassle to mess around trying to get an adaptor made for the heater heat exchanger air inlet so did it as I've done instead . That concertina alu pipe has a hell of a surface area that will help no end in pre heating the fresh air inlet to the heat exchanger I'm sure .
One of my heaters recirculates the hot air. The 2nd heater sucks in cold air as I couldn't be bothered to drill a big hole in the wall for the ducting. TBH it seems to make very little difference although I am sure it must. Air at 20C needs much less warming than air at 4C.The design of these heaters is that the combustion inlet takes fresh air from outside the "vehicle" so as to avoid any combustion fumes entering the occupied space in the event of a fault or backfire. Your setup is correct as far as that goes however if you can keep the air inlet as far away from the exhaust as possible it will ensure that the fuel air mixture is correct. If the exhaust accidently fed back into the inlet due to a breeze etc. there would be less oxygen for combustion and the efficiency will go down. probably not a big issue in this setup but worth noting for other installs.
The space heating is setup incorrectly as the heat exchanger totally isolates the combustion and the space heating. The combustion takes place inside a cast aluminium heat exchanger and the room air is passed over this finned block of aluminium. The maximum temperature of this is below 200 degrees C and more likely only 150 degrees C. You are concerned that this may be a potential ignition source if the internal room air is passed over the heat exchanger which is a healthy attitude to take. However the ignition temperature of petrol, for instance is 220C and cellulose thinners is 475C so not as big a risk as you may imagine.
As you have chosen to take cold fresh air from outside to feed the space heating it will take considerably more power (fuel) to heat the room as the temperature difference will be high to start with and will increase as the room warms. In fact the heater will end up burning fuel for no purpose. In a small space this will be negligible as the thermostat in the controller will ramp down the output. There is however another aspect that you may have missed. As you are pumping air into the space from outside to feed the space heater you must have a vent out of the space to release the same amount of air. This means having a 75mm hole in the wall to allow the heated air out so as to not restrict the airflow over the heat exchanger. This vent should be as low down the wall as possible so that the coldest air in the room is vented first. For this example I have assumed that the doors and windows are well sealed but in reality there may be plenty of natural ventilation to preclude the need for a vent to outside.
I'll get of my lectern now and say its up to the installer to decide what is and isn't safe and it's up to physics to tell you what is and isn't efficient
On my install I've mounted my heater up near the ceiling with an extended vent pointed down which is possibly the worst way to install it but I had no floor space where I could fit it so it is what it is. I have also extended the exhaust along the internal wall and fitted radiator plates on it to gain as much heat output that I can. I used 22mm copper pipe which amazingly was the cheapest way to do it and was a great fit onto the existing exhaust. The radiator plates are some Alu plate attached with 22mm copper pipe clips and it's all painted VHT matt black. It is surprisingly efficient and I can see 180 C at the exhaust reducing down to 40 C where it goes through the wall. It's less than 3m and a straight pipe so does not restrict the exhaust. Because of the length I don't need the silencer (they don't do much anyway) but if I did I would put it at the far end outside the workshop which is 54 square metres BTW.
The groups are ran by people who have bought one not the Manufacturers, but some manufacturers do some how post on them, as they used to get a percentage of returns from people who didn't have a clue how to fit them
I’ve put load of these in boats and plant and lorries over the years.
I wasn't talking about the combustion air but the heating side. Cold combustion air makes no difference. In fact if its like an engine colder air is better.
I was agreeing with you but read it as combustion air not hearing air!
I lost track in the thread
Nah , I just took a measurement of the side of the 10 liter fuel tank of fuel at the start & fuel at the end ... reckoning about 1.2 litres was used .
I cut up the metal cap off a dead wall mounted electric look alike carriage lantern , it had four nicely shaped faces where it fitted to the rest of the lamp , there are four mounting screw holes so I simply cut almost all of one of these faces out the cap and screwed in in place on the outside wall over the 75 mm stainless steel duct , giving it a rain cowl in effect
Yes sure, I'm going solely by feel, I put my hand in front of the heater and feel hotter air travelling at higher speed than I have got from any of the 3kW leccy heaters I've had. To check what was up with that I connected a power meter to my electric heaters and found they drew almost exactly 3kW. Checking the input of the diesel heaters is more involved so i didn't do that, especially as the internet seems pretty sure that they are copies of a 4kW western product.That is interesting. How much fuel do each of these heaters use. To make i excess of 6kW, the fuel usage will need to be more than 0.7l/h. With 22ml pumps, that equates to almost 9Hz.
Have you checked your pump Hz? I doubt very much that it can be running that fast.
The motor speed would also have to be far in excess of its maximum setting, too.
Also, if you really need over 12kW (or even over 6kW) you need to seriously consider some draught-proofing and insulation!
Let us know your findings. Until then, I don’t believe your claim - and neither should anyone else!
My "twice as much heat" comment was more of an expression than to be taken literallyAs I posted, it is simple to get a good estimate of heat output. i doubt these heaters are substantially better than 80% efficient, if even that good.
The pump displacement is unlikely to be in excess of the stated value, so Hz is a good measure of volume delivered. Alternatively, physically measuring the fuel usage is easy enough, but not with a wide marker line on a large shallow fuel tank and a twenty minute run - which often appears to be the level of a lot of the youtubers who post videos on how much their heaters use.
If I want air speed, I get out one of my anemometers for the job. Relying on ‘hand feel’ is not very accurate.
Yes, these heaters are a copy of the Eberspacher type, which, I expect, provide a reliable 4kW (as per their specifications). I would never expect the similar chinese heaters to exceed that specification by 50%. I think the truth is that these heaters actually provide around 40% more hot air than a 3kW electric heater, not twice as much.
I think anyone buying one of these and expecting the output you claimed would be disappointed when reality sets in.But… there are a lot, out there, that claim these same heaters are capable of delivering 8kW (which again demonstrates their level of knowledge regarding these heaters).
I'm happy to accept that these are 4kw heaters.
You need to do a bit of research as to when things like isopropanol , ether , and electrical contact cleaner ( I use all three on a regular basis ) start to vapourise around 20 oC and what happens if that vapour hits a surface of 230 oC or so .
My 8kw heaters are about 4kw output. A true bargain all the same.As I posted, it is simple to get a good estimate of heat output. i doubt these heaters are substantially better than 80% efficient, if even that good.
The pump displacement is unlikely to be in excess of the stated value, so Hz is a good measure of volume delivered. Alternatively, physically measuring the fuel usage is easy enough, but not with a wide marker line on a large shallow fuel tank and a twenty minute run - which often appears to be the level of a lot of the youtubers who post videos on how much their heaters use.
If I want air speed, I get out one of my anemometers for the job. Relying on ‘hand feel’ is not very accurate.
Yes, these heaters are a copy of the Eberspacher type, which, I expect, provide a reliable 4kW (as per their specifications). I would never expect the similar chinese heaters to exceed that specification by 50%. I think the truth is that these heaters actually provide around 40% more hot air than a 3kW electric heater, not twice as much.
I think anyone buying one of these and expecting the output you claimed would be disappointed when reality sets in.
