Brian Peters Posted July 4, 2009 Share Posted July 4, 2009 hi all, i have just cleaned out my fresh water system and pipe work, flushed and filled with fresh water ready for summer use.The problem is that my dump valve is opening causing the system to drain down. The solenoid holds it closed when my Electroblok controller is switched on but as soon as i switch it off, out pours the water. I do not want to leave my electroblok unit on all of the time as doing so fried my old unit and i had to get a replacement. Is there any way of keeping the solenoid activated with my Electroblok switched off or do i have to go down the clothes peg route to hold the valve closed. many thanks in advance. Brian. Link to comment Share on other sites More sharing options...
trooper Posted July 4, 2009 Share Posted July 4, 2009 Just a slight concern, I would have left the fresh water tank empty until just before travelling for health reasons, we always fill on travelling and empty on getting home, I may have misunderstood you posting. Link to comment Share on other sites More sharing options...
Brian Peters Posted July 4, 2009 Author Share Posted July 4, 2009 Hi Trooper, I always leave a bit of water in my tank just before we go away as i dont want to have to bleed the system every time we reach our destination, I never drink from my fresh water tank, only used for washing, and touch wood ive never been affected by its contents in 5 years, but having said that ive never had swine flu before either,lol. thanks Brian. Link to comment Share on other sites More sharing options...
jenkothewanderer Posted July 4, 2009 Share Posted July 4, 2009 Hi in my experience the dump valve should not rely on the electroblok being switched on to remain closed. It should be wired direct to a 12volt supply and should only activate when temperature drops to 4 degrees c or lower. It may also dump if voltage drops too low, can you put a voltmeter across terminals and check. Jenko Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 5, 2009 Share Posted July 5, 2009 As jenko advises, Truma's electrically-operated safety/drain valve (dump valve) should - for obvious reasons - have a 'continuous' 12V power supply. If no (or insufficient) power is available at the valve, then it won't stay closed and the only realistic option then is to jam it shut in the time-honoured way. The dump-valve used for the latest crop of Truma "Combi" heating appliances is non-electrical. If I remember correctly, this valve is designed to open when the temperature near the valve drops to 3°C. Once open, the valve will refuse to stay closed until the temperature near the valve attains 7°C. As there's no direct electrical link between valve and heater, switching the heater on to allow the valve to be closed - as is possible with C-Series heaters having the electrically-operated dump-valve - is a non-starter with the non-electrical valve. There is an optional 12V heater for the latest dump-valve to permit it to be closed irrespective of the air-temperature near it, but I guess most people will resort to the jamming technique. Link to comment Share on other sites More sharing options...
Brian Peters Posted July 5, 2009 Author Share Posted July 5, 2009 thanks for as usual, all the helpful comments, i will see if i can get any reading from my volt meter. thanks again for all responses. Brian Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 5, 2009 Share Posted July 5, 2009 Derek Uzzell - 2009-07-05 9:02 AM ............. As there's no direct electrical link between valve and heater, switching the heater on to allow the valve to be closed - as is possible with C-Series heaters having the electrically-operated dump-valve - is a non-starter with the non-electrical valve. ................ DerekAre you sure about this? With the C series units, was it not the facility to run the heater without water heating that made it possible to get heating, even when the water jacket was empty? By doing this, the heater unit (almost invariably) warms the space where the dump valve is installed, so allowing the valve to be closed and normal service to be resumed. At least, that is how I read the Truma operating instructions.Will this not be equally true for dump valves with no electrical connections?However, it seems quite clear the present problem with this heater is with the battery charge and not the temperature. The heater/water heater will not operate at a voltage below 10.5V, so either the habitation battery is below that voltage, is shot, is disconnected (or has corroded terminals), the charging fuse has blown, or the Electroblok isn't charging it. The Electroblok should monitor battery voltage, and disconnect below 10.5V to prevent permanent battery damage. However, I seem to remember the dump valve by-passes this system so will continue drawing current until the battery is totally flat. For this reason, I think it unwise to keep the mains disconnected for much more than a week at a time. If it has just been re-connected, I guess it is possible the high initial charge to a flat, or nearly so, battery may have resulted in a blown fuse. Link to comment Share on other sites More sharing options...
DESCO Posted July 5, 2009 Share Posted July 5, 2009 Hi Brian. I have a C-series heater, and it is possible to run the heater without water heating, I have done this on numerous occasions. It will heat the area around the manual dump valve and allow it to be reset I would think never had it dump yet in anger Dave Link to comment Share on other sites More sharing options...
Brian Peters Posted July 5, 2009 Author Share Posted July 5, 2009 hi Brian, I dont think my lesuire battery is at fault as it is virtually brand new and showing good vaults on my control panel, i also have a solar panel to keep things topped up. It may be fused related but i dont understand why when my Electroblok is ON my dump valve is ok, but as soon as i switch it off, it starts to dump out???. Brian Link to comment Share on other sites More sharing options...
vindiboy Posted July 5, 2009 Share Posted July 5, 2009 Small point, the dump valve only allows the water heater to drain and not the storage tank or pipe work, so don't rely on it to protect your system from frost, far off I hope. *-) *-) Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 5, 2009 Share Posted July 5, 2009 Brian Peters - 2009-07-05 7:06 PM hi Brian, I dont think my lesuire battery is at fault as it is virtually brand new and showing good vaults on my control panel, i also have a solar panel to keep things topped up. It may be fused related but i dont understand why when my Electroblok is ON my dump valve is ok, but as soon as i switch it off, it starts to dump out???. Brian It sounds as though the dump valve is being controlled via the Electroblok, which it should not be. Has this happened only since your new Electroblok was installed? If so, I'd suspect the wiring of the new unit. Link to comment Share on other sites More sharing options...
Earthmover Posted July 5, 2009 Share Posted July 5, 2009 Hi, Your heater may be different in operation to mine?, But reading the destructions in the Truma book, It says that you MUST first switch the Heater/Water switch ON, then pull UP the automatic release Valve, It will then stay closed, when you release it. If I have drained the system between trips, the wife switches the heater on and I pull up the switch, she immediately switches the heater off and the system is re-filled with water. If you don't switch the heater control ON, first, then the release valve will continue to TRIP. That is what it says in the book , and it works for me. I think a lot of people have not read the book and resort to a peg?. Em. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 6, 2009 Share Posted July 6, 2009 Let's start from Square One... 1. Let's assume that a motorhome is fitted with a C-Series Truma combination air/water heater with the electrically-operated safety/drain valve. 2. Let's assume that the safety/drain valve has a 'continuous' (and adequate) 12V power-supply as advised by Truma. 3. Let's assume that the C-Series heater is empty of water and needs to be filled, and that the drain valve is open. 4. If the air temperature where the safety/drain valve is installed in the motorhome is above 8°C, then the valve's control-knob can be lifted to its 'closed' position and the knob will remain in that position allowing the heater to be filled with water. 5. However, if the air temperature where the safety/drain-valve is installed is 8°C or lower, when the valve's control knob is lifted to the closed position it will refuse to stay there and will drop back down to the 'open' position. This will, of course, prevent the heater being filled with water. 6. If the valve's control knob won't stay in the closed position because the air temperature near the valve is too cold, then the heater can be switched on. Doing this immediately overrides the valve's temperature-sensing feature and, irrespective of the air temperature near the valve, provided that the heater is switched on then the valve's control knob, when lifted to the closed position, will remain there, thus allowing the heater to be filled with water. This is covered in the "Filling the water heater" section of Truma's Operating Instructions for C-Series heating appliances: "Close electrical safety/drain valve at the control knob by lifting up. Attention: At temperatures of around 8°C and less, switch on the heater or water heater first, to make sure the valve does not open again!" To recap, if the air temperature near the safety/drain valve is above 8°C, there will be no need to switch on the heater before filling it with water as the drain-valve's control knob, when lifted to the closed position, will stay in the closed position. On the other hand, if the air temperature near the safety/drain valve is 8°C or less, the valve's control knob, when lifted to the closed position, will immediately re-open by dropping back down. To allow the heater to be filled with water, the heater will then need to be switched on (or the safety/drain valve will need to be jammed in the closed position). The reason Earthmover's technique has worked so far is presumably because, when he has been filling his Truma C-Series appliance with water, the air temperature where his motorhome's safety/drain valve is installed has always been high enough for the valve to remain in the closed position (at least 4°C for recent C-Series appliances according to Truma). If this had not been the case, then, when his wife switched the heater off, the drain valve would have re-opened. It needs to be emphasised that the electrically-operated drain valve's temperature-sensing feature is only overridden as long as the heater remains switched on: as soon as the heater is switched off the drain valve will revert to temperature-sensing mode and, if the air temperature at the valve is below 4°C the valve will open. It's probable that most motorcaravanners who "resort to a peg" are fully familiar with Truma's Operating Instructions, but consider the way the safety/drain valve functions to be more of a nuisance than a benefit. Myself, I'd prefer a simple manually-operated open/closed valve (as I chose to have on my previous motorhome), but, as my Hobby came with an electric valve, I'm not going to mess about replacing it. I just treat the electric drain valve as if it were a manual valve and jam it shut from when I am about to fill the heater with water to when I want to drain it. Link to comment Share on other sites More sharing options...
Brian Peters Posted July 6, 2009 Author Share Posted July 6, 2009 thanks again for all the info. most helpful as per usual. Brian. Link to comment Share on other sites More sharing options...
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