Inverters and truma - techies please

Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
A question for techs please.

our heating/hot water is delivered via Truma. A couple of years ago we had an inverter installed, which I am very happy with. Last year our water and heating wouldn’t work on electric but happy to work on gas. no codes have been displayed on the truma. On investigation, it has been found that the motherboard and element aren’t working for the electric side of things. The thing that I’m being told is that truma don’t like inverters and that in all probability that once remedied probably will happen again. This information has been apparently been given from Truma and that Pure Sine wave inverters Can cause problems. This I am very sceptical about. So have been told that when completing the job he will bypass the inverter. Can anyone shed light on the probability of this being the cause? we have two lithium’s, battery master etc. The only time I would use the inverter for heating is giving it a boost when using gas if off grid. I m so confused. Yes we can just use gas. Van is 2013 vintage
 

funflair

LIFE MEMBER
Dec 11, 2013
14,660
18,836
Guisborough
Funster No
29,351
MH
MORELO palace
Exp
since 2012
My understanding that a good pure sine wave inverter produces power just like the mains BUT it is possible that all inverters are not equal and even some listed as pure sine may not actually be as clean as they should be, is your inverter a good name?
 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
Whilst I appreciate that you would like to use Electric for heating, the Gas system is far more efficient at doing the job.

I wouldn't use an inverter to top up the heating and would rely on Gas only.

Subscribers  do not see these advertisements

 
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
Whilst I appreciate that you would like to use Electric for heating, the Gas system is far more efficient at doing the job.

I wouldn't use an inverter to top up the heating and would rely on Gas only.
In fairness, we usually do this Emmit, It would only be on the odd occasion to use as top up, for a quick blast. And only when batteries can be topped up. We do use it whilst on hook up.
 
Last edited:
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
I bit the bullet, have decided to go with replacement of element and motherboard but to leave the wiring as is. They’d planned to put in a separate circuit for the truma that would only allow electric bit to work off mains only Thus bypassing the inverter. the mechanic seemed to think that the inverter wasn’t pure sine wave. I’ve had clarification by the installer that it is.

My initial question says truma poss Pure sine wave being the cause, this isn’t the case it was a modified sine wave that can cause problems. apologies, this was clarified by mechanic that they advise to use pure sine wave.

Subscribers  do not see these advertisements

 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
Sorry, Confused.
Are you saying that when you are 'Off Grid' your system does not provide blown air through your 12v when you are using Gas as a heating source.

I note that you have a Hobby. Our last van was a Hobby 650 ( Reg.2007) and, after a couple of minutes of starting up the Gas heating, we had what we called 'The Jet Engine' that was the 12v Blown Air coming in.

It sounded like a Jumbo Jet was parking up next door.
 
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
Emmit, at the moment, we have gas water and heating, the blown air does work but not as you suggest-the jet engine- this used to happen but not since realising that the electric side of the truma wasn’t working on electric at all.

ours should works on, either, gas or electric or combination of both.
 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
If I've got this right, once upon a time, when you were off grid, you put on the gas heating and, a short time later, the system provided blown air via a fan that was provided by 12 v.

2. However, something went wrong with the electric side however you found that you could still get the fan to work by the use of the Inverter ie 240v

Ill leave it at that. Can you respond to the above and we'll take it further.

Subscribers  do not see these advertisements

 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
I've reread your original post.
Next question.. Has your Inverter been hard wired into the van (meaning that, whenever you are off grid, your van is supplied with 230v via the Inverter)
 
Jul 5, 2013
9,586
9,778
Tunbridge Wells
Funster No
26,797
MH
A class
Exp
Since 2013
Are you referring to using the inverter to supply mains electrics to the Truma so that you can use electric heating when not connected to a electric hook up? In that case it will not work, or at least not for very long. The Truma uses 1800 watts. That means that a bank of two 100Ah leisure batteries would last for about half an hour at most before they gave up the ghost. And do that a few times and the batteries will be permanently knackered.

If you means that the mains heating is not working when you are on hook up, it will probably be because the elements have failed.
 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
peterc10,

Even with the Lithium batteries he has fitted, (thought he'd written that and took me ages to find it again) I agree with you, using the batteries to fire up the fan won't last long and leave him/her with expensive knackered paperweights, oops? batteries.

Subscribers  do not see these advertisements

 
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
The inverter has to be on to supply electric to the van From EH. it also charges two lithium’s. Electric side of truma worked on both EH and off gird until we were on a rally. I realise that using the electric side will deplete batteries, so wasn’t really used as such, but should I need a quick boost I would have put the combi part, ie gas with a boost of electric to get van warm from cold. For the most part when heating is needed we have EH during the coldest winter months. However, whilst on a rally- July/Aug time last year, with EH, the electrics blew and since then we haven’t had the electrical hot water or heating side of the truma. Ie no water or heating via electric only. We have the fan working but not as powerful as has been in past. whilst on EH we only use gas to get van to temp then use electric only for keeping van at optimum temp. we would use this method the majority of the time as electric has been paid for. Hope this clears up how we use the van.

Van has gone to the repairers, they are saying that the element and motherboard- electric side only, are dead. He also said that truma advised that their equipment doesn’t like non pure sine wave inverters, and very probable that that was the cause of fault. He said to prevent it happening again we should bypass the sine wave(not pure sine wave) by giving it its own direct feed and fuse box. extra £500 too I found out later. Our inverter is a victron 2kw pure sine wave, I have had this confirmed by the company who put the inverter in. However the mechanic says it doesn’t say Pure Sine wave on the box so can’t be. Even though I said I have an email confirming that it is. I just thought it a bit odd That he said it wasn’t a pure sine wave.

After all this we have said that We will have the element and motherboard replaced but not have the direct line and fuse box and assume the risk of it happening again.

Neither hubby or I are techie, that’s why I came asking peeps on here but seem to have confused everyone. Hope this clears up the confusion.
 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
"The inverter has to be on to supply electric to the van From EH. it also charges two lithium’s."

Can you explain the above. Does EH mean electric heating?(just worked this out. You mean EHU)

"it also charges two lithium’s."???
This phrase is baffling me. I assume that your van has two leisure batteries which are lithium. Are you saying that you are charging these batteries with an Inverter that is using power from??? where?
It would be lovely if it were possible but charging batteries with an inverter that is itself being powered by those same batteries is against a law in.... something? Electrical.
 
Last edited:
Dec 2, 2019
1,042
2,288
Amersham
Funster No
67,145
MH
van conversion
Exp
I'm a newbie
The inverter has to be on to supply electric to the van From EH. it also charges two lithium’s. Electric side of truma worked on both EH and off gird until we were on a rally. I realise that using the electric side will deplete batteries, so wasn’t really used as such, but should I need a quick boost I would have put the combi part, ie gas with a boost of electric to get van warm from cold. For the most part when heating is needed we have EH during the coldest winter months. However, whilst on a rally- July/Aug time last year, with EH, the electrics blew and since then we haven’t had the electrical hot water or heating side of the truma. Ie no water or heating via electric only. We have the fan working but not as powerful as has been in past. whilst on EH we only use gas to get van to temp then use electric only for keeping van at optimum temp. we would use this method the majority of the time as electric has been paid for. Hope this clears up how we use the van.

Van has gone to the repairers, they are saying that the element and motherboard- electric side only, are dead. He also said that truma advised that their equipment doesn’t like non pure sine wave inverters, and very probable that that was the cause of fault. He said to prevent it happening again we should bypass the sine wave(not pure sine wave) by giving it its own direct feed and fuse box. extra £500 too I found out later. Our inverter is a victron 2kw pure sine wave, I have had this confirmed by the company who put the inverter in. However the mechanic says it doesn’t say Pure Sine wave on the box so can’t be. Even though I said I have an email confirming that it is. I just thought it a bit odd That he said it wasn’t a pure sine wave.

After all this we have said that We will have the element and motherboard replaced but not have the direct line and fuse box and assume the risk of it happening again.

Neither hubby or I are techie, that’s why I came asking peeps on here but seem to have confused everyone. Hope this clears up the confusion.
Your mechanic doesn’t know much about inverters and sine waves. Tell him, even if it doesn’t says on it, is detailed in the manual. The victron 2kva inverter charger is one of the finest pure sine wave inverter you could find on earth. Tell him that you use a oscilloscope to see the quality of a sine wave, not the writing on the chassis.
What you need to do is go into settings of the inverter with a mk3 interface and change setting. You need the relay ground ticked in the box so it’s active off grid. This will give you a true neutral and your boiler will work better than grid power. I live on victron power off grid in the house and the van. And my boilers are working fine, along with many sensitive equipment. You need to activate the ground relay so the PE earth is bonded to neutral.

Subscribers  do not see these advertisements

 
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
Eh = electric hookup
Emmit, I don’t fully understand it all. The lithium feeds the inverter. That I do know. We have solar too And I know that these charge the batteries, but I also thought with the inverter and battery master that they get charged when on hookup. The inverter has a switch that allows for sending charge to batteries so I thought the batteries can be charged via inverter, I thought this being the case, you can flick the switch the other way and it sends the power from the inverter to the items in van. I am willing to be corrected, but that’s my limited understanding of it. I or my hubby are not technical hence the questions.

Raul, yes this is what I believed to be the case, the reason choosing the installer and system. I’m getting really messed up now with what charges what.

All I know is I trust the installer, it works as I’ve been told It would. My batteries get charged as I expect, through which of the gubbins installed I’m unsure BUT I will find out. I found it disconcerting that the technician (not the original installer) didn’t realise that it was a pure sine wave and that he planned on bypassing the inverter to prevent it possibly happening again based on advice from truma, based on the technician saying that the inverter is not a pure sine wave. I was originally asking, albeit badly, whether anyone had heard that the inverter could be the culprit for the frying of just certain elements of a motherboard and element. I’ve now found out after insisting that the inverter is a pure sine wave and based on what the technician said, the inverter couldn’t have been the cause. The technician has been put right!
 
Last edited:

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
Got that.
What powers your Inverter?
How many leisure batteries have you got and what type and size.
 

eddievanbitz

Trader - Funster
Oct 4, 2007
6,686
26,410
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
"The inverter has to be on to supply electric to the van From EH. it also charges two lithium’s."

Can you explain the above. Does EH mean electric heating?(just worked this out. You mean EHU)

"it also charges two lithium’s."???
This phrase is baffling me. I assume that your van has two leisure batteries which are lithium. Are you saying that you are charging these batteries with an Inverter that is using power from??? where?
It would be lovely if it were possible but charging batteries with an inverter that is itself being powered by those same batteries is against a law in.... something? Electrical.
It is an inverter charger.

When your on hook up it is an 80 amp Multi stage battery charger
When there is no hook up it is an inverter
When there is hook up and you require more power than the hook up can give you, it "makes up the difference"

Simple! ;) (y)

Subscribers  do not see these advertisements

 

Emmit

LIFE MEMBER
Aug 14, 2009
5,301
8,726
Cornwall
Funster No
7,967
MH
Burstner A Class
Exp
Jan.2014
eddievanbitz

Can I borrow your crystal ball. Yours is working better than mine lol.
The OP asked (or seemed to suggest) the same problem in December. He/she got two responses but didn't make any comment.
See:"Truma-anyone experienced this fault? (below)
 

eddievanbitz

Trader - Funster
Oct 4, 2007
6,686
26,410
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
eddievanbitz

Can I borrow your crystal ball. Yours is working better than mine lol.
"it also charges two lithium’s."???

This phrase is baffling me. I assume that your van has two leisure batteries which are lithium. Are you saying that you are charging these batteries with an Inverter that is using power from??? where?

It would be lovely if it were possible but charging batteries with an inverter that is itself being powered by those same batteries is against a law in.... something? Electrical.
I thought that I'd explain it to you :giggler:
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
29,428
50,899
On the coast in West Sussex
Funster No
658
MH
Hymer B678 Dynamic Line
Exp
Since 2008 & many years tugging
Well that's a first I've never heard of anyone trying to do that before, normally when wiring an inverter it should be wired so the fridge, charger and heater can not be powered by the inverter.
Your comment about using the inverter to charge the batteries is a big no, all you will do is flatten the batteries.


FYI.
Trumer C6 Combi max ouput:
Electric 1.8 kw.
Gas 6kw
Gas + Electric 5.5 kw.

Subscribers  do not see these advertisements

 

eddievanbitz

Trader - Funster
Oct 4, 2007
6,686
26,410
Taunton Somerset
Funster No
540
MH
RV
Exp
since 1989
Well that's a first I've never heard of anyone trying to do that before, normally when wiring an inverter it should be wired so the fridge, charger and heater can not be powered by the inverter.
Your comment about using the inverter to charge the batteries is a big no, all you will do is flatten the batteries.


FYI.
Trumer C6 Combi max ouput:
Electric 1.8 kw.
Gas 6kw
Gas + Electric 5.5 kw.
It is an inverter charger, with shore assist.

"If" the total demand of the camper is greater than the hook up available, the Victron will stop being a charger, immediately reducing the demand on the hook up, and switch to invert mode making up the difference to avoid tripping the external supply (hook up)
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
29,428
50,899
On the coast in West Sussex
Funster No
658
MH
Hymer B678 Dynamic Line
Exp
Since 2008 & many years tugging
Thanks for that eddievanbitz but I am buoyed by Lenny HB s comments that this is so niche a fitment, (Well, it is to us mere mortal, average motorhomers) that we have gone numb in a cold 'van (pun intended) trying to help.
A lot of installers install the inverter with a changeover relay to switch the vans electrics between the inverter and the EHU input. They then tell the customer to switch off the charger, and only run the fridge & heater on gas. Customers often accept this as it makes the installation cheaper.
If the job is done properly you wouldn't need to do this.
I wired my inverter and changeover myself and spent the time rewiring the mains so only the mains sockets switch over to the inverter. My fridge & charger will only work from mains when connected to EHU, my heater is gas only.
 
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
eddievanbitz

Can I borrow your crystal ball. Yours is working better than mine lol.
The OP asked (or seemed to suggest) the same problem in December. He/she got two responses but didn't make any comment.
See:"Truma-anyone experienced this fault? (below)
No need, Eddie‘s company installed it. I asked back in December but its only now that we’re having the work done due to lockdowns and problem finding. I beleive, but will check that I thanked everyone or their contribution Back in Dec. I am a women always have been so you can refer to me as a she🤪lol
 
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
A lot of installers install the inverter with a changeover relay to switch the vans electrics between the inverter and the EHU input. They then tell the customer to switch off the charger, and only run the fridge & heater on gas. Customers often accept this as it makes the installation cheaper.
If the job is done properly you wouldn't need to do this.
I wired my inverter and changeover myself and spent the time rewiring the mains so only the mains sockets switch over to the inverter. My fridge & charger will only work from mains when connected to EHU, my heater is gas only.
No, I have not been told to do this.

Subscribers  do not see these advertisements

 
Last edited:
OP
Caggsie1
Sep 2, 2013
851
4,180
North Wales
Funster No
27,897
MH
Hobby
Exp
Since 2008
why? the implication, maybe got the wrong end of the stick here, is that it’s an inferior installation. I am aware that using fridge and heating whilst not on hookup is detrimental, I do however, should I want to I can. So why would the installer have to tell me to turn stuff off to give me a cheaper install? As a rule I wouldn’t have it on in the first place. I like the system I have, it works for our usage, I switch it on enroute to charge batteries, switch over on arrival, if on EH I’ll use it all, if not it’s automatic to switch stuff over to gas. If on 6amp I can use my kettle and heating without it tripping I just switch the dial to 16amp and everything works as should.

Subscribers  do not see these advertisements

 
Top