Truma dump valve problem (1 Viewer)

[Steve Travelvan]

My van is an Adria 600SP and has an in tank water pump. The water pump is working, the one way valve above it is working correctly but no water comes out of the taps. If I operate the Truma frost protection valve by turning the switch on the top the water in the system is dropped. If I then turn the switch on the top a few times and then close the valve water is pumped, the system fills and the taps work. After a while if I try the taps again the pump runs but no water gets to the taps. Does all the pumped water go through the Truma dump valve before getting to the taps? If so the problem must be the dump valve and I will need to dismantle it or am I missing something? Thanks.

 

[Landy Andy]

If your dump valve is open, and your pump operates the water will tend to flow out of that instead of through your taps.
You will get water appearing under the van if this is the case.
To turn the valve off fully you have to operated button, and turn the lever on top.

 

[Landy Andy]

In reality the dump valve is dumping water that has come from your boiler so just your hot water, as it’s job is to protect the boiler, not the full plumbing system.

There is no reason that I can think of that if your dump valve is shut that, if the pump operates you wouldn’t get water, especially cold, through your taps.

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[Steve Travelvan]

Thanks Andy Landy, that is exactly my understanding of the system, that the drain valve drops the water in the boiler and won't interfer with the water flow to the taps. The water is flowing to the taps OK now but it was doing this yesterday but didn't work this morning until I opened and shut the drain valve a few times.

 

[Speve]

If your pump is working and no water out of taps or dump valve you need to check that you don’t have a joint come apart and you are pumping water inside of the van you will have water coming out somewhere

 

[Steve Travelvan]

Thanks Speve, there is no water emerging elsewhere that I can see. The pump is running but from the sound it makes it is not pumping and could over heat. I switch it off before it is damaged. I had wondered about an airlock but the pump produces a very strong jet of water when disconnected from the pipework.

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[Duck Truck]

If the pump is pumping water strongly when disconnected from the pipe work just place your finger over the jet coming out?
does it still pump water strongly?
If yes then you have a problem somewhere within the rest of the water system
If the pump doesnt pump strongly with your finger over the jet of water
it maybe that the diaphragm in the pump has a split in it pumping water OK when no rsistance.
hope this helps

 

[Landy Andy]

Am I understanding this correctly

Sometimes you turn a tap on, the pump runs, but no water comes out of the tap, or appears under the van?

 

[Steve Travelvan]

Yes that's correct Andy Landy. It's a small submersible impeller pump Duck Truck and is producing a lot of pressure.

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[Duck Truck]

ahh Ok

 

[Landy Andy]

The system is a pressurised system, so not using the microswitchs in the taps.

So the system must sense the pressure drop and cut in, so some water or something must come out, and then the common items are pump, pump pickup, oneway valve, then to a T where water would split between hot and cold. So if you are happy with pump, the next common item would be the one way valve.

All that is based on a pressurised system

 

[Landy Andy]

Then thinking again pump, in tank probably a mircroswitch system, so must be pump, pump pick up, one way valve.

Can you bypass the one way valve to test?

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[Duck Truck]

sounds like you may have an air leak into the system
it pressurises at first
So water comes out
then as air leaks in the pressure is lost
I think you need to follow the pipe work from the pump
you may well find just a slight leak

 

[Duck Truck]

is this a new fault?

 

[Steve Travelvan]

The pump is activated by the micro switches in the taps and is a simple pumped system. I have fitted a new one way valve as I thought that the original one had blocked but I don't think that it was the problem. I wasn't aware there was a problem until recently and I can't remember the different steps I have taken. I took the one way valve out of the system and water flowed out of the taps OK but the next day although the pump was running there was no water at the taps. Recently each time this has happened I have operated the dump valve and the system then worked as normal. I will see what happens in the morning, each time that I have tried it today after the failure this morning it has worked. The pipes are under the floor and can't be traced. Thanks for your helpful suggestions Landy Andy and Duck Truck. I will post an update tomorrow. We are not going anywhere until September.

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[TheTwoOfUs]

Probably a stupid question but when you say that you have closed the dump valve have you pushed the button in on the valve after turning the knob on the top?

 

[Steve Travelvan]

Yes, I know that trick having once dumped a lot of water on the frozen ground outside the office at Gerrands Cross campsite when we filled up the water tank on arrival. We were then snowed in for three days.

 

[BouncyBoatFolk]

sounds like you may have an air leak into the system
it pressurises at first
So water comes out
then as air leaks in the pressure is lost
I think you need to follow the pipe work from the pump
you may well find just a slight leak

Not sure if this will help, but I had a similar problem recently, the pump would pressurise the system, but not a lot of pressure flow. Left for a couple of minutes it would need to re-pressurise the system again. I thought I had an air leak somewhere. However, after checking the pump within the water tank I noticed the connection hose to the pump [ the stiff plastic one ], which passes through the removable screw access cap had slightly dropped down of the spigot pipe . All I had to do was push it back firmly onto the spigot pipe passing through the cap, et voilà, fixed, and cheaply. I had ordered another pump, just in case, fortunately not needed yet, which was also just as well as the clowns I ordered it from on Ebay sent the wrong one, despite their info showing the correct one .
Mike

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[Steve Travelvan]

Thanks for that BouncyBoatFolk, the joints are all good. I bought a new length of pipe and remade them. One of the 90 degree push fits was leaking but this was the result of the pressure from the pump when the water couldn't go anywhere. I now have a new 90 degree push fit. I always carry a spare water pump having had two fail over the years.

 

[Duck Truck]

so?
is it still not working

 

[Steve Travelvan]

I haven't checked this evening, will try again tomorrow.

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[scotzsue]

Can I resurrect this thread. We are getting water from our taps both from hot and cold side, no apparent air locks, but when we turn the taps off the pump continues to run and water comes out the dump pipe, doesn't seem to matter which tap we use either. But difficult to check on my own. Thinking back we got a mini explosion of hot water last week from the kitchen tap, but the fault was already there.
Hope that makes sense to someone other than me.

 

[Steve Travelvan]

I had a problem with my pump but that was that it would run but it wouldn't pump water. It is a submersible pump and I found that by banging it on the side of the tank it would start pumping water. It was a new pump and this could have been due to an air lock or a sticking non return valve. The problem hasn't occurred again. I am afraid that I have no suggestions regarding your problem.

 

[scotzsue]

Thanks Steve Travelvan will start a new thread.

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[Coolcats]

In reality the dump valve is dumping water that has come from your boiler so just your hot water, as it’s job is to protect the boiler, not the full plumbing system.

There is no reason that I can think of that if your dump valve is shut that, if the pump operates you wouldn’t get water, especially cold, through your taps.

All the water is dumped in our Hymer cold and hot systems, it’s not just the boiler it’s protecting it’s the whole system. In reality there is also the manual drain down which ask require a send valve to be opened but the automatic system does do a pretty good job

 

[Reallyretired]

All the water is dumped in our Hymer cold and hot systems, it’s not just the boiler it’s protecting it’s the whole system. In reality there is also the manual drain down which ask require a send valve to be opened but the automatic system does do a pretty good job

This also happens on my Hymer, whether by accident or design. The boiler dump valve drains the boiler and presumably siphons the water from the cold tank too. This didn't happen on the previous Rapido unless the pump was on.

 

[Landy Andy]

The frost valve is only fitted to the pipework after the boiler, so unless pump is on it normally will only drain boiler. it shouldn’t be able to drain all the tank as there is a breather on the boiler to stop siphoning and allow vent.

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[Coolcats]

This also happens on my Hymer, whether by accident or design. The boiler dump valve drains the boiler and presumably siphons the water from the cold tank too. This didn't happen on the previous Rapido unless the pump was on.

I wonder if this is one of those small considerations and benefits of Hymer design, I have seen from other posts for example when filling the Water tank it has to be done slowly or water can back up and flow out of the inlet pipe, on our MoHo the water inlet is straight and there is no need to worry about water backing up.