Alde Central Heating

[jd6257]

I am in the process of changing to a caravan with Alde heating and require some practical info please.
1) Can you be selective in which areas of the van you want to heat i.e. are there valves you turn off in the bedroom area for example
2) We normally with our current fire/blown air system just switch the fire on for short spells to take of the chill - would I have to switch the whole system on in the case of the Alde system.
3) How long does it take to heat up from cold??
Any help on this system would be appreciated.
Thanks, John

 

[MikeyW]

Hi John
In our van, a Bailey, I assume it's the same for other make caravans, the Alde system is basically on all the time. You simply turn the temperature control down to lower than the displayed ambient temperature, this stops the van heating up but allows the hot water to heat up. There aren't any valves to turn off so when it's on it warms the whole van. As for heating up time to be honest I haven't really taken much notice, we normally only use it on electricity, I would say you'll start feeling the benefits after about 30 minutes possibly sooner, depends on size of van I guess. You can also run gas and electricity at the same time which would speed things up.

I would add that this is our first van with Alde heating and I think it's a fantastic system.

Hope this helps
Mike

 

[RayS]

A bit of a side track, but does anyone know the weight comparison of the Alde system relative to the Truma warm air system ? i suspect it will be heavier (particularly when filled) but would be interested to know how much.

 

[Surfer]

Difference in weiught is about 9kgs. Takes about 30 minutes to warm up and you cannot select areas to warm up. You can use electric and gas to warm it up quicker. Big diference is that it heats up the caravan a lot better.

 

[ProfJohnL]

Big diference is that it heats up the caravan a lot better.

I challenge that statement:- I have done work on heating and AC systems in caravans, and I can state categorically that a properly installed and adjusted blown hot air system can produce a very even heat distribution throughout the caravan.

For example a 1994 22ft caravan with an outside temperature of -5C was heated with a 3kW gas heater with the blower turned on and after about an hour we achieved +18 at floor level in all areas and +20 head height at front and rear and + 22 over the heater. This may seem like a long time to some, but the conditions weer very severe with a sustained outside temperature of -5C The temperature would creep up a bit further given more time but not by much more as the heaters thermostat started to modulate the flame.

The blown air system is key to the mixing and overall evening out of the temperatures throughout the caravan. The same test carried out with the blower turned off caused floor temperatures of only +4C and a peak roof temperatuer of 28C. - The classic hot head cold feet syndrome.

The Alde systems do have a better heat distribution system, in that it uses a hot liquid circulation, so the radidators will be more evenly warmed but, they rely on being able to convect up the back of seats and through top lockers, and both of these can easiliy become blocked vastly reducing the convetion routes. The top of the caravan will become substantially warmer than the floor area becasue there is no forced circulation of the air to mix it up. (see http://www.alde.co.uk/downloads/alde_cat_mobile_19.pdf)

The heat up time depends on the heat output settings of either system. Which ever system is used, given slightly warmer outside temperatures more typical of the UK, the wam up times will be quicker, and the heat layering (without blowers) would be less pronounced, giving and even more even overall temperature.

For many years UK caravanners have been served well by Truma type blown air systems, It is a fact that many sytems have not been optomised and could actually perform better. Try tweeking the air ouput regulators, smaller opening nearer the heater and larger ones further away. direct the outlet towards the floor, as moving air tends to stick to the surface over which it is travelling so the warmth will cover a wider area. For the technically minded this is the co-ander effect and its what makes aircraft wings work.
Many caravanners are very happy with the Alde system, so its not that one system is necessarily better than the other, they are just two ways of achieving a similar goal.

 

[Guest]

Totally agree John, except, you missed blown air can be adjusted to lower bedroom temperatures, at least to some degree.
Wet systems such as Alde/Primus do have their place, in very cold climates such as Norway they really do come into their own and caravanners there, I know, would have nothing else?!

 

[Surfer]

Big diference is that it heats up the caravan a lot better.

I challenge that statement:- I have done work on heating and AC systems in caravans, and I can state categorically that a properly installed and adjusted blown hot air system can produce a very even heat distribution throughout the caravan.

For example a 1994 22ft caravan with an outside temperature of -5C was heated with a 3kW gas heater with the blower turned on and after about an hour we achieved +18 at floor level in all areas and +20 head height at front and rear and + 22 over the heater. This may seem like a long time to some, but the conditions weer very severe with a sustained outside temperature of -5C The temperature would creep up a bit further given more time but not by much more as the heaters thermostat started to modulate the flame.

The blown air system is key to the mixing and overall evening out of the temperatures throughout the caravan. The same test carried out with the blower turned off caused floor temperatures of only +4C and a peak roof temperatuer of 28C. - The classic hot head cold feet syndrome.

The Alde systems do have a better heat distribution system, in that it uses a hot liquid circulation, so the radidators will be more evenly warmed but, they rely on being able to convect up the back of seats and through top lockers, and both of these can easiliy become blocked vastly reducing the convetion routes. The top of the caravan will become substantially warmer than the floor area becasue there is no forced circulation of the air to mix it up. (see http://www.alde.co.uk/downloads/alde_cat_mobile_19.pdf)

The heat up time depends on the heat output settings of either system. Which ever system is used, given slightly warmer outside temperatures more typical of the UK, the wam up times will be quicker, and the heat layering (without blowers) would be less pronounced, giving and even more even overall temperature.

For many years UK caravanners have been served well by Truma type blown air systems, It is a fact that many sytems have not been optomised and could actually perform better. Try tweeking the air ouput regulators, smaller opening nearer the heater and larger ones further away. direct the outlet towards the floor, as moving air tends to stick to the surface over which it is travelling so the warmth will cover a wider area. For the technically minded this is the co-ander effect and its what makes aircraft wings work.
Many caravanners are very happy with the Alde system, so its not that one system is necessarily better than the other, they are just two ways of achieving a similar goal.

How long have you been using an ALDE system?

 

[RayS]

Duplicate Post

 

[RayS]

Prof J's reply is in line with my own experience and gut feeling, being somewhat experienced in fluid flow matters as a Control Engineer.
Unless it is possible to alter the flow through the Alde radiatiors individually - as you can with a domestic heating system, the temperture distribution will be decided by the original installation and not much you can do about it. I am also a little averse to adding the weight of the water to the already slim margins of user payload, whereas air does not weigh much ! So far as I can see 'balancing' individual radiators is not an option.
I would also prefer to keep my heating and hot water systems as separate as possibe - witness the problems with 'combi' domestic boilers which may be fine for small houses and flats but are not very good for a reasonable size house.

 

[RogerL]

Warm up time is dependent on the internal temperature, the external temperature, the insulating qualities of the caravan structure and the amount of heat selected.
2kw will heat the caravan at the same rate, regardless of whether it's gas, electric or both, Alde or Truma, blown-air or convection - don't try to rewrite the laws of physics with silly arguments.

 

[Surfer]

The two systems are seperate as you cannot bathe in water that has anti freeze added. The addiotnal weight is about 7 - 9 kgs so no mind boggling difference. I am assuming that all those who are thinking it is not a good system do not have it in the caravans which makes them experts on it.
On every caravan forum there are complaints about the Truma system, but I have yet to come acrcoss one about the ALDE system although there must be at least one that compains about heat distribution. We hated the Truma system because it was so ineffective in a large caravan with it switching off and not switching back on and having to fit remote sensors etc.

 

[RayS]

I have to confess I am not familiar with the Alde system in detail, and therefore don't know whether the radiators are connected in series or parallel (as in the a house with normal central heating).
The Truma system with adjustable outlet vents is effectively the parallel situation, as - for a steady heat input from the central unit, you can adjust the amount of warm air discharged into any part of the caravan by adjusting the outlet vents.
If there is just one circuit in which the hot water flows, then the Alde system is effectively series not parallel and is inherently not capable of as much adjustment ( or turn-down). The electrical equivalent is resistors in series or parallel fed by a constant voltage source. I am genuinely interested to know which of these configurations applies to the Alde system but have so far not been able to establish this from the sales literature.
A compromise would be analogous to the old 'single pipe' (as opposed to flow and return) central heating systems still existant in some older houses , including parts of mine.
In UK with adequate wattage from most EHUs this is not a problem. However, when travelling abroad in winter many sites have very limited supply typically 6 amps or even 4 amps, and it is good to be able to direct the available heat to part rather than all the caravan. With Truma hot air, this is easily down by closing all vents at the front of the van and opening one or two at the rear or bedroom area. Thus all the available 1KW can be used where it is needed most.

 

[JTQ]

Our Hymer's Alde system is a "single pipe" one and from my experience this is typically how they are arranged in confined volume application like caravans and motorhomes. There is no reason why it cant be on a twin pipe system or hybrid its a builders choice but mine is single.
So you cant with our system directly alter the balance that was determined by the designer. Indirectly you can easily do this by "blinding" the air flow over say a bedroom radiator with a towel laid along the radiator to reduce the temperature there. Or in applications with wash space towel rails remove the towel(s)from the towel rail during showering/dressing etc so more heat dissipates. Personally I think the Hymer or Alde designer tasked with this one got it quite near right and no playing with the balance is needed. It is significantly biased to heating the lounge area which for us is right. If we were to be picky it could have benefitted from a tad more radiator area in the shower area however leaving that spaces door open for 10/15 minutes prior to using solves that issue.
I also would say in my experience playing with the balance of a blown air system is fraught with problems, not least with a fan speed that is modulated automatically.
Having had examples of both systems then for us to buy another van with blown air then it really would have to have some overwhelming other attribute; it most certainly would not be our prefered heating choice. With this Hymer, Alde was a costed option and for us a no brainer.
"Better" is very subjective and so each to their own conclusion.

 

[ProfJohnL]

Hello Surfer,

I am really not surewhat significance there is of how long I have used an Alde systems for? it dosen't change the facts. Just as I cannot see the necesity to quote a whole post as this makes the thread unessesarily long.
For your information I have used Alde systems,and several different makes of hot air heating in a variety of different instalations.

 

[Surfer]

Hello Surfer,
I am really not surewhat significance there is of how long I have used an Alde systems for? it dosen't change the facts. Just as I cannot see the necesity to quote a whole post as this makes the thread unessesarily long.
For your information I have used Alde systems,and several different makes of hot air heating in a variety of different instalations.

Then you know how it works and that you have even heating throughout the caravan and no hot and cold spots like the Truma system. It is nice to have warm air under and up theback of the front seats and also by our island bed. Something we never had with the Truma system.

 

[Dustydog]

Last winter we were pitched on site at minus 10deg C. Dam cold. The Truma warm air system worked extremely well with no cold spots. At start up we used full 2k electric and full gas for 30 minutes with the blower turned off. After that we reverted to the blower and electric only. The four outlets are at ground level and kept the lounge kitchen bedroom and bathroom more than adequateley warm.
Whilst I have never experienced the Alde system I'd find it hard to find something that could improve on least year's blown air system.

 

[RogerL]

Whilst I have never experienced the Alde system I'd find it hard to find something that could improve on least year's blown air system.

Since it offends those with Alde that anyone without dares to comment, I'll declare I don't have Alde but my next caravan might. But that's not because I think it's better than Truma blown-air, it just happens to be standard for the caravan I'm considering.
The "problem" with the Truma blown-air is the way that most caravan manufacturers install it - when it's installed properly, specifically with a sensibly-positioned thermostat and insulated external ducting, it's excellent - giving even heat, good warm-up time and copes with extreme UK temperatures even on one 2kw power source.
So many caravans weren't built properly by the caravan manufacturer not Truma, with badly-positioned thermostats and/or uninsulated external ducting, that many owners think the Truma is inferior to the Alde - this is unfair on Truma, just a reflection of caravan manufacturers.
I wish that Alde was optional on the caravans I'm looking at rather than standard - then I'd choose the cheaper Truma and spend the saving elsewhere.

 

[Wendy-Norfolk]

We've had experience of both systems and wouldn't choose another caravan without Alde heating - far superior to blown air IMO!

 

[TonyG]

We've had experience of both systems and wouldn't choose another caravan without Alde heating - far superior to blown air IMO!

have to agree Wendy, i also think the hot water heating is superior to the blown air system

 

[Danddandy]

I too have experience of both. .I agree with Dustydog:- When using blown air heating get the system hot before using the fan. Bad positioning of the thermostat can cause the heater to shut down when you want more heat. . On my last caravan to get the heater to restart I had to open the window and waft cold air towards the thermostat. . . I have had 12 months using the Alde system and (once you've got your head round how to operate the control unit!) it is really good and seems to have a bigger reserve of hot water.

 

[Jennifer2]

We too have used both systems. The Alde does seem to give a more even heat in the van, but I think the biggest advantage is that it is virtually silent.

 

[Dustydog]

Whilst I have never experienced the Alde system I'd find it hard to find something that could improve on least year's blown air system.

Since it offends those with Alde that anyone without dares to comment, I'll declare I don't have Alde but my next caravan might. But that's not because I think it's better than Truma blown-air, it just happens to be standard for the caravan I'm considering.
.

Roger
No offence was intended and indeed I qualified my statement I have no experience of Alde. The OP was about "cold spots" etc. Prof John went to some lengths to explain the benefits of a blown air system and indeed my experiences at minus 10 deg C last year proved this. Jennifer has made a very valid point that the Alde is silent.I still don't know if there are cold spots with Alde. In fairness if I but the Wyoming's replacement it will come with Alde as standard so for me the debate may be academic.

 

[RogerL]

Roger
No offence was intended and indeed I qualified my statement I have no experience of Alde. The OP was about "cold spots" etc. Prof John went to some lengths to explain the benefits of a blown air system and indeed my experiences at minus 10 deg C last year proved this. Jennifer has made a very valid point that the Alde is silent.I still don't know if there are cold spots with Alde. In fairness if I but the Wyoming's replacement it will come with Alde as standard so for me the debate may be academic.

My comment was aimed, not at you, but at those who think that only Alde users are "entitled" to join the debate. Like you I find the Truma blown-air exemplary in performance but only when installed correctly.
I've heard comments, voiced as complaints, about the noise from the Alde pump but I suspect that's just poor installations, again. I don't find the Truma noisy as I use the minimal fan setting at night, as recommended by Truma.

 

[Surfer]

Roger
No offence was intended and indeed I qualified my statement I have no experience of Alde. The OP was about "cold spots" etc. Prof John went to some lengths to explain the benefits of a blown air system and indeed my experiences at minus 10 deg C last year proved this. Jennifer has made a very valid point that the Alde is silent.I still don't know if there are cold spots with Alde. In fairness if I but the Wyoming's replacement it will come with Alde as standard so for me the debate may be academic.

My comment was aimed, not at you, but at those who think that only Alde users are "entitled" to join the debate. Like you I find the Truma blown-air exemplary in performance but only when installed correctly.
I've heard comments, voiced as complaints, about the noise from the Alde pump but I suspect that's just poor installations, again. I don't find the Truma noisy as I use the minimal fan setting at night, as recommended by Truma.

I find it hard to understand how people can knock a system that they have never tried themselves. Contrary to what you are saying the ALDE is super quiet, but initially on first use there will be bubbling noises until the system is bled just like a household heating system.
On previous caravans we always found the Truma heating to be troublesome and noisy especially if you had to turn up the fan and on occasions it would be smelly if not used for awhile. No such issues with smell on the ALDE system. In one caravan we had to have the electric part of the heating replaced and a few months later the gas part of it.
Most annoying was when the Truma cut out and did not switch on again until the caravan was nearly feezing cold. On every caravan forum there are complaints about this aspect and that a remote thermostat had to be fitted. We did have a caravan where the heating was Carver and I admit it was brilliant at heating up the caravan.
Another issue with blown air is that it pushes dust etc up into the atmosphere that you breathe which is not good if you suffer from asthma, however its biggest advantage is that it does heat up the caravan a lot quicker.

 

[RogerL]

Surfer - it's clear to me that you had badly installed Truma systems so you're not comparing like with like..
Convection from the Alde heating elements will also stir up dust.
It'll always be quicker to heat air from cold than water/glycol.