Alde Heating-Pro's & Cons

[Hutch]

Madeline, thats strange, our Coachman, in the Winter when the heating starts in the morning sound like a tube train coming into a station, for about 5 minutes then runs fairly silent the rest of the time. Our friends Bailey with the Alde grumbley and rumbles. I prefer the blown air. Wife prefers the Alde wet system, dogs block the blown air vents though.
Enjoy.
Hutch.

 

[SteveC2]

We've just got our first van with Alde heating, it was always blown air in the past. I have to say I'm quite impressed although it played no part in our decision. I haven't noticed any stratification in temperature despite -5 deg overnight. No doubt there is some but it isn't noticeable. I think the widely distributed heat warms the under bed/bench areas helping keep a more even temp than otherwise. Of course the vastly improved insulation on new vans also helps with minimising stratification.

As far as noise goes it's silent provided the circulation pump has been returned to the correct #2 setting from the full speed purge setting with which it's usually delivered. Only possible if the floor mounted pump is fitted rather than the low cost header tank mounted option. If there is no other noise at all and no wind or rain you can just hear the pump if moving your head close to the locker where it lives. I don't hear it when it kicks-in in the morning. Too soon to say if there is any worse reliability issues.

As already said it does take a little longer to heat up but there is about 7kW available if needed using both gas and electricity. We carry a small fan heater and give the van a quick boost if it's cooled right down over many hours in cold weather, leaving the Alde on a 1kW setting which we turn up when the fan heater goes off. To be honest we only use the fan heater when it's really cold. The washroom radiator works much better than our old van using blown air, so we still dry walking gear in the shower like the OP. No problems so far.

 

[ProfJohnL]

......Of course the vastly improved insulation on new vans also helps with minimising stratification.....

Actually insulation only reduces heat loss. it does not does not reduce stratification.

Stratification occurs where you have a fluid (liquid or gas) that changes its density with temperature. Generally density reduces with increasing temperature, so hotter fluid will tend to rise through cooler fluid and settle at the top.

The only way to prevent or reduce stratification is to keep the fluid mixing moving quite vigorously so it is forced to mix .

A very good example is a well insulated hot water cylinder where to can have very hot water at the top held at a high temperature due to the quality of the insulation and the bottom is as cold as the incoming water supply.

I assume that at some point in your life you will have had a house with a hot water cylinder, Which you will recall an still be quite hot at the top yet as cold as the incoming water at the bottom.

 

[SteveC2]

While stratification still occurs, better insulation should mean the temperature gradient from floor to ceiling is less. In fact if the insulation was impossibly perfect there would be little to no gradient as micro air currents from habitation would cause excellent mixing. Assuming human habitation I suppose one would assume the temperature would gradually rise from body heat and the van heating would be off!

A hot water cylinder where no water is consumed has little reason for mixing to occur. In a van people breathe, move about etc.

 

[ProfJohnL]

Im sorry steve, I cant agree that better insulation means less stratification, the two issues are separate. But I do agree that normal habitation will cause some air disturbance but I seriously doubt it wold be enough to remove all stratification..

 

[alanstanley]

We use our van all year round. To return to a blown air system after Alde would be a divorce situation for SWMBO and I have yet to actually speak to a real person who would wish to change
Servicing. The fluid is filled by the dealers. It is their choice to have the 2 year stuff. Because they make money from changing it. Alde themselves will change to the five year cheaper than any dealer I've asked and it's not a difficult d I y.

Much quieter than blown air. With the better pump almost silent.
Retained heat means it's slower to cool down.
You can get a rapid warm up by using gas and electric
You can program it extensively day by day and hour by hour
Program it to turn off the water at night saving power and noise
Best of all is it just feels better. The whole fabric of the van is warm. No dry air or dust smells.
There is a reason why it's fitted to top of the range and so popular on Scandinavian vans. It's 'ALDE'

 

[ProfJohnL]

Hello Alan,

I am not criticising your choice of heating, that is a personal matter for you to choose and if you prefer to go for a wet system then that is absolutely fine. But what I can't let go by without comment are the specific points you covered in your last comment. The implication you make is the wet system is superior because the blown air systems cannot complete on the points you make. I beg to differ:

You state

...Retained heat means it's slower to cool down.

Retained heat where? If you are referring to the heat mass of the caravan then that is virtually the same regardless of the type of heating and is more dependant on the size and insulation of the caravan, not the type of heater. If you are referring to the heater itself, then the mass of hot water in the heating system is actually very small and I seriously doubt most caravanners could genuinely tell the difference in a true blind test.

...You can get a rapid warm up by using gas and electric

You can use gas and electric with most of the current blown air systems, which will still be quicker at heating the caravan from cold than any water based system currently on the market.

... You can program it extensively day by day and hour by hour. Program it to turn off the water at night saving power and noise

With the correct specification you can get the same functionality with the Blown air systems and separate water heating.

...Best of all is it just feels better.

That is a matter of personal choice and preferences

...The whole fabric of the van is warm.

A correctly installed and set up blown air system is equally capable and arguably better at warming "the whole" caravan as the heat is positively driven in to areas where convected heat simply would not otherwise reach.

... No dry air or dust smells.

I do contest the dry air point, as both blown air and the wet systems only heat the air. Neither adds or takes moisture content away. I do concede that blown air systems can more easily distribute dust smells, but if you keep the system clean this is not a problem.

... There is a reason why it's fitted to top of the range ...

I tends to be a more expensive system, and there isn't the flexibility in price structure to enable it to be fitted to mass market caravans and keep the final caravan price down.

Because it's more expensive it is perceived by the caravan market as a more luxurious product. Technically there isn't much to choose between Wet and Dry systems, but as customers like to think they are getting a better and different product, manufacturers have tended to offer the wet systems on more expensive ranges, which also tend to be bigger caravans.

...and so popular on Scandinavian vans. It's 'ALDE'

I had an inkling that Truma purchased Alde in the 1990's and I have found this at:

http://www.swift-owners-club.com/support/oem-handbooks.html
"Alde AB was founded in Sweden in 1949 and today manufactures hydronic (wet) central heating systems for top end caravan and motorhomes, In 1997 Alde 1997 was purchased by German company, Truma GmbH. Alde took over Primus in 2001."

As a matter of interest. Let me point you to the type of domestic heating systems used in the northern Canadian states where temperatures often fall to -30C or lower. Blown air systems significantly outnumber all other systems added together, and yet their houses are toasty warm even with the wild external temperatures. To be fair there are practical reasons for their choices, It's easier to to draw hot air from a multi fuel furnace, and there is no danger of burst or frozen heating pipes if water is not used.

 

[Gafferbill]

.......a very good post Prof.

I agree with all you have written and that the choice is a personal one.

I would add that the Alde system carries a weight penalty over blown air systems.

 

[Britdaz]

Having bought a new Coachman Pastiche with Alde px ing my Ranger gt60 with the complete rubbish blown air what I will add is yes better than blown air but we also bought these Alde extras. Load monitor, battery back up and outside temperature sensor.

Load monitor is a must have as is the battery backup.

 

[RayS]

Having read all I could about heating before buying my current van, I opted for blown air, supplied by Whale underfloor unit.
This has generally done what it said on the tin and has the advantages of avoiding a common mode failue situation whereby a boiler fault deprives you of hot water as well of heat, no high refill costs, provision of an extra cupboard where to traditional heater unit usually sits, and less obstruced bed boxes.
The downdide is that the heating duct runs onder the fixed double bed, heating anything stored there and that the duct installation uses the usual corrugated pipe with some right angle connectors.
By insulating these ducts in the bedbox you can improve the warm up time although I agree the underbed temperature will eventually equalise. By making any change of direction a smooth curve rather than right angle you will (abeit slightly) improve the flow characteristics and again improve warm up time. It's a pity they can't use a duct with a smooth interior

 

[ProfJohnL]

Hello Ray you make some very valid points.

What I should say in relation to anyone who has had a poor experience with blown air systems in caravans, The systems are often compromised by the caravan manufacture installing to a price and time rather than the best installation procedures.

The ducting has to be ribbed to allow it to bend so it can be fed in and routed around the obstacles in the caravan.

As an example back the 1990's, we were asked to look at one caravan where the owner was unhappy with the blown air system. From the first quick look I could see a number of fundamental issues with the system. we removed all the blown air parts, and set about reinstalling it- properly. We used exactly the same parts and in fact saved about 50cm of ducting! but the system was far more effective, especially when the hot air outlet registers were set balanced properly. Result a happy customer.

We basically tried to keep the ducts a straight as possible. We correctly orientated all the tee pieces to maximise air flow to distant points.

The down side is the system would take a little longer to install this way from new and that would cost money!

Just for general information, The performance of a blown air system is more affected by the dynamics of flow than pressure.

The longer a duct the greater the resistance to airflow through it. for ease of system design the general assumption is a moulded 90deg elbow will add as much resistance as 1M of straight duct.

At a tee junction, if air is fed into the one side of the head of the tee roughly 70% will emerge directly opposite, and about 30% will emerge down the leg of the Tee. (though this will be affected by the back pressure created by ducts and fitting downstream of the fitting)

This bit usually requires some experimentation but hot air outlet registers, need to have their opening graduated with the smallest closest to the heat source, and largest at the furthest point from the heat source.

Just as an experiment on one of our colleagues caravans, we re engineered his blow air system. He had a fan on the back of his heater with twin out lets. We extended his ducting so it created a complete loop around the caravan, this made a substantial difference to the warm air in the rear bathroom. The under floor section was also properly insulated with the double skin duct and a insulation filled box covering.

 

[Dustydog]

Fascinating Prof.
A kind of a ring main
I'm tempted to try this out on our TA.
I assume you used both hot air outlets at the rear of the heater with one to the rear, the other to the front and then added a whole connecting pipe front to back  making a joined circuit.
Did you notice any air volume increase or decrease after the alteration.
I do like the sound of this :cheer:

 

[WoodlandsCamper]

I'm of the opinion that wet heating was a solution looking for a problem.

 

[JTQ]

I'm of the opinion that wet heating was a solution looking for a problem.

And didn't it find a glaring one with many of the blown air systems as installed in recreational vehicles.

 

[SirRogerFFS]

Not going to be technical here . Our Van is just over 6 years old now fitted with Alde heater and radiators.For us there is no contest ,much prefer the Alde to the blown air.I am comparing this with our previous vans with blown air and found that we had problems with the blown air getting any air into the bathroom / shower.The Alde system has a rad in the bathroom and heats this area up nicely.To me that makes Alde the winner .
Sir Roger

 

[ProfJohnL]

Fascinating Prof.
A kind of a ring main
I'm tempted to try this out on our TA.
I assume you used both hot air outlets at the rear of the heater with one to the rear, the other to the front and then added a whole connecting pipe front to back  making a joined circuit.
Did you notice any air volume increase or decrease after the alteration.
I do like the sound of this :cheer:

Hello Dusty,

Yes exactly a ring main. and yes both outlets were used to feed each end into the ring.

We didn't actually measure the air flows so I couldn't put numbers to it, but by dint of the fact the rear bedroom section warmed up more effectively, one would conclude that air flows were improved.

Just to be clear, I am not supporting blown air systems over wet. Both systems are capable of making caravanners warm, when they are set up properly. I have seen many blown air installations that do not make best use of the parts that have been supplied, and that unfortunately tends to give Blown air systems a bad press.

I honestly believe that for every caravanner that tells us they've had both blown air and wet systems, and they find the wet system is better, has probably been the victim of a poor installation of set up for the blown air system.

A key characteristic of the wet systems is their ability to get hot water to fill the eating pipe work loop. But whilst the heat is there in the water, the big problem is how to liberate that heat into the living space. This is done using the system radiators, which are not movable, so they only convert heat. The blown air system is less good at getting heat to the extremes of the ducts, but because the air from the duct has more than just buoyancy velocity it can be directed in ways a radiator simply cannot do.

 

[sprite_guy]

I just do not like them. One of the people who stores where we do had his system fail, it was an older van and it cost him several hundred ponds to get put right, plus he had the distressing smell of antifreeze in his caravan for quite a while.
Wife and I see some lovely caravans at dealers but when we discover that the van has an Aldi system we just walk away as we see it as being a bit of a liability.
The only thing that would tip the balance for the sale was if the dealer would agree to remove the Alde system and replace it with a blown hot air system. So far there have been no takers!

 

[Buckman]

ALDE and not ALDI is far more efficient than any blown air system and now the favoured option by many.

 

[GaryB]

I'll be 100% honest here, we had a 2016 Swift with the Alde system for 2 years and I actually struggled to use it! Maybe it was having had lots of caravans with the Lidl, sorry, Truma system, but I just couldn't figure out how to use it properly! The instructions weren't great and I didn't realise for a long time that on arriving on site and switching both heating and hot water on, the water would take priority over the heating (we couldn't understand why the heating wouldn't work!).

The heating system (when I sussed it out to work properly!) was a very efficient system and distributed a nice level of warmth throughout the caravan and didn't suffer the heat losses that a blown air system does along it's pipe runs (especially if routed underneath!).

 

[ProfJohnL]

ALDE and not ALDI is far more efficient than any blown air system and now the favoured option by many.

Factually incorrect, the efficiency (i.e. Energy in vs energy out) of a warm air heater and a wet system is probably virtually identical.

Yes they heat in different ways, and both systems have pro's and con's What might suit one person may not suit another.

The choice of wet or dry is usually taken by the caravan manufacturer,

 

[otherclive]

Well an 8 year old thread has sprung to life. Bets on how many subsequent posts are made?

 

[GaryB]

Well an 8 year old thread has sprung to life. Bets on how many subsequent posts are made?

I don't know how some folks find them (and how some like me don't notice they're old!). I can't find some of my socks let alone a thread from 8 years ago!

 

[JTQ]

Finding socks is no problem, its finding two that make a passable pair I struggle with, both to find and to understand how we got to there.
Cracked it in recent years to a limited extend, now buy all one brand of one design and one colour.

Just been told it's my fault, I should safety pin them together before they go in the laundry bin.

 

[GaryB]

Finding socks is no problem, its finding two that make a passable pair I struggle with, both to find and to understand how we got to there.
Cracked it in recent years to a limited extend, now buy all one brand of one design and one colour.

Just been told it's my fault, I should safety pin them together before they go in the laundry bin.

My wife buys hers from "Odd socks", usually come in packs of 7 and all different. I told her she could save the price-premium commanded by The Odd Sock Co by simply buying a few pairs from Tesco and mixing them up, I just got a blank look.

Not for me though, wearing odd socks is just one step away from wearing odd shoes and I'm not old enough for that yet!

 

[Buckman]

Factually incorrect, the efficiency (i.e. Energy in vs energy out) of a warm air heater and a wet system is probably virtually identical.

Yes they heat in different ways, and both systems have pro's and con's What might suit one person may not suit another.

The choice of wet or dry is usually taken by the caravan manufacturer,

The wet system is more efficient without any doubt and we have had both. For a start the blown air normally has ducting running underneath the caravan resulting in a heat loss. No such heat loss with ALDE system which is internal.

When you switch off blown air heating the heavy loss is quite quick, but with ALDE system the heat is retained fro awhile, whether a good or bad thing I don't know.