I am in the process of removing my alternator and will be having it recoditioned. Having following a number of threads and spoken to auto electricians and had the vehicle tested it would seem that a relay has failed. I have the water cooled 155 amp alternator. One thread suggested that the large output was needed because of the electric heaters on the espace. I have read the owners manual several times but didn't pick up on this fact. Do all espaces have electric heaters. I own a 2007 reg 2.0 T (petrol).
The answer to your last question is 'No'.
You have a Series IV Renault Espace that has nothing to do with Matra. These vehicles have a totally different heating system to the Matra Espace I, II, and III which are conventional except for the auxiliary heater on the diesel models.
Explanation: Diesels use their own engine heat so well and the Espace has such a large interior that on very cold days it would take too long to heat the interior so Matra and Renault decided on the Series III to fit an auxiliary heater (as fitted to truck cabs) to provide additional heating whilst the engine coolant was below 85 degrees (and the outside temp. was below 5 degrees). These use a small amount of diesel straight from the tank to heat the coolant up more quickly so that the interior can be heated quicker. Also on common rail diesels (Series III Espace) they use some glow plugs to also heat the coolant! You will see three or four glow plugs in a block on the left of the engine over the gearbox area.
When Renault took over Espace production and came out with the Series IV they changed the system entirely. The first thing was the location of the heater - normally the heater matrices are at the front, but this means it takes a long while to get heat to the rear of the interior space. So on the Series IV they put the heater centrally under the car, so that the interior heat is fed from the centre and all areas should benefit from heat more or less equally. The second change was that instead of the diesel powered auxiliary heated of the Series III they fitted electric bar heaters (up to 4) which can consume 250 watts each so a max. of 1000 watts! You can imagine the power these require, so the alternators are extremely high powered units which are water cooled! I have seen these turning out 172 amps!! These electric heaters work similar to a home electric fire - you pass current through a resistor, which heats up, and you blow air over it to transfer the heat to the interior.
Obviously the system has to be carefully controlled and therefore the heaters and alternator are managed by the computers - so it will only allow more electric heaters to be switched in providing the alternator can meet the demand. So you may have only one of two heaters switched in if the engine and alternator are turning too slowly to provide sufficient power for anything more as an example. These electric heaters are only there to provide heat to the interior whilst the outside air temperature is very low and the engine coolant is also cold (during the period just after starting) and once the normal coolant can provide the heat they are not used.
So the answer by Colin with his Series III has no bearing on your Series IV. And configuring the auxiliary heater (or boiler) off does not apply to a Series IV which doesn't have that system. Turning it off on a Series III means it will take longer to get heat to the interior - your choice! One of the main problems with these auxiliary heaters is lack of maintenance! They get clogged with carbon, but no one ever cleans them...
Regarding the very high output water cooled alternators - since only certain Espace have them, this is one of the reasons why, when an alternator is changed, you have to use Clip to configure the new alternator in to the system - it has to know what is fitted.
Query - why would you need to allow the motor (or coolant) to cool to fit a new electric heater? In the first place they are underneath, nothing to do with the engine; and being separate from the coolant system you do not need to disturb this either!
Roy