Cold Water is Hot!

When turning on cold water tap on our recently purchased Kemerton,Hot water will run for 5 seconds aprox.When turned off and back on again the same happens and will also run hot,then cold and hot briefly.The van has just been back to the dealers for this problem and Many more and the chief technician said this was normal and not a problem!
    It isn't pleasant cleaning teeth in hot water or having an intermittently scalding wash or shower.
      Has anyone experienced this or have any suggestions or solution?

Check pipe runs, the cold pipes will be in contact with a hot pipe/surface, may be in a few places.

Move pipes, possibly put some pipe insulation on pipes to ensure that contact does not happen.

I don't think the chief technician is correct that it's normal, I've certainly never experienced the issue with any of my van's boilers.

Heat transfer between the hot and cold feeds could warm the cold water side a little bit, but it wouldn't usually go to being hot, then run cold and return to being hot.

Are your taps of the mixer type, or individual hot and cold; and do you have the same problem at each outlet  ie. Kitchen, bathroom and shower ?

Sounds to me like you have a shared pipe, but I can't think how or why it would be plumbed like that???

A possible cause could be the mixer tap cartridge  - it may have failed and therefore maybe allowing some hot water through the tap outlet when drawing cold. 
But as Peter #1 says above; "If you select cold then the water will always run cold unless you have just run hot through the tap"
Generally the water heater is some distance from your tap hence there is always a lag in hot water delivery. 
The most likely cause could be that you have the central heating on and perhaps some of the ducting or a heating vents is pre-warming your cold water feed pipe some where near to the tap?
Liam

After a long run and particularly in warm weather the water in the cold tank may well be somewhat warm (but not scalding!).  The fresh water tank on my Nuevo is just behing the silencer/exhaust/Catalytic converter and picks up heat from that - at least that is my theory.

savobongo wrote:When turning on cold water tap on our recently purchased Kemerton,Hot water will run for 5 seconds aprox.When turned off and back on again the same happens and will also run hot,then cold and hot briefly.The van has just been back to the dealers for this problem and Many more and the chief technician said this was normal and not a problem!
    It isn't pleasant cleaning teeth in hot water or having an intermittently scalding wash or shower.

I've been pondering this problem, and I can't come up with a likely cause unless the pipework is wrongly connected (or interconnected ??) somewhere along the line????

It's not unusual to get a short burst of hot water when turning on the cold tap, if you have recently drawn off some hot water. This happens at home if you have a mixer tap in the kitchen, and the cause is obvious. 5 seconds is far too long however, and it should certainly not happen again when the cold tap is turned off and back on again. Intermittent hot and cold water is a new one on me - an optional extra you most definitely don't want!!

I assume you have described the symptoms accurately (not everyone does at first!  ) in which case I can only conclude that the chief technician needs to look at it again, as what you describe is most definitely not normal.

I would go back to the dealer and (if you didn't already do so) give a full demonstration of what happens, and ask them to look more closely. It's so unusual that the technician may have done a quick test of the cold tap, got hot water at first which quickly went cold, and assumed that it was the common mixer tap anomaly.

Have they run the hot and cold feed pipes along side one another? They may even have taped them together or ran both pipes through a length of protective tube for neatness.

I had this problem many moons ago and it turned out to be a lack of a non-return valve in the feed to the carver heater.
However, your van is about one thousand years younger than mine so I should think that the water heating system will have changed in that time.

Frank

boxerman wrote:I had this problem many moons ago and it turned out to be a lack of a non-return valve in the feed to the carver heater.
Frank

That makes a lot of sense Frank.

Maybe his non return valve is stuffed, or help open by a bit of detritus?

Definitely something to check out.

(Do be a bit more precise though - I hate sloppiness.   His van is 917 years younger than yours according to my maths.  )