Advice needed on old Alde hot water system please...

Jul 27, 2020
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Hi, I am doing up a pretty old Bessacarr Cameo 550GL. Everything is coming along nicely, with one major obstacle to overcome. The hot water system.

This caravan will be permanently sited on bricks, it will never go down a road again. Its just friends and family visiting us. We need hot water for our visitors so they can have a half decent shower. It doesn't need to be powerful, a standard modern caravan shower would suffice (more pressure would be better of course, but not essential).

In this caravan there is what appears to be a gas/240/12v water heating system which does the central heating (not needed) and the hot water to taps. It's very old but I had a gas man out today (our boiler man) and he had a good look. He didn't know as much about it as I hoped, in fact he knew almost nothing except for how the gas part works and obviously understands safety issues which was where I drop tools and get a pro in. Turns out maybe I wasted £70 and we don't have much as it is so pretty disappointing. Anyway... the gas burner fired up nicely. Good start. Here is the control unit for the system:



Behind the burner there is this:



I assume that's a hot water storage tank. If so, it's ridiculously small, yet this caravan was a luxury model and has a lovely shower cubicle, but the best we can get is around 50 seconds of hot water (hot enough for a shower) before it runs cold. The burner is good and definitely producing a good blue flame. So it appears to just be the design of the system. The storage tank looks like a MAX of 2 litres, that would be my guess. It doesn't seem as big as two 1.1 litre milk containers anyway!

Below the 'tank' is this:



I think that's a water heater element. It says 25W on it, and "ohne thermostat" (german for 'without thermostat'), and it says it can run on '1-240v.' But that produces the tiniest bit of lukewarm water. The gas burner doesn't seem to heat water as it passes through, hence the longest you can run the hot tap for is the contents of that teeny weeny tank behind the burner. I half hoped that running it on 240v as well as gas, at the same time, MAY just extend the under a minute shower time! But it doesn't. Annoyingly the central heating works lovely but we have zero use for it, so I am now looking at ripping this whole Alde system out, and replacing it. It's at that point that I get stuck.

I would be really grateful for any advice or thoughts on the current ideas we have, to replace the Alde burner with:

(PS - please keep in mind this caravan will be permanently sited, never will move, and will permanently have 240V supply via a standard (13Amp socket). I can't increase that very easily, so I am looking for the best I can do safely on 13amps)

1. The boiler man suggested a "Rinnai" gas water heater which could be installed outside the caravan, on a fireproof board on the wall or a few feet away maybe. That is an instant gas fired water heater and I think I could just put that in line. I.E. - Rip out Alde system. Feed cold into gas water heater, feed hot from there into van's hot pipe, bobs your uncle. I had this idea myself, although the Rinnai things are very expensive so I was thinking more like a 'chinese cheapie' version of the same thing - something like this https://www.ebay.co.uk/itm/8L-Hot-Water-Heater-Portable-Bath-Shower-Propane-Gas-Instant-Tankless-Ridgeyard/223557047406?hash=item340d09d46e:g:OcAAAOSwQiNc27Z9 - which is a bargain, but may last about 5 minutes. I would be willing to chance it though.

2. He also suggested a "under the sink type water tank" to run on mains, maybe 2-3kw (max). He seemed to think that would supply enough 'heating power' to provide a small tank of readily available hot water plus would heat on the way through to SOME extent, as in just enough to extend the shower a minute or so.

3. I could just try a household type (small one though) immersion tank, so long as wattage was down low.

A few things I am considering, in case anyone has tried any of them in this type of situation! Thanks to anyone with comments, really need to get a usable shower here and a bit stumped as to which way to go. (Oh and PS... we have a 6.4litre per minute Shurflow, very old noisy pump. I may need to replace that so I could up the pressure a bit, but keeping it well below household pressures so pipes don't pop off throughout the caravan!).



https://www.amazon.co.uk/Stiebel-Eltron-Handwash-Water-Heater/dp/B006W7K834/ref=sr_1_18?crid=2MUJVB8NMG71E&dchild=1&keywords=2kw+water+heater&qid=1598545643&sprefix=2kw+wat,aps,175&sr=8-18 - Crikey, that's cheap, if it would provide enough heating capacity for a 6.4litre per minute pump, that could be a very cheap but just about usable shower, maybe?!

Thanks again.
 

Damian

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Mar 14, 2005
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Taking the Alde system to start with, it is very old and most likely is that any tanks are very scaled up with limescale, which, given the age of the unit would be impossible to remove without causing a lot of damage.

If your boiler man who looked at it is not LPG certified then he was not legally allowed to do anything with it.

Going further into your post, the first item you mention ( https://www.ebay.co.uk/itm/8L-Hot-Water-Heater-Portable-Bath-Shower-Propane-Gas-Instant-Tankless-Ridgeyard/223557047406?hash=item340d09d46e:g:OcAAAOSwQiNc27Z9 - )

This item has an open flue and is NOT permitted to be installed in a caravan, no ifs or buts, its a NO .

The other electric items you mention are built with mains pressure being the main essential, so would not be suitable for the caravan water system, which runs at a max of 1.6 Bar.

As for the pump, you would be advised not to try and increase the pressure ,but to possibly replace with the same type, just a new one, but again, internal pumps are noisy in comparison to external submersible pumps.

One option , which are very good, is a Propex unit as here: https://propexheatsource.co.uk/heaters/10l-water-heater.

I have fitted several of these units to vans and the resulting information I have had back from owners has been very positive.
Additionally, Propex are a UK maker based in Southampton and their after sales service and advice is second to none.
 
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Doing a search on Alde here. Shows manuals for the 2920/1 are not available, but 2923 is, is is at least similar and there may be info there.

Another suggestion. But would, I think, need a mains water supply and an improved power supply, more expense but possibly cheaper and easier than other methods. Might be to install an instantaneous shower unit.

Also. There is no way that Alde would expect 25w to heat water.

John
 
Jul 27, 2020
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Hi Damian, thank you very very much for posting that.

First things first - the first link i posted - i said i would install that outside the caravan. I am aware of the risks and wouldn't install inside. I would probably build a weatherproof vented box outside on a plinth, a few feet away from the caravan.

Thanks for the info on pressures, I never really understand this. I assumed (stupidly perhaps) that the immersion tank systems would just use whatever pressure was coming in, but I now realise the caravan only pumps on demand so the tank wouldn't have a constant pressure to do its thing. Makes sense so those are out!

Now then... that suggestion you made - WOW! That looks PRECISELY what I need! Thank God I posted (and you did!). It's a lot of money but there is no way to do any kind of proper job cheaper than that really so we will find it and go for that. I only have two questions and since you've fitted a couple maybe you could help with answers....

1. It says "Fitted Socket 16Amp" - That's a concern. The rest of the description sounded like it was designed for a standard 13a socket, until I read that. Is it a misprint do you think? Just thinking it through (Ohm's Law is it?) 800 watts divided by 240v = 3.33 amps. Hmm. confused, maybe you can clarify? I wouldn't want to draw 16 amps down the cable we have available really.

2. 6 litre or 10 litre - I have NO idea whatsoever what is needed for a short shower, or a long one for that matter. I also have no experience of caravanning really. If in doubt obviously 10 litre would have to be chosen. But I wonder if you know if people can have a reasonably quick but effective shower from a 6L tank?

Thanks again, very much indeed!
 
Jul 27, 2020
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Doing a search on Alde here. Shows manuals for the 2920/1 are not available, but 2923 is, is is at least similar and there may be info there.

Another suggestion. But would, I think, need a mains water supply and an improved power supply, more expense but possibly cheaper and easier than other methods. Might be to install an instantaneous shower unit.

Also. There is no way that Alde would expect 25w to heat water.

John
Thanks John. Yes I searched for hours and found a Swedish manual for one of the Aldes, maybe the 2923. I have lost it so need to find one again, will try your link thank you for that.

Not quite sure I follow your suggestion. Mains water - can do that. Mains power - can do that. not sure what else your suggestion would involve, or exactly what type of water heater. The Propex does look a cracker though, if I can use it on my mains supply.

Regarding your last point, well that was my thought exactly. However...... we are apparently wrong. I have been testing all day. All gas off, cold system, no hot water anywhere. I left the "2KW switch" selected and gave it an hour to see what the electric element could do. It produced more hot water than the gas system did! I was amazed, but still don't quite believe it myself. But I can assure you the gas was off, there is no other way to heat water, and the hot water did run very hot and nice for a good 2-3 minutes. It's ALMOST good enough for a shower, certainly good enough while we save up for the Propex. However I really need to understand how the system works. As I had another idea during testing....

The gas burner seemed to heat up the miniscule water tank very fast. However I now realise the "tank" is even smaller than it appears, as the central heating pipes go through and that's a separate self-contained system, so I can't see how there is even a LITRE of hot water (taps) storage in that 'tank'! But I did wonder .... what about if I found a replacement for the tank, but bigger. So no heater element, I could let the gas burner do that job, but as it feeds out hot water, it could go into something more substantial like a 6 or 10 litre tank. I 'think' that would work, it would in theory in my mind anyway. It's just an in line storage vessel as far as i can tell, but pathetically small. So if, and that's an IF.... I could find a similar tank with the same outputs and inputs (i could go without the central heating though if needed) then I could just swap that over with a bigger tank and maybe the gas will heat up a bigger tank full of water. Just thinking out loud really!
 

Damian

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1. It says "Fitted Socket 16Amp" - That's a concern. The rest of the description sounded like it was designed for a standard 13a socket, until I read that. Is it a misprint do you think? Just thinking it through (Ohm's Law is it?) 800 watts divided by 240v = 3.33 amps. Hmm. confused, maybe you can clarify? I wouldn't want to draw 16 amps down the cable we have available really.

2. 6 litre or 10 litre - I have NO idea whatsoever what is needed for a short shower, or a long one for that matter. I also have no experience of caravanning really. If in doubt obviously 10 litre would have to be chosen. But I wonder if you know if people can have a reasonably quick but effective shower from a 6L tank?
Taking your first point, the unit comes with a standard 13A plug and as it only draws approx 4 A max it only needs a standard socket, which are all rated at 16A.

And your second point, most of the ones I have fitted have been the 10 Ltr units and with the temp set to highest and the mix of cold with hot , it gives a good shower, obviously not as long as if a domestic unit, but certainly much better than other units.
As with all caravan showers it is a case of not having the water running all the time, wet, soap, rinse.
 
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I have to say the judging from the photographs, the caravan is in a rather poor condition, That does not bode well for for some of the equipment in it. I appreciate you recognise you don't have all the necessary knowledge to check out these appliances, and that should perhaps be the point at which you get some professional help.

You need to know which appliances are serviceable, and which can be repaired or which need replacing. Not withstanding your intention to permanently site the caravan which might change what in theory could be possible. It might also cause the caravan to change its designation from touring to a static or mobile home. or even a domestic extension, in which case by law you have to have all gas appliances and pipework installed and serviced by an approved installer.

There is more to your proposals than you may have realised.
 
Jul 27, 2020
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Taking your first point, the unit comes with a standard 13A plug and as it only draws approx 4 A max it only needs a standard socket, which are all rated at 16A.

And your second point, most of the ones I have fitted have been the 10 Ltr units and with the temp set to highest and the mix of cold with hot , it gives a good shower, obviously not as long as if a domestic unit, but certainly much better than other units.
As with all caravan showers it is a case of not having the water running all the time, wet, soap, rinse.
Excellent, thanks very much.
Ah i see, so 16a is the max rating of the socket it can plug into, but it comes with a 13A fuse. I always wonder why things come with max rated fuses when only drawing 4amps as you say. I would think a 5a would be safer, if you can buy those. maybe you can't?! Anyway, my curiosities aside, the unit looks like just the ticket if I have to rip this Alde system out which is now looking 50/50. On that note..... (in case anyone has used one or knows how they work)...

Very peculiarly we decided to run the electric and gas at the same time. When I say electric, I mean that element heater which claims to be only 25W, about enough for a smart watch :D. But what the heck, we ran them both. Things were hot (as it was preheated) then ran colder, but then it warmed up again and seemed to stay at a constant fairly hot (not piping but enough for a shower without cold added) for what must have been 10-15 minutes. I therefore think the power output of the burner is just about enough to sustain the shower running hot only. It's nothing impressive, but it's currently a free option. I definitely would like the electric one previously mentioned, but that could maybe wait until summer next year when funds are easier to come by.

One thing I really don't understand is why (and indeed whether) the Alde system insists on heating the central heating circuit. German summers can be very hot, surely they wouldn't design the system so that if you want hot water to wash, cook, shower etc, you have to have a baking hot caravan too?! It seems like that's the case. The gas is constantly heating the central heating water (I say water, as it is currently just water because I had no glycol or whatever the correct frost resistant fluid is). So energy is 'wasted' heating water I don't want heated. If I could find a solution to that it would be a bonus. I will get reading through the swedish manuals and see if I can make sense of how the system works and whether it's possible to prevent the system heating the central heating fluid.

(The boiler man didn't want the burner running without fluid in the CH system just in case it overheated or cracked due to being run dry inside. He's probably right that it should always have fluid in, but I would like to confirm that too.)
 
Jul 27, 2020
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I have to say the judging from the photographs, the caravan is in a rather poor condition, That does not bode well for for some of the equipment in it. I appreciate you recognise you don't have all the necessary knowledge to check out these appliances, and that should perhaps be the point at which you get some professional help.

You need to know which appliances are serviceable, and which can be repaired or which need replacing. Not withstanding your intention to permanently site the caravan which might change what in theory could be possible. It might also cause the caravan to change its designation from touring to a static or mobile home. or even a domestic extension, in which case by law you have to have all gas appliances and pipework installed and serviced by an approved installer.

There is more to your proposals than you may have realised.
Not really. I am happy with appliances checked so far, the only exception now being this heating/hot water system. The other issues are not a concern, but thanks for raising them.
 

Damian

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(The boiler man didn't want the burner running without fluid in the CH system just in case it overheated or cracked due to being run dry inside. He's probably right that it should always have fluid in, but I would like to confirm that too.)
Absolutely correct.
The Alde system must always have fluid in the central heating circuit or you can do irrepairable damage to the boiler.

If the system you have is similar to the units in modern caravans, and I dont see why it should be different, then the control over the central heating side of it is determined by the thermostat setting for the heating.
It will still heat the tank but not kick in the pump
 
Jul 27, 2020
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Absolutely correct.
The Alde system must always have fluid in the central heating circuit or you can do irrepairable damage to the boiler.

If the system you have is similar to the units in modern caravans, and I dont see why it should be different, then the control over the central heating side of it is determined by the thermostat setting for the heating.
It will still heat the tank but not kick in the pump
Gotcha, thank you. Well I would rather avoid using gas as much as possible so if i only use this for showers and use our trusty old oil filled radiator for occasionally topping up the temp a few degrees, there is a chance this gas burner could do the job. I am about to jump in the shower with a few rubber ducks and see how long it is adequately warm for. Don't be surprised if I come back sneezing tomorrow :D

Oh and yes you're spot on there I think. I forgot about the wall stat. I am still a bit confused by how it works but hoping the manual will confirm if I am not setting things correctly, or more likely just tell me I am doing it right but that's just how it works. If I turn the wall stat on (switch on top), the water heats. It would appear that the water heater doesn't work without that turned on, which is a bit odd to me. If I turn the stat up (past the click) then the little 12v DC motor spins and circulates the water around the radiator pipes. trouble is, even without that motor running (I have left it off all day) the burner alone heats the caravan up a fair bit and it would be horrible in summer! All things are pointing towards the tank you recommended, as soon as we can anyway! thanks again
 
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Not quite sure I follow your suggestion. Mains water - can do that. Mains power - can do that. not sure what else your suggestion would involve, or exactly what type of water heater. The Propex does look a cracker though, if I can use it on my mains supply.
I will clarify what I meant, but tend to think what Damian said as much better.

If mains water was fed to the van with domestic plumbing to take the pressure, this could feed a domestic electric shower unit.

Otherwise, as you said, you used a 2kw switch to turn on the boiler. I can’t think what the 25 watt unit is, perhaps a controller of some sort.

My modern Alde unit has a hot water capacity of 6 litres (from memory). We find that’s enough for two start stop showers. The boiler has one cylinder inside the other so the same gas burner and electric elements, mine does 1, 2 or 3 kw. I think yours must be along those lines.

It would seem to me that if the old system cannot be made to run safely. That the Propex option makes most sense.

John
 
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I will clarify what I meant, but tend to think what Damian said as much better.

If mains water was fed to the van with domestic plumbing to take the pressure, this could feed a domestic electric shower unit.

Otherwise, as you said, you used a 2kw switch to turn on the boiler. I can’t think what the 25 watt unit is, perhaps a controller of some sort.

My modern Alde unit has a hot water capacity of 6 litres (from memory). We find that’s enough for two start stop showers. The boiler has one cylinder inside the other so the same gas burner and electric elements, mine does 1, 2 or 3 kw. I think yours must be along those lines.

It would seem to me that if the old system cannot be made to run safely. That the Propex option makes most sense.

John
Thanks John. It does indeed sound similar.
Here is a pic (its shown upside down to show the writing) of what looks to me like a heating element. It has a fused 13a spur on the wall supplying it. Maybe this isn't the heater at all and as you say, the 2kw element controlled by the switch on the Alde burner control panel, is inside the tall burner itself. Just about to read that manual Damian linked, so may soon know!

 

Damian

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Dang! I couldn't find that for the life of me! I am also looking for the installation manual as I think that will give more detail on how the system works. In case you have a link to that? Don't go looking on my account though, I will get there! thanks again, brilliant!
The installation manual is only that, how to install the unit, it has no user operation information.
 
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Excellent, thanks very much.
Ah i see, so 16a is the max rating of the socket it can plug into, but it comes with a 13A fuse. I always wonder why things come with max rated fuses when only drawing 4amps as you say. I would think a 5a would be safer, if you can buy those. maybe you can't?! Anyway, my curiosities aside, the unit looks like just the ticket if I have to rip this Alde system out which is now looking 50/50. On that note..... (in case anyone has used one or knows how they work)...

Very peculiarly we decided to run the electric and gas at the same time. When I say electric, I mean that element heater which claims to be only 25W, about enough for a smart watch :D. But what the heck, we ran them both. Things were hot (as it was preheated) then ran colder, but then it warmed up again and seemed to stay at a constant fairly hot (not piping but enough for a shower without cold added) for what must have been 10-15 minutes. I therefore think the power output of the burner is just about enough to sustain the shower running hot only. It's nothing impressive, but it's currently a free option. I definitely would like the electric one previously mentioned, but that could maybe wait until summer next year when funds are easier to come by.

One thing I really don't understand is why (and indeed whether) the Alde system insists on heating the central heating circuit. German summers can be very hot, surely they wouldn't design the system so that if you want hot water to wash, cook, shower etc, you have to have a baking hot caravan too?! It seems like that's the case. The gas is constantly heating the central heating water (I say water, as it is currently just water because I had no glycol or whatever the correct frost resistant fluid is). So energy is 'wasted' heating water I don't want heated. If I could find a solution to that it would be a bonus. I will get reading through the swedish manuals and see if I can make sense of how the system works and whether it's possible to prevent the system heating the central heating fluid.

(The boiler man didn't want the burner running without fluid in the CH system just in case it overheated or cracked due to being run dry inside. He's probably right that it should always have fluid in, but I would like to confirm that too.)
Would you run your water heater dry, or your domestic heating dry? Why question the technicians advise?
 
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The installation manual is only that, how to install the unit, it has no user operation information.
Yep but I thought that might help me understand it better, if I know what pipes go where, which power cables go where etc. It might just tell me if there is an electric heater element inside the burner, which would be good to know!
 

Damian

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You can run Alde systems with no domestic use water, ie shower, taps, in the tank.
But you must have central heating fluid in the CH circuit.
 
Jul 27, 2020
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Would you run your water heater dry, or your domestic heating dry? Why question the technicians advise?
No, I wouldn't run those things dry. But those things are not this thing, and such assumptions can be just as likely to lead to mistakes. I merely wondered. My "technician" had no issue with it, is a friend of mine, and indeed wondered the same thing too. He said himself he wasn't sure, but likely to be logical to assume it should have fluid in which I agreed made sense. But I would like to know "for sure", that's all. In my experience, questioning anyone is not only perfectly appropriate, but indeed sensible. Otherwise you hand your hat to the nearest person claiming expert status, and many often fall short of it. You question who you want, I will question who I want, which needn't be offensive but mere curiosity and often opens the road to learning. I accepted and went with his opinion, I merely wanted to know for sure, as he was anything but sure. Ok pal?
 
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No, I wouldn't run those things dry. But those things are not this thing, and such assumptions can be just as likely to lead to mistakes. I merely wondered. My "technician" had no issue with it, is a friend of mine, and indeed wondered the same thing too. He said himself he wasn't sure, but likely to be logical to assume it should have fluid in which I agreed made sense. But I would like to know "for sure", that's all. In my experience, questioning anyone is not only perfectly appropriate, but indeed sensible. Otherwise you hand your hat to the nearest person claiming expert status, and many often fall short of it. You question who you want, I will question who I want, which needn't be offensive but mere curiosity and often opens the road to learning. I accepted and went with his opinion, I merely wanted to know for sure, as he was anything but sure. Ok pal?
Oh so it wasn’t an experienced technician. My mistake
 

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Oh so it wasn’t an experienced technician. My mistake
Hang on !!!
The person who looked at it probably is a Gas Safe fitter but only certified for Natural Gas, and therefore would not have any reason to know about LPG items, and in particular caravan related items, which is why I have to go to the makers of the various equipment to get the training to service and repair them.
It 'aint easy, and it costs a LOT of money !!!!! which is why only about 10% of Gas Safe fitters are LPG certified.
 
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John, I Googled the number on the blue part. It’s the circulation pump.

Also. As Damian said, there is no mains supply to the 2920. But I think yours is a 2921.

I found this.
3B7D22A3-F4A9-4E90-9684-EC329B52AE3F.png


But can’t find any manuals I’m afraid. Looks to me like the 2921 is the 2920 plus mains.
 
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