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Help me out by labeling it correctly.

Thanks, Could you please elaborate where it would terminate. What about the feed pipe?

Hi, I intend to convert an OV system (with F&E setup) Heat only boiler to a sealed system. Is my understanding correct with this kit with the labels? Thanks in advance.

The boiler does fire in room stat mode. Yes, I have CH working in room stat mode. When I connect the WC sensor it doesn't fire. See pic 1 of boiler display (pic 1 in post 9). Viessmann told me to check the resistance of Weather compensation sensor with a multi meter. I have checked it with MM...

Terminal 5 is for cylinder, the cylinder is not attached with this boiler. C - is cylinder demand box which is required to fire the boiler at maximum power when using weather compensation for CH, it works only if cylinder is present and cylinder demand box is also attached. I don't have any of...

This is the CH boiler and I installed a WC sensor in it. Yes (G) are the boiler terminals. Switched Live is provided to boiler from room stat. I'm have sent an email to tech support as well but there instructions is what I have followed but it doesn't fire using WC sensor.

I am resurrecting an old post in hope that contributors of this post have WC working. I am trying to install Weather compensation sensor on 100-w heat only boiler (2018 model; dial type with only 1 flow temperature for CH only). I have connected the WC sensor as per instructions with the...

I have tried to bypass thermostat but still boiler won't ignite (it doesn switch on, the display shows temperature with CH symbol but it won't ignite). I have tried with or without link on port 96 on PCB. Any ideas? Thanks in advance.

Can I just put SL from boiler to number 4 on programmer? 1. It should bypass the roomstat; 2. programmer should turn heating on. 3. Weather compensation sensor should work. Correct? 4. What could be other way if I want room stat to work in conjunction with WC.

Hi, Attached is a basic wiring layout of room stat + programmer working with Viessmann heat only boiler. (pic 1) I have installed a weather compensation sensor as per schematic (pic2). When I switch boiler on it shows the display with temperature and CH symbol but it is not igniting. Is there...

There is only external pump in a heat only boiler? So there is only one pump which is external. As far as I am aware (and pros can advise better), there is a flow switch in heat only boiler (I know viessmann heat only OV) has one. so no flow no go for this boiler that I am aware.

Are you saving any gas with Combi as compared to previous set up? Is combi serving just one shower.

One last thing, where do I put the filling loop and pressure guage in sealed configuration? Do you have a drawing as I am buying things in pieces; have an external EV without a valve and pressure guage.

Same here, that is why I came to this forum for advice. Must have been a typo if I said 120litres anywhere. I can confirm it is 160 litres. Yes, even though it is an open vent boiler but I have checked with Viessmann, it can be put in a sealed configuration. I'll be led by your guidance, in...

Don't know but see attached extracted from a manual for indirect. I have read a term mWC (meters water column). This is similar to mine but a bigger tank volume (500 litres). I am assuming mine with a lower flow rate than 6.5m3/hr would have less mWC (~1m?). Its a heat only boiler with no pump...

Yes, putting the pump on return pipe to boiler. In a system boiler that's where the pump usually is. So it is pumping into the HEX. I could only find the area in sq.m of HEX. Is there a way you could calculate friction loss in HEX if you have surface area

Its 160 litre, single coil type a nd MI with HEX friction loss is also given. I have to connect 3-4 washrooms (3 showers and a kitchen, not baths). so Combi was not an option. 5 adults in house using 3 washrooms. I hav dedicated this boiler to dhw so I don't mind it recovering as we rarely...

Yes, the vitodens has No.5 sensor cables coming out of boiler so its just a matter of putting a thermostat in indirect and connecting the leads to boiler. Correct but it can be used for sealed system as well. Yes, how can I forget it now, we went through 10+pages on this topic when I was...

I stand corrected; 2.4gpm = 9 l/m. Would I be fine using 22mm for primary piping to indirect even though its inlet coil connections are 35mm?