Going green(er) with a Viessmann 200W (& heating efficiency home improvements)

Screwdriva

Episode is live!

https://www.youtube.com/watch?v=UHD_-i5ulms

Reed_Richards

That's a really good video, @Screwdriva.  I can't help feeling that your boiler really wants to be a heat pump so the control methodology is very like the more sophisticated end of heat pump control.  It also strikes me that you will have to wait half a year to set up your heating; you can't do weather compensation from scratch in the summer.

Screwdriva

Reed_Richards said:

That's a really good video, @Screwdriva.  I can't help feeling that your boiler really wants to be a heat pump so the control methodology is very like the more sophisticated end of heat pump control.  It also strikes me that you will have to wait half a year to set up your heating; you can't do weather compensation from scratch in the summer.

All true and wise words. A heat pump would have added £7K net to the bill and would have never recovered that cost, so this was the next most sophisticated option. 

Reed_Richards

Screwdriva said:

....would have never recovered that cost.... 

...based on current gas and electricity prices.  It has become very difficult to predict what will happen in future.  However the infrastructure you have now may well be heat pump ready.  

Screwdriva

Reed_Richards said:

...based on current gas and electricity prices.  It has become very difficult to predict what will happen in future.  However the infrastructure you have now may well be heat pump ready.  

It is heat pump ready. Urban Plumbers did initially spec a Valiant Arotherm+ unit but pivoted when I modeled running costs, ROI, delivery backlog of 3 months etc. 

Let's just say that a 10 year recovery of my incremental spend would require a SCOP that was unattainable on a Air to Water HP, or gas prices that would ensure societal anarchy today. In 10-12 years, I may add one to the system when the technology has evolved.

Reed_Richards

Experience would suggest that social anarchy can be avoided if you raise prices slowly enough or if you have an excuse that seems reasonable enough. 

michaels

Screwdriva said:

Reed_Richards said:

...based on current gas and electricity prices.  It has become very difficult to predict what will happen in future.  However the infrastructure you have now may well be heat pump ready.  

It is heat pump ready. Urban Plumbers did initially spec a Valiant Arotherm+ unit but pivoted when I modeled running costs, ROI, delivery backlog of 3 months etc. 

Let's just say that a 10 year recovery of my incremental spend would require a SCOP that was unattainable on a Air to Water HP, or gas prices that would ensure societal anarchy today. In 10-12 years, I may add one to the system when the technology has evolved.

Probably not until the winter at 12p per kwh...

markin

BUFF said:

Reed_Richards said:

I would have guessed probably a theoretical 98% v 90%.  So "moderate" is really very good except for the fact that you are aspiring to 98%

On my scale, 80% efficiency is "moderate", 90% efficiency is "high", 98% would be "very high" (or exceptional ).

Screwdriva said:

P.S. We've been able to achieve a decent reduction in consumption already

bear in mind that it has been a very mild winter - my gas consumption dropped not only compared to last year (which, for me, was above average) but noticeably below my 12 year average.

  This could be very bad math, knocking off the average for 5 days i come up with 282kwh per degree for 7-18c And 278kwh for 8-18c So a 4kwh average saving per day discounting the warmer winter average.

A heat pump would be heard be someone or everyone, Over the water they aren't really that far away.

Screwdriva

An early preview of what to expect this winter perhaps? August was the first month the cylinder immersion heater wasn't used (given Agile Outgoing prices.) The follow are the actual measured consumption figures YoY:

August 2021 - 20 metre units/ 640 kWh used for DHW
August 2022 - 13 metre units/ 415 kWh used for DHW

Consumption patterns were largely the same. The only variable was pipe lagging. It's clear the Viessmann 200-W has yielded gas consumption savings of ~35% for DHW. If my maths is correct, at the new price cap tariff, this would translate to a savings of £400 per annum for hot water.

70sbudgie

I'd not seen this thread before today - I have found it very interesting, though I'm not sure I understand much of the technical conversations (the bits I find most interesting!)

We have a WB Greenskies boiler (I think), possibly of the same vintage that @Screwdriva has replaced. As well as 3 heating zones - two of UFH and the third of the house's original CH system of radiators. 

Rather than ask a million questions here, can you suggest what I should be reading to get a better understanding? I would like to get my house future HP ready without spending abortive costs and hopefully making some savings on the way.