Measuring CH flow and return temperatures

shiraz99

nofoollikeold said:

For modern systems with condensing boilers it is normal to have a temperature difference of 20 degrees C across the flow and return pipes.  

At the boiler yes but not at individual radiators, it should be around 11, 12 degrees across a rad. Also, that's not always achievable, particularly as we're being told to run boilers at lower temps.

FreeBear

Apodemus said:

FreeBear said:

Apodemus said:

alanobrien said:

No idea what heating engineers use but as an engineer myself i use an infrared non contacting thermometer.
It makes the job quite easy.      Something like the one linked to below except mine is more accurate at +/- 1C


https://www.amazon.co.uk/Etekcity-Lasergrip-Non-contact-Thermometer-58°F-1022°F/dp/B01AT9TON0/ref=sr_1_7?crid=37AX64PSLZLIZ&keywords=infrared+thermometer+gun&qid=1665496998&qu=eyJxc2MiOiI1LjAyIiwicXNhIjoiNC43MSIsInFzcCI6IjQuNjUifQ==&smid=A3P5ROKL5A1OLE&sprefix=infra+red+thermo,aps,131&sr=8-7&th=1

I've got that exact thermometer and it is great for a lot of uses - everything except getting the temperature of CH pipes, especially if they are shiny copper or stainless steel.  It's good for rads and walls, woodburner, pizzas, you name it, but results from pipes are all over the place.

I also have a pair of the same. Used a plastic Talon pipe clip with a 4mm hole drilled in it for the sensor. Slip the clip over the pipe, wait for the reading to stabilise, job done.

Thanks, but my comment was in response to alanobrien's link to the Etekcity IR Thermometer - really useful device, just not for pipes!

My bad. I picked the wrong post to quote.. Now edited.

(It was a long day in court yesterday....)

shiraz99

Apodemus said:

alanobrien said:

No idea what heating engineers use but as an engineer myself i use an infrared non contacting thermometer.
It makes the job quite easy.      Something like the one linked to below except mine is more accurate at +/- 1C


https://www.amazon.co.uk/Etekcity-Lasergrip-Non-contact-Thermometer-58°F-1022°F/dp/B01AT9TON0/ref=sr_1_7?crid=37AX64PSLZLIZ&keywords=infrared+thermometer+gun&qid=1665496998&qu=eyJxc2MiOiI1LjAyIiwicXNhIjoiNC43MSIsInFzcCI6IjQuNjUifQ==&smid=A3P5ROKL5A1OLE&sprefix=infra+red+thermo,aps,131&sr=8-7&th=1

I've got that exact thermometer and it is great for a lot of uses - everything except getting the temperature of CH pipes, especially if they are shiny copper or stainless steel.  It's good for rads and walls, woodburner, pizzas, you name it, but results from pipes are all over the place.  At the moment, the top of my kitchen radiator is showing 44C, while the feed pipe from the boiler is giving me between 27C and 44C and the return 26C to 35C.  I can comfortably put my hand on the return pipe, but not the feed, so I'm guessing high 40s for the feed and mid twenties for the return.

I'm coming to that conclusion too, I found it impossible using my thermometer with surface mode to get a stable reading at the pipes, and I've now seen a number of YT videos where it suggests you only use IR thermometers on the rads themselves, either in the top and bottom centres to check the overall temp and bottom corners for the flow and return. For the pipes it seems they use the proper differential kits with clamps.

Another thing, I have a towel rail in my bathroom which is the first on the CH circuit which has a lockshield on one side and a manual valve (not TRV) on the other but I'm not convinced there on the right side as the side with the lockshield is hotter which suggests that's the flow. Does it really matter, and if I want to restrict it should I still close down the lockshield to a quarter turn, for example.

victor2

FreeBear said:

victor2 said:

shiraz99 said:

What do professionals use to measure the flow and return temperatures on a radiator?

I want to properly balance my rads and check whether the boiler is running efficiently as possible.

Not "professional" equipment, but I got four thermometers from Amazon for less than a tenner:

https://smile.amazon.co.uk/gp/product/B07ZN3QTBV

They all work and agree to within one degree of each other when measuring room temperature. You could put one on the flow and one on the return and do two radiators at a time. Of course you have to give them time to settle, where infra-red thermometers will be instantaneous, but I can live with that.

I also have a pair of the same. Used a plastic Talon pipe clip with a 4mm hole drilled in it for the sensor. Slip the clip over the pipe, wait for the reading to stabilise, job done.

Neat solution! I'd just tied mine to the pipes with the ties that were on the thermometer wires. Bet I've even got some pipe clips lying around somewhere.