Determining the last radiator in the downstairs radiator run

[elmocambo]

I am attempting to find out which one is the last radiator by using a DMM connected to a themocouple. All the valves are completely open.
(The floor is solid concrete)
However they all seem to heat up simultaneously more or less.
The reason for doing this is that a wish to add a radiator or two to a garage conversion
Is there another way of doing this?

 

[Chuck]

It's better, IME, to attach the thermocouple to the pipe providing the flow not the body of the radiator. Another trick is to reduce the pump speed so everything happens slower. You might be able to trace the paths using a thermal camera. If you don't have one they can be rented (or employ a heating engineer who has one on the van).

 

[elmocambo]

Do you mean using a pipe clamp?
The pipes are painted with thick, difficult to remove paint, I'm assuming that will impede heat transfer and affect the measurement.

 

[Chuck]

Do you mean using a pipe clamp?
The pipes are painted with thick, difficult to remove paint, I'm assuming that will impede heat transfer and affect the measurement.

Sure, I'd use a pipe clamp but any small sensor is worth trying. It needs to contact the pipe and then be covered with some insulation, e.g. foam pipe insulation to reduce the influence of the room. The paint is not going to help but you are only trying to establish which radiator receives heat last (by timing the point at which the temperature starts to rise), not win a prize for precision thermometry..

If it's a two-pipe system then there may not be much of a time delay between successive radiators receiving heat. If you've got a couple of kids available to help, let the system cool down then position one kid with their thumb on the feed to each radiator with instructions to shout 'heating' (and remove their thumb!) as soon as they feel the hot water arriving.

All this is second best to actually tracing the paths of the pipework, i.e. thermal imaging.

 

[elmocambo]

I'll have another atttempt bearing that in mind, but no kids to help though!