I have just imported an Abbey 418 1996 Spectrum to NZ all seems to work ok on the electrics except the hot water flow. It has an onboard tank when hot taps turned on only seems to have a drible at the kitchen tap less than a dribble at the bathroom tap and not a thing at the shower tap . but the cold water flows ok Help please for someone new to english caravans
Carver Heating System
- Thread starter Chris_374468517
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- Mar 14, 2005
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Hello Chris,
You will have a Cascade 2 water heater. You don't say if the flow of water to the cold taps is OK or not, but because you specifically refer to the hot water flow I will assume the cold water flow is OK.
If the caravan was stored over winter with any water in the systems, the cold water inlet pipe to the heater seems to freeze quite easily. The action of the water freezing, in the heaters inlet valve can damage the O ring seal on the shuttle of the non return valve.
Usually the 'O'ring jams in the seat of the valve which results in a poor water flow, and the heater will back flush into the cold water system.
If you are lucky you may find that if you carefully disassemble the Non-return valve you may be able just reset the O ring on the nose of the shuttle. If it is more badly damaged you may need to replace the whole Non-return Valve.
You will have a Cascade 2 water heater. You don't say if the flow of water to the cold taps is OK or not, but because you specifically refer to the hot water flow I will assume the cold water flow is OK.
If the caravan was stored over winter with any water in the systems, the cold water inlet pipe to the heater seems to freeze quite easily. The action of the water freezing, in the heaters inlet valve can damage the O ring seal on the shuttle of the non return valve.
Usually the 'O'ring jams in the seat of the valve which results in a poor water flow, and the heater will back flush into the cold water system.
If you are lucky you may find that if you carefully disassemble the Non-return valve you may be able just reset the O ring on the nose of the shuttle. If it is more badly damaged you may need to replace the whole Non-return Valve.
As the cold tap(s) were said to be working then JohnL's diagnosis is a good probability; the non-return valve might well be sticking if the system has not operated for a while.
Whilst this link does not directly help that problem it gives you access to the installation manual:
http://www.gtfavouritecaravanparks.co.uk/advice/instructions/carverheater2.htm
Somewhere I have seen an exploded view of the unit but I cant find it; perhaps others know a link?
Whilst this link does not directly help that problem it gives you access to the installation manual:
http://www.gtfavouritecaravanparks.co.uk/advice/instructions/carverheater2.htm
Somewhere I have seen an exploded view of the unit but I cant find it; perhaps others know a link?
As said the non-return valve is likely to be sticking, I've had a nice chat to Chris last evening, (apart from when he bored me with how pleasant the weather is in Auckland! LOL)... still, he's now trying some suggestions
non return valve,there is way i have discovered when mine went wrong of checking for a faulty non return valve on the carver two.set everything up as normal to fill the whole system.make sure the aquaroll is full of water.remove the drain plug outside on the carver and get someone inside to turn on the water pump for a few seconds.if the non return valve is ok water will flush out rapid.if it only dribbles out then the valve is stuck in line and nearly shut,not allowing cold water in from the pump.i cured mine with a 12 inch water colour brush.this was inserted into the drain hole of the carver two and i pushed the non return valve back.this lasted faultless for more than three years until the van was sold.may work for you too.if you change the NRV be careful not to snap it off.
- Mar 14, 2005
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- 4,367
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Hello Michael,
Whilst your method may have appeared to work, you may have actually dislodged the 'O' ring completely. For caravan with a pressure switched water system, the consequences are not too great, as the pressure switch has a NRV built in, and that will act as a double check to prevent water draining back to the water barrel.
One of the tests for this is to fill you heater with cold water, and turn the taps off. Then turn off the power to your water pump, so it can't run. Lift the pump out of the barrel and let is dangle. Now open the Hot taps. If more than about a litre of water flows back through the pump and continues to flow you have a damaged heater NRV.
In this condition the heater may loose water and might over heat and blow the safety fusible plug or damage the electric element if you have a GE model.
Whilst your method may have appeared to work, you may have actually dislodged the 'O' ring completely. For caravan with a pressure switched water system, the consequences are not too great, as the pressure switch has a NRV built in, and that will act as a double check to prevent water draining back to the water barrel.
One of the tests for this is to fill you heater with cold water, and turn the taps off. Then turn off the power to your water pump, so it can't run. Lift the pump out of the barrel and let is dangle. Now open the Hot taps. If more than about a litre of water flows back through the pump and continues to flow you have a damaged heater NRV.
In this condition the heater may loose water and might over heat and blow the safety fusible plug or damage the electric element if you have a GE model.
hi john,the brush was used to gently push back the non return valve as it was stuck in line.if you jammed it in then the washers will be damaged for sure.as to filling the heater with cold water you will find this is not possible with the non return stuck in line,this why you get no water leaving the hot taps when you have this problem.draining back into the aquaroll is a possibility on all types of heaters.for this reason truma have now introduced a spring return non return valve to prevent this.this was confirmed by email from truma.
- Mar 14, 2005
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- 4,367
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I am sorry Michael, but I have difficulty in rationalising your description based on the technical design of the Cascade 2 heater with which I am very familiar.
The non return valve on a C2 is spring loaded. It sits in the cold water inlet moulding and to allow water through the NRV's shuttle has to be pushed by the flow of water under pressure towards the outside of the caravan.
If the NRV has been affected by frost, there is a build up of ice on the down stream side of the valve. As the ice forms it expands and begins to exert thrust on the nose of the NRV shuttle and O-ring seal. As the pressure builds the O-ring stretches and deforms and allows the shuttle and O-ring to be pushed backwards through the valve seat If it moves far enough (about 2mm) the compliance of O-ring jams the shuttle in the valve seat. Usually the O-ring does not fill the valve seat and a restricted flow of water is possible, but it can flow in both directions. I have never seen it but, I concede it is possible for the O-ring to totally block the water flow, and that would apply to both directions of flow.
Because the main heater casting is cross drilled, if you remove the drain plug from the outside as you describe, you have a direct line through to the incorporated NRV and cold water inlet. The first thing a 12" stick would meet would be the nose of the NRV shuttle. If the shuttle is in its normal position with it's O-ring resting and sealing on the valve seat or if it is in the frost distressed position, any pressure on the shuttle from the inserted stick will push the shuttle further back through the housing and that will only result in the shuttle disengaging from the O ring and ceasing to operate as NRV.
In your case I suspect you have pushed the shuttle right through the valve seat, and as such the O-ring has full disengaged from the shuttle so it is not acting as an NRV or affecting the water flow. You must have a pressure switched water system, which contains a separate NRV to that of the heater. With that in place, the heater will appear to work normally, except you may find that you get some warm water flowing through the cold taps, and that the pump doesn't turn on immediately when you open a cold tap, the reason being the pressure build up in the hot tank is transmitted through the cold system because the heaters NRV is not blocking it.
I stress that every Carver and I believe Truma water heater were always supplied with an NRV, therefore the comment you make:
"draining back into the aquaroll is a possibility on all types of heaters.for this reason truma have now introduced a spring return non return valve to prevent this.this was confirmed by email from truma."
Seems misleading.
I suggest you should arrange to have your NRV replaced, as it is almost certain the 'O' ring will have been lost when the heater was drained down.
The non return valve on a C2 is spring loaded. It sits in the cold water inlet moulding and to allow water through the NRV's shuttle has to be pushed by the flow of water under pressure towards the outside of the caravan.
If the NRV has been affected by frost, there is a build up of ice on the down stream side of the valve. As the ice forms it expands and begins to exert thrust on the nose of the NRV shuttle and O-ring seal. As the pressure builds the O-ring stretches and deforms and allows the shuttle and O-ring to be pushed backwards through the valve seat If it moves far enough (about 2mm) the compliance of O-ring jams the shuttle in the valve seat. Usually the O-ring does not fill the valve seat and a restricted flow of water is possible, but it can flow in both directions. I have never seen it but, I concede it is possible for the O-ring to totally block the water flow, and that would apply to both directions of flow.
Because the main heater casting is cross drilled, if you remove the drain plug from the outside as you describe, you have a direct line through to the incorporated NRV and cold water inlet. The first thing a 12" stick would meet would be the nose of the NRV shuttle. If the shuttle is in its normal position with it's O-ring resting and sealing on the valve seat or if it is in the frost distressed position, any pressure on the shuttle from the inserted stick will push the shuttle further back through the housing and that will only result in the shuttle disengaging from the O ring and ceasing to operate as NRV.
In your case I suspect you have pushed the shuttle right through the valve seat, and as such the O-ring has full disengaged from the shuttle so it is not acting as an NRV or affecting the water flow. You must have a pressure switched water system, which contains a separate NRV to that of the heater. With that in place, the heater will appear to work normally, except you may find that you get some warm water flowing through the cold taps, and that the pump doesn't turn on immediately when you open a cold tap, the reason being the pressure build up in the hot tank is transmitted through the cold system because the heaters NRV is not blocking it.
I stress that every Carver and I believe Truma water heater were always supplied with an NRV, therefore the comment you make:
"draining back into the aquaroll is a possibility on all types of heaters.for this reason truma have now introduced a spring return non return valve to prevent this.this was confirmed by email from truma."
Seems misleading.
I suggest you should arrange to have your NRV replaced, as it is almost certain the 'O' ring will have been lost when the heater was drained down.
thanks john for the reply,as said the strange repair was done a few years ago and ran faultless until sold.we have the truma now and it far better heater.after some had water draining back on the truma i emailed them and they replied saying a new spring return NRV would be sent out.this may be as is or a modified one.sorry for any confusion.
One of the suggestions I made to Chris was more or less to do what Michael did, only using a somewhat heavier screwdriver!
The idea and this only applies to later black plastic fittings, is to rattle the head of the NVR as best you can, given the restricted room it should only be possible to give the merest taps to the NVR.
The simple hope is it dislodge anything that might be jamming the valve, either open or shut, (grit from the filter perhaps), if though however frost has played a part this is highly unlikely to work.
Frost can/will distort not only the '0' ring or it's shuttle but change the shape of the plastic fitting itself, as the shuttle is a tight fit in it's bore, any ovality will jam it and require the whole fitting to be replaced.
The idea and this only applies to later black plastic fittings, is to rattle the head of the NVR as best you can, given the restricted room it should only be possible to give the merest taps to the NVR.
The simple hope is it dislodge anything that might be jamming the valve, either open or shut, (grit from the filter perhaps), if though however frost has played a part this is highly unlikely to work.
Frost can/will distort not only the '0' ring or it's shuttle but change the shape of the plastic fitting itself, as the shuttle is a tight fit in it's bore, any ovality will jam it and require the whole fitting to be replaced.
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