How to find ducted heating air leak

Forums › Home Workshop DIY › How to find ducted heating air leak

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Tinkerisk

4231 posts

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#2660023 20-Feb-2021 03:11

Helium gas + Helium sensitive gas sniffer probe (Dräger) with no remains afterwards and heater switched off. We do it for Nitrogen or Oxygen but that's NOT recommended at home for obvious reasons. ;-)

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SomeoneSomewhere

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#2660050 20-Feb-2021 10:02

Pull the return grill and filter and look through the duct - can you see anything concerning?

Stick cardboard in the return grill and it won't be able to suck any air through it, and will try to suck from the attic instead. This may help you.

Azzura

603 posts

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#2660051 20-Feb-2021 10:06

Smoke pencil .....rig up something to suck air from the exit end.....or run the system with some flow restriction at the exit end.

Go along the ducting with the smoke pencil. Depending on which way you go at it..either the smoke will get sucked into the leak or air will be coming out disturbing the smoke.

timmmay

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#2660054 20-Feb-2021 10:16

@Tinkerisk @SomeoneSomewhere @Azzura those are all really good practical ideas, thanks :)

@andrewNZ I figured that as well, so did the ventilation company, thanks for the thoughts.

timmmay

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#2660745 21-Feb-2021 20:28

RunningMan:

Are the plenums sealed to the roof unit? You might find if they are screws or riveted then there is an air leak around the plenum, or even along the seams of the plenum. Duct tape along the seams would cure it.

I don't think the plenum is taped to the unit. Some photos below, any thoughts? I can see one spot where it looks like tape has a hole in it but I don't know if that matters - first photo near bottom right.

RunningMan

8956 posts

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#2660748 21-Feb-2021 20:37

There looks to be sealant around the edges of the plenum, so presumably it is well sealed. Hard to tell, but in that first photo, looks like a very sharp bend in the duct as it attaches - should be gradual sweeping bends so airflow isn't restricted. If is is restricted, then the vacuum will increase in other parts which will cause any minor leaks to be more prominent.

timmmay

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#2660759 21-Feb-2021 20:57

Thanks RM. Yes I did notice the bend was quite sharp, I might ask if that's good practice. It might make it a bit louder as well.

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Kickinbac

427 posts

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#2660807 21-Feb-2021 22:40

timmmay:

Thanks RM. Yes I did notice the bend was quite sharp, I might ask if that's good practice. It might make it a bit louder as well.

It’s not good practice, should be long gradual bends. Those will suck flat sooner rather than later. Possibly already happening causing your problem.

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