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Vitodens 100 intermittent heating water and radiators

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Discuss Vitodens 100 intermittent heating water and radiators in the Bathroom Advice area at Plumbers Forums

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skir2000

Hi everyone,

I am at my wits end here. Just moved into my new (10yrs old but new to me) house (and now I am broke :tounge_smile:) and have had intermittent problems with my Vitodens 100 gas boiler. I have a Siemens control unit to set the timer, as well as a thermostat in the hallway - I guess for adjusting the radiator temperature.

I have been using the boiler for just 6 weeks now solely for heating water on a timer, and as we move into the winter months, I now want to start using the radiators. However, when I turn on the rads, they don't heat up, but the water heats fine... Then, sometimes, the rads are ROASTING hot, but the water is cold - even though I haven't touched the controls.

Can someone please help me, am I doing something stupid, or do I need to get a repair guy out?

I am desperate here, and hoping for an easy solution - if its a repair job that's needed I will be having one heck of a cold winter :)

- The timer is set to turn on the central heating and the hot water
- I had the thermostat in the hallway set to 0, when I realised the rads weren't heating, I changed this a number of times, but no joy
- I have tried every combination on the timer, HW only, CH only and HW + CH - but still no joy

Thanks in advance,
skir
 
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Think you need to get an engineer in to explain exactly how your controls work
Or maybe there is a fault with one of them, if there is he should pick up on it and rectify it
It seems it's not your forte, so put a post up in the "I'm looking for a plumber"
 
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OK, thanks for the advice jonnyswamp. I am far from being a technophobe though, and I really don't believe it is due to me operating the controls incorrectly. I have downloaded the relevant instruction manuals in order to figure out what is wrong. I have tried everything in those manuals and still, the boiler randomly heats either the water or the radiators - there is no pattern to it :(
 
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where are you located?
 
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i would maybe pm croppie (mod) and ask him if he knows anyone local to you
 
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skir2000 said:
Ireland... there doesn't seem to be the same level of support in Ireland for these boilers. Nobody knows much about them.
Click to expand...

It is going to be a controls issue not the boiler so most heating engineers will be able to fix.
(unless it is being used in weather compensation mode)

Do you know what zone valves you have - 2 x 2 ports or 1 x 3 port ?

Put just the heating on (timer), set the room stat to max & on the boiler turn the righthand temperature dial to 6 and then tell us if the heating comes on.
 
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Thanks for the suggestions Chris
chris watkins said:
(unless it is being used in weather compensation mode)
Click to expand...
What would Weather Compensation mode do, and how can I confirm whether or not that is the cause?

chris watkins said:
Do you know what zone valves you have - 2 x 2 ports or 1 x 3 port ?
Click to expand...

No idea what this means... can you tell me how I can check what this is, and how would this impact what I am seeing?

chris watkins said:
Put just the heating on (timer), set the room stat to max & on the boiler turn the righthand temperature dial to 6 and then tell us if the heating comes on.
Click to expand...

I tried this with just the central heating (CH) turned on just now. The radiators came on very hot. I have tried this in the past and it never came on, seems to be intermittent. I did notice that the water wasn't heated though.

So then I tried just the hot water (HW) to see how that pans out - will post results here when I give it enough time.

One more thing to note... when the timer comes on, it turns on both the HW and the CH simultaneously, as to how I programmed it... Last night, I had no hot water, even though both HW and CH were on, however, the radiators were roasting.


Any further suggestions or help are much appreciated.

Also, I took pictures of the boiler in different stages of operation based on your suggestions. Please use the google drive link to take a look, there are 3 images in the link https://drive.google.com/folderview?id=0B8VnNR_b4BYPUUk1VmYwMzliOUU&usp=sharing
 
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Just to confirm, I have the HW ONLY on for approx 30 mins. Radiators are gone colder and hot water is hot.

This is weird as I tried this a number of times before and it doesn't work sometimes - with just HW, just CH and both combined.
 
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ShaunCorbs said:
do you have a cylinder?
Click to expand...

Yeah, we have a house spread over 3 floors. Hot water cylinder is quite big and is situated on the middle floor, and we have a pump that makes a lot of noise when running our shower :)

Someone mentioned did we have an expansion tank - now this is one thing I have never had in any previous house I lived in... There is a big red tank sitting at the top of the cylinder in the hot press.
 
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skir2000 said:
Yeah, we have a house spread over 3 floors. Hot water cylinder is quite big and is situated on the middle floor, and we have a pump that makes a lot of noise when running our shower :)

Someone mentioned did we have an expansion tank - now this is one thing I have never had in any previous house I lived in... There is a big red tank sitting at the top of the cylinder in the hot press.
Click to expand...

mains pressure ok on top floor? and could you take a pic of the cylinder room?
 
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Can we haves a photo of the pipes coming in & out of the bottom of the boiler please.

It sounds like you have a diverter valve installed so you can have heating or hot water but not both at the same time.

The cylinder cupboard is a d.i.y lash-up & by the looks of it the expansion vessel is flat/full of water if the system pressure gauge on the boiler is anything to go by.

You need a pro to come and take a look.
 
Last edited:
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ShaunCorbs said:
gravity hot water with dual impeller pump and pressurized heating

thank you very much one last question could you take pics of above and below the boiler? (sorry to be a pain)
Click to expand...

This is great, It's not a pain if you can help me figure out the problem. Added pics of top and bottom pipes for the inlet/outlets. Also included a pic of the pressure gauge again, have had HW on for past hour and its humming nicely at the moment
 
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skir2000 said:
This is great, It's not a pain if you can help me figure out the problem. Added pics of top and bottom pipes for the inlet/outlets. Also included a pic of the pressure gauge again, have had HW on for past hour and its humming nicely at the moment
Click to expand...

not showing in your google drive as of yet
 
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chris watkins said:
Can we haves a photo of the pipes coming in & out of the bottom of the boiler please.

It sounds like you have a diverter valve installed so you can have heating or hot water but not both at the same time.

The cylinder cupboard is a d.i.y lash-up & by the looks of it the expansion vessel is flat/full of water if the system pressure gauge on the boiler is anything to go by.

You need a pro to come and take a look.
Click to expand...

What's a DIY lash-up?? Also, I thought pressure gauge at 2.5 bars is acceptable? Pretty sure I read that somewhere... Added photos to the same google drive shared space

https://drive.google.com/drive/folders/0B8VnNR_b4BYPUUk1VmYwMzliOUU

You mention only having hot water or rads, but not both - I'm not sure if this is relevant or if you haven't already figured it out from pics (not even sure if this is normal for these set-ups)... when I turn the dial on the left down from 6 to 0, nothing happens. When I turn the dial on the right, the boiler would switch itself off (I hear it power down) and the temp gauge would not increase.
 
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skir2000 said:
This is great, It's not a pain if you can help me figure out the problem. Added pics of top and bottom pipes for the inlet/outlets. Also included a pic of the pressure gauge again, have had HW on for past hour and its humming nicely at the moment
Click to expand...

not showing in your google drive as of yet

there up and thanks and diy lash means its not a very neat/good install

right pressure is fine (should be around 1.2 bar cold and 2.5 hot)

can you answer this as you look underneath (boiler) are these pipes connected to anything in red

4pipe viessmann.jpg
 
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