what's a 1 pipe system?

[ColJack]

it's been mentioned in several posts this past week..
what is it and how does it work?
enquiring minds would like to know..

 

[doitall]

Its an older type of heating design whereas the flow and return is taken from the same pipe, by gravity.

Still installed in some commercial and large properties.

 

[ColJack]

nothing in the WIKI about it..
so how's that work then?
one loop and it goes though every rad?
doesn't that mess you up for ballancing? the first rad is hot, the last one is only luke warm?

 

[dextrous]

Yep, it's all about careful balancing.
Basic version:

Untitled

• dextrous
• 27 Aug 2009
• 1

 

[ChrisR]

Not always fravity circulation, a lot of domestic ones were pumped.

There isn't always a bypass pipe under the radiator either, which is mad, but there you go.

 

[D_Hailsham]

Not always gravity circulation, a lot of domestic ones were pumped.

Another misleading use of the term "gravity circulation".

In this case, and in "gravity hot water system", it has nothing to do with gravity but density. Hot water is less dense than cold water, so it rises.

On a single pipe system the flow is connected to the top of the rad and the return to the bottom at the other end. The bypass is adjusted to allow a proportion of the flow to enter the radiator via the top connection. The water cools down, exits the rad by the bottom connection and mixes with the water coming through the bypass.

Each radiator therefore receives slightly cooler water than the previous one. This is compensated by making the radiators larger than required. There is a complicated formula for calculating the enlargement. The temperature drop over the whole circuit is still 11°C.

 

[Goldspoon]

Plumbers of old used to add washers to the radiator feed - washers with different sized holes for balancing...

This is an interesting read:
http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating.shtml

 

[simond]

On a single pipe system the flow is connected to the top of the rad and the return to the bottom at the other end. The bypass is adjusted to allow a proportion of the flow to enter the radiator via the top connection.

What bypass?

Very rarely see a bypass on a one pipe. That would just reduce the flow cumulatively. In most cases the gravitational circulation works fine with no need to force the circulation within a radiator.

 

[doitall]

On a single pipe system the flow is connected to the top of the rad and the return to the bottom at the other end. The bypass is adjusted to allow a proportion of the flow to enter the radiator via the top connection.

What bypass?

Very rarely see a bypass on a one pipe. That would just reduce the flow cumulatively. In most cases the gravitational circulation works fine with no need to force the circulation within a radiator.

Saying that modern one pipe systems, use pitcher tees, tongue tees, and injector tees with give a venturi effect.

 

[Agile]

The domestic one pipe systems you read about on here are pumped 15 mm cheap systems mostly fitted during the 60s.

There were gravity circulation systems fited during the 50s mostly in older houses with large diameter pipes typically 1 1/4"

Tony

 

[gassafeman]

Coljack

A 1 pipe system operates through a single pipe which comes from the boiler running along at floor level to each radiator. A pipe is branched off the feed pipe to take hot water to (usually) the top of the radiator where it passes through the radiator coming out, a little cooler, to mix with the hot water in the main feed pipe again.

If Im on ignore, I guess you wont see this???

Paul

 

[twgas]

This is an interesting read:
http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating.shtml[/QUOTE] had a quick read of some of this, then got a little disheartened "A cubic foot of water at 180 degrees F takes up about five percent space than a cubic foot of water at 40 degrees F".

 

[dextrous]

This is an interesting read:
http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating.shtml[/QUOTE] had a quick read of some of this, then got a little disheartened "A cubic foot of water at 180 degrees F takes up about five percent space than a cubic foot of water at 40 degrees F".

You misunderstand one key aspect - a cubic foot will be different at different temperatures due to expansion/contraction of the ruler used to measure it

 

[doitall]

This is an interesting read:
http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating.shtml[/QUOTE] had a quick read of some of this, then got a little disheartened "A cubic foot of water at 180 degrees F takes up about five percent space than a cubic foot of water at 40 degrees F".

It's called expansion twgas

Everything expands as it gets hotter.

 

[dextrous]

This is an interesting read:
http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating.shtml[/QUOTE] had a quick read of some of this, then got a little disheartened "A cubic foot of water at 180 degrees F takes up about five percent space than a cubic foot of water at 40 degrees F".

It's called expansion twgas

Everything expands as it gets hotter.

Apart from ice, for a bit anyway