Recent content by desktop987456

Yes. This is what I have put; a 13kw heat only boiler (Viessmann vitodens 100-w). I have a two pipe system. I didn't change any pipework, its an open vent system. All single glazed windows. I had to change a couple of radiators upstairs since old ones were single panel and were inadequate for...

I had two 24+18kw old boilers serving two separate zones in my house. All single glazed windows, poor insulation no cavity walls. I plugged all draughts and holes. I carried out HL calculation and it turned out I need 12kw for 4 beds, a huge lounge (600sq.ft), 3 baths. Installed 13 kw Viessmann...

Fill in these details and I can calculate it for you.

I am a home user and not a pro and would like to clarify as a user that I did check with Viessmann UK and they confirmed and it is written in MI as well that OV boiler can be used in a pressurised or seal system too.

Couldn't agree more. I have a double storey 4 bed + 4 baths + Lounge Upstairs (650sq.ft with a fancoil unit) and a Lounge downstairs. We heat our bedrooms (1200mm rads) , baths and Lounge (1200mm rads) mostly during day time. The heatloss of my property (which I did it myself in Excel) turned...

Have you tried resetting the timer? Is pump connected to pump port on pcb or in wiring center? I have the same boiler and programmer. My pump is connected to one of the port on boiler PCB so it is getting power from boiler and it works fine in 'timed' or 'on' mode.

Please share your experience after installing it as I might follow your lead though I have a different boiler than yours.

Thanks John for your detailed working on this, I will measure the condensate output again. I have been very meticulous in terms of gas usage and logging m3 consumed almost every hour during boiler operation but have not been able to control the usage.

Can't say they are perfectly balanced but as far as I can tell from copper pipes of rad at flow and return, they seem to be balanced. I need to play a little with pump speed though. Flow-return delta on boiler increases if I set the pump on c1 setting (return drops to 35.5Degc), but I felt rads...

I have also tried to change the pump speed to its lowest setting (C1) but at this flow temperature, heating in rooms couldn't get to temperature. Rads were luke warm and boiler kept on running at its minimum flame level and was on a bit longer than usual. Once CH is upto temperature the boiler...

Correct. I have measured the return temp of boiler, collected and measured condensate which was about ~1.5 litres per hour. This tells me that boiler is condensing but when I try to calculate efficiency based on heatload they don't add up? The boiler's turn down ratio is 1:3 so at 12.9 kw max...

Rads are the same as last year when I had non condensing boiler. I think I may have skewed heatloss calcs a bit, not sure. Hence this post.

Hi, My viessmann heat only boiler 13kw (OV) is running at flow temp of 54.5DegC and a return temperature of 40DegC. I know it is a crude way of getting the return temperature on boiler. In the 2nd picture showing the return temperature you can spot the sensor attached to return pipe next to...

For rads output at different flow rate I use the attach table which is roughly the same as you stated in your post. So in my case I just multiply the T50 rad output with Rad temperature rating e.g. 51.5 in my case hence the 8.1kw number I am getting in my spreadsheet against 11.8kw of heatloss...

Correct. My rads oversized and I have stated the name plate or stated output of the rad in this column. The next column is oversized factor which is 'Heatloss divided by stated output' Correct. I don't know the return temp to boiler but flow temp of boiler is 49.5DegC. Rooms get to the...