Condensing boilers

[Dave Plowman (News)]

More numbers plucked out of the air.

If it were 55% and your modern boiler was 108% or whatever it would near half the gas consumption. And not even the wildest of advertising claims that.

[Dave Plowman (News)]

If I did, it would need servicing at least once a year. Is this how you fuel yours and why you insist on yearly servicing?

And is this were you get your figures for '55%' efficiency?

[Doctor Drivel]

[Doctor Drivel]

Yes 55 is a number.

[Doctor Drivel]

It is clear you know sweet nothing about boilers.

[RedOnRed]

Before you embark on a load of misleading figures. The efficiency of a 25 year old boiler is likely to be around 55% efficient. Like the one I just got shot of.

[RedOnRed]

I thought kettling was more to do with the age of the boiler, in so much that they all fur up eventually and are then prone to kettling?

I'm sure it does mean that. But doesn't it regulate the power too? If an old boiler fires up only in 1st gear, a modulating boiler can use several gears...thus increasing the heat output? Just an analogy.

[Dave Plowman (News)]

It really depends on the type of 25 year old boiler. In 1980 there were plenty that bettered that and by quite some margin.

[Dave Plowman (News)]

Assuming it's not a combi, there's no reason why it should fur up if properly maintained.

Older boilers fired up on maximum burner rate. They controlled the water temperature by switching on and off. A modulating boiler can reducing the flame size. So assuming the output and heat exchanger are the same, there will be no difference in heat up time.

[RedOnRed]

So what's the point of the modulating large and small flame?

Isn't it to control the rate of heat?

My old boiler wouldn't modulate and would heat on fixed flame which would be lesser then a full on modulating one in my new boiler, which would surely heat faster on full modulation?

A bigger flame means quicker heat doesn't it? Or is my sense of logic not modulating right?

[informer]

"Doctor Drivel" wrote

They might have to be but most aren't

I had my one serviced for the first time when it broke down after 14 years.

[Andy Hall]

The only reason that a newer boiler, be it condensing or not would heat faster than an older generation one would be that the newer one would typically have a stainless steel or aluminium heat exchanger and the older one perhaps cast iron.

The point about modulating is three-fold:

- The boiler can run continuously rather than on/off for more of the time. Cycling, especially with a cast iron model is less efficient, especially with an old conventional or non-fan-assisted model where excess heat at the end of the cycle ends up outside.

- A modulating boiler can begin to turn down the heat close to the desired temperature for the house and reduce temperature overshoot.

- On a condensing boiler, operating at a lower temperature results in more efficient operation.

[Doctor Drivel]

You are totally irresponsible and should be prosecuted. The house is in danger.

[RedOnRed]

Time to get your fluffy handcuffs out you keep next to your bed for a citizens arrest. But don't forget to take your gimp boy outfit off prior to apprehension of this hardened recidivist.

[John]

No-one seems to have picked up on the rating of a replacement boiler. If the old boiler was 60,000BTU/hr and ther new one is also 60,000BTU/hr then it will modulate "down" from there and never up past it. Thus the rate of heat up at maximum will only be the same as before. (Give or take a little bit for a cleanbrand new heat exchanger)

[RedOnRed]

In the mist of a shed load of confusing remarks on this debate, someone at last makes sense.

[Capitol]

1973, Ideal Standard efficiency, 76%

Regards Capitol

[John Rumm]

If you wander through the SEDBUK database, there are very few that are as low as 55% (39 models out of over 3,300 listed - mostly poxytons).

There are a few hundred at 65%, but the vast bulk are 70% or better.

[Andy Champ]

OK, sentence by sentence:

(1) No problem, I understand this one.

(2) misadvice? Advise is a verb, not a noun. But I;m not sure misadvice is a word either!

(3) Boilers

(4) Enough of the pedantry, and the real point. What does that sentence mean?

Andy

[RedOnRed]

Seems simple enough to understand to me, until you complicated it with profound pedantism and your hilarious subtle brand of condescension - that is.