Possible Combi Boiler Issue!

Mr Mcgoo

Mr Mcgoo

Mr Mcgoo

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Hi everyone. So i have the Viessman's vitodens 100-w condensing combi boiler and it would seem i may have an issue with water temps for both heating and DHW (domestic hot water). I have both set to 60c yet both my heat up to 75c then cool down to 65c to then heat back up again. This is well above the set water temp. Even if i drop the setting down to 50c the exact same thing happens. It acts as if the set temperature is ignored. My trouble is, i'm renting and if i call a gas engineer out and no fault is found i will be charged a call out fee £60, so would rather avoid that if possible. Anyone hear able to help before i risk a £60 loss before crimbo?
 
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Not familiar with that particular model, but round this time of year it's quite common for boilers to lose pressure due to colder temperatures.

Might be worth checking - has the landlord provided a manual for it at all? (It's usually it's pretty obvious anyway as the dial will have a green/highlighted section for the correct pressure range).
 
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Thanks for the quick response. It has a pressure gauge and is reading 1.5 bar under operation. The manual states 0.8 bar minimum but no recommended pressure value. online i can see between 1-2 bar is the right value so i am all good there.
 
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In that case, short of being able to find it as a common fault and a simple solution online, I don't have any other ideas, sorry :(
 
Richie said:
Have you had a look here - https://www.viessmann-us.com/conten...ions/original.media_file.inline.file/file.pdf
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That is the manual for an older boiler. However, i already have the manual for my boiler thanks :) Shame that the manual does say anything in regarding to this issue nor can I find it online.
Haggisman said:
In that case, short of being able to find it as a common fault and a simple solution online, I don't have any other ideas, sorry :(
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Not to worry thanks for your help anyway :)
 
Well this is creepy. I read your post then a hour later my boiler stopped working and its the same boiler as yours and the same problem but mine also gives a error code of FF.
Not had it serviced for 11 years so its done well and saved £££'s
Now fault FF says electrode needs replacing easy to do have just removed mine and its worn out cost £39 for a replacement.
Page 25 and 26 https://static.viessmann.com/resour...pdf#pagemode=bookmarks&zoom=page-fit&view=Fit
This is the part https://www.cityplumbing.co.uk/p/viessmann-ignition-and-ionization-electrode-block-7828718/p/799123
If yours is a newer boiler just look for yours and its the Installation and service instructions manual you are looking for.

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It might not be your problem but thought I would share anyway.
 
That's seriously bad timing. Hope you get it fixed soon. I have no error code but my boiler is only 3 years old and has a yearly engineer come out to check for any issues. I am not due an inspection for another 8 months. Timing is just great. Right as the heating will start to come on :(
 
How long ago was it serviced? I think it’s partially blocked, like the hoses inside of it, so it can’t regulate properly, a flush out and clean would solve it I think

Had one similar a while ago, the main flow and return hoses inside the boiler where full of debris, aswell as the plate heat exchanger

I’d defiantly get that looked and and pretty sure it will be the problem

Picture of the stuff I got out the pipes - https://flic.kr/p/2pgcYph
 
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Mr Mcgoo said:
4 months ago i had a service and i get one every year.
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Do they take that heat exchanger out like in my pic? And the main flow and return rubber pipes within the boiler? I’d think it’s that causing your problem mate

That was on the same Boiler a couple of months back, was doing the similar things which yours is !
 
PishY said:
Do they take that heat exchanger out like in my pic? And the main flow and return rubber pipes within the boiler? I’d think it’s that causing your problem mate

That was on the same Boiler a couple of months back, was doing the similar things which yours is !
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i didn't pay much attention so will ask them to check it out next service. thanks for the info :)
 
Mr Mcgoo said:
i didn't pay much attention so will ask them to check it out next service. thanks for the info :)
Click to expand...

No worries mate! Be interesting to see if it is the same, my mate is the king of viessmann boilers in the midlands! He’s got me into them!
 
ok so boiler has been fixed. turns out it has been locked to a setting and eco was disabled. any setting i changed wouldn't save but now it does and pressure is now at 2 bar while heating and 1.2 bar while off/eco mode. Strangely another issue has arrived. Really strong garlic/onion smell when the heating is on and a slightly lower garlic/onion smell with hot water running. This was a smell we had last year but was very light and we had a new foreign family move in next door thinking they maybe used a lot of garlic/onions. However the smell was mainly during the winter (highest boiler use). Winter again and the smell is worse. Anyone know what this smell is as the boiler is in the small bedroom and stinks the house out and is really bad for hours after the heating has been turned off.
 
yeah seems that a gas leak is what other have said it could be. will get the plumber out tomorrow and check to make sure :)
 
Mr Mcgoo said:
ok so boiler has been fixed. turns out it has been locked to a setting and eco was disabled. any setting i changed wouldn't save but now it does and pressure is now at 2 bar while heating and 1.2 bar while off/eco mode. Strangely another issue has arrived. Really strong garlic/onion smell when the heating is on and a slightly lower garlic/onion smell with hot water running. This was a smell we had last year but was very light and we had a new foreign family move in next door thinking they maybe used a lot of garlic/onions. However the smell was mainly during the winter (highest boiler use). Winter again and the smell is worse. Anyone know what this smell is as the boiler is in the small bedroom and stinks the house out and is really bad for hours after the heating has been turned off.
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Is the smell coming from the boiler specifically or is it just present when the boiler is running.
Could it be burning plastic?
 
Only when the boiler is running but it's not a plastic burning smell. Still waiting on my landlord to send someone out. He said to be safe he will get someone on it and have yet to hear back. So will give until Thursday and call back to make sure it's sorted in case it's something more serious.
 
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