hbarnett Posted June 11, 2009 Share Posted June 11, 2009 We are currently on holiday in our van in Spain, the water pump failed. I obtained a replacement and fitted. I then realised the old pump had a built in non-return valve. I fitted an inline nrv. Now, the cold water runs fine but the hot water needs to bleed air as if the water pipes are draining back to the tank. Therefore we have no hot water, can anyone guide me to find a solution to this problem. Kings regards Howard Link to comment Share on other sites More sharing options...
Guest peter Posted June 11, 2009 Share Posted June 11, 2009 Sounds like you've got an air leak somewhere. Because once you've bled the pipework and shut off the tap the water should stay in the pipe, because there is no air to replace the water that's in the pipe. If that makes sense. The pump only pressurises the cold supply to the heater, which in turn displaces the hot water when you open the taps. Much like a domestic imersion heater system. Is it a pressure pumped system or a submersible with micro switches on the taps? Link to comment Share on other sites More sharing options...
hbarnett Posted June 11, 2009 Author Share Posted June 11, 2009 thankyou for this response, the pump is a submersible type with micro switches on each tap, the non return valve holds the water in the pipes, when the tap is open to select cold water the flow is instantaneous, when hot is selected the air escapes and takes a long time before water flows? :-( :-( Link to comment Share on other sites More sharing options...
hbarnett Posted June 11, 2009 Author Share Posted June 11, 2009 the problem is very much like when in cold weather the frost protection valve opens and the water drains out of the system, when the valve is re set it takes a little while for the air to be expelled out of the pipes. Link to comment Share on other sites More sharing options...
Brian Kirby Posted June 11, 2009 Share Posted June 11, 2009 I know it may seem a bit obvious, but is there any possibility that you have installed the nrv in a position where it prevents drainback in the cold water side only, but does not prevent drainback from the water heater supply? Link to comment Share on other sites More sharing options...
hbarnett Posted June 12, 2009 Author Share Posted June 12, 2009 the original pump had the nrv built into the outlet, i have installed an inline nrv as close to the pump as was practically possible and prior to the pump failure everything was fine. Link to comment Share on other sites More sharing options...
BrianR Posted June 12, 2009 Share Posted June 12, 2009 hbarnett - 2009-06-12 6:51 AM the original pump had the nrv built into the outlet, i have installed an inline nrv as close to the pump as was practically possible and prior to the pump failure everything was fine. I am puzzles by this statement, as surely this must make it impossible to drain the cold water pipes to prevent them freezing when laid up in the winter. In my 'van the non-return valve is in the feed to the water heater, so that the cold water pipes drain back through the pump when the fresh wayer tank is emptied and the hot water pipes drain through the water heater drain valve. Sorry to ask this, but are you absolutely sure? The non return valve is there to prevent the water from the water heater getting into the cold water pipes. When the fresh water tank is full there is no "drain back", even without a non-return valve. Link to comment Share on other sites More sharing options...
hbarnett Posted June 13, 2009 Author Share Posted June 13, 2009 Hi brian, I get your point about the frost protection, my van has a stat valve which opens when the temp drops below it's set point. Being that this valve is lower than the pump outlet, i hope that when open it does drain the pump outlet. it doen't drain back to the tank though, but through a pipe to outside. After saying this, I have finally cracked the problem, the valve was aflappy rubber type i bought from a marine chandlers. There was not a sufficient head of water to properly seal this flap, I visited a Motorhome dealer in Cambrills who was able to supply me with a ball type NRV which now works perfectly. I guess the moral of this story is, make sure you get a proper replacement. Thanks everyone H Link to comment Share on other sites More sharing options...
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