Search results

All valves open. The boiler has a flow switch, I'll check if it works.

I can tell you from experience; I live in a milder weather than yours (not in UK) where sun is available from 1000-1430hrs in winters; In Jan my 10.8kw Solar array generated 750kWh (I doubt it you'll get half of it with UK weather). As correctly stated above Solar gives you nothing when you need...

Update : I have installed a dedicated boiler Viessmann 100-w heat only boiler with external pump and an EV on boiler's flow. The intent was to connect it to a vented hot water cylinder. I have filled system with pressure guage showing 1.5 bar on boiler piping, the boiler turns on but it keeps...

Thank you Mottie and Rob for your help.

space heating only

I have corrected the labeling, I didn't label the cold inlet as it was obvious. I am unsure how water when expanded will go into EV. Secondly, what does the arrow on PRV signify.

Correct and I am trying to grab the concept before taking it on as a DIY.

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.