Anyone got a Warm Air Unit Service Checklist?

[arran197]

I haven't seen a WAU for years, never mind even working on one. But I've got to service one this afternoon. I've got my ticket to do it, it's just been a long time!

I know I have to check to heat exchanger with a torch, but is there a special way to do the flue flow?

 

[Mike Jackson]

Flue flow just the same as any OF appliance. Spillage from the draught diverter unless it's a slot fit. Fan out, burner out, inspection lamp in combustion chamber, look for light from above. I also put a smoke pellet in the combustion chamber and run the fan on summer setting and see if any smoke is drawn into the ducting.

Don't forget to check flue in roof space. Lot of these are on ridge terminals and suffer from broken bolts.

Check return air path, check plenum is correctly sealed. Watch burner as fan kicks in disturbance of the flame can indicate a split heat exchanger.

 

[Pssst]

Check flue in loft
check terminal
check ventilation
check fireproofing of cupboard
check labelling

and above all

Check,check and recheck the presence and security of the return air ducting

 

[lame plumber]

glad all I do is reccommend its replaced as i never got the ticket🙂

 

[arran197]

I went and did the service. Couldn't check the flue as it goes up through the ceiling and through 2 flats above. Then out the roof on a metal cowl. Checked the burner, removed fan and checked heat ex, checked flue flow and inspected burner. Re-assembled, checked burner pressure and spillage, checked safety device. Ventilation was too small, so switched it off.