Vaillant boiler [London] - fluctuating hot water

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  #1  
Old 11-27-05, 02:47 AM
jnaylor
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Question Vaillant boiler [London] - fluctuating hot water

Morning,

Another boiler problem. Have read through the posts, but it seems that whilst there are some generic "issues", it's always a specific problem to the boiler.

Have a Vaillant VP5-ZE 15 heating/water boiler.

Heating appears fine - haven't noticed any issues with the radiators. At this time of year, it's timed for approximately 4 hours morning/evening.

However, the hot water is a little inconsistent. Previously a couple of parts were replaced - I could find a list if this would help - including an external Expansion tank. From the best of my memory the hot water was fine before this - although it was summer and no heating was being used, but the parts were replaced due to leaking, amongst other minor problems.

Now, the hot water is quite inconsistent. Whilst the boiler fires up when the hot water comes on, it only fires for a few minutes, before 'shutting down'. Generally, it will fire up again after a minute or so, before 'shutting down' again, on, off, on, off, etc, etc.. It certainly makes for frustrating showers.

Anything simple that could be the cause of this? I was hoping there was a pressure knob I could adjust, but maybe it's not quite so easy. Thanks in advance for any advice.

J
 

Last edited by jnaylor; 11-28-05 at 12:13 AM. Reason: forgot to add the part
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  #2  
Old 11-27-05, 08:14 AM
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Possible cure

The installation of a tempering or mixing vavle should help in making the domestic water temperature more uniform.
 
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Old 11-28-05, 12:16 AM
jnaylor
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Seems like it's first in first served. I was unlucky number 5 today, and had hot water for about 30 seconds. Nothing whatsoever after that.

However, I did venture to the boiler, cover off, and manually moved the small spring-held arm (sorry for my scientific explanations) over to the left, which made an electrical connection and set the burner going. The water flowed warm after that. It's as though the act of turning on the hot tap did not activate the boiler???
 
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Old 11-28-05, 05:48 PM
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Pics?

Any chance of hosting some pics & providing a link to them, of your boiler & specificly close ups of the controls (with the cover off).
 
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Old 11-30-05, 01:07 AM
jnaylor
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Ahhh... yes, I think I can do that. Give me an evening or two to get it sorted.
 
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Old 12-05-05, 11:13 AM
jnaylor
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Here we go, finally. First photo is the front of the boiler, cover off:

http://www.flickr.com/photos/[email protected]/70572504/

Secondly, the small black arm (spring-held) that appears to move when hot water (or potentially heating) is required. It then causes the metal plate to make contact with the small red thing. By jamming a screwdriver in here for 5-10 minutes I can get constant hot water (dodgy I'm sure, but it works):

http://www.flickr.com/photos/[email protected]/70572505/
 
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Old 12-05-05, 06:03 PM
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Valliant

Sorry but this configuration is completely foreign (sorry no pun intended) to me.
 
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Old 12-08-05, 01:05 AM
jnaylor
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Hey, thanks anyway, worth posting just in case. Appreciate you taking the time.
 
  #9  
Old 12-12-05, 03:03 AM
gasmandan
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Hi,

The problem you are having here could be caused by the diaphragm in the water section of your boiler.

It is positioned under the area you photographed, when you draw water the water pressure under the diaphragm moves a spindle up which makes a microswitch (red thing in your picture). If your diaphragm is wearing your water could be intermittent. If it is they only cost a few quid.

You could try adjusting the microswitch. On the top left of the switch is a nut. Loosen it slightly and push the switch towards the black arm then tighten. Also the spindle can be adjusted. to get to this you have to move the servo valve out of the way. A screw at the bottom left will allow this undo, move the valve towards you and the spindle can be lifted out and extended.

If the diaphragm is wearing this would only be temporary fixes, but may enable you to have a good shower!
 
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Old 12-14-05, 03:50 AM
jnaylor
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Hey, thank you for your reply. I appreciate your time... unfortunately, you might need to describe some of these parts slightly better - I had a peruse last night and couldn't find the nut on the top-left of the switch (red thing), although I do understand your theory.

I think it's more to do with the black arm itself... sometimes if the water fails to kick in when the hot tap runs, I can simply give the black arm a nudge myself (without permanently using the screwdriver) and this does the trick. Almost as though the spring holding the arm back is too tight, for instance.
Now perhaps that is the second suggestion you have made, regarding shifting the spindle slightly.

Give me another couple of nights to have a look.

Thanks.
 
  #11  
Old 12-27-05, 03:39 AM
maddox
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Vaillant boiler

hi

I hope you got your boiler working. I too am having hot water problems in London. I did a diagnostic on the control panel and it displays F20 which indicates that the boiler has overheated and automatic cut off has kicked in??

Not sure whether this is a fault or the boiler is overheating because it is owrking harder during this cold spell?

Did you run a diagnostic check?
Cheers

Maddox
 
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