Eberspacher D4W

[Guest Simon B]

We`ve just downsized from a coachbuilt to a Murvi Morello with the Eberspacher D4W heater fitted. We only picked up the van on the 20th December so I`m still learning about the heater. The main question I have is regarding the heat output as the heat from the living area outlets doesn`t seem to be much, even after operating the heater for half an hour. Am I expecting too much or is more heat taken initially by the calorifier. I am reluctant to use the cab boost as this draws power from the van battery. I intend to check the fan matrix and before the spring get it serviced by an approved Eberspacher agent. As we`re going to the Shepton show in January, any information would be welcomed.

[Guest Don Madge]

Simon, We to downsized from an A Class to a hightop. We have the D2 in our Timberland and if anything it gets too hot if the thermostat is set to high. It's the best heater we have ever had in 35 years of caravan and motorhomes. Don.

[Guest Derek Uzzell]

Don's D2 appliance is a straightforward Eberspacher "Airtronic" blown-air heater with a maximum output of 2.2kW - plenty adequate for a panel-van conversion. However, your Murvi has a D4W "Hydronic" wet system, with an under-bonnet burner-unit, hot water storage in a calorifier tank and air heating via fans blowing through water-filled matrices. I believe the D4W can produce 4.3kW at full blast and (even if water is being heated simultaneously) I would expect there to be plenty of hot air after half an hour. From what I recall there are water-valves in this system that can be twiddled to adjust hot/cold water 'balance', but I don't know if that's anything to do with your problem. As you are still on the learning-curve, are you sure the reason little hot air is emerging from the fan matrix is not simply because you've got a thermostat turned too low. (Presumably you've got Eberspacher documentation for the system?) I suggest you contact Eberspacher UK (www.eberspacher.co.uk) or a local agent to see if they can offer a quick diagnosis before you head off to arctic Shepton Mallet. (You might also try Murvi.) Regarding your follow-up question, I think you are right to be wary of running the heater when there's cleaning additive in the diesel fuel, but only Eberspacher or their agents will really be competent to rule on the advisability of doing this.

[Guest PeteC]

Derek for info We have the D4W (had to get the book out to check) We have a water valve in the water suppl ylines to the sink taps. Dont know if this is the one that you recall That (did) adjust the flow of hot & cold water to the hot tap Say did as we found that during travelling an air lock was formed for some reason. So,while away on a vacation; I disconnected the mixer valve as a test, and connected the hot water directly to the Hot inlet to the standard mixer tap As this worked and 1 Got rid of the air locks 2 Didnt scold us with hot water when used after some longish journeys So the mixer tap is still disconnected There is acheck valve that controlls the flow of water That has three different ways of connection each requiring different fittings You can take Hot water from either the engine or EH through the heater elements (pipes) Or the HWater can come from engine or Eber controlled by a thermostat On ours Hot water from the engine does not flow through the heater pies until the engine is up to temperature You can (and we have done on several occasions) switch on the van heater to a) Heate the engine block b) provide a boost to the cab area and demist/ deice the screen

[Guest Derek Uzzell]

Petec: I remember a (1999?) MMM report on a Devon with a Hydronic system where the tester couldn't get hot water from the hot taps. It was mentioned that there was mixer valve that blended the very hot water in the calorifier with cold water to bring the temperature down to a bearable level and make the heated water go further. This apparently had been set so that only cold water was being delivered to the hot taps. Simon: I've referred back to Di Johnson's MMM Owner Report (December 2003, page 143) on her 2001 Murvi Morello fitted with Eberspacher Hydronic heating. Nothing was said about the sort of limited hot air output you refer to and the only negative comment related to heater start-up noise. I've also looked up a couple of French articles on diesel-fuelled heaters. One gives the D4W heat output as 4kW, 3.3kW or 1.5kw (High, Medium or Low settings) and also advises that, for prolonged use over 1500m altitude, a special kit should be installed - something that was highlighted by Don Madge in his posting of 23/12/2005. The other article gave heating performance data for two medium-sized coachbuilt motorhomes fitted with the same diesel-fuelled system. Exact details of the system weren't given, but, as it had 4kW output, a 28 litre calorifier and 3 fan-matrices for warm air distribution, it was probably based on an Eberspacher D4W. With a constant outside temperature of 5C and a starting temperature of 7C within the vehicles it took about 2 hours to reach a maximum of 18C in one vehicle and about 1.5 hours to reach the same temperature in the other. In the latter case, the heating system was able to increase the temperature further to a maximum of 23C after 2 hours. (The heaters were both run at full power and the fan units at maximum speed, so presumably the findings reflect individual vehicle installation and insulation variations.) With 'wet' systems like Hydronic you can't expect the instant hot air provided by Airtronic-type heaters or gas-fuelled blown air appliances, so (if the water in your heating system is cold to begin with) there may well be a goodish delay before you get really warm air from the fan unit(s). I've no practical experience of Hydronic, but I'm presuming that the water in the calorifier is heated indirectly. If this is correct, although the heated water passing through the pipes within the calorifier will lose some of its warmth, this reduction will be nothing like as severe as if the large quantity of stored water were being heated directly. As petec has a D4W perhaps he can advise on these points.