CARVER CASCADE 2 DRAINING BACK INTO BARREL

[sgtangel]

Hello all,

Thanks to the particularly wintry weather , our planned getaways so far were all cancelled due to snow / severe weather. We are planning our "new" first trip away later this month (fingers crossed) but while prepping the van have had some issues with the water heater.

We have a 1993 Swift Corvette Diamond. The hot water was fully drained at the end of last season.
Initially we had cold water, but no hot water entering the tank. We diagnosed a faulty non return valve, which we replaced relatively easily (appears to have been replaced previously).

We then had air / water leaking at the hot water outlet. This was more complicated to repair as it was an original fitting, and as expected it snapped leaving the threads inside the housing. We persevered, and managed to remove them, and fitted and new inlet (using additional sealant just to be sure).

We left it overnight to cure, and tested this morning. Tank fills, hot water flows, all good we thought, however it appears that hot water is flowing BACK into the barrel when the taps are closed. When we close the hot taps off, and leave it for 10 minutes or so, then turn them back on, there is air in the system, and you can hear the tank refilling. This has never happened before, and we have had the van 4 years.

My questions - does this indicate a faulty non return valve ? (despite it being brand new) or could this be an issue with the pressure relief valve on the outside of the flue ? which I have no clue how it operates, and cannot find any guidance online.

As a secondary query, can anyone advise How does the pressure release valve operate ? Is it adjustable ? how do i test it ?

Thankyou for any help / advice you can offer.

Sgtangel

 

[sgtangel]

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[Anseo]

There are no images showing, OP needs to upgrade his Photobucket account :dry:

 

[Damian]

I have removed the links to the photos as they did not work as the OP's Photobucket account needs upgrading.
As most will be aware, they now charge for the service.

As far as the questions go, the air getting in may be due to a damaged NRV when you were replacing it, or a leak somewhere else.
The pressure relief valve is not adjustable, it is simply a plunger on a spring which is either open or closed.
In the closed position an over pressure will push agains the spring and open the valve, when the pressure drops the spring closes the valve.

 

[VicMallows]

Many of the non-return valves are not spring assisted, and rely solely on the backflow and/or gravity to close. I had precisely your symptoms of hot draining back into the barrel.

I improved matters by arranging the NRV vertically so that gravity assisted the closing, but only fully cured the problem when I fitted a spring-assisted NRV. (John Guest do a 12mm push-fit one, but they take some searching to source).

The spring-assisted NRVs do need enough pressure from the pump to crack open, but my standard Crystal submersible pump manages fine.

 

[sgtangel]

Sorry, I wasnt aware of the changes to photobucket

 

[Craigyoung]

Try the website " postimages " for your pictures

 

[sgtangel]

Many of the non-return valves are not spring assisted, and rely solely on the backflow and/or gravity to close. I had precisely your symptoms of hot draining back into the barrel.

but only fully cured the problem when I fitted a spring-assisted NRV. (John Guest do a 12mm push-fit one, but they take some searching to source).

The spring-assisted NRVs do need enough pressure from the pump to crack open, but my standard Crystal submersible pump manages fine.

Thankyou for this information - do you know what diameter of pipe is in a standard 1993 swift van ? i.e would the 12mm push fit be able to be fitted into my existing pipework ? I see that truma sell a 10mm inline NRV - available online.

I would be happy to fit an inline if it solved my issue ( i cannot face stripping down the valves a third time

 

[ProfJohnL]

Many of the non-return valves are not spring assisted, and rely solely on the backflow and/or gravity to close. I had precisely your symptoms of hot draining back into the barrel..

For your information the Carver specification for the NRV did include a spring closure.

 

[ProfJohnL]

Thankyou for this information - do you know what diameter of pipe is in a standard 1993 swift van ? i.e would the 12mm push fit be able to be fitted into my existing pipework ? I see that truma sell a 10mm inline NRV - available online.

I would be happy to fit an inline if it solved my issue ( i cannot face stripping down the valves a third time

Its not critical that a carver part is used, so the Truma one is an option but it should be fitted as close to the heater as possible.

However I think you may have some other issues that also need addressing. Air should not be able to get back to the heater tank, so you do have either leak somewhere on the hot pipe work, of the hot taps aren't sealing properly when turned off.

Water should not be able to flow back to the water container, so you may have a compromised NRV on the cold supply where it enters the caravan.

 

[sgtangel]

Thanks for all the advice.
I have traced all the pipework, and stripped down both sets of taps, and have found 2 potential causes - loose inlet to the hot tap at the kitchen, plus leak at the toilet sink tap (the kind that pulls out to become a shower). Its amazing how this can all happen over a winter
I have resealed everything as necessary, and will give it overnight to let the sealant cure before re-checking.... fingers crossed

 

[Hutch]

Thanks for all the advice.
I have traced all the pipework, and stripped down both sets of taps, and have found 2 potential causes - loose inlet to the hot tap at the kitchen, plus leak at the toilet sink tap (the kind that pulls out to become a shower). Its amazing how this can all happen over a winter
I have resealed everything as necessary, and will give it overnight to let the sealant cure before re-checking.... 7fingers crossed

Stangle, thanks for the good feed back, something that doesn't happen too often.
Hutch