Truma Combi 6 flue cover. Cluster flies.

[WonkyBass]

On sunny days last November a lot of cluster flies settled on our white Hymer. As evening approached they would seek shelter in the door seals and, more importantly, inside the Truma Combi 6e flue outlet and air intake. Some left when I fired up the boiler but I had to dismantle the pipe work to remove the rest. We did get an unpleasant smell of burning insects but there has been no apparent ill effect on the boiler.

Truma do not appear to sell a flue cover for the Combi. I infer from this, from the manual entry “Keep the cowl for the exhaust duct and combustion air intake free of contamination (slush, ice, leaves etc.) at all times”and from general knowledge that forgetting to uncap flue might damage the boiler and Truma perhaps choose not to supply a part that could be misused.

The outlet cowl has a diameter of 110mm. I searched for a similarly sized cover and discovered drainage systems have the same diameter pipe (110mm or 4 inch). Plastic Express supply a ‘105 - 115mm flexible cap” which I have found fits snuggly over the outlet cowl. It can be secured using the supplied stainless steel jubilee clip and will then stay in place while driving.

Removing the 20A fuse marked Heizung from the Electroblock prevents me firing up the boiler with the cover is in place. I tuck the blade fuse into the wiring bundle from the Electroblock to store it in the same way I keep the fuse from the solar panel when not wild camping.

 

[tonyidle]

That's a super neat and efficient solution. Never had those flies in a flue but once had so many round the door that they startled me when I opened it ?.

I have to ask though - why do you remove the solar fuse when not wild camping?

 

[Stealaway]

I cut some copper mesh up I had in the garage, an inner and outer ring. I wondered if it would interfere with the boiler operation but I've fully tested it this summer and it's been fine.

 

[WonkyBass]

I have to ask though - why do you remove the solar fuse when not wild camping?

I am referring to the fuse between the panel and the regulator.

I no longer leave my batteries constantly on charge 24/7 365 as I believe it is unnecessary and potentially damages them. When all the appliances and habitation electrics are off, I charge the habitation batteries for 24 hours and then disconnect the chargers. I monitor the habitation battery voltage with a Victron BMV700 and reconnect the chargers for 24 hours if necessary after several weeks. When we‘re travelling the alternator charges the batteries and on-site it‘s either EHU or solar.

With the panel fuse removed, if anyone were to disconnect the batteries there is no danger of the solar regulator getting fried by the panel pushing power into an unloaded regulator.

I’m no engineer. These are just recommendations I’ve read that makes sense to me.

 

[WonkyBass]

I cut some copper mesh up I had in the garage, an inner and outer ring.

That’s a sensible solution. Why can’t Truma do that within the product? Dometic fridge vents have fly screens built in.

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[tonyidle]

I am referring to the fuse between the panel and the regulator.

I no longer leave my batteries constantly on charge 24/7 365 as I believe it is unnecessary and potentially damages them. When all the appliances and habitation electrics are off, I charge the habitation batteries for 24 hours and then disconnect the chargers. I monitor the habitation battery voltage with a Victron BMV700 and reconnect the chargers for 24 hours if necessary after several weeks. When we‘re travelling the alternator charges the batteries and on-site it‘s either EHU or solar.

With the panel fuse removed, if anyone were to disconnect the batteries there is no danger of the solar regulator getting fried by the panel pushing power into an unloaded regulator.

I’m no engineer. These are just recommendations I’ve read that makes sense to me.

Understand about accidental disconnection but not about constant "charging." If the PSU and Solar Regulator both revert to float when tbe battery is fully charged (and they do) then no harm will result from permanent connection. In every installation where lead-acid batteries are on standby in case of mains failure (household burglar alarms is an obvious case) the battery is on permanent float. It is the normal state for the battery.

 

[HandyAndy]

stainless steel mesh.. cut to size, dab of sika to hold in place, screw cover on, jobs a goodun.

 

[Reallyretired]

My solar (400w) is on all the time, but doesnt seem to damage the batteries. Of course in winter may be only a few hours of daylight.
I have cooked batteries by having ehu permanently connected though.

 

[WonkyBass]

If the PSU and Solar Regulator both revert to float when tbe battery is fully charged (and they do) then no harm will result from permanent connection.

The most balanced statement I have read on this is “float charge does cause some deterioration in the cells but this deterioration is often less than the damage caused by the batteries being left in an under charged state.” Yuasa are a little stronger on the website when they state “Battery Maintenance in Non-Automotive Float Applications ... Continuous charging, even from a well-controlled charging system, will result in internal degradation of the battery”. I have replaced the worn our lead acid batteries in our continuously charging house burglar alarm and computer UPS several times but it is not practical to control the charging regime within these units.

My AGM battery headaches are thankfully well behind me now and I’m happy with Varta LFD90s which I monitor and care for but not obsessively. I aim for a regime that minimises harm and is practical for me. A failed battery can also damage chargers and the alternator.

Our motorhome is in use, on average, one day in four throughout the year including fifteen to twenty days camping without EHU. Our reliance on batteries is small but important. I frequently hear of power problems from fellow festival goers (batteries dead, alternator failed, charger not working properly) when all was well last time they used it. Most people don’t obsess about their battery systems but a bit of awareness might reduce replacement frequency, preserve the life of other components and avoid spoiling a trip.

 

[tonyidle]

The most balanced statement I have read on this is “float charge does cause some deterioration in the cells but this deterioration is often less than the damage caused by the batteries being left in an under charged state.” Yuasa are a little stronger on the website when they state “Battery Maintenance in Non-Automotive Float Applications ... Continuous charging, even from a well-controlled charging system, will result in internal degradation of the battery”. I have replaced the worn our lead acid batteries in our continuously charging house burglar alarm and computer UPS several times but it is not practical to control the charging regime within these units.

My AGM battery headaches are thankfully well behind me now and I’m happy with Varta LFD90s which I monitor and care for but not obsessively. I aim for a regime that minimises harm and is practical for me. A failed battery can also damage chargers and the alternator.

Our motorhome is in use, on average, one day in four throughout the year including fifteen to twenty days camping without EHU. Our reliance on batteries is small but important. I frequently hear of power problems from fellow festival goers (batteries dead, alternator failed, charger not working properly) when all was well last time they used it. Most people don’t obsess about their battery systems but a bit of awareness might reduce replacement frequency, preserve the life of other components and avoid spoiling a trip.

Given the widespread ignorance about batteries, charging systems,and electrical stuff in general amongst the caravanning & motorhoming community in general (not on this forum I hasten to add - it's discussed too often for that) it isn't surprising that failure occurs. You're correct that keeping a close eye on the state of batteries is vital. My use is longish trips throughout the year with a gap from November to January. My longest off-grid trip is much the same as yours. I do leave everything connected when parked at home including EHU - I did the same throughout years of caravanning - and I'm happy with overall battery life. Whatever works I suppose ?.

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[Lenny HB]

Another way if closing off the Truma vent is to wrap a piece of rope or plastic or cable piping around the gap.
You don't need to take the fuse out as it won't fire up with the vent blocked.

 

[WonkyBass]

You're correct that keeping a close eye on the state of batteries is vital.

I do leave everything connected when parked at home including EHU - I did the same throughout years of caravanning - and I'm happy with overall battery life. Whatever works I suppose ?.

We agree that awareness is the most important factor. Failing to check or notice that something is not right may cause problems when you come to rely on the batteries.

I was a “100% plugged-in at home person” for the first two years. I believed (from anecdotal evidence) that I was doing the best for the heath of my batteries. Always fully charged, always ready. My Banner AGMs started to fail, I discovered A and N Caravan Services and spent hours trying to understand a complicated subject. I no longer think constant float is the best for my batteries. I make no claim to higher knowledge here. My only “original thought“ in this is choosing which bits to follow and which to ignore. Constantly floating a battery is convenient, it might reduce battery life, a cell might fail unattended leading to more serious damage. “Might”.

 

[WonkyBass]

You don't need to take the fuse out as it won't fire up with the vent blocked.

It‘s a good reminder with no negative consequences though. And putting it in my post stops somebody claiming that blocking the Truma flue will do irreparable damage. I don’t need the hassle.