Vitodens 100 intermittent heating water and radiators

[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

 

[skir2000]

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

I think I understood you... added another picture of the bottom. the B and D pipes coming from bottom of the boiler are blanked off...?

 

[ShaunCorbs]

thnx and that pic is great now the hunt begins you looking for something that looks like this will be one or the other

 

[skir2000]

thnx and that pic is great now the hunt begins you looking for something that looks like this will be one or the other

What do you mean, I have to buy them?

 

[ShaunCorbs]

What do you mean, I have to buy them?

no you need to find one or the other there will be one on your system somewhere

 

[skir2000]

no you need to find one or the other there will be one on your system somewhere

ah jaysus... Will be back to you tomorrow then

 

[ShaunCorbs]

ah jaysus... Will be back to you tomorrow then

not a problem should be accessible eg cylinder room pipes on show etc

 

[skir2000]

no you need to find one or the other there will be one on your system somewhere

Got any suggestions of where to look? Where would these normally be?

 

[ShaunCorbs]

Got any suggestions of where to look? Where would these normally be?

above post

 

[skir2000]

above post

Found it behind the cylinder... That box, one pipe runs from the cylinder into the bottom, and the other pipe runs into the top of the red tank from my previous image... working on adding them all to one photo

 

[ShaunCorbs]

Found it behind the cylinder... That box, one pipe runs from the cylinder into the bottom, and the other pipe runs into the top of the red tank from my previous image... working on adding them all to one photo

(best when cold if pos) turn hot water off and then turn heating on only heating do you feel any warmth / flow through 1 on your pic? if you dont 80% the valves faulty

 

[skir2000]

above post

added more images... see "Box" and the other two new ones there - is this what you wanted? Sorry for crap quality of images, the ligthbulb went on me

 

[ShaunCorbs]

added more images... see "Box" and the other two new ones there - is this what you wanted? Sorry for crap quality of images, the ligthbulb went on me

there fine see above comment quick q tho does pipe 1 just go to the red vessel or does it t off?

 

[skir2000]

there fine see above comment quick q tho does pipe 1 just go to the red vessel or does it t off?

Damn, posted a comment but think I lost it... Added another 2 images to show you the cut off.

Also:
a: the pipe from the red vessel is cold
b: the pipe going from centre part of cylinder to the bottom (or #2) part of the box is barely warm

Now, when you said to turn on the CH only, I have a problem. Selected the unit to run CH only (using the +1hr button) and the boiler hasnt fired up. The display on control panel seems to think it has done its job, the red light to denote that the CH is on is glowing happily

 

[ShaunCorbs]

Damn, posted a comment but think I lost it... Added another 2 images to show you the cut off.

Also:
a: the pipe from the red vessel is cold
b: the pipe going from centre part of cylinder to the bottom (or #2) part of the box is barely warm

Now, when you said to turn on the CH only, I have a problem. Selected the unit to run CH only (using the +1hr button) and the boiler hasnt fired up. The display on control panel seems to think it has done its job, the red light to denote that the CH is on is glowing happily

i would say 3 port valve needs replacing

 

[skir2000]

i would say 3 port valve needs replacing

3 port valve, is that the little box you had me searching for? Are they standard/common to get?

 

[ShaunCorbs]

3 port valve, is that the little box you had me searching for?

yes where you labeled 1 and 2 (1 is heating 2 is hot water)

do you have a room stat if so that should be set to max just incase (im sure you have done this already)

 

[skir2000]

yes where you labeled 1 and 2 (1 is heating 2 is hot water)

OK... so from my image with the 1 and 2 on it

1. goes to red tank (expansion tank?)
2. goes to the cylinder
and then the 3rd part goes off into the wall somewhere... that correct?

Now, do I have a second problem with the actual controller? Heating won't switch on!

I added another 2 images - the boiler display shows no temp change and below that it doesn't show that boiler has fired up like the previous display images. As you can see in second image, the controller thinks CH is running. See the "BoilerNotFiring" images.

 

[skir2000]

yes where you labeled 1 and 2 (1 is heating 2 is hot water)

do you have a room stat if so that should be set to max just incase (im sure you have done this already)

Yeah, room stat is at max

 

[skir2000]

Yeah, room stat is at max

Actually no, that's a lie!!! it wasn't max (thought it was). I moved it to max and it kicked off the boiler! Why would that be causing it not to fire up?

 

[ShaunCorbs]

OK... so from my image with the 1 and 2 on it

1. goes to red tank (expansion tank?)
2. goes to the cylinder
and then the 3rd part goes off into the wall somewhere... that correct?

Now, do I have a second problem with the actual controller? Heating won't switch on!

I added another 2 images - the boiler display shows no temp change and below that it doesn't show that boiler has fired up like the previous display images. As you can see in second image, the controller thinks CH is running. See the "BoilerNotFiring" images.

1 should go to the expansion tank and to the rads (should be a t somewhere on that pipe)
2 goes to your cylinder
3 is from your boiler supplying hot water

as for your controller press the red button it should change red column if not your controllers at fault and causing other issues

 

[ShaunCorbs]

Actually no, that's a lie!!! it wasn't max (thought it was). I moved it to max and it kicked off the boiler! Why would that be causing it not to fire up?

do rads get warm give it 10 mins to heat up should stay fired (boiler)

 

[skir2000]

1 should go to the expansion tank and to the rads (should be a t somewhere on that pipe)
2 goes to your cylinder
3 is from your boiler supplying hot water

as for your controller press the red button it should change red column if not your controllers at fault and causing other issues

View attachment 23499

Thanks again, for the millionth time

I have been using the timer perferctly fine on the controller. The stat on the wall in the hall is what I changed. I used the +1hr function just to kick off CH on its own.

So if I need hot water, I run HW only. If I need hot radiators, I run CH only. If I need both, I assume I need to run both simultaneously? This is the issue I guess, why i need the valve replaced? Sometimes only one is heated when I have timer to bring on both...

 

[skir2000]

do rads get warm give it 10 mins to heat up should stay fired (boiler)

Yeah, the rads are already hot

 

[ShaunCorbs]

Thanks again, for the millionth time

I have been using the timer perferctly fine on the controller. The stat on the wall in the hall is what I changed. I used the +1hr function just to kick off CH on its own.

So if I need hot water, I run HW only. If I need hot radiators, I run CH only. If I need both, I assume I need to run both simultaneously? This is the issue I guess, why i need the valve replaced? Sometimes only one is heated when I have timer to bring on both...

if you have both on and yes thats is (both on either auto for a pre set time or manual on thats fine) and room stat or cylinder stat calling (needing heat eg cold) then yes valve would be the go to first

keep an eye on it for a week you might be fine now

what you need for boiler firing

heating side

heating - clock - room stat - motorized valve - boiler firing

hot water side
hot water - clock - cylinder stat - motorized valve - boiler firing

 

[skir2000]

if you have both on and yes thats is (both on either auto for a pre set time or manual on thats fine) and room stat or cylinder stat calling (needing heat eg cold) then yes valve would be the go to first

keep an eye on it for a week you might be fine now

heating side

heating - clock - room stat - motorized valve - boiler firing
hot water - clock - cylinder stat - motorized valve - boiler firing

This has been extremely helpful!! I can't thank you enough, particularly for your patience.

Would you recommend that I keep the room stat on max all the time? Or does that use the temperature of the house to determine how long the boiler will run for? and just tops up the temp when needed?