My first post on this forum :) We recently acquired our first motorhome (2012 Avan) that has a Truma Gas/Electric HWS. It heats up fine and when using the 12V pump it delivers hot water. BUT, when I turn off the pump and connect to external water (hose) I only get cold water (both on cold and hot water settings). Previous owner had ordered a new water pressure reducing valve (where you plug the hose into) as his service person believed that to be the problem. I installed that and no difference. I am on NSW south coast (Batemans Bay) and service people are hard to get onto (they don't answer phone) and one in Ulladulla can book it in for April. Not sure if local ARB can fix it but will ring them tomorrow. Anyone else had this problem so I can give "whoever" looks at some direction? I have attached photo if that helps.
I doubt that ARB could diagnose a fault in a plumbing system - They do suspensions and 4X4 parts. You will need to ensure your water hose is connected to allow water through - many have a one way valve at tap connection end. After ensuring water supply, turn pump off and make sure you have flow at internal taps -set taps to full hot, if no flow then you have a blockage/obstruction - turn off hose water and disconnect inlet to heater and check for flow again - if no flow you have a faulty valve/restrictor in plumbing somewhere.
Test your system bit by bit to locate problem.
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Possum; AKA:- Ali El-Aziz Mohamed Gundawiathan
Sent from my imperial66 typewriter using carrier pigeon, message sticks and smoke signals.
The 12V pump is working on house batteries (not gas or 240V)
Yes, the taps work on mains. All taps flow cold when connected to mains even if they are fully in hot position. When on pump (mains disconnected), they all flow hot in hot position and cold in cold position.
Can't see if water is going into boiler.
Thanks for the questions, hope this clarifies my issue?
It doesn't appear I have a blockage. When usng 12V pump (via house batteries), I have cold water in cold position and hot water in hot position (hot water has been heated using 240V connection).
When I turn off pump and connect hose (mains), I have cold water in cold position and cold water in hot position.
The 12V pump is working on house batteries (not gas or 240V)
Yes, the taps work on mains. All taps flow cold when connected to mains even if they are fully in hot position. When on pump (mains disconnected), they all flow hot in hot position and cold in cold position.
Can't see if water is going into boiler.
Thanks for the questions, hope this clarifies my issue?
Fraser, I'm a knobhead for not re-reading my post.
I meant to ask what is the HWS on (gas or 240V) when using the 12V pump..........I take that the water is hot as you said it is working fine.
So when you connect the mains water on......what source are you using to heat the HWS ? Gas or 240V ?
I'm trying to ask if you are using the same power source as the pump.
Something very odd if cold water coming through with tap in hot position (on mains) as that would mean water bypassing heater - I suspect a blockage or a misdirection of plumbing - A little food colouring (dye) added to inlet can be used as a reliable trace.
It may be that the plumbing has been "iffy" since manufacture - They are built by day labour in most instances ( ie unskilled labour).
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Possum; AKA:- Ali El-Aziz Mohamed Gundawiathan
Sent from my imperial66 typewriter using carrier pigeon, message sticks and smoke signals.
Very interesting observations and suggestions. The vehicle (though 10 years old) has only done 55,000km and had 2-3 owners. Interestingly the cold water hose looks very new (unused) which means it is actually new or has virtually no use. It is possible (though I would have thought unlikely) that the previous owners only ran HWS off the pump and it was the person I purchased from who found it didn't work through mains connection hence he ordered the new water pressure reducing valve thinking that might fix it. I will examine the water connection diagram in the manual to what is actually installed and see if I can identify a mis-installation as you suggest.
EDIT: I have looked at the connections best that I can as it appears some of it is under the flooring. The only place the hot and cold appear to come together is at the RMC Heatguard (see attached). So, I am wondering if the Heatguard is either faulty or isnt handling the pressure from the mains connection and the cold water is just being forced through the unit and not mixing with the hot water from the boiler? As mentioned, I installed a new pressure reducing valve so I am not sure how I would test that other than having the mains tap down so low to mimic the 12V pump pressure? Else maybe the heatguard is faulty (though I do get hot water when using the pump). Any thoughts on the above. Also photos attached.
-- Edited by fraserp on Wednesday 26th of October 2022 11:48:19 AM
It sounds like the HWS is only operating when the 12v pump is operating and a separate system is utilized when connected to the mains, ie to use the HWS, you have to use the 12v pump.
Unfamiliar with your set up - can you put some food dye in system to see if it is going into tank or bypassing it - use pressure relief to see if coloured water gets into heater tank.
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Possum; AKA:- Ali El-Aziz Mohamed Gundawiathan
Sent from my imperial66 typewriter using carrier pigeon, message sticks and smoke signals.
Hi
What is the clear pipe feeding, having hot (untempered) water through that would panic me
What ever its feeding does hot water come out of it . If not plumbing problem upline, if hot water flows boiler and plumbing ok
I would remove the tempering valve (temporarily ( or permanent if no small kids)) failing that just follow the pipes and keep disconnecting and reconnect as best you can
Regards Gerry
NB once all sort consider changing that clear pipe for reinforced pipe
On looking at the picture it would appear that the clear tube is the inlet from the mains . please check where this clear pipe is coming from. if so it is plumbed incorrectly.
If it is the inlet from the mains. The clear tube should go to the blue pipe which is the outlet from the pump into the heater and tempering valve The red pipe is the hot water out from the heater. If cold water is introduced via the clear tube eg mains .You will only get cold water as this bypasses the heater when switched to mains. When switched to pump you will get hot water as this clear tube is off line . Hope you can understand .
On looking at the picture it would appear that the clear tube is the inlet from the mains . please check where this clear pipe is coming from. if so it is plumbed incorrectly. If it is the inlet from the mains. The clear tube should go to the blue pipe which is the outlet from the pump into the heater and tempering valve The red pipe is the hot water out from the heater. If cold water is introduced via the clear tube eg mains .You will only get cold water as this bypasses the heater when switched to mains. When switched to pump you will get hot water as this clear tube is off line . Hope you can understand .
Gary
The clear pipe looks to me as some sort of overflow from the hot water coming from the boiler, is that red device some sort of relief valve and the clear tube probably goes outside the vehicle.
Should be a junction of two blue pipes feeding one for the cold inlet, I can see the blue pipe feeding the boiler and the tempering valve. Need to look further back along the line Fraser.
I have the same boiler, but slightly different pipework
Unfortunately I can not take a pic of mine, without dismantling the bed
It appears to me that as the outside water line, produces much more pressure than the pump The cold water may be going straight through your pressure/temperature valve
Don't worry about the clear hose, mine is the same and my boiler was made in 2006, or thereabouts
I would be trying to adjust the pressure/temperature valve If that does not work, then I would be using the pump only, until a plumber could check the system out
Hope that this pic of your pic, can explain it a bit better
Let us all know the final outcome, as it may help others in the future
Thanks Tony...... excellent markups on the photo :)
Texted the previous owner again and he advised the tempering value is brand new. Spoke to RMO Heatguard and they thought if it was working on pump then it should be OK and it is likely to be a pressure problem elsewhere (?). I'm also not sure how it adjusts as the top just seems to spin around. I will google instructions for it.
So, it could be the inline "pressure reducer" which I have shown in attached photo as circled in yellow.
For an installation like this, is a regular plumber recommended or do I need to book into a RV service place?
You mentioned previously about using food dye. Given the situation, do you have any suggestion about the best way to go about this? Obviously dye into the mains end, but what order of hot or cold tap on or off would you think would give best result?
I would progress from inlet to taps in segments where you can open flange or guest fittings.
Dismantle at heater inlet and ensure coloured water gets to that point first section. Once pipework is open you could add granular dyes or use syringe to squirt liquid dye in tubing. Potassium permanganate (condy's crystals) granules would turn water purple and is safe we used to use it to sanitise our tank water back in the day, can be purchased at the big green shed. IGA or Coles should have food colouring in their baking aisles.
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Possum; AKA:- Ali El-Aziz Mohamed Gundawiathan
Sent from my imperial66 typewriter using carrier pigeon, message sticks and smoke signals.
A quick update. I have finally found a plumber that will look at it, hopefully on Monday. I did a bit more testing this morning to try to determine if it was a pressure issue. I turned the pressure on the external hose to a very very very slow rate (roughly equivalent to the rate that comes out of the sink). To my surprise, nothing changed. Cold water still came out of the tap when on the full hot setting. BUT (and this was an oversight on my part as I hadn't test this), when I turned the tap to full cold, the flow slowed to a virtual trickle/nothing.
So, I doubt it is going to be a pressure problem. Seems more likely a wrong connection or a major problem with the tempering valve, which apparently was recently replaced by previous owner who was also seeking a solution.
I will update once (hopefully) the plumber finds an answer. Very weird .... and it is doing my head in a bit.
An update to this water issue after a plumber investigation. Once I described the "symptoms" he immediately said that there is a crossover of plumbing and "somehow" the external cold water is connected to the hot water line. He confirmed the diagnosis by disconnecting the tube at the external connection point (ie at the water reducing valve where the hose connects to the outside of the MH. When 12V pump was turned on, hot water was collecting in his tub indicating that hot water was being pumped back down the cold water line. The problem is, this dodgy connection is not visible and must be under the floor somewhere. So, his suggestion, without pulling the flooring up to find to crossed connection, is to abandon that external point and install a new one on the other side of the MH where it can be correctly connected into the cold water line on the correct side of the pump. It's not ideal but I can't think of a better option. Anyone else got any thoughts?
