Efficiency of old boilers

[bengasman]

It's more wrong than right.

Fair enough maybe, but your response, as far as it goes, is not helpful.

That is probably because your post was a rather irrelevant contribution to an irrelevant thread.
What does it matter where the wasted energy goes? What does it matter why the energy is wasted? The only possible point of interest about the whole efficiency story ( at which point does it become financially interesting to replace a low efficiency boiler with a HE model ) has not been mentioned.
It's a bit like asking why exactly it is bad for you to be massively obese, and which disease you are most likely to die of as a result.

 

[ajrobb]

at which point does it become financially interesting to replace a low efficiency boiler with a HE model

Yes, but there is a world of difference between thermal efficiency and effectiveness. Modern boilers are arguably less effective because they seem less reliable (OK I am jaded as I have two Kestons, but there are extra issues with disposing of the acid condensate), cost more to maintain and maybe need replacing more often. The total cost of ownership for a new condensing boiler is likely to be higher than keeping an inefficient old open-flue or balanced-flue boiler. This is especially true for smaller properties.

 

[bengasman]

Total tosh. A good quality HE boiler that is installed as per instructions and maintained as per instructions is as reliable and durable as a SE boiler.

 

[ajrobb]

A survey about 1983 ("The Engineer") showed that 80% of boiler failures occurred within 3 months after routine maintenance. Unfortunately, things have changed and the average boiler needs more routine maintenance.

 

[bengasman]

A survey about 1983 ("The Engineer") showed that 80% of boiler failures occurred within 3 months after routine maintenance. Unfortunately, things have changed and the average boiler needs more routine maintenance.

It is highly arguable that a roomsealed boiler needs more maintenance than an old open flue Kingfisher for example. It's just that the ole Kingy would keep working long after it became unsafe.

Personally, I wouldn't argue that the brakes of a Morris Minor were better than those of a Lexus because the abs of a Lexus can fail, whereas the Minor would not have that problem.

 

[mysteryman]

A room sealed boiler is burning in cleaner air - no dust.

 

[ajrobb]

It is highly arguable that a roomsealed boiler needs more maintenance than an old open flue Kingfisher for example. It's just that the ole Kingy would keep working long after it became unsafe.

The problem is that condensing boilers run with near-stoichiometric mixtures and are sensitive to gas pressure and quality. For example, the technical guide for the Veissmann Vitodens W200 states that German inspection periods extend to 5 years with Lambda control (from 2 years?). Most other condensing boilers however require setting up and frequent inspection to check the CO levels. Non-condensing boilers often allow visual inspection of the flame.

Most condensing boiler have 'Morris Minor brakes' (no closed-loop mixture control) compared to the Veissmann 200W 'ABS brakes' (closed-loop mixture control). Non-condensing boilers by comparison only need an 'anchor on a piece of string' as they run so lean. I don't know if this analogy is any use, perhaps it might be better to think of carburettors and fuel injection (but that is not so much an analogy, rather its a similar problem.)

 

[bengasman]

If we ignore for a moment yet another bit of arbitrary legislation, what is the realistic danger of a boiler producing too much CO, as long as it is safely blown into the open air?
CO is very unstable and will cease to exist in no time.

If there is no substantial answer to this question, it becomes very arguable that there is a technical need for more frequent inspections of a roomsealed boiler, than there is for the inspection of an open flued boiler which can spill CO into the dwelling.

 

[simond]

Yes, but there is a world of difference between thermal efficiency and effectiveness. Modern boilers are arguably less effective because they seem less reliable (OK I am jaded as I have two Kestons) but there are extra issues with disposing of the acid condensate), cost more to maintain and maybe need replacing more often. The total cost of ownership for a new condensing boiler is likely to be higher than keeping an inefficient old open-flue or balanced-flue boiler. This is especially true for smaller properties

Crikey, you are giving advice on here and you have TWO Kestons? I'd have someone certified if they just bought ONE. Is the second a spare?

The acid condensate thing is a non issue. I had a customer telling me that we hadn't run the condense properly while I was trying to do the annual service, and how dangerous it was, being acidic.

Her son's friend was an expert, you see.

I politely explained that there was nothing wrong with our work, so when she carried on, I casually drank the condense out of the Vaillant trap while she was rabbiting. She suddenly stopped talking at that point.

Couple of days in hospital and I've made a full recovery.

 

[bengasman]

Yes, but there is a world of difference between thermal efficiency and effectiveness. Modern boilers are arguably less effective because they seem less reliable (OK I am jaded as I have two Kestons) but there are extra issues with disposing of the acid condensate), cost more to maintain and maybe need replacing more often. The total cost of ownership for a new condensing boiler is likely to be higher than keeping an inefficient old open-flue or balanced-flue boiler. This is especially true for smaller properties

Crikey, you are giving advice on here and you have TWO Kestons? I'd have someone certified if they just bought ONE. Is the second a spare?

 

[ajrobb]

TWO Kestons

Not my choice, I'd requested a microgen boiler in 2002 (not sure if that is worse).

I casually drank the condense out of the Vaillant trap while she was rabbiting.

Probably no worse for you than cola. But cola at least is useful for treating rusty iron.

 

[Schmill]

As this thread already seems suitably de-railed, AND as the issue of acidic condensate has come up, can I drop in a quick question?

Our neighbour recently had their boiler changed for a new 'condenser' boiler. However the existing vent point is straight out through the external wall at just below waist height right next to the drive.
When it was installed (by BG I think) they have installed a right angle on the vent with approximately a 10' vertical chimney on it, before then venting the gases out over the garage roof.

I just wondered if this was required or not? I think BG said something about the new gases damaging the paintwork of the car if it was parked near, but it is the only house I've ever seen with this boiler chimney on the side, so I was just wondering?

Thanks in advance for satisfying my curiosity!