Radiator inlet/outlet positions
Julian
heating radiators, the ones I am interested in have the inlet valve at
the top and the outlet at the bottom diagonally opposite, will this
work just as efficiently as having both inlet and outlet at the bottom
as modern radiators usually seem to have? I assume the old radiator
connections are unlikely to unscrew so I will have to use them in the
positions they are in. Thanks
Roger Mills
It will work - but it will look very messy! Chances are that the rads
were part of a series flow system using quite big threaded pipes - so
you'll need to use reducing bushes (maybe several in series) to get them
down to 1/2" BSP. These would be far less noticeable at the bottom.
The radiators will almost certainly have four connection points, with
blanking plugs in the unused ones. These will be tough - but by no means
impossible - to remove. You need to lay the rads down on a flat surface
and either clamp them down or get someone to sit on them to hold them in
place. Then you need to grip the flats of the fittings with a Stilson -
if necessary using a metal tube slid over the handle to get extra
leverage. Once they start to turn - having broken through the decades of
dried up Boss White - they'll come out quite easily.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.
fred
<5423e840-b18f-4910...@y8g2000vba.googlegroups.com>,
Julian <grif...@btinternet.com> writes
That's Top Bottom Opposite End (TBOE) and even on modern radiators they
work marginally more efficiently that way (a few percent only). On cast
iron radiators where there is a high thermal mass and a wide open
channel along the bottom there is a risk in Bottom Bottom Opposite End
(BBOE) that the flow passes through at the bottom without initiating the
convection required to distribute heat around the rad so I would suggest
sticking with TBOE.
On aesthetics I know someone who has a this kind of setup and it looks
fine, TRVs are mounted vertically on the feed (high) side and don't look
obtrusive.
Watch out for leaks and seized iron fittings, exp bleed screws.
--
fred
FIVE TV's superbright logo - not the DOG's, it's bollocks
Graham.
"fred" <n...@for.mail> wrote in message news:PtzzXQEd+UMOFwgm@y.z...
Often wondered about the piping configuration of radiators, I wondered why
they weren't plumbed more often to the manifolds at the top and bottom.
It surprises me that they work the "normal" way at all.
If you do plumb to the diagonals, is there an advantage in having
the flow at the bottom?
--
Graham.
%Profound_observation%
harryagain
"Julian" <grif...@btinternet.com> wrote in message
news:5423e840-b18f-4910...@y8g2000vba.googlegroups.com...
There are four connections on almost all radiators.
Diagonal connections work the most efficiently as the water circulates in
the best way.
The other alternative (both bottom connections) works less well, the water
tends to go straight across.
I would say don't buy unless you have a return agreement. When they are
manhandled and banged about old cast iron radiators often leak at the many
joints. They are virtually impossible to fix if they do leak.
(There is a joint between each section assembled by LH/RH thread
steel/malleable iron couplings)
You might get the fittings out of the ends, but the interior ones (if it
leaks) need a special tool and are usually really well seized up/corroded.
Also hard to get the couplings.
fred
>
>Often wondered about the piping configuration of radiators, I wondered why
>they weren't plumbed more often to the manifolds at the top and bottom.
>It surprises me that they work the "normal" way at all.
>
on tall ladder type towel rail radiators where there is a wide open path
at the bottom and the heat is failing to reach the top. IIUC they should
have baffles at the bottom to fix this but in modern low water content
panel radiators <sic> it does not appear to be necessary.
>If you do plumb to the diagonals, is there an advantage in having
>the flow at the bottom?
>
If you mean flow at the bottom and return exiting at the top then that
is bad, hot inlet water will rise by convection and exit quickly at the
outlet point leaving a cold patch in the bottom corner opposite the flow
connection.
Julian
> In article <j0so5o$mu...@dont-email.me>, Graham. <m...@privacy.com> writes
Thanks for all your replies, I'm going to look at the radiators again
next week and now I have some more information I will be able to
decide whether or not to make a purchase.
docholliday
> On 28/07/2011 09:05, Julian wrote:
>
> > Hi, I am thinking of buying some old cast iron 4 column type central
> > heating radiators, the ones I am interested in have the inlet valve at
> > the top and the outlet at the bottom diagonally opposite, will this
> > work just as efficiently as having both inlet and outlet at the bottom
> > as modern radiators usually seem to have? I assume the old radiator
> > connections are unlikely to unscrew so I will have to use them in the
> > positions they are in. Thanks
>
> It will work - but it will look very messy! Chances are that the rads
> were part of a series flow system using quite big threaded pipes - so
> you'll need to use reducing bushes (maybe several in series) to get them
> down to 1/2" BSP. These would be far less noticeable at the bottom.
>
pipe systems, where the water circulates in a single pipe; at each
radiator a fraction of the total is diverted to the radiator with a
special tee, then rejoins the main circulation pipe after the
radiator. Although the circulation pipe is quite large (often up to 2
inch in domestic systems, maybe even more if it's a larger building
like a school or church hall) the pipes going to the radiator are
smaller - most of the radiators I recall from my parents' house would
have had a 3/4 inch BSP connection, so only a relatively small
reduction to get to 1/2 inch.
The diagonal connection was necessary to get the water to circulate in
the radiator rather than just passing straight through.
Onetap
They were usually connected TBOE, because most started life on gravity
circulation heating systems which needed the flow in the top, return
out of the opposite bottom connection.
I assumed TBOE would give the highest heat output, but the CIBSE
Journal published a series with some useful rule-of-thumb estimating
figures in the early 80s which gave the BBOE connections about 10%
more heat output.
fred
<8e28cd8b-3539-4f2f...@n28g2000vbs.googlegroups.com>,
Onetap <One...@talk21.com> writes
Guide, Volume B, Installation and Equipment Data of about 1994.
B1-5, Heating
"For the testing of radiators, BS 3528 specifies top and bottom opposite
end connections (TBOE). Measurements have shown that other connection
arrangements have a marginal effect on heat output. Taking the heat
output for TBOE connections as 1�0, the following values can be
expected:
top and bottom same end connections (TBSE) 1�04
bottom opposite end connections (BBOE) 0�85"
Interesting that TBSE is higher than TBOE and the difference between
TBOE and TBSE is more than I expected, TBOE being greater by 17% when
using BBOE as the baseline.