Dump Valve.

I emptied the hot water tank in our Nuevo in November by moving the dump valve to vertical. 
Today l filled the main tank on site only to find it leaking water, l checked the valve which was horizontal but when l pressed it l could hear pressure being released. I pressed it for a while suspecting an airlock but it seemed to make little difference.
The pump is coming on very regularly which makes me suspect a leak 
Any help appreciated.

Open and close it several times, tiny grit can stop it closing properly.

Paulmold wrote:Open and close it several times, tiny grit can stop it closing properly.

Many thanks for the reply Paul and sorry for my late reply to you but I have a few days in the Lake District and I am sure I don't have to tell you what the Internet is like there.
I tried your solution and it didn't work but I now suspect the filler cap that I bought last year, you jam it into the fresh water inlet and leave it to fill up the tank unattended, which it does but it builds up huge pressure in the system and blows the cap out with some force when it peaks .I suspect that the pressure has dislodged a pipe or joint somewhere. I now have to investigate in the next couple of days.

mcalid wrote:

Paulmold wrote:Open and close it several times, tiny grit can stop it closing properly.

Many thanks for the reply Paul and sorry for my late reply to you but I have a few days in the Lake District and I am sure I don't have to tell you what the Internet is like there.
I tried your solution and it didn't work but I now suspect the filler cap that I bought last year, you jam it into the fresh water inlet and leave it to fill up the tank unattended, which it does but it builds up huge pressure in the system and blows the cap out with some force when it peaks .I suspect that the pressure has dislodged a pipe or joint somewhere. I now have to investigate in the next couple of days.

Ouch - that isn't unattended. Can you not drill a vent hole in the cap hat lets the air out and emits water once the tank is full. Seems a stupid design as it stands!

inspiredron wrote:

mcalid wrote:

Paulmold wrote:Open and close it several times, tiny grit can stop it closing properly.

Many thanks for the reply Paul and sorry for my late reply to you but I have a few days in the Lake District and I am sure I don't have to tell you what the Internet is like there.
I tried your solution and it didn't work but I now suspect the filler cap that I bought last year, you jam it into the fresh water inlet and leave it to fill up the tank unattended, which it does but it builds up huge pressure in the system and blows the cap out with some force when it peaks .I suspect that the pressure has dislodged a pipe or joint somewhere. I now have to investigate in the next couple of days.

Ouch - that isn't unattended. Can you not drill a vent hole in the cap hat lets the air out and emits water once the tank is full. Seems a stupid design as it stands!

I like your thinking and it makes a lot of sense, it is supposed to release the pressure but a drilled hole would work better I think.
I am going to get to the bottom of it tomorrow when I have some time to do it and I suspect that Paulmold is probably right in identifying the dump valve as the culprit as the leak seems to be coming from that direction.
Thanks for your reply and I hope that I can be of help to you in the future.

Caraman wrote:If you are talking about filling the freshwater tank, it should have a breather at the top of the tank that allows air to escape when filling it and provide an overflow.  The breather should allow air into the tank when water is being drawn out of it into the internal water system.  This should be unrelated to the pressure of the internal water system and its dump valve.

Hi Caraman, l have had some time to investigate the problem further and l have found a leak in the shower room behind a panel which hides the piping behind it and holds the shower tap. I haven’t attempted to remove the panel as it is sealed and l don’t want to make a mess of the decor when either removing or replacing it. I can hear the water running when l turn the pump on. 
Thanks for your advice.

Possibly the shower tap water pipe connection that’s blown apart , would know how to get to it though

FreelanderUK wrote:Possibly the shower tap water pipe connection that’s blown apart , would know how to get to it though

I have every confidence that you are correct but a job for the experts I think. I can't get a repair slot with the Dealer before 1st.May, no big deal as the van is still useable but a sign of the times. I was in Braithwaite last week and it was packed at the weekend but the state of the toilets left a lot to be desired at the weekend compared to midweek...how much effort does it take to flush a toilet???