Alde Central Heating

[ProfJohnL]

There are a lot of ifs and buts but looking purely from an efficiency perspective Its possible to be precise about this matter:-

Firstly it us unfair to make direct comparisons between a touring caravan and a domestic building in terms of thermal mass, and insulation. They are very different especially as the thermal mass of a caravan is much much less than a typical room in a house.

The small thermal mass in the caravan allows it to respond quickly to a heat input, both the air and the fabric warm almost equally together. Put the same heater into a domestic room, and whilst the air may heat up the fabric lags a long way behind.

For the set up I reported on earlier as 3kW heater took about an hour to raise the internal temperature to 25C above ambient (-5 to +20C) When it reached 20C, the heaters thermostat started to modulate the flame size to maintain 20C. Using some fairly exotic gear it was established that to maintain that temperature the heater was turning down to about 1kW (from 3kW)

Armed with that information it is possible to say that if the caravan was maintained at 20C for 10 Hours over night it would use 10 x 10kW or fuel.

If the heater was turned off over night and the caravan allowed to cool for 9 hours then it was turned on full for the tenth hour it would use only 3kWh - a saving of 7kWh.

The above ignores any argument for convenience or comfort or reducing heat input for a lower temperature, but if we were to assume the heat input rate fell to only 500W for 10 hours that still 5kWh and still more gas used compared to turning the heater of completely.

On purely efficiency grounds turning off over night is better than just turning it down BUT if you are also considering comfort and convenience then the extra cost of burning the heater over night might been seen as good value - that is a personal choice.

 

[Dustydog]

On purely efficiency grounds turning off over night is better than just turning it down BUT if you are also considering comfort and convenience then the extra cost of burning the heater over night might been seen as good value - that is a personal choice.

And that is probably why Steve is facing a 15% hike in his charges.

John,
I have also noted the modern caravan has lots of floor level ventilators that do cause the odd draught from time to time. Ignoring Alde for the moment the blown air system gets rid of these draughts.

 

[Jennifer2]

18 degrees!!

On the weather forecast they talk about "an uncomfortable night for sleeping" when it is that warm overnight.

Is 18 degrees not the temperature below which office workers can go home as it is considered too cold in the office for them to sit and work?

I can see that elderly people with breathing problems and heart problems need to be kept warmer, but for a healthy person I would think a bedroom at 18 degrees would be far too warm. Even your 16 degrees would be too warm for me, Roger.

 

[Guest]

Sorry John if you think I'm comparing a house with a caravan, at least directly, I obviously realise there is a big difference in the thermal mass. However, to suggest a van warms thoroughly to +20C from -5C in an hour, is wrong, very wrong?
I've been here several times at those temperatures and with gas and electric on full, circa 5.5Kw in total, (Carver 5500), it takes at least two hours before the gas can be turned off and 2Kw electric keep on top of 'soaking' heat into the van. Only then will the electric moderate to a low output.
Not test conditions but living in it, that's the difference, until the vans soaked fully, you feel a chill, what we used to call in the trade, a 'cold heat'?!

Bear with me here because it is relevant to really understanding the issue, I served my time as a Blacksmith, working under steam hammers with two gas fired furnace feeding me.
Well, from time to time these furnace needed relining, thankfully very rarely!, the outside was about a 10 foot cube but inside it was perhaps only a little over 3ft cube, in other words the brickwork was very thick. So having been allowed to cool fully down it was then relined, it was fired for several days at a low temperatures to dry it out, gradually being raised to a few 100C before then taking up to 1220C forging temperature ready for use.
Now this is the point, for the next few days, and it was run 24/7 on two shifts, the billets would be a devil to forge due to not getting to full temperature, even though it said it was on the Calibrated Pyrometer. Basically, heating time was based on 20 minutes per cross sectional inch, but after around this time you could still see them clearly, you should barely see them if everything is at the same temperature/colour inside the furnace. Eventually all would settle down and the billets would come up to full temperature and forge as normal, this took about another week in total. Not good for wages if your on piecework, but also a lesson learnt and never forgotten!
Extreme example but it is no different to any structure, only the soak time varies, until then you get a cold heat and in the human sense, that means your sitting in a chilly caravan/house, rather than being cosy, even though the thermometer says it's 'up to temperature'

I'd say then, your test gave false results, because, the fabric was never given time to soak in the first place and the gas heating was forever playing expensive catch up?

 

[RogerL]

18 degrees!!
On the weather forecast they talk about "an uncomfortable night for sleeping" when it is that warm overnight.
Is 18 degrees not the temperature below which office workers can go home as it is considered too cold in the office for them to sit and work?
I can see that elderly people with breathing problems and heart problems need to be kept warmer, but for a healthy person I would think a bedroom at 18 degrees would be far too warm. Even your 16 degrees would be too warm for me, Roger.

18 degrees overnight ambient temperature will give much higher temperature indoors - due to solar heat gain during the day, all electrical equipment and bodies themselves, both people and pets.
If 18 is the lower limit to sit and work - why wouldn't it apply while asleep as the body generates less natural heat then.
According to the medical profession, it's not just those with breathing problems or heart contitions - but all elderly, ie over 65 - who am I to argue?

 

[RogerL]

Extreme example but it is no different to any structure, only the soak time varies, until then you get a cold heat and in the human sense, that means your sitting in a chilly caravan/house, rather than being cosy, even though the thermometer says it's 'up to temperature'

That's exactly right - until the house/caravan has fully heat soaked, the surfaces will be cooler than the air temperature which feels cold.
I can remember arriving on site in Scotland in mid February for our first holiday of that year, the caravan having stood unheated for 4 months - the daytime temperature was -4 and it took a full 24 hours to FULLY warm the caravan up - but that was only using the 2kw electric as I'm meaner than any Scot !

 

[Jennifer2]

18 degrees!!
On the weather forecast they talk about "an uncomfortable night for sleeping" when it is that warm overnight.
Is 18 degrees not the temperature below which office workers can go home as it is considered too cold in the office for them to sit and work?
I can see that elderly people with breathing problems and heart problems need to be kept warmer, but for a healthy person I would think a bedroom at 18 degrees would be far too warm. Even your 16 degrees would be too warm for me, Roger.

18 degrees overnight ambient temperature will give much higher temperature indoors - due to solar heat gain during the day, all electrical equipment and bodies themselves, both people and pets.
If 18 is the lower limit to sit and work - why wouldn't it apply while asleep as the body generates less natural heat then.
According to the medical profession, it's not just those with breathing problems or heart contitions - but all elderly, ie over 65 - who am I to argue?

I don't think we need it as warm when asleep as sitting about as we have the bedclothes to keep us warm.

However, we are probably quite unusual in having a very well insulated house, with an unusual layout, our bedrooms are downstairs, and ours is aslo on the north side of the house. So in summer our bedrooms are always nice and cool, and the insulation in the house keeps it cooler in summer and retains the heat in winter. Which is how we like it.

We have large , south facing windows in the living rooms, so these benefit from the solar gain in winter, but are shaded in summer, when the sun is higher in the sky, by a large roof overhang and effective blinds. In winter, any excess heat in the living rooms can be circulated by 2 slow-running fans to the north side and the lower floor, so the whole house benefits. Only on really cold, dull days do we need daytime heating at all.

Having read the BBC link you gave, I am really depressed to hear that we are now considered "elderly" , and should be sleeping in warm bedrooms!

 

[thursdays child]

Hiya folks, we have had both versons of heating in our vans and the present one has the Alde system.Each version has its pluses and minuses.The biggest advantage we have found with the Alde system is the ability to maintain a more constant temperature.However I think a lot depend on the layout of the van and how open it is.Our particular layout has the bedroom at the back with radiators at top and bottom of the bed.We keep the bedroom door open to disperse the heat evenly. Personally I like a nice cold face and a snuggly warm bed.If I have trouble sleeping I get up and when I get chilled I get back into my nice warm bed BLISS!!! I suppose most people like to replicate their home environments whenever possible.With energy costs soaring we might all have to resort to hot water bottles again!!
Thursdays Child

 

[ProfJohnL]

Hello Gary,

Again its not fair to compae furnaces to caravans.

The function of the fire brick in a furnace is not only to provide thermal insulation but to also provide thermal mass and a high level radiation body. The majority of heat transfer in a furnace is achieved through radiation and not air temperature. Even a few degrees short of optimum and the radiated heat quota drops off quite considerably. Caravans neither have large thermal mass or need to be incandescent!

I was very specific to relate my comments to the caravan in the test. Your caravan is a different size, a different heater, and you may have had to contend with a wind chill. So I stand by my comment.

With regards the heat soak into the caravan structure, the wooden fittings do lag the air temperature but not by very far - wood being both insulative and low thermal mass so the surface temperature follows the air temperature quite quickly a matter of a minute or two - not tens or hours. It does take longer for the heart of thicker wood components to warm up.

Even allowing for some of the variables between your caravan and the test one, if you are after economy, then if the caravan is not heated for more than about 5 hours you will save energy.

I reiterate I have limited my comments to efficiency not comfort or convenience.

 

[Dustydog]

Hiya folks, we have had both versons of heating in our vans and the present one has the Alde system.Each version has its pluses and minuses.The biggest advantage we have found with the Alde system is the ability to maintain a more constant temperature.However I think a lot depend on the layout of the van and how open it is.Our particular layout has the bedroom at the back with radiators at top and bottom of the bed.We keep the bedroom door open to disperse the heat evenly. Personally I like a nice cold face and a snuggly warm bed.If I have trouble sleeping I get up and when I get chilled I get back into my nice warm bed BLISS!!! I suppose most people like to replicate their home environments whenever possible.With energy costs soaring we might all have to resort to hot water bottles again!!
Thursdays Child

That's my Dame TC.
You're my kind of girl.

We love to be snug as a bug in a rug

Up the Woosies

 

[xtrailman]

The ALDE heating is overall far superior to the blown air system.
Any heat losses occur inside the caravan, unlike the ducted systems running under the caravan.
I had a 1997 Avondale with ducted air, it was very warm and cosy, not a problem.
Then i had the misfortune to assume all ducted air systems were installed correctly, which unfortunately my 2004 senator proved otherwise.
The caravan had around 4 meters of ducting under the caravan to the rear washroom, which was always cold, even with air completely diverted to the washroom.
The only answer was to use a fan heater, after that the heating was again fine.
The only advantage blow air has over a wet system is rapid warm up, unfortunately after than the temperature can never be a constant as a wet system. Even with the remote sensor installed correctly.
In the home
I had ducted air at my home for 25 years, so I'm an expert. Another advantage of the system is no wall radiators, and a long life boiler, due to its simplicity, my boiler was 30 years old.
Disadvantages heat losses under the floor and loft space, lots of heat loss.
I have no doubt that the new owners will have fitted a combi ! a backward step IMO.
The only down side to a wet system (12 years use) is the potential leaks, and the wall space lost. The life of the boiler.
But overall it is a superior system, temperate control is more evenly controlled, less temperature fluctuations.
In a caravan.
As i said the adle has all heat losses inside the caravan so very efficient, as its a series system with no individual radiator (heat exchanger) adjustment, then its important to get the system balanced correctly, although in a caravan simply leaving any inside door open will balance out the temperature.
Even so i like to have the temperature very hot when i shower, so a fan heater is used as required, i do this at home also.
You can blank off radiators by covering the heat outlets, i did this to the one behind the front drawer unit, in fact i covered the rad with some loft insulation, as i found the drawers were too hot.
Also with the ALDE you have the option to program day and night temperatures, although the programming sequence isnt very intuitive, and i should know as i programed such things for a living before retirement.
The boost function can also be used to increase the hot watertemperature set point to 85 degrees, if i recall correctly, we used this all the time, as nearly always the system is only running on the 1kw electric setting.
No other water heater i know of heats to this water temperature on electric only .
Things not to like with alde, increased weight, increased cost.
And it is possible to hear the side mounted circulation pump at night, its a very faint whine, but not loud enough for me to bother doing anything about it.
What system would i choose in a caravan, answer ALDE every time.
What system would i choose at home, blown air, for its simplicity, and its long life, but the system cant be retro fitted, and costs more to install.

 

[jd6257]

Thanks for all your responses to my Alde heating queries.
But here is one more, the system in my new van can also be controlled via a text message.
Has anybody got & tried this electronic wizardry??
Once again you input would be appreciated.
Many Thanks, John

 

[jd6257]

Duplicate Post

 

[xtrailman]

Not heard of that one, what caravan are you buying?
There are refinement's to the unicorn ALDE that may interest you.
1/ a mod to put a permanent 12v supply to the controls, to retain programming.
2/ a mod that automatically reduces the ALDE power consumption, by monitoring the current consumption, you select the max limit.
3/ The fitment of a outside temperature probe.
All available on the ALDE web site.
Apparently the top end caravans may have a newer ALDE version that uses fans as well as the usual heat exchangers.

 

[JTQ]

I have not got the text message extension to my Alde but a friend with the "Fifth Wheel Company" Rambler has and likes it. Yes it would be nice for those days spent out and about from the van but I have to stop spending on my toys.

 

[MichaelE]

As far as i know Alde dont make their own text interface but Truma do, they call theirs Text Control and will interface with the Alde system.
The Elddis Buccaneer has it as standard.
Easy to use
The unit, which needs to be fitted to your caravan, works via an ordinary SIM. In order to get you up and running in no time at all, your Text Control unit comes complete with a pay-as-you-go T-Mobile SIM card.
All you need to do to set up is text the word HELLO to the unit, which automatically stores your mobile number and replies with a confirmation message. You then personalise your display to pair up with the appliances and you’re ready to go. Now you’ll be able to activate your heating and hot water so you have a nice warm welcome when you come home.
It really is that easy; you can text in upper or lower case to switch your system on or off, you can even read the temperature inside your caravan.
Your T-Mobile SIM will have some credit pre-loaded to get you started, and can be topped up at any ATM or supermarket as and when required.

 

[Surfer]

On another forum someoen won one of teh Truma text units at the NCC show but wants to sell it. Personally I cannot see any use for it at £250 as the caravan even with ALDE heating only takes abourt 20 minutes to warm up. If you are in a porr reception area, tough it will not work.