marshian

I don’t think I’d be calling an engineer out if no repetative fault - £144 is a lot of money - will be an interesting conversation OP “here I saved screen shots of the fault” GE “no fault in system now - £144 please - cash or card” Good luck

I don’t think he meant a 19kW heat loss - he meant the gas engineer proposed a 19kW boiler and he asked for 32kW to be installed

The oversize element (32 v 19kW) doesn’t matter it can modulate to a silly low figure cos Viessmann and if it’s a combi you may need the 32kW for HW. The “sue Viessmann” made me laugh a lot - it’s thrown up an error code for the first time in 2.5 years - it’s under warranty if a reset (power down) fixed it then move on with your life it was a glitch - if it needs a reset every day or week then get an engineer in

Oooff - you’ve done well in that age building - well done

I’d want to be closer to 40 deg C flow temp to move to a HP - 50 is at the top end of HP range and you might not get the COP you would need to break even on energy cost (3.0 to 3.5 unless you have a cheaper tariff for electrickery)

Yes it cycles more ~32 fires/starts in 24 hr period with a higher WC and sheduled heating that would be ~12 cycles in 24 hrs however I am not seeing a huge increase in gas consumption with the current boiler (the prev glow worm yes big increase when cycling more than 3 cycles per hour but it had a 10kW min output)

schedule heating (on/off/on/off) I’m running WC curve of 1.4 Constant on (with setback temps instead of off) I’m running a WC curve of 0.8 I’m working my way towards on (no setbacks) and I think that will be a WC curve of 0.7 Logging HDD data v gas consumption (minus HW) I thing last stage will be 5 to 10% more usage but house comfort will be better (more heat pump like)

That’s not a huge circuit IMO On the bypass valve (my system is boiler rather than HP) but I have it set to only open when the circuit pressure is driven up to the point where just 1 rad is in circuit (from memory that’s about 0.3 bar on the scale) and that stops me dead heading the pump and keeps the flow rate up enough for the boiler to fire once flow temp has dropped enough

All of the above Viessmann 100 W heat only (16 kW) Not a single rad remains from the original house set up 95% of the rads were changed a couple of years ago when I was running a 24kW glow worm boiler the point I was is that rads correctly sized for flow temps and room demand will work perfectly well whatever the heat source is

I don’t get the heat pump and rads comments I could run a heat pump instead of a boiler with the same flow temps I’m running a gas boiler 13 rads with a flow temp of 30 - to 40 deg depending on outside temp - it’s an early 1980’s with some insulation improvements (loft insulation is mainly 70mm so sub standard) and I’m running it 24/7 with setbacks at night and during the day when there is no one home - rad delta is around 6 to 9 deg (depending on flow temp) none of the rads are in the traditional sense hot but room temps are comfortable.

Is the output of the boiler capped for HW for either temp or boiler power? I can understand the output being capped for CH because 26kW boiler feeding a 3kWh heat loss is massively oversized but it makes no sense to me to have only 7kW and 40 deg water Have you got the ViCare App so you can see what the boiler is doing? In my app I can set HW temp different to CH (100-W heat only with 115L cylinder and HW demand box) I'm pretty sure the app would enable you to increase the HW set point to say 50 and the boiler would modulate according to HW flow. I really don't see the point of trying to hack the boiler to do both at the same time - with a heat loss of 3kWh you aren't going to see a house temp drop even if you are running a really big and deep bath!!!

Company I have worked for since early 90’s embraced that same concept - all software central - little boxes instead od desktop PC’s all in the name of effeciency and cost saving on IT It was a bloody car crash and I got to see it implemented and the business suffer the workrate of everyone go down the toilet and the IT dept run around like loons trying to make it work…… 18 mths later pretty much everyone was back to proper desktops or new fangled laptops

Is there an option to lift the floor and run that cable underneath?

Sounds a lot nicer than a park home……..

I'd be starting at the slowest speed possible and seeing how the system responded If the rad circuit has been balanced using the lockshields for a pump set to max you might have to allow a little bit more flow thro the rads but it may not be necessary - I can run my pump on 1 or 2 with no re-balancing required - only difference is the difference between flow and return on each rad drops with an increase in pump speed.