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Heat shield btwixt boiler and seat?


rambling robin

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Hello

 

I am a total novice on the MH front. It is over 30 years since I was last in a DIY converted LHD VW Type 2 and things have changed a bit! They even have heating and bathrooms these days - amazing...8-)

 

We took delivery of our 2012 Bentley on Thursday and after a few very stressful moments things seem to be settling down nicely :-D

 

In common with most designs ( I guess) the Truma boiler/fan heater lives under one of the lounge seat/beds. Due to heat rising from the boiler the bed does get a bit warm and I am someone who hates too much heat in bed. So, it seems to me that it should be possible to make up some kind of heat shield between the two. Since it is just convected heat from the boiler it shouldn't be too complicated, but what would be the best/most appropriate material? Once upon a time a sheet of polystyrene would have done the trick but it is a little dangerous in flammable situations!!!

 

Has anyone tried this or got any advice/suggestions on best materials etc?

 

Thank you

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I'm not familiar with your van make.

 

Is there a gap between the heater and sleeping?

 

There are several insulation board types around with a foil reflective surface. I doubt that foil on its own would do a lot. Perhaps a slatted material so allowing the passage of warm air to divert away from the bed material, it would probably still need a cover over the slats for comfort. How much height do you have. More higher the slats, more cooling.

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There's not a huge space between the bed slats and the top of the boiler - 2" max I'd say.

 

Further grovelling around suggests that I'd either need to fit some sort of reflective board to the non-moving slats of the bed frame, or to the base carcass. Trip to a DIY store to look for reflective foil radiator backings seems to be required methinks!!!

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Assuming you aren't using the heating overnight, I assume this is the residual heat from the stored hot water. If so, reflectives won't do much good: you'll need insulation.

 

However, have you considered increasing ventilation to the under-bed enclosure, to reduce heat build-up? If the heat can escape easily from around the heater, it should reduce temperature in the locker, and so the impact on the mattress. I assume the mattress will in any case be foam based, so should provide quite a high degree of insulation in itself.

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A sheet of aluminium or lightweight steel is used by some makers but before doing so you have to consider what the heat will do if it cannot escape and extra ventilation in the locker front may be a good idew - in fact extra ventilation alone might aleviate your problem - either that or get the wife to sleep on that side of the bed!

 

 

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The boiler will be encased by insulation . I think that packing more rockwool in poly bags around it should prevent the heat escaping to your bedding and will save on hot water and the heat will be delivered were you want it. Just be careful that you don't disdurb any connection or block off any air intakes.
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If intending to follow the above advice to insulate around the heater, I would first carefully consult the (presumably) Truma installation instructions before doing so. The less heat the heater can lose, the hotter all the controls and PC boards will be likely to run, and I'm fairly sure Truma give minimum clearance figures for the enclosure, plus a minimum ventilation requirement as well. They are expensive bits of kit, and the parts aren't cheap either, so better not to fry it, trying to stop it frying you! :-)
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The boiler in our Tracker FB is under the fixed bed in the locker. Most of the heat we feel when in bed comes up the both sides of the mattress rather than be radiated through it so the only solution for us is to turn it off after we have washed up at night and turn to boost in the AM for a shower. If it is really cold at night we sometimes leave it on and use it as a heater. This seems to be one of the compromises you make as a motorhomer.
Cheers Gary.
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Thank you one and all for the inventive suggestions and advice, all of which are very welcome.

 

So far I have come up with some thin poly-something wrap used in packaging some sort of electrical device. It's only a couple of mil thick but seems to reduce heat transfer. I'll lay that over a large carpet tile and we'll see what happens.

 

Although I would love to just give up the bed to my wife she has, for some years, been enjoying the female experience of getting very hot for no reason. Consequently the idea was not greeted with enthusiasm. (^) (^) (^) :D :D :D

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rambling robin - 2015-09-28 6:28 AM

Although I would love to just give up the bed to my wife she has, for some years, been enjoying the female experience of getting very hot for no reason. Consequently the idea was not greeted with enthusiasm. (^) (^) (^) :D :D :D

 

Ah - the seven deadly dwarves - itchy, bitchy, sweaty, sleepy, bloated, forgetful and PYSCHO !!

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Just a thought (I do have them occasionally)

DIY superstores sell roof insulation that is foil wrapped & quite thin. I think it may be feasible to Tyrap to the underside of the bed slats. This would eliminate almost all of the heat transfer without compromising the air gap required by the Truma installation instructions.

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flicka - 2015-09-28 9:55 PM

Just a thought (I do have them occasionally)

You need to be careful - I had one of those once - took weeks to get over it :-D

DIY superstores sell roof insulation that is foil wrapped & quite thin. I think it may be feasible to Tyrap to the underside of the bed slats. This would eliminate almost all of the heat transfer without compromising the air gap required by the Truma installation instructions.

This certainly does have appeal - it's just that it seems to be foil on bubble wrap. and once I get that in my hands, well, you've got to pop *just the one* haven't you............foil anyone? *-)

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Tracker - 2015-09-29 10:08 PM

 

Personally I would be less inclined to retain the heat in the locker and much more inclined to dissipate it by ventilation, possibly fan assisted?

This does address a fundamental problem with all heating systems which is that they waste heat. Condenser boilers do a good job in domestic conditions but the physical mass of the boiler still gets warm and that heat can be 'lost'.

The seat/bed measures 5x3x2 - roughly. That's 30 cubic ft. Given that over half the volume of the space is taken up by boiler and 90l fresh water tank the actual volume of air is probably no more than 10cu.ft. A 30 CFM 12v computer case fan would cost around £5. Add a simple 12v temperature switch for around £12 and thereby cool the seat and increase heating to the living space. This in turn would reduce the amount of time it takes for the area to heat up and therefore save gas/leccy.

You would need to duct in cool(er) air from somewhere - probably the cab area - otherwise you're just sucking warm air back into the boiler space and just aggravating the problem.

The bed itself is being warmed by heat rising from the boiler case so you're trying to intercept that heat which would still mean a heat shield of some sort, other than that and the wiring in plus another 2 holes in the woodwork and we're sorted.

Right - there's a little cottage industry for someone...........!

 

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