System error E517H on truma system

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I have the same van as BB. My only gripe about the Truma is that it doesn't have a variable fan speed like I had on my previous van with a Whale system. In fact the instruction booklet recommends not running the fan at the high setting lest the bearings wear out. The trouble is, the default low setting is but a whisper.

Ours has an Eco setting which I tend to leave it set on. That seems to vary the fan speed dependant on requirements. Earlier in the week when we had minus 3 at night it was running substantially faster than it was this morning with the temperature well above zero. I assume it is linked to how easy the system is finding maintaining the set temperature.

Yes, mine is variable speed on ‘Eco’ responding to the conditions. The other ‘interesting’ feature is the water temperature. I think it should hit 60c on ‘high’, but it often shuts down at significantly less than that. I’ve never really understood the ‘boost’ feature but that seems to do its own thing as well.

The hot water does seem a bit of a mystery. If unused ours seems to let it get well below 60c without switching on (symbol  flashing) However, as soon as a cupful is run off it starts heating and takes it back up to temperature. I assume it’s an ecological function.

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Ours has all the latest gizmos which my OH asserts that she fully understands.After 42 years of marriage I know better than to argue with her.I use the smartphone App to operate it for two reasons:the backlit bright blue and white screen  is easier for me to read and I can turn on the hotwater/heating without getting out of bed and being told off for "clattering".

Funny thing is she always has the first shower and I get sent off with the dog.My shower always seems to be lukewarm when I come back despite her assurances that it is on"Boost";not that I would ever question her certainty of mind.....

surely the obvious thing to do is to use it in 'manual mode' (forget the phone and press the buttons....) for a trip or so....at least you'll be able to conclude whether the issue is in the unit or the way its controlled.

CY, it should have an Eco (low fan) setting and a HIGH (faster speed) setting...

in addition, the difference between the ambient temperature and the proposed new temperature makes a difference.

moving the temperature up from (say) 19 to 20 deg will be done quite gently...moving the temp from 19 to (say) 23 will make the fan spin much faster...

all electronic kit has a finite lifetime (built in obsolescence) and running the High setting more, probably will reduce life....but by how much and how quickly? actually, when its cold or we are not on hook up, i find using gas and ECO a really good combination, warms the van quickly and very quietly.

the two most misunderstood settings on the Combi are Boost and Mix.

Boost (for water heating) does a number of things...

a) it heats to 62 deg not the 60 deg which HOT does...BTW, ECO heats the water to 40deg..

b) it prioritises water heating over space heating....if the space heating is ON and heating the van, it will stop in favour of water heating.

c) The water temperature is then kept at the higher level (about 144 °F (62 °C)) for two subsequent heating cycles. When the water temperature is reached, the room is heated again.

BOOST for room heating gives Fast room heating - Available if the difference between the selected and the current room temperature is > 18 °F (10 °C). if wqter heqting is also running that will be stopped in favour of the room heating.

Mix (I or II) is a great setting as it combines gas and electric...using upto 2kw gas (on the Combi 4E) or upto 4kw gas (on the Combi 6E) pluse either 900 or 1800w depending on which Mix setting.

so, on space heating, Mix 1 gives a total power of 2.9kw (4E) or 4.9kw (6E)

Mix II gives a total power of 3.8kw (4E) or 5.8kw (6E)

on water heating, although Mix can be selected, there is no Mix mode and the unit defaults to EL at the Mix setting I or II.

lastly, when selecting gas only for water heating, only the lowest burner setting (2kw) is used, therefore there is little difference in using EL II or Gas.....1.8kw v 2kw.

as above, the Combi is a great unit but, due to its 'water jacket surrounding an air burner' construction, it isnt quite as simple as one might think...

12years of mutual respect (and a pretty good knowledge of the manual) has made it work extremely reliably for us...incl 2 showers from one tankful each morning....but thats another story.