How to add another radiator to a microbore system?
 

Hi all

Just finished the job I started last week - fitting a TRV to one of my
radiators on my microbore system. Actually removed the rad yesterday,
flushed it out with a hosepipe- then cleaned the threads for the
valves with a toothbrush - used '5 turns' of tape on the valve threads
- and reconnected. Dry as a bone now!

Anyway, I would like to add another rad to the downstairs circuit. As
far as I can see, the circuit of fed on a 22mm pipe from the boiler to
a manifold - where lots of 8mm pipe branches off the the rads. The
retur pipes are the same. To add another rad, can I simply but an
equal T joint into one of the micorbore feeds, and the same on the
return? If I do it on the feed to the closest existing radiator, will
it work?

I understand that there would be a temperature drop in the existing
rad, but that is the one I have fitted a TRV to - because the room
gets very warm - so shouldn't be a problem. I only want to run about
4m of pipe from it - and put on a small new rad in a corner of the
kitchen that is about 18 feet from the nearest other rad - and gets
quite cool...

Thanks in advance

Simon

In an earlier contribution to this discussion,
Simon Hawthorne wrote:

Hi all

Just finished the job I started last week - fitting a TRV to one of my
radiators on my microbore system. Actually removed the rad yesterday,
flushed it out with a hosepipe- then cleaned the threads for the
valves with a toothbrush - used '5 turns' of tape on the valve threads
- and reconnected. Dry as a bone now!

Anyway, I would like to add another rad to the downstairs circuit. As
far as I can see, the circuit of fed on a 22mm pipe from the boiler to
a manifold - where lots of 8mm pipe branches off the the rads. The
retur pipes are the same. To add another rad, can I simply but an
equal T joint into one of the micorbore feeds, and the same on the
return? If I do it on the feed to the closest existing radiator, will
it work?

I understand that there would be a temperature drop in the existing
rad, but that is the one I have fitted a TRV to - because the room
gets very warm - so shouldn't be a problem. I only want to run about
4m of pipe from it - and put on a small new rad in a corner of the
kitchen that is about 18 feet from the nearest other rad - and gets
quite cool...

Thanks in advance

Simon

There are rules of thumb (which I'm sure others will quote) about how much
heating capacity you can get from an 8mm pipe. If it's less than the
combined output of your two radiators, then you shouldn't be doing it. I've
never used microbore, but my understanding is that it's usual to have
individual feeds for each radiator from the manifolds. Have you got any
spare tappings on the manifolds? The other alternative is to tap into the
22mm flow and return pipes using 22x22x8 tees.
--
Cheers,
Set Square
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On Sun, 14 Nov 2004 13:03:49 -0000, "Set Square"
wrote:

Have you got any
spare tappings on the manifolds


Hi SS

Nope - the manifold is not like the one upstairs - the end of the feed
pipe from the boiler ends in what looks like a load of 'tentacles' -
which just spout straight from the end of the pipe.

I like the idea of the 22mm into 8mm though - but that would be in the
pipe before the manifold/tentacle split - suppose it should be OK. I
think, depending on flow, 8mm pipe can supply 4kw - and this is far
more than the two rads that would be on the pipe.

I can't find any 22mm/8mm tees - so might have to go 22mm to 15mm then
down to 8mm....

Thanks for your help

Simon

"Simon Hawthorne" wrote in message
...
On Sun, 14 Nov 2004 13:03:49 -0000, "Set Square"
wrote:

Have you got any
spare tappings on the manifolds


Hi SS

Nope - the manifold is not like the one upstairs - the end of the feed
pipe from the boiler ends in what looks like a load of 'tentacles' -
which just spout straight from the end of the pipe.

I like the idea of the 22mm into 8mm though - but that would be in the
pipe before the manifold/tentacle split - suppose it should be OK. I
think, depending on flow, 8mm pipe can supply 4kw - and this is far
more than the two rads that would be on the pipe.

I can't find any 22mm/8mm tees - so might have to go 22mm to 15mm then
down to 8mm....

Thanks for your help

Simon

===============
What you're proposing will certainly work provided that the heat loss to the
original radiator is acceptable.

Tee-ing into the two 8mm pipes (flow and return) will be much easier than
trying to Tee into the 22mm pipes because you'll be able to bend the 8mm
pipes to insert the 8mm Tee. The 22mm pipes will be fixed quite firmly and
you may not be able to get Tees in without substantial dismantling.

Cic.

On Sun, 14 Nov 2004 12:25:13 +0000, Simon Hawthorne
wrote:

Hi all

Just finished the job I started last week - fitting a TRV to one of my
radiators on my microbore system. Actually removed the rad yesterday,
flushed it out with a hosepipe- then cleaned the threads for the
valves with a toothbrush - used '5 turns' of tape on the valve threads
- and reconnected. Dry as a bone now!

Anyway, I would like to add another rad to the downstairs circuit. As
far as I can see, the circuit of fed on a 22mm pipe from the boiler to
a manifold - where lots of 8mm pipe branches off the the rads. The
retur pipes are the same. To add another rad, can I simply but an
equal T joint into one of the micorbore feeds, and the same on the
return? If I do it on the feed to the closest existing radiator, will
it work?

I understand that there would be a temperature drop in the existing
rad, but that is the one I have fitted a TRV to - because the room
gets very warm - so shouldn't be a problem. I only want to run about
4m of pipe from it - and put on a small new rad in a corner of the
kitchen that is about 18 feet from the nearest other rad - and gets
quite cool...

Thanks in advance

Simon

It depends on the radiator sizings, Simon. Over a few metres, 8mm
tube will support 1500W. So take a look at the sizing and calculate
the rating of the existing radiator. Obviously if the room is
getting very warm some under-running may be OK. There would be some
interaction between the radiator behaviours if you tap off near the
first radiator, less if you tap off nearer the manifold.
As long as you're not trying to get more than about 2kW or so in total
it should be reasonable, albeit it not ideal

It would be better to plumb back to the 22mm.


--

..andy

To email, substitute .nospam with .gl

In an earlier contribution to this discussion,
Simon Hawthorne wrote:

On Sun, 14 Nov 2004 13:03:49 -0000, "Set Square"
wrote:

Have you got any
spare tappings on the manifolds


Hi SS

Nope - the manifold is not like the one upstairs - the end of the feed
pipe from the boiler ends in what looks like a load of 'tentacles' -
which just spout straight from the end of the pipe.

I like the idea of the 22mm into 8mm though - but that would be in the
pipe before the manifold/tentacle split - suppose it should be OK. I
think, depending on flow, 8mm pipe can supply 4kw - and this is far
more than the two rads that would be on the pipe.

I can't find any 22mm/8mm tees - so might have to go 22mm to 15mm then
down to 8mm....

Thanks for your help

Simon

BES 7231 looks like it would do the job - albeit at a silly price!

If you *do* tap into the flow and return pipes, make sure that you do it on
the right site of any zone valves you might have in your system - otherwise
you might have a red hot radiator in the middle of summer!
--
Cheers,
Set Square
______
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On Sun, 14 Nov 2004 13:23:20 +0000, Simon Hawthorne
wrote:

On Sun, 14 Nov 2004 13:03:49 -0000, "Set Square"
wrote:

Have you got any
spare tappings on the manifolds


Hi SS

Nope - the manifold is not like the one upstairs - the end of the feed
pipe from the boiler ends in what looks like a load of 'tentacles' -
which just spout straight from the end of the pipe.

Ah, one of those. It's still a manifold.

I like the idea of the 22mm into 8mm though - but that would be in the
pipe before the manifold/tentacle split - suppose it should be OK. I
think, depending on flow, 8mm pipe can supply 4kw - and this is far
more than the two rads that would be on the pipe.

I can't find any 22mm/8mm tees - so might have to go 22mm to 15mm then
down to 8mm....

That would be a way.

If you think you might add more radiators later, it would be better to
purchase a slightly different type of manifold which comes with
blanking plugs. Attach this to the existing 22mm feed using a
22x22x22 tee.



Thanks for your help

Simon


--

..andy

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