CH Boiler recommendations?

[DavidM]

I'm looking to replace my old central heating boiler with a standard (i.e. not combi) condensing boiler. I will have it installed by a professional, but want to be more informed about available boilers rather than just accept what the heating engineer offers.

I have heard that the heat exchanger (HE) on condensing boilers can have a limited life, that cast iron HEs are to be avoided, aluminium are ok (ish) and that stainless steel HEs are best. Anyone have any views?

I've also heard that Potterton are unreliable (for condensing boilers) even though my old (non condensing) Potterton has served me well for nearly 35 years!

Any other points tpo watch out for?

Does anyone have any recommendations (or otherwise) on makes/models of boilers?

Thanks, David.

[Andy Hall]

Very wise. People tend to fit what they know or whichever promo programme is the best this month.

That's basically it.

They are a shadow of their former selves.......

Manufacturers in Germany and Holland have been making them for 15-20 years and are at 4th generation products in most cases. Therefore the better products are made in or are designs from these countries.

Typical good products:

- Vaillant

- Worcester-Bosch

- MAN

- Viessmann

Your installer may have heard of the first two. The second two are higher end.

[John Rumm]

I would go along with what you said... (ali heat exchangers ought to be fine if silicon coated).

Look for one with a single heat exchanger rather than one that has had a secondary one bolted on - this is usually an indication of an old design that has been updated to operate as a condensor rather than been designed that way from scratch.

Also look for a downward firing burner. This will prevent it being exposed to either as much soot or acidic condensate.

true sadly.

To comply with building regs you may have to upgrade your boiler controls, and fit a fast recovery cylinder if you don't already have one. You will need TRVs on all rads except the one in the room with the main stat. If the house is big you may need to zone the heating also.

The ones Andy mentioned are usually very well regarded. Some of the ones from Ideal like the icos seem good as well.

[Pilgarlick]

I have a cast iron cored boiler still plodding away after 30 odd years. It may be that the newer boilers are more efficient but this is generally achieved at the expense of longevity i.e. thinner (but more efficient heat exchanger cores), nevertheless with today's fuel prices a more efficient core may be preferable even if it is necessary to replace the boiler a little more often than would be otherwise needful. Condensing boilers have corrosion problems since parts of them are subject to "condensation", hence enhancing the corrosive effect of the flue gases.

I would doubt if even the stainless steel boilers are made with the heat exchanger from top grade materials and thus the rate of corrosion will only be slower than other cores and not zero.

Regards

Pilgarlick

[John Rumm]

More correctly -poorly designed condensing boilers suffer corrosian problems. A well designed one will use materials that are not affected by the (mild) acidity of the condensate, and a layout that places critical parts out of the path of any collecting or falling condensate (downward firing burners etc).

[John]

A lot of the newer Aluminium heat exchangers are coated to protect the substrate metal. Works fine as long as the coating is not scratched. Once it has been damaged then you are wide open to corrosion. Stainless Steel is the way to go in my book