Water Question

[Ian_374227936]

I have just bought my first caravan and I think I am having a problem with the hot water, the cold is fine when you turn on the tap you get a nice strong stream of water but when you turn on the hot it starts out very strong and then in a mater of about 10 - 15 seconds dies to a dribble and continues like this until you turn it off and then after you leave it for a while it is the same again starts off strong and then fades. The pump is a Whale and when you turn it on it doesn't stop! I know I am new to this but I would have thought when it has filled the hot water tank it should stop or it will just kill the battery. Any suggestions on what to look at or try would be greatfully received.

Cheers,

Ian

www.terrileeracing.co.uk

 

[Val & Frank]

Hi Ian

What van do you have and what's the model ???

Val & Frank

 

[metz]

Hi Ian, If you have a carver cascade water heater fitted in your van then the chances are the non-return valve on the heater is breaking down.As you look at the back of the heater in the van it's the bottom right connector,it will need replacing.

 

[Ian_374227936]

Hi Thanks for the replies. It's a 1990 Elddis Cyclone GTX. Water heater is a Carver but must be a little different as I found the non-return valve under the outside cover, it looks ok but do they look ok when they are no good? Can I test this some how?

Ian

 

[ProfJohnL]

Hello Ian,

If it is a caraver then the None Return Valve is inside the van. What you have probably identified is the pressure relief valve.

The NRV is screwed into teh teh main casting where teh cold water pipe enteres the heater. In teh very early Cascade 2 heaters it was actually fitted inside the cold water in let pipe.

What has almost certainly happened, is that the water system was not fully drained whilst in storage. A small amout of water was left in teh heater or pipework and froze. The actin of the ice expanding distorts the valve and causes it to jam. On refilling the system, teh NRV is only partially open, so the water heater fills up but slowley due to the resrtiction. as the heater heats up the tank developes some pressure and compresses a small air cap in the tank, so when you open teh tap the pressure causes the water to emerge quicly, but as teh pressure drops teh flow also drops, and eventually the flow will only equal the amount of fresh coldwater capable of getting past the NRV.

 

[ProfJohnL]

Hello Ian,

If it is a caraver then the None Return Valve is inside the van. What you have probably identified is the pressure relief valve.

The NRV is screwed into teh teh main casting where teh cold water pipe enteres the heater. In teh very early Cascade 2 heaters it was actually fitted inside the cold water in let pipe.

What has almost certainly happened, is that the water system was not fully drained whilst in storage. A small amout of water was left in teh heater or pipework and froze. The actin of the ice expanding distorts the valve and causes it to jam. On refilling the system, teh NRV is only partially open, so the water heater fills up but slowley due to the resrtiction. as the heater heats up the tank developes some pressure and compresses a small air cap in the tank, so when you open teh tap the pressure causes the water to emerge quicly, but as teh pressure drops teh flow also drops, and eventually the flow will only equal the amount of fresh coldwater capable of getting past the NRV.

Oops sorry for thr poor spelling, I pasted the wrong piece.

 

[ProfJohnL]

Hello Ian, Improved spelling & typing

If it is a Carver then the None Return Valve is inside the van. What you have probably identified is the pressure relief valve. The NRV is screwed into the main casting where the cold water pipe enters the heater. In the very early Cascade 2 heaters it was actually fitted inside the cold-water in-let pipe.

What has almost certainly happened, is that the water system was not fully drained whilst in storage. A small amount of water was left in the heater or pipe work and froze. The action of the ice expanding distorts the valve and causes it to jam.

On refilling the system, the NRV is only partially open, so the water heater fills up but slowly due to the NRV restriction. As the heater heats up the tank develops some pressure and compresses a small air cap in the tank, so when you open the tap the pressure causes the water to emerge quickly, but as the pressure drops the flow also drops, and eventually the flow will only equal the amount of fresh coldwater capable of getting past the NRV.

Another symptom, can be warm water finding its way into the cold taps.

Consequently it is vitally important to ensure the water system is completely drained if it is to be left and there is a danger of frost.

 

[gary]

First you found the Quick Drain Valve' outside, the non-return valve is part of the cold water inlet where Metzs says it is, at yours age it will also look similar to the QDV unless already replaced with the modern black plastic one.

The older white ones come apart just by the hose connection and you can unscrew this end to inspect the very small white 'O' ring that does the sealing. It fits on a plastic plunger which is pushed by a spring, the 'O' ring should be clean and perfectly round, if kinked it will cause your problem.

Later black ones are different and are best just replaced.

However another reason for poor hot water pressure is a blockage. this is in the narrow passage up into the tank from the water inlet. The cause is generally loose limescale washed into the passage during the last drain down, one big bit lodges and small pieces solidly fill in the gaps.

A quick fix is to back flush through the drain hole with a hose pipe, this should push any blockage back into the tank. While you try this though the hot taps must be open to allow air or water in the tank to escape, don't and it won't clear the blockage and you get soaked!!

Finally while on the subject of poor water pressure in general but more with the modern van and the 10mm bore 'semi rigid' pipe.

A couple of instances recently have proved its manufactures use of far to many tight right angled fittings to join short lengths of pipe together is the cause, and not as many people tend to think an inadequate pump

 

[Ian_374227936]

I'm that new to having a caravan that until the wife said did you fix the water in the caravan I had forgotten all about having one!!!

Found the NRV and as described the small white 'O' rings was knackered so I am hoping that sorts it but I can't test it until I sort out my new taps as I can't work out how to wire them up. Just posting that thread.

Thanks for all the help.