Mick H. Posted April 10, 2009 Share Posted April 10, 2009 Anybody out there know where I can get a layout plan for the water pipes in a Hymer 694.Got a funny prob, and before I toddle off to Truma for a boiler check,I thought I would see if the pipework setup might give me a clue. Mick H. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 11, 2009 Share Posted April 11, 2009 Mick Good luck with your quest, as I've yet to see a useful water-system layout-diagram for a motorhome. I've always believed that motorhome designers specified where the water 'appliances' went and Joe Bloggs or Hans Orff, who was building the motorhome in the factory, then ran water-hoses between those appliances using a route that was easiest for him, irrespective of whether that route was logical or sensible. You might try describing your problem on the forum, just in case someone can offer an explanation. Truma equipments are essentially straightforward and, if the problem is external to your boiler (presumably a version of Truma's C-Series combination air/water heater), you could save some cash. If you do want comments, it would be helpful if you provided the model-year of your Hymer and the exact model (B-694SL?): also the Truma boiler's model-type (C-6002?) Link to comment Share on other sites More sharing options...
Mick H. Posted April 11, 2009 Author Share Posted April 11, 2009 Hi Derek.Thanks for input. I guessed as much with the pipe plan. My van is a 1998 Hymermobil 694 Why B69400 Serial no.10 98 30 12.The boiler system is a new Trumatic C 6002 EH fitted in November 08.Has worked brilliant with electric or gas.The prob with the water supply is the sump pump is working ok.(Have removed it from pipes and it blasts water.)but the water doesnt come out the taps as it should. The cold side is about half of what it should be, the hot is a not much at all, but whichever tap I open, on the hot or cold side all three are the same, the cold water from the pump goes on through to the truma boiler and flows out the overflow.Are all three taps blocked,on hot and cold side?Is there some kind of diverter built into the system that sends the cold supply either to the taps or to the boiler.Could this be creeky.Have noticed recently that the system was drawing a little air and the water didnt flow immediately Any advice will be gratefully received. Mick H. Link to comment Share on other sites More sharing options...
lennyhb Posted April 11, 2009 Share Posted April 11, 2009 Check the non-return valves there will be at least 2 one in line with the cold feed to the boiler & one in line with the loo (this one shouldn't have any effect on the problem) there may be one after the pump. Also check for a kinked pipe it doesn't take much to reduce the flow at the taps as the pumps aren't very powerful. From new the shower pressure in our van always seemed a bit on the low side, after doing some additional wiring & had to move the water pipe from the tank about a bit to get my cables through the shower pressure has improved considerably. Link to comment Share on other sites More sharing options...
Mick H. Posted April 11, 2009 Author Share Posted April 11, 2009 Hi Lenny not wishing to be thick but where would I locate the non return valves seeing that there is very little pipe showing.Also do you know if it is poss. to isolate the boiler so that I could use something a bit caustic through the cold water part of the system to try and dislodge any illegal immigrants. Mick Link to comment Share on other sites More sharing options...
lennyhb Posted April 11, 2009 Share Posted April 11, 2009 I don't think there is any way to isolate the boiler. The valves will just be inline somewhere but where? It's just a case of feritting around the one for the boiler is usually close to the cold water inlet on the boiler. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 12, 2009 Share Posted April 12, 2009 Mick I assume that your motorhome has the usual Hymer arrangement of a 'submerged' water-pump in the fresh-water tank and that the pump is triggered by micro-switches on the taps. Despite your having confirmed that the water-pump seems to be working OK, this is still the most likely culprit in my opinion, especially if the pump is the original and now 11 years old. Your test will have been with the pump running 'free' and will not necessarily reveal its pumping efficiency when it has to move water under pressure through narrow-bore pipework. As submerged pumps are relatively cheap and easy to install, I'd be tempted to replace your present pump with a new one and see if that removes the problem. Even if it doesn't, you will have removed the prime suspect from the frame and you'll have the old pump as a functioning spare. If the pump proves not to be the cause of the low water-pressure, then the logical deduction is that there is some sort of obstruction to the water-flow between the pump and where the pipework branches to feed either the cold taps or the hot-water heater. As lennyhb advises, such an obstruction might be caused by a partially-closed non-return valve. Non-return valves are often integrated into a submerged water-pump's casing, or separate but attached to the pump. As the purpose of the valve is to prevent the water in the pipework from siphoning back into the fresh-water tank through the water-pump, they are normally positioned as close as practical to the pump itself. Of course that doesn't mean there won't be a non-return valve elsewhere! Your observation that water does not flow immediately from the taps and that air gets into the system suggests that a non-return valve may not be functioning properly. Kinked hoses used to be a common problem in the days when hoses were not reinforced. It is certainly worth checking for, though I think the type of hose used by Hymer in 1998 will have been pretty resistant to kinking. If a kink in the hose has developed, I would have expected that you might have noticed a gradual deterioration in water pressure as the hose deforms. (You haven't said whether the reduced water-pressure problem has suddenly become evident or has been worsening over time.) I'm perplexed by your statement that "the cold water from the pump goes on through to the truma boiler and flows out the overflow", as Truma C-Series appliances don't have overflows. Perhaps you mean "drain valve", though this should be 'upstream' of the heater to be effective. It's possible (I guess) that, when the drain valve(s) in your Hymer's water pipework are closed, something within a drain valve (a swollen seal?) is partially obstructing the flow in the pipework. It's unlikely that all the taps and the pipework leading to them are similarly 'gunged up', so I don't think introducing 'drain cleaner' into the water system will be worthwhile. However, if you wanted to try using a cleaner, then I suggest you fill just the cold-water side of the system (as this will minimise the amount of cleaner needed to carry out the test) with a strong solution of wine-vinegar and leave for 24 hours or so before flushing out. It would be simple enough to isolate your C-6002EH by detaching its input hose and plugging the hose's open end (that assumes, of course, that you can reach the heater's inlet to do this!!), but there's really no need. Fill the system completely with water, making sure all air is vented, then - with all taps firmly shut and the water-pump immersed in your 'cleaning solution' - open and close the COLD-water taps sequentially allowing enough time for the solution to feed through to each tap in turn. As long as the hot taps remain closed the solution will be unable to enter the hot water side. In any case, if you use wine vinegar, even if it did get into the boiler it would do no harm. Me, if I couldn't spot anything obvious and if it's difficult to inspect all the pipework, I'd just replace the water-pump and pray to Saint Aquarius for a miracle cure. Link to comment Share on other sites More sharing options...
Mick H. Posted April 12, 2009 Author Share Posted April 12, 2009 Derek Uzzell - 2009-04-12 9:36 AM Mick I'm perplexed by your statement that "the cold water from the pump goes on through to the truma boiler and flows out the overflow", as Truma C-Series appliances don't have overflows. Perhaps you mean "drain valve", though this should be 'upstream' of the heater to be effective. It's possible (I guess) that, when the drain valve(s) in your Hymer's water pipework are closed, something within a drain valve (a swollen seal?) is partially obstructing the flow in the pipework. Me, if I couldn't spot anything obvious and if it's difficult to inspect all the pipework, I'd just replace the water-pump and pray to Saint Aquarius for a miracle cure. Hi Derek. No, not the drain valve. The pipe I'm referring to is on top of the hot water outllet, like an expansion pipe on a domestic system.Also with regard to not opening hot taps when flushing the system to avoid cleaner going through the hot tank, even with only the cold taps open the water is still going out the expansion pipe on the boiler. Perplexed, Mick Link to comment Share on other sites More sharing options...
Mick H. Posted April 12, 2009 Author Share Posted April 12, 2009 Another idea I have had and please tell me if you think it won't work is to drain the system, remove the cold water inlet to the boiler,remove the hot water outlet from the boiler and joining these two pipes together, thus removing the boiler from the system and then running some strong cleaning fliud through the pipes without tainting the boiler.Then obviously flushing with copious amounts of clean water. So what do you think. Mick. Link to comment Share on other sites More sharing options...
Mick H. Posted April 12, 2009 Author Share Posted April 12, 2009 Just to confirm the pipe that the water is flowing out of the boiler Here is picture of same. Link to comment Share on other sites More sharing options...
lennyhb Posted April 12, 2009 Share Posted April 12, 2009 Hi Mick, Just had look at the installation in my van & can see the overflow pipe you are referring to. Had a look at the installation instructions on the Truma website and the connection it goes to (T connector with the hot feed) is described as a venting valve. From this I would assume it is pressure relief valve if it is & it is stuck open it could be your problem. Pump turns on water flows through the boiler & out the venting valve which would also reduce the pressure at all the other outlets . Link to comment Share on other sites More sharing options...
Mick H. Posted April 12, 2009 Author Share Posted April 12, 2009 Had me really excited there Lenny,been out and taken said venting valve off. all it is, is a T connector with nothing built in. The pressure valve as you describe would I think have to be like a two way tap that either feeds the hot supply or if problem goes to outlet. Mick Link to comment Share on other sites More sharing options...
lennyhb Posted April 12, 2009 Share Posted April 12, 2009 Worth a try, must work just like a domestic system with an open vent. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 13, 2009 Share Posted April 13, 2009 Mick The water reservoir of a Truma C-Series heater/boiler is a closed pressure-vessel that neither needs, nor can have, an 'overflow'. However - exactly as lennyhb says - these appliances do have a 'vent valve' assembly and that's what the "soft plastic" hose in your photo is attached to. The vent-valve assembly is not mentioned in C-Series Operating Instructions, but it is (again as lennyhb advises) referred to in the "Water Connection" section of the Installation Instructions together with an exploded-view diagram showing its component parts. The vent-valve assembly comprises 1. An outer plastic 'T-piece' that carries the heater's hot-water output hose on the T's downwards-pointing arm. On the other upwards-pointing arm is a soft plastic 'breather hose' (as arrowed in your photo) that curves through 180° before exiting through the motorhome's underside. 2. An inner plastic nut that can rotate on the heater's metal hot-water outlet-stub. This nut screws on to the horizontal threaded-section of the T-piece. 3. A vent-valve component (carrying an O-ring) that fits within the assembled nut + T-piece and is clamped firmly to the heater's metal hot-water outlet-stub when the nut is screwed tightly on to the T-piece. The purpose of the vent-valve assembly and its breather-hose is to allow air to enter the heater's water reservoir when the heater's electrical safety/drain valve opens to protect the appliance in freezing weather conditions. Think about an inverted bottle of water with its neck placed beneath the surface of a bowl of water. As no air can enter the bottle it will not drain, and that would be the same for a C-Series heater if there were no vent-valve. During 'user draining' a tap would be opened deliberately to allow air to enter the heater's water reservoir, but obviously that won't be the case when the safety/drain valve opens spontaneously to protect the heater from frost damage. The vent-valve is designed to have two modes of operation. During normal heater usage (when the reservoir is full of water) the valve remains shut, preventing air from entering the water reservoir via the breather-hose and stopping water from entering the breather-hose from within the water reservoir. When the safety/drain valve opens to protect the appliance from freezing-up, the 'weight' of the water in the boiler 'sucks' the vent-valve open permitting air to enter the boiler via the breather hose and allowing draining to commence. At no time should water flow from the boiler through the breather-hose in any quantity (though it's not uncommon to see the occasional air/water bubble passing through the breather-hose when the boiler is being filled with water). As you have sufficient water passing through your heater's breather-hose to make you think it's an overflow, then the vent-valve is plainly malfunctioning. And there's no doubt that this will produce the low water-pressure symptoms you have described. I've never seen the internals of a Truma vent-valve in the flesh, so I'm not exactly sure how it works (and I'm not taking my own C-6002EH's valve apart to find out!) The principle is probably quite simple - like a loose ball-bearing - and, if you remove the nut + valve from your heater, you may well be able to establish without much difficulty how it functions. If your valve is just stuck open (rather than being defective) removing it, poking at it, cleaning it (etc.) then refitting the whole assembly to your heater may encourage it to work as Truma intended. Otherwise, you'll need to obtain a replacement valve from Truma. This should be no problem as I'm pretty sure the valve is standard for all C-Series appliances since the Year Dot. Link to comment Share on other sites More sharing options...
Mick H. Posted April 13, 2009 Author Share Posted April 13, 2009 Hi Derek. Thank you for that but as I said before I have taken the T piece off the top of the boiler and all it is, is a T piece connector with nothing inside. Wheter there was and it has gone I don't know.I shall carry on the investigation today. Mick Link to comment Share on other sites More sharing options...
lennyhb Posted April 13, 2009 Share Posted April 13, 2009 Hi Derek, Interested to know where you found the info on the vent valve as I always like to know how things work, always useful when things go wrong when you are miles from anywhere. I had come to the conclusion that it could not be an open vent if it was the pipe would have to go upwards and be above the highest outlet. It must have some type of valve, I was thinking along the lines of a pressure relief in the event of the boiler overheating. As you say it must be a faulty valve & like you I'm not going to poke about on mine. As the boiler is only a few months old I wonder if has been defective from new & Mick has only recently noticed the problems. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted April 14, 2009 Share Posted April 14, 2009 Mick I thought I made it clear in my description of the vent-valve assembly that the 'T-piece' (ie. the part you have removed from your boiler) is just that - a simple T-shaped plastic part with a male-threaded body that a plastic 'nut' screws on to, and with a breather-hose connected to the T's upwards-facing arm and a hot-water hose that feeds the hot-taps connected to the downwards-facing arm. When you remove the T-piece and examine it, there will be nothing inside it because the vent-valve component itself will (hopefully!) still be attached to the boiler's hot-water outlet. When installing the vent-valve assembly on the boiler, the 'nut' is slid over the boiler's hot-water outlet 'stub', the vent-valve component is slid on to the stub, the body of the T-piece is slid over the vent-valve component, the 'nut' is screwed on to the T-piece's body (to hold the 3 parts together), and the breather-hose and hot-water hose are then attached to the top and bottom arms respectively of the T-piece. This process is explained in Truma's Installation Instructions that also carry a drawing of the vent-valve assembly's various parts. I'm trying not to be censorious, but, if you haven't bothered to look at the Installation Instructions (downloadable via www.truma.com) and are just relying on intuition, there's a strong chance that you are going to get things wrong. lennyhb I don't recall how I know about the vent-valve's functioning - perhaps Truma told me in the dim distant past. There's nothing documented about this in Truma's 'user literature' as far as I'm aware. The following advice is included my C-Series Installation Instructions document: "Attention: To ensure that the water contents are completely drained, always use the elbow connection with integrated vent valve at the hot water connection." So it's not that hard, I believe, to deduce what the vent-valve is for. (I notice, on checking the Installation Instructions for Truma's Ultrastore boiler range, that similar advice is given and that the same vent-valve assembly is employed.) If the vent-valve on Mick's boiler had been defective, or malfunctioning, from the onset, then it's fair to assume that the problem he has sought advice on would have been evident from the beginning too. With low water-pressure at cold taps, virtually no pressure at hot taps and water emerging from beneath the vehicle, it would have been immediately obvious that something was amiss. (One of the more frustrating aspects of playing Agony Aunt on motorhome forums is that people rarely say whether a problem has suddenly become apparent or has been around for a while. In this instance I've chosen to assume Mick's motorhome's water system was functioning OK but now is not.) It's possible (I guess) that, in removing the T-piece, Mick has somehow dislodged the vent-valve component from the boiler's output 'stub' and it has fallen off, but then the 'nut' + T-piece would be loose on the stub and, when the boiler's water-reservoir was being filled, water would be spurting out from around the outlet, not just exiting through the breather-hose. Another possibility (I suppose) is that Mick's experimentation with the vent-valve assembly has managed to break off the outer part of vent-valve component, or to lose/damage the O-ring seal. If all the requisite parts of the vent-valve assembly are present and visually undamaged, but water continues to flow through the breather-hose, then the vent-valve component will need attention/replacement. According to Truma's Installation Instructions, internal pressure within a C-Series water reservoir during the heating phase can be up to 3.5bar (51psi approx.). A higher pressure (resulting, say, from the appliance continuing to heat the water beyond its design maximum-temperature cut-off point) should cause the over-pressure device integrated in the Truma safety/drain valve (electrical or manual versions) to react to relieve the excess pressure. I don't know how the safety/drain valves do this, nor whether 'jamming shut' a Truma electrical safety/drain valve (as many right-thinking motorcaravanners - including me - habitually do) compromises its over-pressure functionality. I've never heard of a Truma boiler actually 'boiling' its water, but the possibility is clearly there and, consequently, it makes sense to use a genuine Truma safety/drain valve as a precautionary measure. As a general aside, Truma used to combine Operating and Installation Instructions into a single document, but, with more recent appliances, the two instruction-sets are separately documented. The result is that buyers of new motorhomes with Truma appliances tend to be given Operating Instructions (if they are lucky!), but not Installation Instructions. It's well worth having the latter, if nothing else to check how well (or badly) the motorhome manufacturer has installed the Truma appliance. Operating and Installation Instructions can normally be downloaded from the Truma main website, or Truma(UK) will usually be in a position to post hard-copy versions to you if you e-mail them and say what you want. Link to comment Share on other sites More sharing options...
Mick H. Posted April 14, 2009 Author Share Posted April 14, 2009 Hi Lenny hi Agony aunt. Many thanks for your input over the weekend.I found one severely blocked tap which has been cleaned along with the system excluding the boiler.With regard to how long this been happening it was only over a couple of weeks that the water took a second or two to come through but no loss of power at the taps.But at the end of the day I bow to superior intellect that yes there should be a two way float in the hot outlet T piece but I think why it dissapeared was the tap was blocked and the pressure build up with excessively hot water killed it. So You are right Derek Which has been confirmed by Truma, Who by the way fitted it,and a new T piece with valve is in the post. Many many thanks Mick. Link to comment Share on other sites More sharing options...
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