Water flow path through radiator

MelloPeck · Nov 16, 2018

I have been trying unsuccessfully to find a diagram that shows the path water takes when flowing through a domestic radiator.
Anybody got any ideas?

Riley · Nov 16, 2018

Is it to highlight something or just interested?? It will also depend how it’s piped

hammers4spanner · Nov 16, 2018

Generally in one end and out the other,

Hope that helps

MelloPeck · Nov 16, 2018

Riley said:
Is it to highlight something or just interested?? It will also depend how it’s piped

Hi, I mean the direction it flows through all the channels, does it flow from top to bottom or up some channels and down others?

ShaunCorbs · Nov 16, 2018

nope its open in there unless its a fancy column rad

standard rad is indented to give the rad more surface area which increase the heat capacity a bit

Chuck · Nov 17, 2018

MelloPeck said:
Hi, I mean the direction it flows through all the channels, does it flow from top to bottom or up some channels and down others?

Typically it goes up the first one or two vertical channels closest to the flow inlet, which I'm assuming is at the bottom, and down the remainder.

fixitflav · Nov 17, 2018

MelloPeck said:
Hi, I mean the direction it flows through all the channels, does it flow from top to bottom or up some channels and down others?

If it's piped like most rads, flow and return at the bottom, if the water is going up in some places it must be going down in others.

Gasmk1 · Nov 17, 2018

uses natural convection currents. if you feel a rad as it heats up its starts getting hot at the flow end then gradually increases across the rad.

Tim Watts · Nov 17, 2018

With a normal radiator it depends on whether both connections are at the base or one top and one opposite bottom.

Both connections at the bottom (all of mine) are slightly weird, but explainable - you tend to get convection lifting the hot water over just one side, then the top gets hot and eventually the other side gets hot in a top to bottom way until the whole thing is steady.

Try turning a cold rad on and feel which bits heat up in which order - that's an approximation of your water flow.

Rob Foster · Nov 18, 2018

Tim Watts said:
With a normal radiator it depends on whether both connections are at the base or one top and one opposite bottom.

Both connections at the bottom (all of mine) are slightly weird, but explainable - you tend to get convection lifting the hot water over just one side, then the top gets hot and eventually the other side gets hot in a top to bottom way until the whole thing is steady.

Try turning a cold rad on and feel which bits heat up in which order - that's an approximation of your water flow.

In the old days ....before my time the practice was to put feed on top stabbing and return lower stabbing on opposite side. Then it was discovered that convection flow allowed in and out on bottom stabbing son opposite sides, sludge builds up on bottom between in and out and results in cold spot along bottom of rad . See pics of this to determine heat flow, or point your iPad on thermal camera at a cold rad to see fir yourself
Rob Foster aka centralheatking

Welder · Nov 18, 2018

Rob Foster said:
In the old days ..before my time the practice was to put feed on top stabbing and return lower stabbing on opposite side. Then it was discovered that convection flow allowed in and out on bottom stabbing son opposite sides,

Morning Rob.
Rads 'were' always designed as you say. AFAIK that still works and is the most efficient & effective piping arrangement.
The change to bottom in bottom out was led by nothing more than the technical and moral depths of 'fashion' in the late 60s. It was deemed 'ugly' to have pipes on show so, being the sheep we all are, everyone copied it and we have what we have. Where I am 'allowed', I still pipe rads top in bottom out - 'she' don't like it tho

Tim Watts · Nov 18, 2018

YorkshireDave said:
Morning Rob.
Rads 'were' always designed as you say. AFAIK that still works and is the most efficient & effective piping arrangement.
The change to bottom in bottom out was led by nothing more than the technical and moral depths of 'fashion' in the late 60s. It was deemed 'ugly' to have pipes on show so, being the sheep we all are, everyone copied it and we have what we have. Where I am 'allowed', I still pipe rads top in bottom out - 'she' don't like it tho

Annoyingly, the vertical rads I have in 3 rooms would have been easier with one pipe in the top - as would the towel rail as I'm on a drop system (solid ground floor). But the rads all required bottom inlets (verticals have a separator in the top bar halfway).

Gasmk1 · Nov 18, 2018

top and bottom entry was originally used as nearly all systems were one pipe when two pipe systems came in the both bottom was adopted, that is what i always thought.

Best · Nov 18, 2018

Top and bottom connections also were done on the old systems that were all gravity with no circulating pump.
Rads on gravity also work better on top to bottom connections

Water flow path through radiator

MelloPeck

Riley

Super Moderator

hammers4spanner

MelloPeck

ShaunCorbs

Super Moderator

Chuck

fixitflav

Gasmk1

Tim Watts

Rob Foster

Welder

Tim Watts

Gasmk1

Best

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