Are Cast Iron Radiators more expensive to run?

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I have recently bought some cast iron radiators to fit into a new build and have been told by the plumber that they are significantly more expensive to run that the standard modern radiators. Is this really true?

I understand that the larger the radiator, the more expensive it is, but on a like-for-like basis, are modern radiators more energy efficient that old cast iron ones?
 
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The Guide to Radiator outputs is what it says.

A 1kW rad is a 1kW rad, irrespective of what type it is. The advantage of the modern flat steel rad with 'convection' fins on the back and double radiators is that you get the same amount of heat but the radiator is smaller than the equivalent cast iron one.
 
The mass of the radiators will make the system less responsive to the controls.

It will take longer for the boiler to heat up the relatively large mass of cast iron compared with a pressed steel rad.

Once the cast iron has got up to temperature, it will continue to deliver it's heat output for longer after the boiler has shut down.

As you eventually get back what you lose at the start of the heating cycle, it may be something to bear in mind when you set up your heating controls.
 
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I think they're significantly heavier for the plumber to lift ;)
That`s cuz hes a Gas Fitter - Not a Plumber :LOL:. Seriously though - a modern modulating boiler may not " like " them and their characteristics previously described :idea:
 
I think they're significantly heavier for the plumber to lift ;)
That`s cuz hes a Gas Fitter - Not a Plumber :LOL:. Seriously though - a modern modulating boiler may not " like " them and their characteristics previously described :idea:

Err? why would that be?

the greater the system volume the less the boiler have to cycle. a modern modulating condensing boiler should love them.

we don't want rapid heating and cooling...the aim is to have stable room temperatures, reduce cycling and to run boiler at the lowest flow temp that keep the house warm.
 
Good post.

Low water content radiators are going to be slightly more efficient, just like low water content boilers can heat up quicker.

But then you take the heatstore argument, where there is a large thermal mass buffer store, and you can forward good reasons why this reduces boiler cycling etc.

Go ahead with your cast iron rads and enjoy them, they are fab.

I just hope you bought reclaimed ones, not the new imported replica stuff ;) .
 
Is it true that cast iron radiator need half-inch pipe instead of three quarter inch required for press steel radiators? I’ve been told that the radiators are linked on a loop and that if I have the cast iron ones fitted the last one in the loop won’t work.

Is the plumber just trying to get out of fitting the cast iron ones because they’re very heavy?

The plumber buried the heating pipes in concrete at the start of the build and says it will cost extra to dig it up and lay half-inch pipe for cast iron radiators.
 
I'm sure the experts will have something to say on this but it sounds like a load of BS to me.

The required pipe diameter is largely determined by the flow rate, run lengths, and the pump power. All are nominally the same whether you have cast iron or pressed steel radiators, and you can even mix'n'match if you want. If the fittings to the radiator itself don't match then there are adaptors.

I don't know what sort of pipe layout you have but I'd imagine it is a standard two pipe system on a new build. Each radiator bridges between the out and return pipes and takes a portion of the total flow. If the ones at the end receive insufficient pressure then the system needs to be balanced by partially closing off the ones closest to the pump, just as with pressed steel radiators. If it is still not possible to get flow through the furthest radiators then the system has been incorrectly designed, pipes too small or pump too weak but not because you changed the material the radiator is made from.
 
We've recently fitted a load of cast rads. They should be piped in exactly the same way as normal rads.

They're ridiculously heavy, a pain in the a$$ to put together, and seem prone to leaking from the joints (customer-supplied Biasi ones, don't know if others would be better). They were also full of steel shot from the shotblasting process. All this meant more effort and time to fit them and clean them out, and the customer was charged accordingly, but the actual mechanics of fitting them wasn't a problem beyond the above.

I think your plumber just doesn't want to fit them. Does he work on his own or have others helping him? If he's on his own this may explain it, he doesn't want to move them by himself (and can't ask you as the customer for help as if he does and you're injured helping him you can sue him, which he won't want either)
 
I like cast radiators almost as much as I like gas fires..... But then I mainly work on my own and have a glass back
 
I think your plumber just doesn't want to fit them. Does he work on his own or have others helping him? If he's on his own this may explain it, he doesn't want to move them by himself (and can't ask you as the customer for help as if he does and you're injured helping him you can sue him, which he won't want either)[/quote]

He's got at least four other plumbers with him and as the client i'd be more than happy to help position them into place. :)
 

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