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Gas and Electricity Prices

To recap: UK energy prices rise by 54%. French energy prices rise by 4% (Reuters).

Cherry picking at it's best there Tony, a better example from the same report is Germany, where.

Some 4.2 million German households will see their electricity bills rise by an average 63.7% this year while 3.6 million face gas bills 62.3% higher than in 2021 as suppliers pass on record wholesale costs, industry data suggests
 
Yes, that poor. I gather anything less than 89 or 90 % is old hat now.

Though condensing boilers only achieve those headline 90% efficiency figures when they are actually in condensing mode.

The rest of the time they run around 75% efficient.
Strangely the marketing/sales blurb usually fails to mention that.

A condensing boiler running without condensing, would be allowing at least 8% of the energy from the combustion process to escape out of the boiler flue.

https://theintergasshop.co.uk/content/187-why-your-new-gas-boiler-isnt-efficient
 
When do they switch out of condensing mode? Is this something that depends on demand, or ambient conditions, or what?
 
Cherry picking at it's best there Tony, a better example from the same report is Germany, where.
As successive German chancellors decided to trust the tender mercies of Vladimir Putin, Gazprom etc. for their energy supply, and deferred to their constituents' "Atomkraft, nein Danke!" principles/prejudices, one can only assume they are satisfied with paying through the nose for one of the dirtiest energy supplies in Western Europe.
 
When do they switch out of condensing mode? Is this something that depends on demand, or ambient conditions, or what?

Condensing boilers condense at 54 degrees C so if you run the boiler thermostat at that setting the boiler will condense however the surface temp of the rads will be about 50 degrees ie a bit tepid so that radiator temperature is really only effective if you have a super well insulated home/property ie you're only raising the property ambient temperature by about one degree c.

Personally I have a weather compensating programmable thermostat and an outdoor weather sensor so that makes my boiler about 97% efficient but I run the flow/boiler thermostat at 80degrees C cause the weather/temperature here in sunny Glasgow is mostly baltic all year round.
 
When do they switch out of condensing mode? Is this something that depends on demand, or ambient conditions, or what?

That's why I posted the link, but here is another extract.

Looking across social media platforms, lots of installers are retrofitting condensing gas boilers to existing heating systems, without maximising the efficiency of the new condensing boiler. Most boilers I see are being ‘swapped’ in a day, with very little thought about changes in radiator output, flow temperatures or correct flow rate balancing. The fact is, a condensing gas boiler with a return temperature of 50°C would only be circa 89% efficient (89p recovered for every £1 you spend), however the majority of condensing boilers have return temperatures much hotter than this, due to mismatched flow rates and high return temperatures. A condensing boiler needs the return temperature to be as low as possible, and at 30°C a condensing boiler would theoretically obtain 95% efficiency. Condensing boiler manufacturers typically state two outputs in their manuals; one at higher temperatures (70/50) and one at lower temperatures (50/30) to reflect the energy available at different flow and return temperatures.


Higher flow temperatures are 'required' as the outside temp drops to provide a comfortable interior. Turn up the boiler thermostat, but that can reduce the efficiency.
Hence why, Weather compensation control works, which alters the boiler stat to suit the external temperature.
This is why you need a heating engineer, as opposed to a 'plumber'.
Actually you just need someone who knows and cares. After all I'm technically a cabinet maker :)
 
Though much bigger radiators, think 30/40% should do the trick, though many would balk at the cost.
They will be needed when we switch to electric heated central heating though. Currently 5X the kWh cost of gas....

Called Air Source Heat Pumps.
 
When do they switch out of condensing mode? Is this something that depends on demand, or ambient conditions, or what?

Condensing mode is dependent on the return water temperature. If you have TRV’s fitted as they shut off the flow to some radiators the heat loss becomes less and the return temperature could rise above the condensing range.
 
As successive German chancellors decided to trust the tender mercies of Vladimir Putin, Gazprom etc. for their energy supply, and deferred to their constituents' "Atomkraft, nein Danke!" principles/prejudices, one can only assume they are satisfied with paying through the nose for one of the dirtiest energy supplies in Western Europe.

Though in the USA, one of the largest oil/gas producers in the world gas prices have risen 40 %
in the last year.

My brother lives there and is really pissed off about it, as I said to him the other week you don't even have Trump to hold responsible for it.
 
Condensing mode is dependent on the return water temperature. If you have TRV’s fitted as they shut off the flow to some radiators the heat loss becomes less and the return temperature could rise above the condensing range.
It’s interesting that you get marked down on energy surveys if you don’t have TRVs!

There must be a tricky trade off between heating unused rooms to keep efficiency high vs heating fewer rooms thereby using less gas overall, albeit at reduced effiency.
 
Heating systems, more complicated to get right than hi-fi systems ?

I wonder if pipe lifters and special cable to the boiler would work.
I can see a whole new industry, special water for the system and everything.
 
In our case the boiler really needs replacing anyway so any savings in running costs would be a bonus. We've already got TRV's on most of the radiators in the house and we do use them, as there are only the 2 of us (and the dog!) in the house now so a lot of the rooms don't get used all that often.
 
For the record my Ideal Vogue boiler has had the burner on for 6473 hours with 44% high efficiency and 56% super efficiency (condensing mode).
Though my 5 bed detached house was built in 1865, so has an insulation value of less than the square root of very little.

It's a superb boiler BTW been in 9 years, no problems and tells me lots of useful information for forum threads when gas prices rocket.
 
For the record my Ideal Vogue boiler

Would this be your recommendation against a Vaillant, which is my other option (plumber is agent for both)? Thank you for the link above, which I'm sure is a very good analysis of condensing boilers and their requirements, but unfortunately dementia set in about half-way through. I frequently see plumes of white whatever shooting out from neighbours' flues; esp. after turning on, I think, and wondered what this was, as my ancient Potterton doesn't do that; in fact, there's rarely anything much to see, even in frosty conditions.

How does one ensure that the return temp. of the water (htg. or just water or both?) is at that efficient condensing level, esp., as with Steve G above, unused rooms are either on tick-over and bedrooms are off during the day (with doors closed, of course)?

As I'm awaiting a quote for a refurb. (boiler, cylinder + a couple of TRVs etc.), I'd very much like to get this installation right as well as operate it as efficiently afterwards as poss. (vented system here). I gather that anything will be massively better that my eighties boiler but I'm a little sceptical, though the whole system is underpowered and clogged up after it was last emptied, but not flushed, 12+ years ago.
 
In our case the boiler really needs replacing anyway so any savings in running costs would be a bonus. We've already got TRV's on most of the radiators in the house and we do use them, as there are only the 2 of us (and the dog!) in the house now so a lot of the rooms don't get used all that often.

Trvs are worse than useless anyway they really are only a comfort control although they do add 5% efficiency to the boiler/heating system.

Wireless remote programmable TRVs are much better because you can have multiple heating zones ie every rad with a WTRV is a zone so 45 rads 15 zones ergo the boiler can be programmed to heat only one zone ie rad however WTRVs are still only comfort controls ie they won't save you dosh unless you have a boiler that has a modulation ratio of 1:10 but those boilers are few and far between are are very expensive.

Here's one with a modulation ratio of 1:8 what that basically does is reduce the heating output to about 4.5 KW on a 35kw boiler so you're only using the minimum amount of heat to heat one of those zones/rad but 5 KW is a big rad and the WTRVs are about £60 each plus a controller.

No-one but but no-one is interested in the above all they want is a boiler that works and costs as little as possible to buy and install so adding the extra cost of the high modulation ratio boiler plus about £1500 for around ten MTRVs and controller is a no no.

https://www.vokera.co.uk/homeowners/boilers/unica-max-c/
 
Would this be your recommendation against a Vaillant, which is my other option (plumber is agent for both)? Thank you for the link above, which I'm sure is a very good analysis of condensing boilers and their requirements, but unfortunately dementia set in about half-way through. I frequently see plumes of white whatever shooting out from neighbours' flues; esp. after turning on, I think, and wondered what this was, as my ancient Potterton doesn't do that; in fact, there's rarely anything much to see, even in frosty conditions.

How does one ensure that the return temp. of the water (htg. or just water or both?) is at that efficient condensing level, esp., as with Steve G above, unused rooms are either on tick-over and bedrooms are off during the day (with doors closed, of course)?

As I'm awaiting a quote for a refurb. (boiler, cylinder + a couple of TRVs etc.), I'd very much like to get this installation right as well as operate it as efficiently afterwards as poss. (vented system here). I gather that anything will be massively better that my eighties boiler but I'm a little sceptical, though the whole system is underpowered and clogged up after it was last emptied, but not flushed, 12+ years ago.

All you're seeing is the boiler flue plume there's less NOX in the POCs in a condensing boiler (products of combustion) hence the white cloud other than that old SE boilers and new condensing boilers POCs are more or less the same albeit the plume can be a bit annoying if it's blowing into your garden etc.

Re the return temp all you do is set the boiler heating thermostat to about 55C but don't get wound up about that stuff.

Just buy whatever boiler your installer recommends or do your own research and buy whichever one he'll be happy installing.
 
As it happens we've just got the renewal in for our Scottish Gas HomeCare cover on our heating system and they mention in the proposal that some parts for our old boiler are becoming difficult to get, so they may not be able to fix it if it breaks down. So I've booked them to come and do a survey on Friday to give us a price to replace the boiler with a Combi and I'll use that as a baseline to get another couple of quotes.
 
No-one but but no-one is interested in the above all they want is a boiler that works and costs as little as possible to buy and install so adding the extra cost of the high modulation ratio boiler plus about £1500 for around ten MTRVs and controller is a no no.

We might be selling the house soon anyway, if my wife and I go ahead with our plan of retiring when I turn 55 - so while I think it is going to be worthwhile to replace the boiler I wouldn't want to spend a lot more at this point. I'll probably just go with whatever the recommended Worscester Bosch combi is.

Our cottage (where we'll initially be retiring to) had a new oil fired combi boiler fitted last year (which I think is a 26KW one) but doesn't have a main thermostat (it relies on all the radiators except one having thermostats) so I think we are likely to make some upgrades to that as it'd be useful to be able to turn the heating up remotely when we're driving there. We've discussed that with the folks that installed and now service the new boiler so will probably go with their recommendations.
 
We might be selling the house soon anyway, if my wife and I go ahead with our plan of retiring when I turn 55 - so while I think it is going to be worthwhile to replace the boiler I wouldn't want to spend a lot more at this point. I'll probably just go with whatever the recommended Worscester Bosch combi is.

Our cottage (where we'll initially be retiring to) had a new oil fired combi boiler fitted last year (which I think is a 26KW one) but doesn't have a main thermostat (it relies on all the radiators except one having thermostats) so I think we are likely to make some upgrades to that as it'd be useful to be able to turn the heating up remotely when we're driving there. We've discussed that with the folks that installed and now service the new boiler so will probably go with their recommendations.

Worcester Bosch 8000 life which is basically an upgraded Cdi which is their best ever boiler.

Fit whatever the boiler manufacturer's programmable room stat is so if the oil boiler is a Worcester OFB then buy their controller.
 


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