Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Andrew Gabriel" wrote in message
...
Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]


Never used one so I am not familiar with their operation, but is it possible
to fit it on the outlet side of the rad?
--
Tinkerer

On Mon, 06 Jun 2011 12:18:33 +0000, Andrew Gabriel wrote:

Just wondering if anyone has come across any suitable product for a
single pipe system?

Fitted Danfoss RAS-C2s on the rads on my mum's single-pipe system
(actually two parallel single-pipe systems) and they work OK. Maybe just
a matter of getting more oomph from the pump?


--
John Stumbles -- http://yaph.co.uk

The ant has made himself illustrious through constant industry industrious
So what? Would you be calm and placid if you were full of formic acid?

On Jun 6, 1:18*pm, (Andrew Gabriel) wrote:
Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There were special TRVs for single pipe systems. It has much larger
valve body. There is no way you will get a two pipe system TRV to work
here.
I have had a look, no-one seems to be making anything anymore.
Your best bet is to get a motorised valve to control the circuit.
The pressure drop across the rad depends on the type of tees.
There are plain tees, swept tees and cup tees in ascending order of
preference.

On Jun 6, 6:24*pm, harry wrote:
On Jun 6, 1:18*pm, (Andrew Gabriel) wrote:



Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There were special TRVs for single pipe systems. It has much larger
valve body. There is no way you will get a two pipe system TRV to work
here.
I have had a look, no-one seems to be making anything anymore.
Your best bet is to get a motorised valve to control the circuit.
The pressure drop across the rad depends on the type of tees.
There are plain tees, swept tees and cup tees in ascending order of
preference.

Why not just restrict the flow in the shorting pipe more? With an
adjustable valve.


NT

On Jun 6, 6:35*pm, Tabby wrote:
On Jun 6, 6:24*pm, harry wrote:





On Jun 6, 1:18*pm, (Andrew Gabriel) wrote:

Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There were special TRVs for single pipe systems. It has much larger
valve body. There is no way you will get a two pipe system TRV to work
here.
I have had a look, no-one seems to be making anything anymore.
Your best bet is to get a motorised valve to control the circuit.
The pressure drop across the rad depends on the type of tees.
There are plain tees, swept tees and cup tees in ascending order of
preference.

Why not just restrict the flow in the shorting pipe more? With an
adjustable valve.

NT- Hide quoted text -

- Show quoted text -


This would prevent the whole system from working!

"harry" wrote in message
...



This would prevent the whole system from working!

It would increase the total head on the loop, it may still work, depending
on the pump.

If someone wanted to do that I would try an auto bypass valve to give a
small (0.1bar) head across the section.
It may cause noise /if/ the valve keeps opening and closing though.

On Jun 7, 6:28*am, harry wrote:
On Jun 6, 6:35*pm, Tabby wrote:



On Jun 6, 6:24*pm, harry wrote:

On Jun 6, 1:18*pm, (Andrew Gabriel) wrote:

Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There were special TRVs for single pipe systems. It has much larger
valve body. There is no way you will get a two pipe system TRV to work
here.
I have had a look, no-one seems to be making anything anymore.
Your best bet is to get a motorised valve to control the circuit.
The pressure drop across the rad depends on the type of tees.
There are plain tees, swept tees and cup tees in ascending order of
preference.

Why not just restrict the flow in the shorting pipe more? With an
adjustable valve.

NT- Hide quoted text -

- Show quoted text -

This would prevent the whole system from working!

how on earth would adding a little more restriction do that?


NT

On 2011-06-06, harry wrote:

discussion about single pipe system and full-flow TRVs edited out

The pressure drop across the rad depends on the type of tees. There
are plain tees, swept tees and cup tees in ascending order of
preference.

The Americans use Monoflow tees for single pipe systems, see:

www.heatinghelp.com/article/17/Hot-Water/74/Diverter-Tee-Hot-Water-Heating

I have never seen Monoflow tees for sale in the UK, but have come across
proposals to fabricate a venturi tee out of a tee and reducer, such as:

www.torrens.org.uk/HowTo/Injector/index.html

Anyone tried this to soup up an older UK single pipe system?

MJA

In article ,
harry writes:
On Jun 6, 1:18*pm, (Andrew Gabriel) wrote:
Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only.
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

There were special TRVs for single pipe systems. It has much larger
valve body. There is no way you will get a two pipe system TRV to work
here.
I have had a look, no-one seems to be making anything anymore.

Ah, that was a good clue. They're called full flow TRVs, and it
looks like Danfoss still make them (single pipe systems are still
common in large commercial installations). Danfoss RA-G.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Jun 7, 11:51*am, Tabby wrote:
On Jun 7, 6:28*am, harry wrote:





On Jun 6, 6:35*pm, Tabby wrote:

On Jun 6, 6:24*pm, harry wrote:

On Jun 6, 1:18*pm, (Andrew Gabriel) wrote:

Just fitted a TRV (Drayton TRV4) to a radiator on a single pipe
system, partly as an experiment (if it works, there are about
another 6 to do).

However, it seems not to work. The flow restriction through it
when fully open is too much resistance to get enough flow through
the radiator, resulting in a hot area along the radiator top only..
I might try moving the inlet to the top so the hydrostatic
pressure difference between the hot and cooling water helps the
flow, but I'm not hopeful this will make enough differemce to
notice.

Just wondering if anyone has come across any suitable product
for a single pipe system?

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

There were special TRVs for single pipe systems. It has much larger
valve body. There is no way you will get a two pipe system TRV to work
here.
I have had a look, no-one seems to be making anything anymore.
Your best bet is to get a motorised valve to control the circuit.
The pressure drop across the rad depends on the type of tees.
There are plain tees, swept tees and cup tees in ascending order of
preference.

Why not just restrict the flow in the shorting pipe more? With an
adjustable valve.

NT- Hide quoted text -

- Show quoted text -

This would prevent the whole system from working!

how on earth would adding a little more restriction do that?

NT- Hide quoted text -

- Show quoted text -

The pumps are very low head/pressure on a single pipe system
(Resistance is low the pipe is of quite large diameter with no
obsructions.)
If you throttled any part of the single pipe it would affect all the
radiators.