Central Heating, how does the heat get distrubuted evenly?

[rednaxela]

Hello All,

It looks like my radiators come off the feed and return pipes from the central heating system in parallel.
The pump is pumping hot water around the system, but how does the heat get to all the radiators?

My point is, Is the pipe design layout critical to each system? or will the heat just find its way to any radiator in parallel, be it upstairs or down, big or small?

(I am planning to add radiators to my extension & would like to understand a little more on how it works before I get the plumber in. I can at least figure out the new pipe routes and save a few pounds by preparing the holes etc)

many thanks,
Alex.

 

[Rob]

MAGIC...and balancing. Creating an evenly distributed restriction in all directions.

 

[JohnD]

balancing

//www.diynot.com/forums/viewtopic.php?t=37170

(bah, too late)

 

[rednaxela]

hhhmmm sounds like I should leave the planning to the experts.

 

[rednaxela]

thanks for the link..

 

[BoxBasher]

MAGIC...and balancing. Creating an evenly distributed restriction in all directions.

Not forgetting the complex system of levers and pulleys...

 

[Softus]

... and the pixies....

 

[Agile]

Balancing is so simply I really dont understand why so many so called professionals dont seem able to do it properly.

As Rob has mentioned its all about creating a flow resistance in the path to each rad.

Tony

 

[Softus]

Balancing is so simply I really dont understand why so many so called professionals dont seem able to do it properly.

Hm. Using an apostrophe is so simple I really don't understand why so many so called English people don't seem able to do it properly.

It must be such a burden to be perfect.

 

[Polly1]

I would like to add that gravity helps as well. As with hot and cold air, hot water rises and cold water falls.

So as long as the balancing is right and gets hot water to the feed of each radiator, the heat will rise into the rad.

This can cause confusion when there are airlocks, as it can seem heat is getting to a rad, but not enough. The reason the heat gets to a rad in an airlock situation is that the heat/cold rises and falls within the pipe that hasn't got an airlock in it & the airlocked pipe causes the main flow to be stopped.

 

[DP]

Polly, what are you on about?

Balancing is to do with the correct amount of water passing through each radiator. In other words, water flow through each radiator is set (by in most cases adjusting the lockshield valve), resulting in temperature drop of say 12 degrees.

If pipe sizes are correct and pump is set to correct speed, 12 degree (this can be any figure between 11 and 20 degrees C) differential between inlet and outlet at each radiator is possible. Use a straw many meters long to feed a large radiator, only the inlet will heat up. It is the quantity of water (i.e. the weight of water) that carries the heat.

 

[Polly1]

Polly, what are you on about?

Balancing is to do with the correct amount of water passing through each radiator. In other words, water flow through each radiator is set (by in most cases adjusting the lockshield valve), resulting in temperature drop of say 12 degrees.

If pipe sizes are correct and pump is set to correct speed, 12 degree (this can be any figure between 11 and 20 degrees C) differential between inlet and outlet at each radiator is possible. Use a straw many meters long to feed a large radiator, only the inlet will heat up. It is the quantity of water (i.e. the weight of water) that carries the heat.

In addition to the 6 boilers I mentioned in another thread, I also have a solid fired heating system. It's a complicated system heated from a wood fireplace, but when all the pumps are off and the valves are open, the heat still flows to the upstairs rads only helped by rising heat and falling cold. It's a fact!

I also dealt with a problem last year of two rads in a loft conversion on a combi system. No amount of balancing would clear the airlock to activate the rads, however my tenants were confusing me because they were telling me that they were getting a small amount of heat to the first rad. Once I got there myself, I could see what they meant, 1 stem was heating just a little, but the rads weren't hot apart from the small amount of warmth leaking in. Clearing the airlock involved shutting off every other radiator in the house to force water through the pipe & all was well from there & I balanced the system to try to prevent airlocks forming in the same place again through good flow.

Would you dispute that immersion heaters are hot inside at the top & colder at the bottom? That's a result of rising heat, falling cold. Why dispute this then?

 

[Softus]

In addition to the 6 boilers I mentioned in another thread, I also have a solid fired heating system. It's a complicated system heated from a wood fireplace, but when all the pumps are off and the valves are open, the heat still flows to the upstairs rads only helped by rising heat and falling cold. It's a fact!

I presume you're referring to the principle of convection, which, empirically, works by virtue of differing densities, and needn't have anything to do with heat.

I also dealt with a problem last year of two rads in a loft conversion on a combi system. No amount of balancing would clear the airlock to activate the rads

It's not obvious why you think the problem was an airlock, rather than (a) blockage or (b) weak/worn pump. What is obvious is that your plumbing knowledge is very sketchy, and that arguing a technical point would be unwise on your part.

Would you dispute that immersion heaters are hot inside at the top & colder at the bottom? That's a result of rising heat, falling cold. Why dispute this then?

If by "immersion heater" you mean "DHW cylinder (or tank)", then I rest my case.

 

[EliteHeat]

Clearing the airlock involved shutting off every other radiator in the house to force water through the pipe & all was well from there

Why are you telling us this? did you think that perhaps we were unaware of how to remove an airlock?

 

[Softus]

did you think that perhaps we were unaware of how to remove an airlock?

No - it's an attempt to demonstrate plumbing competence, which has rather backfired because it demonstrates a basic lack of understanding.