One of the rads in my lounge has developed a leak. It's a single panel type,
seam topped and with a wavy bit of metal at the back. It measures approx 75
cms across the panel vertically, and 158 cms across the top water gallery.
What 'official' size is this for obtaining a replacement - or is it even
directly replaceable still ? About 25 years old. There seems to be a
distressingly large range of rads around those sizes, but I would like to
get a 'ringer' if possible because I would really like it to just be
'drop-in' due to current time constraints for DIY. Would there be any
advantage to replacing it with a double panel rad if someone has one ? Are
the fittings still the same sizes now ? I'd hate to get one and find that
the original couplings were some obscure imperial size, now replaced by some
equally obscure metric size.
Any advice and general thoughts on the job, most gratefully received ...
I'd have thought the fittings would be the same then as now. Doesn't sound
like a standard current size to me but best to google and see what you can
find. You can buy extension pipes etc like this:
http://www.toolstation.com/shop/p13659 which may help.
Bear in mind though that modern radiators will be much more efficient than
what you've currently got, so if you were to fit an identically dimensioned
radiator nowm, chances are it would be over-specced for the room (though
that's not as bad as being under-specced, obviously.
A double-panelled radiator is approx twice as powerful as a the
equivalently dimensioned single rad, so that won't be the answer to your
The 'correct' way to do it is to use one of the on-line calculators to
determine how many BTUs you need for the room, and buy the appropriately
dimensioned radiator for that. Once you have the correct BTU output
needed, you'll find there are lots of differently dimensioned radiators
with more or less the same heat output that you can choose from. Screwfix
is a good starting point (try their drill-down menus for height, width,
But you may have to bite the bullet and do a bit of pipework!
Wouldn't that be 'effective' rather than 'efficient' for given dimensions?
When looking for radiators I see they're often labelled 'super
efficient' but I don't see how, energy-wise. They may provide more heat
for a certain size, but I can't see how they provide more heat per kW/hr.
It's going to be belting out a lot of heat to achieve a low return,
isn't it? So a system that cycles frequently and hot rather than steady
Is this the valve to tail fitting? Normally a taper, so a washer wouldn't
help. By all means use some PTFE if it makes you happy - but it shouldn't
really be needed.
If it's the tail into the rad, I'd certainly use PTFE.
*IF ONE SYNCHRONIZED SWIMMER DROWNS, DO THE REST DROWN TOO?
Dave Plowman firstname.lastname@example.org London SW
Most valves these days seem to use compression joints to connect both to
the tail and to the external pipework - but 25 years ago the valve to
tail connections were mostly taper.
If yours are taper, clean up both bits of the taper - male and female -
with wire wool, and put a smear of LS-X on the mating parts when you
I'm really surprised at that if it's a normal domestic rad. Mine are more
like 40 years old and use exactly the same tails as today's ones. I fitted
all new thermostatic valves recently, and since they were a different make
had to change the tails too.
*Why do we say something is out of whack? What is a whack? *
Dave Plowman email@example.com London SW
Me too, if it's only 20 years old. It was more common to have larger
threads (3/4" or 1" BSP) 40 years or so ago because maybe not all
systems were pumped in those days. When I moved in to this house nearly
40 years ago, a couple of the radiators had 3/4" BSP (I think) threads
with reducing bushes in them to enable normal 1/2" BSP tails to be used.
One aspect of an "efficient" radiator would be one that has low heat
capacity. This means you are not wasting energy heating up, say, a
giant lump of cast iron and loads of water before you start getting
heat out into the room, and similarly, it doesn't take ages to cool
down and stops heating the room when the room has reached the set
point without overshooting.
I replaced some radiators in my brother's place a few years ago, and
it was quite noticable that the new ones cool down very quickly when
the heating goes off, but the old ones, being thicker steel and larger
water channels, take much longer to cool down.
No, just needs to be larger. I did that with the central heating system
I installed. It actually performed better than I had intended, and can
keep the house at normal room temperature when running at 45/40C
flow/return, with no boiler cycling. That means the boiler is running
just about as efficiently as it can, and wasted flue gas heat is only 50C.
[email address is not usable -- followup in the newsgroup]
Radiator sizes used to be Imperial (although yours doesn't sound like
anything in particular!) but are now metric - so you're very unlikely to
get a new one which is exactly the same size. The good news is that the
plumbing fittings are the same - so a new one will have the same 1/2"
BSP female threads as the old one into which to screw the tails for the
Radiators seem to come in 100mm (10cm) steps for both width and height.
700mm is a fairly common height (but less common than 600mm) - but that
would be a couple of inches shorter than the existing one. Width-wise,
you'd be looking at 1500mm or 1600mm. As others have said, you can get
extra-long valve tails to compensate for the radiator being a bit
narrower, but an extra 40mm per side is quite a lot. If there's a bit of
flexibility to spread the feeder pipes, you might get away with a 1600mm
rad with standard valves and tails.
In all events, the brackets are likely to be different - so you'll have
to do some careful measuring to determine where to fix the brackets to
the wall in order to get the water connections in the right place.
Most single panel rads have fins on the back these days, which increases
their heat output size for size by about 50% (as long as you balance the
flows to suit!). Unless the current rad is seriously under-sized, I
wouldn't go for a double. They don't look very pretty and will almost
certainly have their plumbing connections a bit further out from the
wall - so you may have to adjust the pipe-work. [That may not matter if
you're having to adjust it for a different size of radiator, anyway].
Myson still do Imperial sizes
27x61" = 690x1556mm sounds the closest, but not close enough to simply
drop in, so you might as well fit a metric replacement if you've got to
adjust the pipework ...
Sounds like an unusual size... 700x1600 would be easy enough to get though.
If you have difficulty getting the room warm enough, then yes.
The rad normally just has 1/2" BSP sockets, and the actual coupling come
with the valve. So you can remove the tails from the old rad and install
them in the new - then it will march the valves perfectly (if they reach!)
On my 20 year old radiator I had to use a reducing adapter to match the
new valve I needed to fit. The tail on your older valves may be a larger
diameter than the (threaded) hole in the new radiator that it needs to
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.