#96010  by MikeBravo
 Mon Jul 06, 2015 10:59 am
Heaters' ratings can be quite misleading. I installed a 1.9kW Propex(?) gas-fired heater in my old van some years ago, thinking that since our 2.3kW 230-volt fan heater warmed it up very quickly when we were on mains power, a 1.9kW heater would do almost as well. Boy, did I get that wrong!
When I read the documentation carefully I discovered that the quoted 1.9kW is the heat output of the burner, NOT the heat output of the heater. In fact, 0.8kW of the heat disappears out the exhaust, and only 1.1kW of heat appears in the van. In other words, the heater is only 58% fuel-efficient.
So it pays to be careful to find out the actual heat output into the van, not just the rating of the burner, of any heater you're planning to install. If you can't discover that before buying it, you're probably safe in halving the quoted rating to determine if it produces enough useful heat to make a serious difference in a cold climate.
Had I the choice, I'd go for diesel, for two reasons — it's easier to replace the used fuel (every serice station has diesel, but fewer have gas) and it doesn't have the reluctance to boil off in the bottle that gas can suffer from in freezing temperatures. I also prefer to keep gas plumbing to a minimum if possible, since the less there is, the lower the likelihood of a problem.
 #96055  by RaymonD
 Mon Jul 06, 2015 9:45 pm
We have both, Propex 1800W gas, and a Eberspacher D2 2KW diesel, of the two, the diesel is tops, and with fitting a digital controller it is better still. (when we got ours some years ago the did not come with a digital controller )
 #96075  by suiram
 Tue Jul 07, 2015 11:44 am
The Motor Caravaner issue #315 June/July 2015 on page 27 has an Burnsco ad page with Propex 2kw heaters. Heat input: 2.1kw, Heat output:1.9kw. Loose is therefore only approx 10%. There will always be a loose of energy in a room sealed appliance but 58% seems very high.
 #96351  by MikeBravo
 Wed Jul 15, 2015 10:51 am
Suiram, an output of 1.1kW from an input of 1.9kW implies a fuel efficiency (not a loss) of 1.1/1.9 = 58%. The loss is 42%, not 58%.
If we are to believe the figures in the ad (and frankly, I don't), the loss in that heater is (2.1-1.9)/2.1 = 14%, not 10%.
 #96373  by purdiegood
 Wed Jul 15, 2015 6:26 pm
Hi Folks, interesting reading, those 5Kw units from China look good at the price. Anyone wanting to sound proof an enclosure should look at a product that marine people put into inboard motor covers. Its a product designed for the job and has a high density foam with a lead covering, used it in an other engineering job some time back so wonder if its still available, it did work very well.
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