BALANCING QUERY?

[Agile]

They are almost useless for serious heating setting though.

Not if you know what you are doing.

I like to think that I know what I am doing in relation to basic matters and I must disagree.

The problem comes because people think they will measure the temperature of pipes as required for balancing. The angle of view will not cover a 15 mm tube and the tube is round and not flat either.

Then there is the emissivity of the surface. If everything was painted matt black then they would not be too bad but on white or shiny copper they are both inaccurate and misleading if anyone believed the reading.

They can be used for comparative readings if its realised that are not showing the real temperature. For balancing use on the rad flat surface at the inlet and outlet rather than the pipes as DIYers expect to.

The contact thermometer is the only way to get correct accurate readings!

I actually do this kind of practical work whereas we gather that D Hailsham is a retired armchair expert who may not even own an IR thermometer.

 

[D_Hailsham]

The angle of view will not cover a 15 mm tube and the tube is round and not flat either.

The angle of view for most IR thermometers is too large in most cases so, if held even six inches away from the pipe, it will give an average temperature over the field of view. You have to hold it in contact with the pipe. The fact that the pipe is round is irrelevant.

Then there is the emissivity of the surface. If everything was painted matt black then they would not be too bad but on white or shiny copper they are both inaccurate and misleading if anyone believed the reading.

I agree that emissivity can be a problem, but only if the pipes have not been painted. IR thermometers are normally calibrated for an emissivity of about 0.95. Normal white paint use on pipes has an ε value of about 0.9, so it will read about 5% low, ie a temperature of 75C will read as 71 and 65C as 61.6. So your differential will be very slightly out, but not enough to worry about.

If you need to measure the temperature of an unpainted copper pipe, you can always wrap some black insulating tape round the pipe and measure the temperature off the tape.

Yes, I do own an IR thermometer and have done for many years.

I was going to carry out an experiment to compare the results of measuring the temperature off the pipe and off the surface of the rad, using my IP thermometer and my thermometer with a K type temperature probe (yes, I own one of those as well). However the heating is off - flow temp down to 25C - so it will have to wait for another day.

 

[Agile]

Thanks again for the info.

So would it affect the order the rads heat up if I didn't touch valves at all?

Cheers.

You seem to have some kind of fixation about the order that rads heat up!

Dont you realise that when properly balanced they all all heat up at the same rate commenserate with their size ?

What you should do is set ALL the lockshields to open just 1/2 turn and then make fine adjustments starting from that setting.

In reality it will be pretty well balanced without futher adjustments in most cases!

Tony