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Rapido Heating


stevec176

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I'm having a problem with the heating in my Rapido 665f and hope someone out there can be of more help than the dealers are. I went away for a couple of weeks in late November and the outside temp was around the 0 so efficient heating was essential. For the first week it worked fine, set at 21, lovely and cosy but then the heating wouldn't go above 19 and I couldn't feel any hot air being blown out of the vents. If I put my hand near the vents I could feel hot air flowing out but not like it had. I booked the van into the dealers and explained everything exactly what the problem was but when I got the van back all they had done was bleed the system and told me they got the temp up to 23 in their workshop. When I got the van home I plugged it in and set the heating with the outside temp at around the 0 and this morning the temp is reading 19 and no airflow. So If anyone has any ideas then I'd be grateful.
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Some people expect to be able to heat using electricity alone. If that's your case, use gas as well. You have up to 8 kW output with gas and electricity. Rest assured that electricity will be used at all times. The gas will be used to help out when 2kW electricity is insufficient.
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So it's a wet system? Are there any fan assisted heat exchangers, or is it all convective? If any of the heat exchangers are fan assisted, and the output seems to have diminished/failed, it might indicate that the fan isn't running. This might be because the fan is thermostatically controlled, and the output has only been checked during a period when the 'stat isn't calling for heat, or because the fan has lost its connection, or has failed. If all the heat exchanging is convective, it seems to indicate that either the heater 'stat (i.e. the one that controls the temperature of the circulating water, assuming there is one, and that it can be adjusted as on a domestic boiler) is set too low, or possibly that the room 'stat is not working correctly. Some of these 'stats are quite coarse, with a noticeable variation between the temperature at which the 'stat is satisfied and switches the heating off, and that at which it again begins calling for heat. I think you may need to refer the problem to an Alde specialist.
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Apologies for not saying what type of heating the van had, it is the Alde a wet system with blown air. Usually the system works well and you can feel the hot air being blown from the vents which is what I haven't been able to feel recently so the van heats up slower than usual and only able to get up to 19° after several hours. The dealers have had it in their workshop, which is obviously warmer than outside, and tell me they are able to reach 21°.

Thanks for advice.

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I'd hope that the dealer would know what they're doing and certainly be familiar with the 'regular' faults. You should be able to get the moho to an unbearable temperature. 21deg is not good enough for a maximum, so something (thermostat?) is not working correctly.

I assume that the water is being heated OK?

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The dealers dont seem to know much at all. I explained it fully to their techy and all he said was 'I'll give it a good bleed'. I pointed out that there was plenty of heat but no air flow to circulate it but in the end they just bleed the system. The water is generally too hot to put your hands in.
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So it's only the blown air unit that's not functioning? - The rest of the van is being heated satisfactorily?

I don't have much experience of these systems but don't suppose they give off much heat anyway. Their ability to produce hot air will depend on the temperature of the air going into the unit and the temperature of the exchanger fins. Is there a rated capacity (kW output) for your blown air heater? If you take an electric blown air heater and put it in similar conditions on the lowest (1kW) setting, how does that compare? I've a feeling that you may be expecting a bit too much from a small exchanger. It may perform better if it's close to the outgoing run from the boiler but there will be less heat in the water towards the return end (and little that you can do about it).

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When you say the water is too hot to put your hands in, I wonder if you are referring to the hot water supply (washbasin etc) and not the circulated heating water?

 

If I understand correctly, your van has a wet central heating system that is heating hot water satisfactorily, but not heating the van itself.

 

You have referred to blown air units which, if I've understood correctly, are fan assisted water to air heat exchangers. You have not said how many of these there are, or how they are controlled, but to get heat from them (it?) the fan must run.

 

The fan/s should be quiet, but will still be audible, so can you hear them whirring?

 

It sounds as though the hot water is getting to where it is needed, but that the fans are not blowing air over the heat exchanger/s to heat the van. If my suppositions are correct, you need to find out why the fan/s aren't running as it could be a thermostat (or a thermostat actuated relay) that is at fault, or a fan (especially if there is only one) that has failed, or even that something is blocking the air supply (in or out).

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stevec176 - 2017-12-12 7:09 PM

 

Dont think so as it worked perfect for the first week and then we lost the air flow, infact while it was working a friend who was visiting complained about the heat being blown around the van being too much.

 

If it worked OK, once, try and track any changes that might have happened since.

I assume the one you are referring to is heated by the Alde and not the engine?

There could be a switch/valve you need to turn and it could've been knocked.

If it last worked in warm conditions, it could still be that the air going into the exchanger is much colder now, so not as warm coming out.

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Yep, you got it correct, much the same as the heating system in a car and if you turn the fan off then that is how my system is working. Unfortunately the dealer can't seem to understand that part, I'll just have to keep trying till they do so I can use the van during the winter.

Thanks all.

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Steve,

I'm not sure why you "cannot use your van in winter". If the rest of the system is working, your van should warm up nicely. Or is it that the fanned air is a cheap solution for hearting the cab area without needing to run pipes around that bit?

rogher

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Rapido describes the ALDE heating system fitted to the 665F model as “Comfort Plus Artic central heating with Frost-control + bedroom temperature control". There’s a fuller description with a schematic partway down this webpage

 

http://www.rapido-motorhome.co.uk/rapido_rapidos-savoir-faire_expertise-in-five-points_unrivalled-comfort.phtml

 

but (as the note on the schematic suggests) the complexity of the system can vary from model to model. For example, the 665F model’s system will not include “full double floor heating” because the 665F does not have a double floor. I’m pretty sure a 665F does not have windscreen heating and it may not have the heat exchanger that exploits engine coolant. A 2018 665F has the options of a heated habitation-area floor-surface and/or a heated cab-carpet, but I don’t know if Steve’s (2016?) motorhome has these.

 

My 2015 model-year Rapido User Manual includes guidance for an ALDE heating system based on the 3020 Compact unit (ALDE manuals here)

 

http://www.alde.co.uk/manuals.php

 

The ALDE digital control-panel shown in my Manual seems straightforward to use and the operation and purpose of the bedroom-area thermostat switch is explained.

 

Also covered in the ALDE-related section of my Rapido Manual is a switch for a Truma “Multivent” fan that “...enables you to increase warm air circulation in the living area”. This switch has 3 positions - slow speed, Off, or high speed. There’s nothing to suggest that this fan-unit is directly linked to the ALDE system - it just seems to be there to aid warm-air circulation. An ALDE ‘wet’ system’s heat output is normally provided via simple convector radiators with fan-convectors or fan ‘boosters’ as an option. However, it appears that Rapido may use a Truma fan-unit to produce ‘blown’ warm air and, if that’s no longer happening, the Truma unit (assumming a 665F actually has one!!) may not be operating.

 

I came across this recent-ish MHFun Rapido/ALDE discussion

 

https://www.motorhomefun.co.uk/forum/threads/new-rapido-10000dfh-alde-heating-3020-3010-issues.151475/

 

but I’m doubtful it helps with Steve’s specific problem.

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stevec176 - 2017-12-12 9:07 PM

 

No, sorry I meant the heating for the habitation is similar to car heating. The habitation side isnt heating proprly so it only gets to about 19°, a bit on the chilly side.

 

I’d like to be able to help but I’m struggling to understand which bits are working and which are not. I believe the hot (tap) water is working but all of the central heating is only feeble.

Has the heating been left on (electric + gas) for any length of time (at least an hour)? It takes time for Alde systems to get going/heat up. I’d try touching the outgoing pipework from the boiler when it’s on and the (tap) water has had time to heat up. The circulating pipe should be very hot when the heating is on but below the requested temperature. (Pipes may be awkward to find.) The return pipe to the boiler may be cool, initially, but should get hot, later.

I think there may be a circulation problem, so the suggestion to try bleeding the system is not unreasonable. If an airlock is not responsible you are looking for a physical blockage. Is any part of the van getting hot? If there is some kind of separate control for the sleeping area, say, I’m wondering if there is a valve that’s in the wrong position, somewhere. I have no idea how a separate control might be achieved, you’d really need separate circuits. This seems to be a rather sophisticated system. Shame that it’s not working correctly.

 

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Thanks all for you help, just have to wear thermals till it gets warmer. I know its a strange problem and its dufficult to try and make it clear but I'll try once more. The habitation heating was working fine fir the first part if our holiday and hot air could be felt gushing out of the vents and the inside if the van reached 21° quickly. As I'd said a friend who was sitting in the captains chair complained about the heat coming from the vent being too hot. After a few days the heating wouldnt get above 19° and where previously you could feel hot air gushing from the vents now it was greatly reduced even though it was still hot, if you put your hand in front of the vents you could only bbjust feel it coming out, so it wasnt being pushed around the van. The problem doesn't seem to be the flow of hot fluid around the system just its lack air flow out of the vents.

Again many thanks for all your advice.

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stevec176 - 2017-12-12 9:07 PM

 

No, sorry I meant the heating for the habitation is similar to car heating. The habitation side isnt heating proprly so it only gets to about 19°, a bit on the chilly side.

I think it more helpful to see this as akin to a domestic central heating system than to a car system. It has similar components: boiler, radiators, a feed and expansion tank, and a (maybe more) fan assisted radiator (or convector), a temperature controller for the circulating water, and at least one living area thermostat. According to the Alde handbook, the flow temperature for the circulating water is pre-set to 85C, and seems not to be user adjustable.

 

Is there any possibility that you are running the boiler on electricity, and not on gas? If you are, I suspect it will not reach the set temperature with low outside temperatures.

 

If you have access to the main flow pipe coming from the boiler this can be tested (roughly) by placing something like a jam thermometer on an un-lagged section of this pipe with the boiler running, to see if the temperature achieved is in the vicinity of 85C.

 

I note that the main circulating pump is adjustable, with a suggested setting of 3 for a motorhome. It would be worth verifying this setting, and also that the pump is running (audible or slight vibration?).

 

I would suggest tracing the heating pipework around the system, taking its temperature as you go, to see if the heat is distributing as intended. It will drop as you go round, as all heat exchangers seem to be in series. It may be worth also taking the return temperature at the boiler, to see by how much the flow and return temperatures vary.

 

But from what you have said about lack of perceptible airflow, I suspect the problem is with that fan assisted convector, and that the fan is not operating as intended. It is unclear at present how operation of that fan is controlled. I think this is where to concentrate, having verified that the boiler is running on gas and is generating a flow temperature, at the boiler, in the region of 85C, and that the pump is at setting 3.

 

(It is a bit difficult to understand how the bedroom area thermostat is intended to control the bedroom temperature as to do this properly a motorised valve and by-pass would normally be required, and Rapido make no mention of such. I suspect there are just two 'stats in parallel, and the boiler responds to whichever calls for heat, but as that isn't the central issue, it is not worth digressing onto.)

 

I wouldn't be too taken aback that the dealer's technicians aren't fully au fait with the Aldi system. I know they should be, but the great majority of systems installed in vans are Truma blown air systems, so they probably haven't had many Aldi based systems to contend with, and so lack hands-on experience with these. There is a telephone number in the downloadable manual Derek linked to, so I still think it would be worth contacting them to see if they can shine some light - or even come and sort it out!

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Many thanks Brian, did have both gas and electric selected, think maybe I was expecting too much and not understanding the system and then I couldnt understand why one day it heats the van up quickly and the next it seems to struggle when nothing has changed. I dont understand how the bedroom thermostat works either.

Thanks.

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stevec176 - 2017-12-13 2:06 PM.................... think maybe I was expecting too much and not understanding the system and then I couldnt understand why one day it heats the van up quickly and the next it seems to struggle when nothing has changed......................Thanks.

I can't understand that either. I wouldn't accept a heating system that has "moods" about how it will work. It is a engineered installation that works within defined parameters. If, on one occasion it is satisfactory, and on another it is not, it has a fault. Your descriptions to date persuade me that the fault is most probably in that fan convector (assuming one is present), or in its controls. If the dealer can't make it work properly, I still think contacting Aldi in UK for advice would be the way to go. It could just be that the dealer hasn't followed the recommended routine for removing air-locks, and the fan convector itself is air locked, or that there is a failure affecting the fan convector. I'm assuming the van is still under warranty, so I'd get it dealt with well within the warranty period, so that there is scope for a second bite at the cherry if necessary. Alde will offer their own warranty on their parts of the installation.

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You should be nice ‘n comfy with Alde heating, even without the blown air, so something is not right and I think it’s the circulation from what you have said. I think you have only one circuit (most common) and the pipework rises up at the heat exchanger for the blown air, then returns down again. If air is in the system, it may collect there and slowly reduce the flow around the system. See if there is a venting point near the top of the blown air unit. If there is, I’d turn the system off and bleed out any air. Make sure the header tank is back to the right level after and then switch heating back on. The header tank ought to be topped up with glycol mix but a small amount of tap water should not matter too much.

I hope you can get the heating to work so that you can enjoy the van more. You should not be getting cold in it, even in this weather.

 

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.Alde is not blowing hot air via multiple spiral plastic pipes and the outlet holes in numbers. They have however options which can include a fan.Do your home work first on your equipment before asking others. Because as the forum master said to me many times . I do not understand what you are talking about. I Am from barcelona.
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Steve, your heating … first the cause, then a cure. Its where and how the thermostat is fitted which is probably down to the individual installer and may vary on every van.

 

1. Take an empty van, its cold and damp, 'hang' a thermostat in free air space where it can be seen. Set your control to your desired temperature (21). As soon as the temperature reaches that setting the thermostat activates. Wonderful the occupants are warm !

 

2. Take another empty van, its cold and damp. Fix your thermostat firmly to a piece of cold and damp timber. Even better make sure its secure in a small cold space with no air circulation.

 

3. Set your control to 21 as before. The heater will activate and continue to run to well above your original setting. Its impossible to de-activate because of its position. Your friend complained of the heat, yes of course.

 

4. Its impossible for the thermostat to heat the living space correctly until the cold damp timber and the small isolated space has itself been heated enough to allow the thermostat to operate according to the number you set (21). From then on of course the van's free space is being controlled by the thermostats tight position, it rapidly reaches your setting of 21 and can never function correctly.

 

5. And … as Steve says … after about a week very little heat was leaving the ducting … of course because thermostat was now activating according to its very own 'warm' space where it lived.

 

6. So … Steve, you either find out where the thermometer is and reposition it … or decide to go camping on a one week only basis, so allowing the body work to go dead cold and you start again.

 

Most problems in life are very simple.................... if looked at in reverse ?

 

Will

 

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