Search results

No its not and hence the post. The boiler is working in CH mode only (with your help off course). I have bought the cylinder, will hire someone to do the pipework. I have attached a photo of pipeloop with mid position valve which I intend to utilize with cylinder installation. The mid position...

GC Number 41-819-21 But W plan uses a 3 port so can't I use my 3 port valve? If not then what do you suggest. Just to be clear, If I go that route, I would be needing a 2x 2 port valves for CH and DHW circuit? I was trying to not let go the items I already have but if in your opinion an X plan...

Message from viessmann tech support

Correct on 3 port mid position valve. The instruction sheet I have sent in previous note says that DHW can run with weather compensation + cylinder demand terminal box of viessmann. I just want to make sure that it does what it says before I buy terminal demand box.

I have a two pipe heat only boiler (viessmann) so a 3 port valve is required to run PDHW, but that would be a Y plan or PDHW? What is viessmann cylinder demand box used for (see attached instructions) and I am confused about which configuration to run. As OP, I am in similar position and trying...

Yes, a project for summers! But my boiler cannot handle two flow tempearture. It has only one dial setting for temperature so either it has to be CH or DHW not both? Correct. I also intend to install Weather compensation, how it will integrate for DHW in my scheme? You are suggesting:1. S Plan...

Hi, I have a Viessmann vitodens 100-w (compact 13kw) boiler installed in OV configuration (2 pipe system) for CH only. It has a drayton (LP722) timer and a dial type Room Stat. My CH load is under 7 -8 kw. This year I have bought a Weather compensation sensor and cable which is straightforward...

Pros in the forum would be interested in - existing Pipework; - rads sizes; double or single panel - existing or prior HW arrangement in the property - which boiler did you have in the property and were there any issues - are you upgrading the heating system or just the boiler etc.

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.