Non Return Valve

[Gagakev]

Simple to start with, is there a NRV in my Pressure Switch?
I have a Trauma Carver compact socket with pump to suit.

On last outing at Easter overnight the water barrel would refill.

Now to complicate things if there is no NRV in Either the pressure switch ot Trauma inlet, Im guessing it could be in the water heater. But think I may have damaged the heater by leaving it switched on without water, ever since our last outing last year, so it was on over christmas and 3 or 4 times when switched on at home to top up the battery.
The heater does work just to clarify.
Van is Fleetwood Sonata Symphony (Built by Adria)
Thanks folk's I know you will come up with the answer.

 

[waffler]

Do you have a drain valve by the boiler? If so there is probably a NRV. My recollection is that there is overheat protection in the boiler. Should reset itself but someone might know better than me.

 

[Gagakev]

Do you have a drain valve by the boiler? If so there is probably a NRV. My recollection is that there is overheat protection in the boiler. Should reset itself but someone might know better than me.

Hi Waffler there is a drain valve after the pressure switch looking from the outside in if that makes sense.
Thanks for reply.
Ah could be peace of mind on the boiler, great thanks,

 

[Craigyoung]

This used to happen to me on our Bailey Orion , I would forget to turn off the water heater when disengaging everything when finishing up for the weekend and returning back to going out and setting them up with everything still on water heater would come on without any water being in and would trip , I would then have to reset everything and start from scratch making sure it was switched off then for the water t be filled then switch the heater switch on .

 

[Gagakev]

This used to happen to me on our Bailey Orion , I would forget to turn off the water heater when disengaging everything when finishing up for the weekend and returning back to going out and setting them up with everything still on water heater would come on without any water being in and would trip , I would then have to reset everything and start from scratch making sure it was switched off then for the water t be filled then switch the heater switch on .

Thats the strange thing, no tripping just carried on working.

 

[ProfJohnL]

Simple to start with, is there a NRV in my Pressure Switch?
I have a Trauma Carver compact socket with pump to suit.

On last outing at Easter overnight the water barrel would refill.

Now to complicate things if there is no NRV in Either the pressure switch ot Trauma inlet, Im guessing it could be in the water heater. But think I may have damaged the heater by leaving it switched on without water, ever since our last outing last year, so it was on over christmas and 3 or 4 times when switched on at home to top up the battery.
The heater does work just to clarify.
Van is Fleetwood Sonata Symphony (Built by Adria)
Thanks folk's I know you will come up with the answer.

For a pressure switched water system to work it must have a non return valve (NRV) fitted before (Upstream) the pressure sensor. All the caravan pressure switches I have come accross do have a non return valve fitted to their inlet as part of the assembly.

If you have water returning to the water container, then the NRV in the pressure switch must have failed.

That doesn't mean there arn't other possible problems with the system, but the symptom you describe there must be a faulty NRV at the Pressure switch.

 

[Beehpee]

I’ve connected up to electric on site several times and tripped the water heater, it usually happens because the routine is, connect electric, fill the kettle from a bottle of water or mains tap and have a well earned coffee or 3, then I do everything else, then I find water heater on but not getting hot, from my experience to reset the water heater you simply switch it off wait 5 minutes or so and it resets itself, so if you connect the electric and it’s on, when you disconnect the electric it will reset itself, I don’t think you have to actually do anything, I now put a piece of black tape over the water heater switch when I pack up on site and that reminds me not to switch it until it’s filled

 

[Craigyoung]

That's the same thing I was on about in my explanation . You just need to switch off and restart . Make sure you'll bring your water through the system then switch it on .

 

[ProfJohnL]

I have given this a little more thought.

As the heater still apparently works, then the thermable fuse and temperature trips have not been operated, so that is a positive. Consequently the comments relating to elctical trips do not address your problem:- which is the water returning to the external barrel.

Pressuming the water sytems system is a standard arrangment, the water pump will either opperate by a micro switches in every tap ( all connected in parallel so any tap will power the pump) or through the use of a pressure switch, which MUST have a non return valve in circuit, and is usually part of the pressure switch assembly.

As you haven't made any mention of the pump auto cycling when all the taps are turned off ( Which it wold do if the system used a pressure switch with a failed NRV) Then I have to conclude you have micro switches in every tap and NO pressure Switch. With a Micro switched system ther is no need for the caravan water inlet to have a non return valve, becasue the cold pipe work is not kept at pressure when the taps are turned off.

When the taps are turned off not only is the power to the pump shut down, the fawcetts should seal preventing air from entering the pipes and thus preventing the water from draining back.

However the hot side is different. Because the caravan uses a 'storage water heater' typically 9 to 10 litres of water is held in a tank and heated. The heater is designed to keep a small air cap at the top of the tank that accomodates the expansion of the cold water as its heated. as this happenes the pressure in the hot side of the system increases and it is locked in the system becasue the water heater will have a Non return valve fitted in, or close to its cold water inlet pipe.

Now its a question of how much water is returning to the external tank. If its only a couple of litres maximum, then I would suspect its a cold tap thats not fully sealing when its turned off. The volume of the cold pipe work can only be abut 2L.

If its more that a couple of litres, then I would suspect its is the NRV on the cold water inlet to the heater may be at fault, and its allowing the expanded water to run back, but also we mustn't forget the air cap in the heater will also have been heated and its pressure will also expel more water. It will be even more if any of the hot taps dont seal properly.

Incidentally its not Trauma its Truma, though sometimes it can feel like a trauma.

 

[Gagakev]

I have given this a little more thought.

As the heater still apparently works, then the thermable fuse and temperature trips have not been operated, so that is a positive. Consequently the comments relating to elctical trips do not address your problem:- which is the water returning to the external barrel.

Pressuming the water sytems system is a standard arrangment, the water pump will either opperate by a micro switches in every tap ( all connected in parallel so any tap will power the pump) or through the use of a pressure switch, which MUST have a non return valve in circuit, and is usually part of the pressure switch assembly.

As you haven't made any mention of the pump auto cycling when all the taps are turned off ( Which it wold do if the system used a pressure switch with a failed NRV) Then I have to conclude you have micro switches in every tap and NO pressure Switch. With a Micro switched system ther is no need for the caravan water inlet to have a non return valve, becasue the cold pipe work is not kept at pressure when the taps are turned off.

When the taps are turned off not only is the power to the pump shut down, the fawcetts should seal preventing air from entering the pipes and thus preventing the water from draining back.

However the hot side is different. Because the caravan uses a 'storage water heater' typically 9 to 10 litres of water is held in a tank and heated. The heater is designed to keep a small air cap at the top of the tank that accomodates the expansion of the cold water as its heated. as this happenes the pressure in the hot side of the system increases and it is locked in the system becasue the water heater will have a Non return valve fitted in, or close to its cold water inlet pipe.

Now its a question of how much water is returning to the external tank. If its only a couple of litres maximum, then I would suspect its a cold tap thats not fully sealing when its turned off. The volume of the cold pipe work can only be abut 2L.

If its more that a couple of litres, then I would suspect its is the NRV on the cold water inlet to the heater may be at fault, and its allowing the expanded water to run back, but also we mustn't forget the air cap in the heater will also have been heated and its pressure will also expel more water. It will be even more if any of the hot taps dont seal properly.

Incidentally its not Trauma its Truma, though sometimes it can feel like a trauma.

Hi Prof thanks for the replies, as my first post it's defo a pressure switch system and yes I did forget to mention the auto cycle of the pump.
So after the replies and talking to a mobile caravan engineer I have the two NRV's to check, first one on the inlet and the 2nd on the pressure switch. I do actually carry a spare pressure switch if it is required.
I'll let you know when I have had time to take a look and if all that fails I will insert an inline NRV.
Thanks again.

 

[ProfJohnL]

Hello again Kev,

Give the latestest revalation about the auto cyling, then yes you have a pressure switched system.

Generally I rate PRV's to be more reliable than microswitched systems, they are certainly easier to work on as its only one set of contacts to worry about, and they are generally more accessible thn teh undersides of taps..

But back to your problem.

Not all water inlet fittings have a Non return valve, so you will have to research yours a bit more. But without any doubt the pressure switches NRV must have failed if water is able to return to the external tank. And my reasoning about the quantity of water still holds true, so if its more than about 2L then it's quite likely the NRV on the water heaters has also failed.

Assuming we have explained the symptom and identified the culprits, the next question is why have two NRV's failed. Two possible answers come to mind:-

The first is that the water systems was not fully drained over winter, and some residual water actualy froze in the NRV's causing them to be damaged. This was certainly one of frequent cause of failure of the Carver Cascade NRV's.

The second thing that comes to mind, is if you have or have had a carbon based filter in the supply, If the filter is not changed each season, there is a danger it will detriorate and the packing that holds the carbon granuals in place has broken down and allowed some of the granuals to escape the filter and lodge in the NRVS, and preventing them from sealing.

Best of luck