25 vs 30kwh combi boiler - running cost difference over 10 years?

mrcheez

Have been quoted €2.8K to install a 25Kwh combi boiler, but an extra €100 to upgrade it to a 30KwH (with a better flow rate).

I've been told that the 30KwH won't use that much extra energy, but is that the case?

Would the running cost be much higher over 10 years?

mrcheez

That's 2.8K ex VAT btw.. €3,234.75 inc VAT

mrcheez

Specifically the 2 boilers are Greenstar 25i ErP vs Greenstar 30i ErP

mrcheez

I did a little digging around and apparently 30i is better if you want to run a bath, vs 25i which is purely for short showers.

I do like my long showers and occasional bath so 30i looks like the only option.

But then I see that the "i" range is discontinued and 4000 is the one to go for instead?

Sigma101

Plumbers have a tendency to oversize boilers. However, as it's a combi boiler 30kW is not that big. Although the rated power is 20% bigger, the additional running costs should not be that much greater. The boiler will start at full tilt when you start to draw water, but it will modulate down to adapt to the flowrate. It's sometimes a problem with combis that they don't deliver enough heat. With the 30kW there's a better chance of you not turning a shower cold by running a hot tap at the same time. I think the length of your shower shouldn't matter. There is no HW tank. The boiler should be able to deliver water at a steady state for however long you want it.

mrcheez

Should I opt for a 4000 or will the 30i be serviceable for next 10 years?

I think the 4000 is supposed to be more efficient though.

Also is €2,800 (circa €3,250 inc VAT) a standard enough price to upgrade, or should I look at someone offering a scrappage of my old boiler?

Sigma101

Sorry, I don't know enough about individual models to say which is better. But check with the plumber that the boiler he's proposing has the full manufacturer's warranty (typically 10 years). 

The price will depend on the amount of work involved. The website below gives some guide prices. A direct like-for-like combi replacement with the Greenstar 30si is "from €2590". Ideally you would get alternative quotes, but it's so difficult to get even one registered gas installer at the moment that, unless they're outrageously expensive, you'll probably have to go with the one you've got. When we got our boiler replaced a couple of years ago, to the best of my memory, the installer applied for the scrappage and the price he quoted was net of the scrappage allowance.

https://www.gasworks.ie/gas-boiler-replacement-cost/

mrcheez

I'll ask about scrappage thanks

mrcheez

Actually curious, is it possible for me to scrap it myself?