Viessmann 200-W Gas Boiler - The most efficient boiler sold in the UK?

MeteredOut

Waywardmike said:

After reading through this thread I can't help but go back to original post and wonder how you use so much gas to begin with and even now, with an 'A' rated house.  Are there 10 of you living there? Do you throw massive dinner parties where you cook for long periods of time?

I'm in a leaky 4 bed >100 year old detached dormer bungalow with uninsulated solid walls on the ground floor, 9' ceilings and a PIV system pumping cold air into the hallway (small sacrifice considering it essentially cured our condensation issue overnight).  We use less gas than you even after your savings.  We don't cook with gas though and have an iboost so our boiler is essentially off over the late spring/summer early autumn.  We've had a battery the last couple of years so the iBoost doesn't doo much now in the darker months as the battery has PV priority.  Our boiler and cylinder are only 4 years old but made by Ideal so hardly 'high end' and I would assume has none of the fancy tricks the Veissmann has.  I'd probably argue ambient temperatures in London are higher than here, slightly North of London, so our heating system has to work harder.

Confirms what I believe about the EPC system of rating houses, it's pretty useless.

Here is our gas usage for those months if anyone's interested?

Nov   478.8

Dec 1839.1

Jan  2211.5

Feb 1410.6

Are those usages m3 or kWh?

Cardew

Your point about 'tweaking' ASHP settings, and for that matter modern condensing boilers, is well taken.

However the the conclusions of the EST's original trial on Heat pumps made the strong point that getting them to run correctly in all conditions  was beyond the capability of Mr & Mrs Average. 

That observation is still true and I shudder to guess what percentage of occupants are capable of getting optimum performance from their ASHP/boiler - if the house ain't warm enough, turn up the temperature dial in room or boiler(or both) - simples!

For that matter some heating 'engineers'(I use the term loosely) often have little idea, or incentive, to set up systems correctly. Who checks on them- certainly not MCS. 

QrizB

Cardew said:

However the the conclusions of the EST's original trial on Heat pumps made the strong point that getting them to run correctly in all conditions  was beyond the capability of Mr & Mrs Average. 
That observation is still true ...

I've read the EST's reports and am sure they were correct at the time but heat pumps do seem to have improved in the decade(?) since their latest field trial.

All bar 12 of the 69 systems here are reporting COPs of 3 or more.

Accepting that those HPs are probably owned by enthusiasts, it's notable that the median COP seen in the "Electricifation of Heat" project is 2.8. That's an increase on the 2017 RHPP trial, which was itself an increase on the EST trials.

JSHarris

Cardew said:

Your point about 'tweaking' ASHP settings, and for that matter modern condensing boilers, is well taken.

However the the conclusions of the EST's original trial on Heat pumps made the strong point that getting them to run correctly in all conditions  was beyond the capability of Mr & Mrs Average. 

That observation is still true and I shudder to guess what percentage of occupants are capable of getting optimum performance from their ASHP/boiler - if the house ain't warm enough, turn up the temperature dial in room or boiler(or both) - simples!

For that matter some heating 'engineers'(I use the term loosely) often have little idea, or incentive, to set up systems correctly. Who checks on them- certainly not MCS. 

This very much matches my experience!  For a time I was on a forum discussing heat pump problems and there were a large number of very unhappy heat pump owners there.  Almost all had installation/setting up related problems.  Often heat pumps were wrongly sized (typically far too high a capacity so they couldn't modulate down low enough), almost always they were set up badly, more often than not the emitters weren't sized to match the optimum flow temperature.  Clearly some of this was installers going up a steep learning curve; many wrongly assumed that a heat pump was a drop-in replacement for a boiler.

There's also a more general problem of tradespeople (any trade not just heating) not being adequately trained.  There's no real substitute for a fairly long period of one-the-job experience, mentored by someone competent.  The idea that someone can do a 6 week college course and come away supposedly "fully qualified" seems a complete nonsense, yet I met an "electrician" a while ago that had done just that.  I'd employed him on our self-build but sacked him after one day, as he was dangerously clueless, even though had all the right bits of paper.

BikingBud

Given this array of capabilities there is no excuse for a poor set up on commissioning.
Once designed, by Viessman, and installed, by trained installers, the geeks in the customer service centre should able to exploit the web-enabled tech to ensure the system is optimised and users can then just enjoy the comfort of a great system and the benefit of reduced bills.

Total support should be included for the first 12 months to achieve this and on a repayment basis for subsequent interventions.

Should be exactly the same for ASHP. 

Anything else is just taking the mick!

Waywardmike

MeteredOut said:

Waywardmike said:

After reading through this thread I can't help but go back to original post and wonder how you use so much gas to begin with and even now, with an 'A' rated house.  Are there 10 of you living there? Do you throw massive dinner parties where you cook for long periods of time?

I'm in a leaky 4 bed >100 year old detached dormer bungalow with uninsulated solid walls on the ground floor, 9' ceilings and a PIV system pumping cold air into the hallway (small sacrifice considering it essentially cured our condensation issue overnight).  We use less gas than you even after your savings.  We don't cook with gas though and have an iboost so our boiler is essentially off over the late spring/summer early autumn.  We've had a battery the last couple of years so the iBoost doesn't doo much now in the darker months as the battery has PV priority.  Our boiler and cylinder are only 4 years old but made by Ideal so hardly 'high end' and I would assume has none of the fancy tricks the Veissmann has.  I'd probably argue ambient temperatures in London are higher than here, slightly North of London, so our heating system has to work harder.

Confirms what I believe about the EPC system of rating houses, it's pretty useless.

Here is our gas usage for those months if anyone's interested?

Nov   478.8

Dec 1839.1

Jan  2211.5

Feb 1410.6

Are those usages m3 or kWh?

kWh, they're from my bill.

Reed_Richards

@Screwdriva, what's your annual gas usage?  In my old house it was 19500 kWh per year, averaged over 15 years.  This was a 4-bedroom house in Cambridgeshire, built in the 1960s and we used gas for heating and hot water.  I had an Atag gas boiler, which was very advanced for its time.

Screwdriva

Reed_Richards said:

@Screwdriva, what's your annual gas usage?  In my old house it was 19500 kWh per year, averaged over 15 years.  This was a 4-bedroom house in Cambridgeshire, built in the 1960s and we used gas for heating and hot water.  I had an Atag gas boiler, which was very advanced for its time.

Pre all improvements, including the boiler replacement, our gas consumption was ~22500 kWh. Now, after improvements and receiving the EPC A rating, we consume ~12500 kWh for heating, cooking and hot water, with dramatically increased comfort levels. 

Grizzlebeard

Too much to absorb in this thread but....

The average consumer tweaks nothing.

The enthusiast tweaks everything.

Thumbs up to the enthusiasts, but to reach the energy savings the planet needs all the average consumers require a tweak free system.

(An eldery retired ex-tweaker.)

InvertedVee

Cardew said:

Your point about 'tweaking' ASHP settings, and for that matter modern condensing boilers, is well taken.

However the the conclusions of the EST's original trial on Heat pumps made the strong point that getting them to run correctly in all conditions  was beyond the capability of Mr & Mrs Average. 

That observation is still true and I shudder to guess what percentage of occupants are capable of getting optimum performance from their ASHP/boiler - if the house ain't warm enough, turn up the temperature dial in room or boiler(or both) - simples!

For that matter some heating 'engineers'(I use the term loosely) often have little idea, or incentive, to set up systems correctly. Who checks on them- certainly not MCS. 

I retired 2 years ago to a brand new well-insulated home with a Worcester Bosch 30i combi. When we moved in, the installers had commissioned the system with 75C flow temperatures and I set about learning how to make the very best of it. I enjoyed learning and working my way through the installers' manual to experiment to squeeze the most out of it. Things I have changed:

• Replaced the on/off Honeywell programmer with a Tado thermostat.
• Wired the Tado and boiler to use modulation via the EMS bus.
• Limited the maximum heating power to the lowest setting of 7.4kW. The installer had left it on 24kW, which is just crazy for a house with a 2.5kW heat loss at -2C.
• Set the flow temperature to 50C in winter and 48C in the spring and autumn. (The system runs most of the time on the lowest modulation with a flow temp of around 40C.) 
• Set the hot water temperature from 60C to 52C.  
• Set the anti fast cycle time to 10 minutes.
• Changed the anti fast cycle flow temperature to 13C.
• Opened up all the radiator TRVs to maximum, so the whole heating envelope is treated as one zone.

Lots of tweaking then, quite a lot of fun. But I know I'm in the 0.1% of people who enjoy this sort of thing.

I expect that most of my neighbours are getting 24kW of boiler output to blast their radiators up to 75C.