Auto Drain from M/H Heater (1 Viewer)

[Revolvor]

Our M/H is fitted with a Webasto Dual Top Evo 6 Diesel Heater.

The Auto-drain to prevent frost damage to the boiler is a bit over sensitive, and dumps the water if the temperature gets below about 5° or 6°. That means that some recent cold (but not icy) mornings it has dumped the water in the night.

I have read that some people use a clothes-peg on the safety valve to prevent draining. Does anyone know if it is possible on the Webasto unit? When draining, the water dribbles from a Ø40 mm hole in the base of the unit. I assume the dump valve is recessed in there.

Thanks, John.

 

[Deleted member 29692]

It's not over sensitive, 5° is about right.

The physical temperature sensing part is a pretty basic thing and for practical purposes they can't be made completely accurate, there is always a wide tolerance. I don't know exactly what the standard is but it will be something like operate at 4° +/- 2° to ensure it operates before anything can freeze. Obviously aiming for it to operate at say 1° with that same +/- 2° tolerance is asking for trouble

The clothes peg thing isn't any better an idea than anything else that bypasses safety features. If it gets colder than you expect, or if you forget to remove it after a trip, and your system freezes and pipes split how are you going to feel?

 

[Revolvor]

It's not over sensitive, 5° is about right.

The physical temperature sensing part is a pretty basic thing and for practical purposes they can't be made completely accurate, there is always a wide tolerance. ....... Obviously aiming for it to operate at say 1° with that same +/- 2° tolerance is asking for trouble

The clothes peg thing isn't any better an idea than anything else that bypasses safety features. If it gets colder than you expect, or if you forget to remove it after a trip, and your system freezes and pipes split how are you going to feel?

I think maybe I asked the wrong question as:

a) I agree that 5° is about right and that to expect a tighter tolerance would result in a much more expensive sensor.
b) Yes - over-riding Safety Devices is not a good idea!

However it is 15° here today, and water is still draining from the heater when I switch the pump on.

Maybe I need to try and build up pressure and hope it re-seats.

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[funflair]

I believe you will need to reset manually, you do on the Truma version.

Martin

 

[Revolvor]

I believe you will need to reset manually, you do on the Truma version.

Martin

Thanks Martin, but I can't find any reference to a Manual Reset in the Instruction Booklet.

 

[Revolvor]

Maybe I need to try and build up pressure and hope it re-seats.

I have just tried that, and water is still draining once full pressure is achieved. It's time to get under the van and examine the unit more closely.

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[rosalan]

I do not know your drain unit but on my Truma unit, giving it a gentle tug upwards stops the draining. It is always possible that a foreign body is preventing yours from re-seating. All the best, for I do know that frustrating feeling when something does not work as you expect.

 

[Deleted member 29692]

QUOTE="Revolvor, post: 2315482, member: 33737"]Maybe I need to try and build up pressure and hope it re-seats.[/QUOTE]

Martin is right. It will definitely need a manual reset.

I don't believe there's any such thing as one that resets itself.

Here are a couple of the more common ones to give you an idea of what you're looking for. It will be easily accessible from somewhere inside the MH.

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[jonandshell]

You need to keep the heater on the frost protection setting at least to avoid this.
There is no bypass of this safety feature on the Dualtop.

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[jonandshell]

I think maybe I asked the wrong question as:

a) I agree that 5° is about right and that to expect a tighter tolerance would result in a much more expensive sensor.
b) Yes - over-riding Safety Devices is not a good idea!

However it is 15° here today, and water is still draining from the heater when I switch the pump on.

Maybe I need to try and build up pressure and hope it re-seats.

Have you actually switched off the drain valve?
Once auto drain occurs you need to close the valve via the control panel.

 

[golly]

Found this on line, don't know if it helps.

Operating Instructions Dual Top Evo 6
12
4.3 Frost
There are several features that protect the water supply system against frost.
• Drain water contents manually when there is risk of frost and when storing the
vehicle for a longer period.
See paragraph 4.3.1: "Draining the boiler manually".
• The boiler is drained automatically in case you forgot to drain manually.
See paragraph 4.3.2: "Draining the boiler automatically".
• In case you don’t want to drain the water supply system and you don’t heat the
interior of the vehicle, you can select the frost protection mode.
See paragraph 4.3.3: "Frost protection mode".
4.3.1 Draining the boiler manually
Drain water contents manually when there is risk of frost and when storing the vehicle
for a longer period.
1 Interrupt power for vehicle system water pump (main switch or pump switch,
depending on instructions of the vehicle manufacturer).
2 Open hot water taps in kitchen, bathroom, shower, etc. (set pre-selecting mixing
taps or single-lever valves to "hot").
3 The electrical safety/drain valve is opened by turning and holding the mode
selector knob (A) against the spring force in the position drain boiler (6) for at
least 5 seconds.
Then, release the knob.
The electrical safety/drainage valve will open for approx. 90 minutes.
During drainage, all green icons on the control panel, as well as the red indicator
on the mode selector knob (A), are blinking.
The boiler content is now discharged to the outside through the electrical safety/
drainage valve.
Place a container beneath the outlet to check whether the water in the boiler has
completely drained away (approx. 10 litres!).
NOTE
Any kind of water from the vehicle has to be discharged at a proper disposal facility.
NOTE
Drainage can be stopped by again moving mode selector knob (A) to drainage mode
(6) for at least 5 seconds and then releasing the knob.
NOTE
Avoid the formation of micro-organisms in the lines and in the boiler during storage and
make sure that the water supply system is completely drained. To do this, open all water
valves, connect an air pressure of approx. 2 bar to the hot water line and leave it
connected until the residual water is completely drained off.
4.3.2 Draining the boiler automatically
The electrical safety/drainage valve is opened electrically.
If the water temperature at the electrical safety/drainage valve is less than 6 °C, the
boiler water contents may discharge automatically.
This function is active when:
• the appliance is switched "OFF";
• in winter mode (heating without hot water production) during a period when there
is no heating action in the heater (e.g.: selected interior temperature is reached, low
outside temperature);
• if battery power is too low;
• there is a failure!
NOTE
Note that it only works when a 12 V power supply is available!
During drainage, all green icons on the control panel, as well as the red indicator on the
mode selector knob (A), are blinking.
After approx. 90 min, the electrical safety/drainage valve will be closed again.
Dual Top Evo 6 Operating Instructions
13
The drainage outlet of the electrical safety/drainage valve must always be kept clear
(free from dirt, ice, leaves etc.)!
To avoid water loss and to protect the heater and boiler against frost, select the frost
protection mode (5).
NOTE
When the frost protection mode is selected, diesel and electrical power are used. Make
sure that there's enough diesel in the tank and the battery is charged. Check this
frequently.
NOTE
Draining the boiler as well as the frost protection mode protect the heater and boiler
against frost. Not all water lines in the vehicle can be protected against freezing due to
installation variations.
When storing the vehicle, either choose a place that is well protected against low
temperatures or drain the whole water system, including all lines and tubes (e.g. with
air pressure, see note in paragraph 4.3.1: "Draining the boiler manually").
There shall be no warranty claims for damage caused by frost!
NOTE
Drainage can be stopped by moving mode selector knob (A) to drainage mode (6) for
at least 5 seconds and then releasing the knob.
4.3.3 Frost protection mode
This mode is a safety feature for the heater only. It does not prevent the water circuits
inside and outside the vehicle from freezing.
Store the vehicle at a place that is well protected against frost or drain water contents
if there is a risk of frost!
To avoid freezing of the tubes and the boiler move mode selector knob (A) to frost
protection mode (5).
The indicator (C) on the control panel lights green when the equipment is switched on.
The red indicator on the mode selector knob (A) illuminates.
The heater functions as in the winter mode, heating with hot water production, but
with lower values for air and water temperatures.
NOTE
Make sure that the boiler is filled with water when choosing frost protection mode.
NOTE
The frost protection mode enables the user to park the vehicle for a short time without
being observed and without having to worry about frost and frost damage.
During winter storage or when parking the unused vehicle for a longer time, the entire
water system should be drained and the heater disconnected from the battery to avoid
unnecessary battery discharging or possible frost damage.

Don't know if you have this info, or if it helps

 

[jonandshell]

If, despite having reset the drain valve, it still leaks, you sound like you need to descale the boiler. You possibly have a piece of limescale trapped in the valve.
This is unlikely with an Evo however, due the valve being fitted with a mesh filter.
Descaling instructions are in the manual.

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[jonandshell]

Duplicate post.

 

[Revolvor]

@NickNic @golly & @jonandshell Thank you all for your input. I did have a copy of the instructions, but just re-reading your post has prompted me to drain the boiler via the control panel, in the hope that a good flow may flush away any debris. Prior to that, with the water pump stalled out, there was a slight dribble from the drain, but that increased to a steady flow when I operated the drain.
I may try and back-flush the boiler while it is draining, as a next step.

Limescale could be a problem. We are in a very hard-water area. We have a glass electric kettle at home, and after de-scaling it goes opaque after boiling it twice!

I'm pretty certain there is no manual drain valve - it is all controlled from the panel.

 

[laird of Dunstan]

5 Deg is the standard setting for frost protection ,in large buildings that have their own management systems ,frost protection starts at 10 deg for what is termed ist stage ,2nd stage is 5 deg .

Its a lot less hassle IMHO to fill some water than to change a frost damaged heating system

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[Revolvor]

5 Deg is the standard setting for frost protection ,in large buildings that have their own management systems ,frost protection starts at 10 deg for what is termed ist stage ,2nd stage is 5 deg .

Its a lot less hassle IMHO to fill some water than to change a frost damaged heating system

I quite accept that. My problem now is that having drained, the valve will not reseat, despite temperature of 12 degC

 

[GWAYGWAY]

On mine it tripped and I had to turn the knob and push the blue button, it only worked after I blew the hot air gun on it to raise the temperature to over 15 degrees, then it clicked and stayed closed.

 

[Deleted member 29692]

On mine it tripped and I had to turn the knob and push the blue button, it only worked after I blew the hot air gun on it to raise the temperature to over 15 degrees, then it clicked and stayed closed.

Trying to fill mine once in the winter and the water from the tap/hosepipe was so cold it was making the valve operate.

We ending up holding it closed by hand until we could get enough water in and run the boiler to warm everything up. Took ages.

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[Minxy]

If you are able to run the habitation heater part without water in it, it may warm it up sufficiently for you to close the dump valve.

 

[Revolvor]

If you are able to run the habitation heater part without water in it, it may warm it up sufficiently for you to close the dump valve.

UPDATE - I contacted a local habitation company, who said they would call in, in few days, even though they were not familiar with the Webasto. In the meantime, I contacted Autotrail who have me details of a local Webasto agent in Gloucester. They said that sometimes the O-ring on the drain solenoid goes hard, and that running it on full heat for a couple of hours should soften it. Unfortunately, the leak was so great that the boiler kept cutting out, because of lack of water.

When the habitation guy came, he insisted on looking at it, and suggested using an air line to gently blow in the vent, with the solenoid open. We tried it a few times, and the leak decreased to a few drops a minute. I then ran it at max heat for two hours, and now it seems to be leak free!