Radiators to use with combi boiler

[gordonmurr]

I have a combi boiler which was fitted last year, the radiators are very, very old. Can i use normal radiators to replace them?

[The Natural Philosopher]

Of course not.

They must be preserved, including the patina, sludge and corrosion of ages, at all costs, not only to save the planet, but Britain's Heritage.

:-)

[Roger Mills]

Assuming the answer could possibly be 'no', where do you suppose people fitting combi boilers in new houses will be able to get very, very old ones to match yours?

What is *abnormal* about yours, apart from their age?

[gordonmurr]

When i went to buy new ones from B&Q, it states on the new one that it is not to be used with combi boiler systems, only sealed sytems. Do you think i am making this stuff up? Is it wrong to expect a simple answer to a simple question?

[The Natural Philosopher]

A combi boiler is a sealed system.

[Roger Mills]

I suspect that you may have mis-read or mis-understood what it says.

Most combi boilers *do* use sealed systems anyway.

Can you quote a reference to your source information on the B&Q website?

No, but it helps if you carry out a sanity check on it before asking it.

[John Rumm]

Which makes no sense at all. The majority of combis use sealed systems, although a few will also run in a vented configuration. However there is no real connection between the two things - a combi is just a boiler that providers on demand hot water, and a sealed system, is the common way that boiler s of all types are plumbed these days.

See:

you think i am making this stuff up?

Not at all, although I expect you may have misread something along the line. It is equally possible that B&Q are talking out of their corporate behind as well though.

[gordonmurr]

may i thank all who took the bother to properly reply to me

[Dave Plowman (News)]

Either you read this wrong or they made it up.

There is no intrinsic difference between rads for a sealed or vented system anyway. But sealed systems are the norm these days whether a combi is fitted or not.

[Jason]

You take the wheat with the chaff in the real world here. You may get the answer you want to hear, and you may not. It also may take a few steps to get there, which often involve getting you to ask the right question in the first place, and not just *half a question*. It will be as hard for other people to answer your questions as you make it to answer. Please don't denegrate those who have got you to the answer you wanted - they have all given valuable answers. It is just plain insulting.

[Mark]

If the radiators are old I would recommend them being changed anyway.

It's likely that they are partially blocked and you can buy more efficient radiators nowadays (i.e. A radiator of the same size can output more power).

Also if the new boiler is a condensing boiler you may need to increase the power of the radiators anyway.

Mark

[Dave Plowman (News)]

Why? Just curious.

[Tim Downie]

I think he just means that your radiators should ideally be over-sized/over-rated as condensing boilers work best with low return flow temperatures.

Tim

[John Rumm]

Because the boiler can run more efficiently at lower return temperatures (which implies lower flow temperature or larger temperature drops during operation). To take full advantage of this, may require oversizing the rads compared to what you might install for a conventional boiler so that you can still get enough heat out.

Needless to say this is not usually an issue for any but the coldest days.

[Dave Plowman (News)]

Ah - right. Totally missed the condensing bit - I was still thinking about the combi.