Ok, I've just bought an IR thermometer with laser guide (IR89 - awesome) and have began balance my rads in earnest.
I have a choice of 2 rads which could be considered closest to the bolier. One rad has a 4 degrees C drop across it (20-16) but the other, get this, has an increase across it (21-27)? Have the builders put the wheelhead/lockshield valves on the wrong way round? Would the central heating system still work ok if this were the case?
Any advice greatly received as always.
I'll buy that rad off you!
The majority of valves these days are not sensitive to the direction of flow, and as such you can fit them either side. The system will still work fine.
If those are your CH temps in the middle of winter, I think you've got bigger problems than not understanding that water cools when it flows through a rad.
NT
A radiator can't *heat* the water - unless it's got an electric heater inside it! So what you *think* are flow and return are actually the other way round.
In what units are you measuring the temperature? I don't know of *any* measurement units in which a number in the 20's would be a sensible reading for a radiator! Or maybe you're pointing your IT thermometer at the *wall*?
If you're measuring pipe temperatures in the 20C range, try switching the heating on?
IR thermometers are the work of the devil. They are *very* difficult to use and even in the hands of an expert can often give misleading results.
Firstly, apply some common sense. Touch the radiator, does it *feel* like it's 20C? (That's room ambient for most rooms).
Next calibrate the meter. The instructions to do should have been supplied and you will require an object of known temperature and with the same characteristics in the IR range as your radiator. TBH it's probably easier to measure the temperature of the radiator with a proper thermometer then use that to calibrate the IR meter!
Finally return it to the shop.
That is cobblers! They give very quick - and reasonably accurate - readings, which is what you need when you are checking a *lot* of radiators in quick succession. If you stick a little square of black tape on each bottom corner of each radiator - right next to the input/output connections - you can get very consistent results. The readings don't need to be accurate to a fraction of a degree because you are measuring the *relative* temperature drop across a number of radiators. This is by far the quickest way to do it.
It's probably a PPPro IR thermometer and he's pointing it where the laser is pointing ;-)
MBQ
Completely disagree with you, I'm afraid. IR thermometers are far more accurate, reliable and, most importantly, rapid than any conventional one, provided you understand how they work and how varying emmissivity effects readings.
You only have to use ones that measure human temperature to realise that an IR gives clearly an accurate reading, whilst a non-IR one invariably underreads. I have built an IR thermometer from scratch 10 years ago at university and understand how they work.
To get accurate results on metal pipes, it is advisable to reduce the reflectivity of the surface, and just as importantly provide a fixed emissivity for comparison. This is easiest done by applying some black tape and aiming at that.
Conventional thermometers are a faff and complete waste of time.
Christian.
Yes and no.
If you use a surface probe thermocouple with shield connected to a proper meter then the results are very good.
e.g.
However, one would need to spend £100 or so for a reasonable meter, themocouple adaptor and probe.
Sorry, I'm in a bit of a bad mood today and my previous post was a little simplistic. Allow me to explain...
IR thermometers measure IR radiation and from that infer the temperature of the object. Which is great if other significant variables are controlled but all too often they are not and as it's (non-visible) IR we're talking about generally the user isn't even aware the variables exist.
In the case of a home user measuring radiators in a number of rooms the result is going to altered by the surface finish of the radiator: one that is matt black (or with your black sticky tape on it) will tend to give a more sensible reading than one which is highly reflective to IR. Indeed, depending on the size of the measuring spot on the meter, one which is highly reflective to IR might even give a very different reading as the meter is moved so that it points to a different part of the "fold" of the surface.
The ambient IR will probably also be different from room to room and will change the results although for the task of radiator balancing it shouldn't change the differential.
My job sporadically involves worrying about how hot various bits of electronics get during operation. Usually when things have already gone wrong and we're looking for a cause. An IR profile of a PCB can help but it can also mislead you if you don't understand what can effect the readings. (IR measured temperature of the case of that polished-top IC - that'll be the temperature of the ceiling then sir).
As for the OPs situation I wonder if he's using the sort of meter which re-calibrates each time you press the ON button and then shows a live reading as you move it around. If it is one of those then he's probably just listed the temperature delta between some random floor/wall/whereever-he-was-pointing-it-at when he pressed the button and the radiator itself. The common sense rule still applies: if it feels hot it certainly isn't 20-something C.
1 Read the balancing FAQ if you haven't already
Phil The uk.d-i-y FAQ is at
new to diy wrote
They have obviously fitted a cooler by mistake instead of a radiator.
You should ask for it to be exchanged at once.
I found the original radiator finish gave a good indication. The copper pipe feeding the radiator needed the black tape to give a sensible reading. I assume the radiator manufacturers (Barlo in this case) coat the radiators with a high emissivity coating at IR, even though it is white for visible radiation.
Calvin wrote
I still agree with Set Square. Each rad you check will generally be of the same material and finish at each end. We are less interested in the actual temperature than the drop, so a lot of the problems you describe don't matter.
And from personal experience, I can get my system more or less balanced easily, before I had the IR I wasn't in with a prayer.
[snip good stuff, I totally agree.]
I would definitely go the IR method, it gives an accurate enough readout in a couple of seconds for each radiator. By the time the thermocouple stabilises you could have checked several radiators with an IR thermometer.
It also showed up some cold spots in my walls and ceilings in a scan lasting seconds rather than hours. I now have to get round to sorting out the deficit of insulation.
I was about to suggest that the heating has to be switched on during nthe process ?!?
IR units work fine just done try measure any shiny pipes - painted rads give good results (colour and finish not significant IME).
Maplin sold one for £30. Who else sells them?
I agree with you that an IR thermometer is suitable for radiator balancing. However, the shielded ribbon type of themocouple stabilises in under a second.
Even I can't get around radiators that quickly :-)
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