That's interesting, thanks! Vaillant is one of those I am considering so I would be interested in knowing more about where the extra costs will be (e.g. the boiler itself, flue, parts)?
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Opinions on boiler upgrade plans?
- Thread starter dannyboy85
- Start date
That's interesting, thanks! Vaillant is one of those I am considering so I would be interested in knowing more about where the extra costs will be (e.g. the boiler itself, flue, parts)?
My first Vaillant combi was great and so when it became EOL, I replaced it 12 years ago with an EcotecPlus and it’s been very unreliable. Heat exchanger, diverter valves and numerous flow sensors replaced. Not much fun when the 7 year warranty ran out although due to lack of reliability they gave me an extra year. I believe new Vaillant combis are much less sensitive to contamination (Adey magnetic filter fitted that collects a bit of contamination and inhibitor in system) but the heating engineers around here don’t rate Vaillant and prefer Baxi.
Any boiler, running on a dirty system, with little or no maintenence to the water quality, will ingest and trap any rubbish and will choke on it daily.
Multipipe heat exchangers like the Giannoni used in Vaillants will suffer more and quicker and are impossible to flush.
Multipipe heat exchangers like the Giannoni used in Vaillants will suffer more and quicker and are impossible to flush.
I am long retired.
Now, my new boiler has been in since July so I've had a few monthly gas bills in, with the gas usage detailed to the n'th degree, and my Mrs and I use the shower every day, albeit not at the same time (that malarkey stopped a good while ago) Furthermore we've had some cold weather in recent weeks so I've been able judge how well the boiler actually functions in winter and whether or not the burner spends all day cycling on and off (it doesn't).
The economics will vary wildly, depending on how your heating is used, and how you use hot water. I have never said a heat only, is more economical in all circumstances, because it is not.
I have never suggested there would be an inadequate flow from a shower, that is one of the things that a combi excels at doing. What I have said, is that a combi will be much slower than a system with a cylinder of hot water, to fill a bath. To the good, the combi can provide unlimited amounts of hot water, without delay.
To the bad - each and every time you turn the hot tap on, you waste lots of water, and lots of gas, waiting for the heated water to appear. The gas has to heat the heat exchanger, then the water, In order to have the Kw available to produce instant hot water. Often, that can mean the Kw of the boiler, needs to be twice that, or more, needed for central heating. Everyone agrees, that a boiler Kw which is too high, makes them less economical.
You said you have had your old boiler, replaced with a new modern one - of course it will be more efficient.
You claim to be a competent DIY plumber. As such, you should be aware, that nearly all the clever gubbins, which can fail, is tucked away inside that boiler casing. Which means most of the issues with your heating and hot water system, which once on a heat only boiler system, you could have fixed your self - now need a GSR engineer to attend.
This is all old ground, all covered at length, so I will not be drawn any further into the pros and cons, of combi v heat only boilers. This is dannyboy85's thread, it is rude to kidnap it..
Feel free to hijack the thread as much as you all like! The debate is still interesting!
Thank you, Harry. All received.
I won't respond too much further, dannyboy, as Harry has advised me that it's rude and that I've kidnapped the thread, but it was my intention to highlight my own experience and to say, after many years of my own personal prejudice against Combis, that my recent experience, having had one installed, has made me reconsider. There is truth in that, apart from the controls, everything IS contained within one box - and I gave that a vast amount of thought beforehand, but took into account the fact that by having everything in one box then everything is covered by a 12 year manufacturer warranty and my experience of Ideal's area engineer has boosted my confidence even more as he is a time served engineer (26 years with Ideal) and his knowledge knows no bounds.
The flip side of the above is, of course, that if something within the boiler caused the boiler to stop working completely, then I'm at the mercy of either Ideal or the local firm that installed it. And fortunately the local firm that installed it has a dozen engineers on the books and my experince has shown them to provide a prompt, efficient, knowledgable service. So, at the moment, I'm learning as I go but feel fairly confident that I did the right thing. The loft is now clear of tanks and pipes and the airing cupboard now houses vacuum cleaners, an ironing board and towel rails and is heated via a radiator in winter and a 40w tubular heater in summer. So, again. I seem to have struck lucky.
Finally, I agree that if a DISTANT hot water tap is opened in, say, summer, when the heating is off then there it will take a period of time and a quantity of water to get hot water at the tap ..... conversely, in winter, the boiler is already operating and additionally, the shower is a couple of metres from the boiler and, in reality, hot water comes through within seconds, so there's no wastage of water, or gas or anything else.
I will stop there, but appreciate dannyboy's invitation to respond - thank you dannyboy.
I won't respond too much further, dannyboy, as Harry has advised me that it's rude and that I've kidnapped the thread, but it was my intention to highlight my own experience and to say, after many years of my own personal prejudice against Combis, that my recent experience, having had one installed, has made me reconsider. There is truth in that, apart from the controls, everything IS contained within one box - and I gave that a vast amount of thought beforehand, but took into account the fact that by having everything in one box then everything is covered by a 12 year manufacturer warranty and my experience of Ideal's area engineer has boosted my confidence even more as he is a time served engineer (26 years with Ideal) and his knowledge knows no bounds.
The flip side of the above is, of course, that if something within the boiler caused the boiler to stop working completely, then I'm at the mercy of either Ideal or the local firm that installed it. And fortunately the local firm that installed it has a dozen engineers on the books and my experince has shown them to provide a prompt, efficient, knowledgable service. So, at the moment, I'm learning as I go but feel fairly confident that I did the right thing. The loft is now clear of tanks and pipes and the airing cupboard now houses vacuum cleaners, an ironing board and towel rails and is heated via a radiator in winter and a 40w tubular heater in summer. So, again. I seem to have struck lucky.
Finally, I agree that if a DISTANT hot water tap is opened in, say, summer, when the heating is off then there it will take a period of time and a quantity of water to get hot water at the tap ..... conversely, in winter, the boiler is already operating and additionally, the shower is a couple of metres from the boiler and, in reality, hot water comes through within seconds, so there's no wastage of water, or gas or anything else.
I will stop there, but appreciate dannyboy's invitation to respond - thank you dannyboy.
Vs the equivalent Vokera, in round numbers
Boiler +£400
Filter +£100
Flue +£15/length
Flue terminal +£40
Flue 45° bends +£25
Controls +£150-250
If i may summarise the main points, if people have space for a cylinder, a condensing boiler with unvented cylinder (i.e system boiler, i.e not gravity fed) is preferable to a condensing boiler on its own (combi), in terms of durability and efficiency or if multiple bathrooms are involved because higher flow rates can be achieved with a cylinder, all else being equal.
A combi has to work at much higher temperatures to produce instant hot water so is more prone to limescale build up in the secondary heat exchanger whose narrow waterways is also more likely to block up and cause other heat related failures in the boiler such as leaks. On the other hand, with a system boiler, there is no secondary heat exchanger to block up and there is no necessity to even turn on because more often than not there is already a cylinder of hot water ready to go that was heated up earlier in the day at a leisurely pace.
The other disadvantage of combi is in the case of boiler failure, there will be neither hot water or central heating. With a system boiler though, with a boiler failure you still have hot water because the cylinder often has a back up heating mechanism in the form of an electrical immersion heater that heats the water in the cylinder if the user decides to turn the immersion on.
A combi has to work at much higher temperatures to produce instant hot water so is more prone to limescale build up in the secondary heat exchanger whose narrow waterways is also more likely to block up and cause other heat related failures in the boiler such as leaks. On the other hand, with a system boiler, there is no secondary heat exchanger to block up and there is no necessity to even turn on because more often than not there is already a cylinder of hot water ready to go that was heated up earlier in the day at a leisurely pace.
The other disadvantage of combi is in the case of boiler failure, there will be neither hot water or central heating. With a system boiler though, with a boiler failure you still have hot water because the cylinder often has a back up heating mechanism in the form of an electrical immersion heater that heats the water in the cylinder if the user decides to turn the immersion on.
That would work
But an unvented cylinder indirect coil often is 20kW or more yet the radiator loading often is 12- 15.
When cylinder is getting required input of heat, reheat times are fast ( have seen 15 minutes to get to 75% duty)
Some boilers are dual input allowing boiler output to be matched to the load
170l Megaflow is rated at 24 kW
140 L at 18
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