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Overflow?


alanedwin

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Posted

Hi, while away at the weekend I noticed a dripping from under our 2002 hymer b544. It turned out to be from a very thin pipe emerging from under the water heater. It is not the drain from the frost protection valve. I have never noticed it before. It is directly over the rear wheel inside the arch. Does anyone have any ideas?

Alan

Posted

Hi. With our Hymer B584 the cassette housing is above the wheel arch, with a drain pipe into the wheel arch. In front of that we have the wardrobe with the boiler underneath .From there we have three drain pipes, the main boiler drain, and two small plastic drain pipes, these connect to two small turning type valves on the floor by the boiler. these drain from the hot and cold pipes. If yours is similar check if the valves are fully closed.

Brian B.

Posted

Hi,again. Following on from my other post I have just had another look at our boiler and found another drain pipe this exits at the front of the wheel arch. This is an expansion / overflow pipe that starts off as a clear plastic pipe connected to the hot water outlet near the top of the boiler, this pipe extends about 3" above the top of the boiler before turning down to the outlet, it is full of water to the top level of the boiler. If this pipe was displaced and the 3" height reduced water could syphon off to the outlet. Worth checking if the pipe has this clearance above the boiler.

Brian B.

Posted

Brian,

That looks like it. I think what has happened is that we did not have the water heater on but it filled with water because the hot water taps were used. This must be an overflow/ expansion pipe. I have not noticed it before but I have just had a habitation check and perhaps he unblocked it.

Thanks for the advice.

Alan

Posted
alanedwin - 2013-06-03 7:45 PM

 

...This must be an overflow/ expansion pipe...

 

This is not an "overflow/expansion pipe".

 

Truma refers to it as a 'breather hose' or 'venting hose'. It's connected to the vent-valve that's integrated into the hot-water outlet of the heater (presumably we are talking here about a Truma C-Series combination air/water heater?)

 

The function of the breather hose is to allow air INTO the heater if the frost-protection/drain valve opens - otherwise the heater would not drain. A small amount of water may well leak from the breather hose when the heater is being filled, but water should not leak/drip from the hose in normal use.

 

As the vent-valve in the heater's hot-water outlet is there to let air into the heater, but to prevent water coming out, even if the breather hose were displaced (or removed completely) siphoning of water from the heater should not occur.

 

Drawing "K" on the 2nd page of this Truma document should be helpful:

 

http://dealer.truma.com/_anweisungen/Truma-Katalog/pdf_verzeichnis/30_000/34000_94600.pdf

 

See also this earlier thread and the photo in the 12 April 2009 11:37 AM posting:

 

http://www.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Water-pipe-plan-for-Hymer-694/15452/#M164218

Posted
alanedwin - 2013-06-04 1:46 PM

 

It looks like my vent valve is faulty because there is water in the pipe.

 

You might expect to see some bubbles of water in the vent-tube but, if the tube keeps drippng, the valve is probably faulty.

 

(You could try opening the frost-protection drain-valve (without opening any taps) so that, when the heater drains, the vent-valve will (should!!) open to let air in. Then, when you refill the heater, the vent-valve will close and (hopefully) might make a better seal. Replacement valves are relatively cheap if that doesn't work.)

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