Whale blown air heating

Oct 18, 2010
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Just come back from a long weekend visiting our eldest in Newcastle upon Tyne,
We woke up to frost on the ground on Monday morning to give an idea of temps,
& for the first time we felt that the Whale blown air heating on our new 840 was struggling to maintain the 20'o it was set at overnight,

I have done some investigating today & found out that the piping for the awning heater (which is useless btw!) runs under the caravan from the O/S to the N/S with the "valve" being about 6" from the outlet, so hot air is being pushed along this pipe all the time & being cooled by the draught under the caravan!

My plan is to blank off at the T piece the run to the awning vent & to insulate the remaining pipes,

Has anyone else carried out any mods to the Whale system or recommend a lagging for the air pipes?
 
Mar 14, 2005
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Go for it.

It is most likely the case the caravan manufacturers will install a heating system as cheaply as possible. I have seen many such systems, and the effectiveness of the system is often compromised by the incorrect alignment of duct fittings, or as in your case lengths of duct under the floor, and unnecessary sharp bends in the ducts.

The longer a duct is the more resistance to air flow it will produce. As a rough guide fro every 90 degree bend in the duct its the equivalent of adding an extra Metre of duct, so bends can be a significant factor.

In some caravans, it can be possible to re-route the ducting to reduce the numbers of sharp bends, with real benefits to hot air flow to the end outlets. Even the duct fittings can be re positioned to encourage a better flow of air. In one caravan design, I recall it having a "tee" piece with the flow in on one end of the head of the Tee and the, other end of the head going to the first outlet which was close to the heater. This out let was very toasty hot, but the outlets further down the line were very poor. Simply changing the first out let to the leg of the Tee and the down stream duct to the head of the tee, made a significant improvement. No parts cost implications, just slightly more fiddle to do, but would the manufacture change the way they did it - No.

Basically the caravan manufactures are looking for the quickest and cheapest way to fit this gear, and with little regard for the efficiency of customer satisfaction.
 
May 7, 2012
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I agree with the Prof, you should try the modification. Not sure about the Whale system but the Truma blown air on ours is probably at about its limit on the shorter 5.6 m body on our caravan and I am wondering if the Whale is up to the longer body you have.
 
Oct 18, 2010
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Ok so tonight I have removed the T piece & through a series of trial & error found that an aresol lid fits nice & snug in the bottom of the T piece,
One thing that worries me is I would imagine this plastic lid will get quite hot & not knowing much about plastics I'm concerned this may cause problems?
 
Mar 14, 2005
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panther1 said:
Ok so tonight I have removed the T piece & through a series of trial & error found that an aresol lid fits nice & snug in the bottom of the T piece,
One thing that worries me is I would imagine this plastic lid will get quite hot & not knowing much about plastics I'm concerned this may cause problems?

Obviously without measuring temperatures and knowing exactly what material the lid has been manufactured in we cannot be precise, but I believe the majority of blown air fitting are manufactured in ABS, and its likely the aerosol lid will use similar materials. Air temperature in the duct drops off fairly quickly so if the lid is more than meter of duct away from heater, my hunch is you wont be experiencing spontaneous combustion, I would be more worried about the stability of the moulding, it may distort. You could try pushing it home with a layer of aluminium foil covering it
 

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