Alde Caravan Wet Central Heating System

Erwlon

UK

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PeeJayBee · Newbie

I wonder if anyone could offer me advice on maintenance of my Alde wet central heating system?

The system is working well and I have the van on my drive permanently hooked up with it on the "frost" setting so the heating comes on if the temperature drops to 5C.

The handbook explains how to top up the system through expansion tank with "suitable anti freeze solution", but does not say how to test or completely drain it.

1. How do I drain the system?

2. How do I test the mixture of antifreeze solution?

3. What is a "suitable solution" Is it a special solution or will car antifreeze do?

Apologies for my ignorance. As my van was second hand I would like to completely change the solution for peace of mind.

mechanic · Full Timer

Hi,
on the system will be a dedicated drain valve, will normally look like a hose barb, this is so that you can connect a hose, open the valve and drain the system. If not fitted then you can disconnect the radiator and drain it that way but will be more messy.
As for the anti-freeze, you could contact the manufacturer, but all glycol anti-freeze products are basically the same so a car anti-freeze should work and you can get a car anti-freeze measuring tool from most car places, Halfords do one, it measures the concentration of anti-freeze to water and tells you what temp range it will cover and as car engine coolant systems run at a much higher temp than you will need for a heating system you should be fine. But please note I do not have this system on my van and am only going from experience with heating systems.
Tony

Flatcap · Newbie

Hi,

I don't know if this will help you but I have a Alde 2923 Heating system in my 1998 Buccaneer Caravan.

The system holds 3.61 litres of Glycol/Water mix.
Glycol should be 40% mix.
If you intend to go camping below -25c then increase to 50% but do not go above a 50% mix.
Never drain the system and leave it empty.

If it is the same model as yours and you wish to drain and refill the system over the next few days I suggest the following:
You will need:

1 Clean watering can
2 1 pair of pliers
3 1 Screw driver
4 Dry cloths
5 Approx 1.5 Litres of Glycol Antifreeze ( same as used in petrol cars)

6 A Bottle of Whiskey ( optional ). its cold out there!

First switch of the 240 volt system.

Make sure the Caravan is Level.

Go around inside the caravan and trace all the Heating Pipework, look for the lowest level of pipework,( Buccaneers are under the oven) the rubber joints have a tee peice with a rubber drain stop in it leading through the floor to outside,
Remove drain plug, squeeze spring clip with pliers, or undo jubilee clip.

Unscrew top of expansion filler tank and lift out the pump, wrap pump in a cloth so as not to get water dripping on control panel electrics.

When all water has drained out replace drain plug and refill with clean water using watering can, fill SLOWLY to halfway between max and min, replace pump ( be carefull removing and replacing pump) tighten filler cap and start pump using 12 volt system. run for approx 5 mins stop pump remove and re drain the system.
You need to repeat this process and flush about 30 litres through or untill all water coming out is clean and clear of any dirt.

Look for highest point of pipework there should be a bleed valve, (In Bathroom on Buccaneers) you may need to open this to clear any trapped air later.

Ensure all water is drained from system, refit drain plug and ensure it is tight.

Mix the required amount of Glycol to Water in a clean container, place in watering can and pour in to expansion filler tank SLOWLY.

Glycol/Water level: when system is cold the level should be approx 1cm above Min.

When the system is filled replace pump tighten filler cap, Start pump to circulate.

Check for Air locks in system, air will come out through expansion tank or can be bled through bleed valve.

Tip: When I do mine I use HOT water to flush out and refill with Glycol, that way you can feel where any Air locks are and it is quicker to warm the system up to check everything.

Tip: When filling the Expansion tank if you pour very slowly you will hear the air escaping around the system and it will be easier to bleed.

Tip: Feel at the Inlet and Outlets of the Boiler and you will be able to follow the hot water, any cold area is air, be carefull not to burn your hand if you have the boiler running, Top is Outlet, Bottom Inlet. the system is basically a steel pipe with small fins that runs around the caravan.

I hope the above helps and is not to long and boring.

When all is done and tested, get the heating on and have a whiskey.

Job done.

ocsid · Rally-er

Our current Alde is a Compact 3010, and Flatcap's excellent write-up is basically sound for that.
All I would add, is normal anti-freeze [typically blue or green] has a two year inhibitor life so has to be changed every two years.
Modern Long-life high spec anti-freezes [typically orange or red]have a five year inhibitor life so it is better to change to these newer types.
However they are not really compatible so dont mix them; Flatcaps flushing will be fine to allow you to "up-grade" to the modern product.

Just make sure any anti-freeze you use states that it is Glycol based and is suitable for use in "aluminium" engines. There are some non Glycol products but these are not acceptable to Alde.
I use Land Rovers modern Orange anti-freeze which is good for 5 years.

Bleeding the system can be a "B----r", it might help if your struggling to tip the van first one way then the other with the nose-wheel, bleeding rads each time.

Its a great heating system.

There is some info on earlier Alde unit, including filling and bleeding in this Swift publication, about page 65

http://www.swiftgroup.co.uk/uploads/HandBooks/caravans/2002%20Handbook/1043696%20Caravan%20Owners%20Hbook%202002.pdf

PeeJayBee · Newbie

Thanks Flatcap for the comprehensive and thorough information, as yet I havn't located the drain valve, although had not thought of looking under the oven! Obviously a job for this weekend. It does seem an excellent system and is very effective at warming the caravan. Mine is the 3000 model, although I am sure they are all very similar.

Thanks also to ocsid for the info on the antifreeze. The type I have for the car is red, I will study the container to find out the lifespan. I am always nervous interfereing with something that is working fine but clearly the antifreeze is an important element that needs changing.

Regards - PJ

ocsid · Rally-er