Balancing Rads

[bengasman]

Your problem is not the size of the rads, but the fact that your roomstat is in the wrong place.

As for the location of the room thermostat. It doesn't matter where it is

Well it's tricky to decide what to do with completely contradictory advice!

Well, one comes from an experienced engineer who makes a living out of doing this stuff, the other comes from somebody who has never installed a boiler in his life.
Maybe that makes the choice easier.
If it doesn't, you could ask yourself if the location really does not matter. How effective would it be to have the roomstat in an spare room used for storage?
If you still don't know, just gamble; any action is better than no action.

I've blocked up the chimney and balanced the rads since that costs nothing.

That alone could make a huge difference. Don't forget to do the obsolete vents.

Next is to either get the walls and floors insulated or get TVRs fitted and move the thermostat. The arguments for insulation, thus reducing the heat requirement of the lounge seem more logical and compelling.

This may be a good time to replace the old mechanical stat with a modern digital programmable roomstat.
Much more convenient than the old system, more versatile too. Wireless models for about £30-£50 more than hardwired type. Makes the installation quick, easy and a lot cheaper than hardwired version.

Various subsidies available for insulation, worth checking out carefully as not all are as good as they seem.

 

[D_Hailsham]

Rough rule of thumbs shows the second 8 degrees will take twice as much as the first 8 degrees temperature rise, which means you would need 15 kW output just for the lounge; twice as much as the calculation.

Where did you dig that one up from and what is the justification for saying that?

As for the location of the room thermostat. It doesn't matter where it is, provided each room has the correct size radiator.

I could not have given a better example of the difference between a google hero and a pro, if I had tried.

Think about what I said (the bit in bold is the important bit) - it's not so daft as you try to make out.

 

[bengasman]

As for the location of the room thermostat. It doesn't matter where it is, provided each room has the correct size radiator.

I could not have given a better example of the difference between a google hero and a pro, if I had tried.

Think about what I said (the bit in bold is the important bit)

That is exactly the point that shows your ignorance about how things work in the real world.
You can not learn our trade, or any other form of engineering from behind your keyboard.
If you have never installed/repaired heating systems, you simply have no more of a clue than somebody going up for a driving test after only doing the theory.

 

[D_Hailsham]

Rough rule of thumbs shows the second 8 degrees will take twice as much as the first 8 degrees temperature rise, which means you would need 15 kW output just for the lounge; twice as much as the calculation.

Where did you dig that one up from and what is the justification for saying that?

No reply to this, then?

I wonder why not!

 

[bengasman]

Rough rule of thumbs shows the second 8 degrees will take twice as much as the first 8 degrees temperature rise, which means you would need 15 kW output just for the lounge; twice as much as the calculation.

Where did you dig that one up from and what is the justification for saying that?

No reply to this, then?

I wonder why not!

Because you can argue this til the cows come home; it's a rough rule of thumb.
It has to do with average temperature, differential temperature, average dissipation, and most of all: experience; none of these are on your list.

I can walk into a house, go through the rooms, and accurately estimate the size of the rad in 5 seconds flat. It's been years since I had the slide rule out, and can not remember the last time I was wrong.

 

[D_Hailsham]

I can walk into a house, go through the rooms, and accurately estimate the size of the rad in 5 seconds flat. It's been years since I had the slide rule out, and cannot remember the last time I was wrong.

Of course you will never be "wrong" if the rads are oversized!

 

[bengasman]

Of course you will never be "wrong" if the rads are oversized!

Oversized is a term that has effectively become obsolete, I always use it between " ".
You can compare it with saying cars have an oversized engine when the top speed is above 70.

Due to sophisticated controls having become common place, spare rad capacity will be automatically turned off when not needed and thus not cause energy wastage.

The remaining positive results of a radiator being considerably larger than the minimum requirement ( which was considered the “correct size” in the seventies ), are:

1.faster response time resulting in improved comfort
2.allowing the boiler to run at a lower temperature improving efficiency in steamers
3.spare capacity for periods of extreme cold ( like we had two winters in a row ) so you can still be comfortable, which of course would not be possible with “correctly” sized rads

The negative results are:

A slight increase in the installation cost ( unimportant unless you are a skinflint )

A bit of extra wallspace taken up which can be counter acted by using your brains before you hang them at the first available bit of wall, or “where we have always put them”.
By doing this, I have in many cases actually gained usable wall space for my clients.

It may be hard to understand all this sitting in your arm chair, it makes perfect sense once you have actually done it.

 

[bengasman]

edit

 

[ajrobb]

I've certainly noticed it takes much more than twice as long to heat up a house by 8°C than it does by 4°C. I put that down to having to warm the fabric of the house as well as the air. I'm not convinced it takes 3 times as much heat to keep a house 16°C above outside temperature as it does 8°C; that flies in the face of U-value calcs.

Generously (oversized) radiators should work well with weather compensation. Not worth it just to get the slight savings but can help in extreme cold weather too. Looking at the Screwfix catalogue, basic steel radiators cost around £16/kW rated output (from memory).

 

[D_Hailsham]

Oversized is a term that has effectively become obsolete, I always use it between " ".
You can compare it with saying cars have an oversized engine when the top speed is above 70.

The comparison is not a valid one.

If you put an engine capable of 150mph in a car which is speed limited to 70mph by the engine management system, then you could argue that the engine was oversized. (But it would do OK at the traffic lights GP )

Due to sophisticated controls having become common place, spare rad capacity will be automatically turned off when not needed and thus not cause energy wastage.

That's just an excuse to justify spending more of someone else's money.

1.faster response time resulting in improved comfort
2.allowing the boiler to run at a lower temperature improving efficiency in steamers
3.spare capacity for periods of extreme cold ( like we had two winters in a row ) so you can still be comfortable, which of course would not be possible with “correctly” sized rads

I wouldn't disagree with any of those, though it all depends on what is meant by a "correctly sized rad". I take it to mean that the rad will give out the required amount of heat to meet the specified conditions. So, if the customer ask for the room to be at 25C when it is -10C outside with the water temp at 70C/50C, the rad must be sized to meet those conditions. Compared to the "standard" (21C, -1C, 75C, 65C) it will appear to be "oversized", but it isn't.