Truma UltraRapid Hot Water System problem

Submitted: Saturday, Dec 07, 2019 at 12:04
ThreadID: 139399 Views:7203 Replies:6 FollowUps:13
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Ive posted this on an other forum but wanted to get it sorted ,so put it out there in search of someone who might know what to do!

Im search if anyone with knowledge of Truma UltraRapid Hot Water Systems. Ive had on going issues with mine since new and it now its out of warranty.

It works fine on AC. Often it will work fine on 12v but about 40% of the time it doesn't light on 12v/gas. I get initial sound of the system lighting then after 30 seconds lots of ticking as if trying to light again then the red led fault light comes on.

Ive had the van in the get checked but each time the system worked fine, one of the major issues with fault is the fact its so intermittent. I do find the it more regularly seems to work after we have driven, and tends to stop working after we have been parked up for a while . Although this is not completed consistent.

Ive had the gas pressure checked at the bottles and its all good, but I've heard it should be checked at the HWS though.
Ive tested the voltage at the HWS during the lighting process and it remains the same as the battery voltage (over 12v)
The vent cap is off
The wind isn't an issue
There is water in the tank

Thanks
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Reply By: Allan B (Sunshine Coast) - Saturday, Dec 07, 2019 at 12:37

Saturday, Dec 07, 2019 at 12:37
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Paul,

That sounds very much like insufficient 12v at the heater. The fact that it is more reliable soon after driving but then fails after being parked signals this. Your battery is being charged whilst driving so its voltage is at its best for a while after stopping, then drops away. This may also be a sign of a poor battery and the current-carrying capacity of the wiring to the heater can play a part. The fact that it works fine on ac also supports this.

I know that you observe "over 12v" at the heater but I still question if this is correct. How accurate is your voltmeter? Can you compare it to another one?
Re the "over 12v" you have observed...... is this reading obtained whilst the heater is actually "ticking", that is, with the heater load on the battery? With a freshly charged battery you should be seeing at least 12.5v

It is also possible that the heater is needing more voltage than "over 12v" and when using mains power the ac-dc component of the heater is providing this higher voltage so it then works OK, but fails on the possibly lower voltage when operating from the battery. Measuring voltage on the downstream side of the 230v to 12v component would check this.


Cheers
Allan

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Follow Up By: Paul W33 - Saturday, Dec 07, 2019 at 20:53

Saturday, Dec 07, 2019 at 20:53
I don't see why my voltmeter would be incorrect. I wrote over 12v as each time I test it it is slightly different voltage, sometimes 12.4 and sometimes over 13v.



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Reply By: RMD - Saturday, Dec 07, 2019 at 12:43

Saturday, Dec 07, 2019 at 12:43
Paul
I haven't seen inside a Truma unit but it sounds like the flame detector isn't always telling the circuitry there is a flame and so it won't continue or run the main burner either. The gas pressure would be the same as the reg pressure and probably is checked while running. Is it possible to view the flame detector for obstruction or dust etc. That may be not be detecting flame and so switches off the gas. Being intermittent. Are you able to see if it does in fact light up then stops and retries?
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Dec 07, 2019 at 12:58

Saturday, Dec 07, 2019 at 12:58
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How do you account for....... "It works fine on AC" ?

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Allan

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Follow Up By: bobsabobsa - Saturday, Dec 07, 2019 at 13:36

Saturday, Dec 07, 2019 at 13:36
AC side would be via 240 volt element nothing to do with 12 volts
Bob
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Follow Up By: Allan B (Sunshine Coast) - Saturday, Dec 07, 2019 at 13:59

Saturday, Dec 07, 2019 at 13:59
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Ah yes Bobsa, I assumed from Paul's post that it was fully gas with either 230v 0r 12v for controls. I now see that it uses an element for 230v heating, not gas.
Nevertheless my comments still apply except the last paragraph.
Apologies also to RMD.

Cheers
Allan

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Follow Up By: Paul W33 - Saturday, Dec 07, 2019 at 20:55

Saturday, Dec 07, 2019 at 20:55
Ill look into it too see if I can see the flame.

Thank you.
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Reply By: bobsabobsa - Saturday, Dec 07, 2019 at 14:10

Saturday, Dec 07, 2019 at 14:10
Low gas pressure is listed as a cause of red lamp failures after approximately 30 seconds, but marginal gas pressure can cause intermittent red lamp failures at any time. The manual recommends 2.75kPa for Propane, which would have to be checked by a gasfitter.

Why not try a new regulator if you can, sound like gas pressure to me
bob
AnswerID: 628999

Follow Up By: Crusader - Saturday, Dec 07, 2019 at 14:53

Saturday, Dec 07, 2019 at 14:53
We were having the exact problems you have described. A gasfitter told me almost word for word what bob has said above. We had the regulator replaced and ...bazinga .... problem no more.
Its certainly worth trying.

Cheers
C
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Follow Up By: Paul W33 - Saturday, Dec 07, 2019 at 20:56

Saturday, Dec 07, 2019 at 20:56
That is an option, is it possible for a regulator to work intermittently? I know the Truma unit is sensitive to a particular pressure range.

Thanks
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Follow Up By: RMD - Sunday, Dec 08, 2019 at 10:33

Sunday, Dec 08, 2019 at 10:33
Low gas pressure/delivery could mean NO Flame and so the flame detector says keep trying to light. Either obstruction or no gas means no flame detection to me.
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Follow Up By: Ron N - Sunday, Dec 08, 2019 at 21:09

Sunday, Dec 08, 2019 at 21:09
Mud dauber wasps have been known to be responsible for blocking up gas lines if you happen to leave the gas bottles or lines disconnected for any period of time.

Cheers, Ron.
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FollowupID: 903708

Reply By: Dave B18 - Saturday, Dec 07, 2019 at 19:37

Saturday, Dec 07, 2019 at 19:37
Technically your Truma is definitely not out of warranty under Australian consumer law. Your Truma infact has Statutory Warranty which Consumer Affairs in your state I would expect the unit to be good for service for a minimum of three years and would expect five years. Consequently your unit is definitely not out of warranty by Dometic or your caravan manufacturer. Tell your caravan dealer to fix the Truma unit to your satisfaction otherwise you will proceed to Consumer Affairs who will back you up 100%.
There may also be an issue with a kink or bad connection to undersize piping on the hot water system. Being a Truma a faulty oxygen sensor wouldn't be out of the question either.
AnswerID: 629008

Follow Up By: Paul W33 - Saturday, Dec 07, 2019 at 20:58

Saturday, Dec 07, 2019 at 20:58
Thanks Dave

That interesting, Ill get back onto Domectic.
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Reply By: Member - pedro1 - Saturday, Dec 07, 2019 at 23:04

Saturday, Dec 07, 2019 at 23:04
These units have had there problems, you will find Domectic have passed the baton onto another company. Dust in the area around the air inlet have caused some of these problems, Give a good cleanout with a blower vac. Try turning it on after dark and watch what is happening through the outside vent.
Other things to look out for is loose connectors on the PC board , loose PC board in its female connectors
Broken capacitors on the PC boards and fine leaks caused by expansion of the boiler welds when water is hot .
All the above caused by corrigations and dust -
" They are not made for constant or off road conditions" - quote from the service agent !
AnswerID: 629015

Follow Up By: Dave B18 - Sunday, Dec 08, 2019 at 19:55

Sunday, Dec 08, 2019 at 19:55
These Truma hot water systems overall have been highly reliable when installed correctly, and mains pressure water not used. Tanks that have never been subjected to mains pressure have never failed. They don't fail from the mains pressure, but from hydraulic ram in the water lines. Never had a PC board fail or any other issues. The only time people have other failures like oxygen sensors is because they travel with the outside cover off.
Sadly these Truma hot water systems are much maligned, and unfairly so. The Truma hot water system in my own vehicle has survived the worst roads and tracks and is 13 years old. Take the cover off, flick the power on, and away it goes - always fires up first ignition sequence. Has never been on mains pressure and never travelled with the cover off.
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FollowupID: 903705

Follow Up By: Member - pedro1 - Monday, Dec 09, 2019 at 00:30

Monday, Dec 09, 2019 at 00:30
Dave - you must have a good one, I have seen three different gas only models used in the same vans over the last three years --- ( none are connected to mains ) - in early 2016 vans it was the grey version , then later that year the black version ( both spot welded ) then the later version (spun welded ) with a relief valve -
The service agent told me the water in Qld and WA created problems as well as the spot welding.
My current one, which is a replacement for a previous one under warrranty, now has corrosion around the relief valve outlet. The current service people say that it is not a warranty issue till it leaks !
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FollowupID: 903711

Reply By: Mikee5 - Sunday, Dec 08, 2019 at 16:25

Sunday, Dec 08, 2019 at 16:25
You do not say if the gas ingites then goes out, or if the gas fails to ignite at all? Mine is not a Truma but will ignite the go out, it will then try to reignite and I can hear the sparker clicking. Usually this is caused by dust or dirt even wasp nests in the flame tube or adverse wind. A good blow with compressed air mostly gets it working.
AnswerID: 629021

Follow Up By: Dave B18 - Sunday, Dec 08, 2019 at 20:00

Sunday, Dec 08, 2019 at 20:00
If you have a Suburban you MAY either have an incorrect flue assembly, or an incorrect door - or both that caused ignition problems. The incorrect flue is not easy to identify without a picture, and the incorrect door is easily identified by small rectangles. You can just see the large rectangles on this door, which is the correct door.
https://www.caravansplus.com.au/6270aaw-suburban-outer-door-frame-vented-p-3788.html
The incorrect doors and flues should have been replaced under warranty. I have a spare correct door lying around brand new. Had no idea they were such a price. Think I will stick it on eBay.
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FollowupID: 903706

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