Trane XL80 blower speeds

[JoeSix]

Can someone tell me the rated air flow for a Trane XL80 with a 3-ton blower on low and on medium low?

(The specific model number is TUD060R936K)

Thanks.

[BaldLoonie]

What's the static pressure?

[JoeSix]

0.4" W.C.

[BaldLoonie]

877 & 1005

[kytech05]

Low speed @ .04 888 cfm and Med. Low is 1033cfm

[JoeSix]

OK, thanks.

So, with a 2-ton condenser you would almost certainly set the blower on low. (Why a builder in the south would ever think you need a furnace this size with a 2-ton A/C escapes me).

This does raise one more question, though. I'm not staring at the control panel now, but if I recall the the default blower speed tap configuration for this furnace had the heating mode speeds on (1) low (red wire) for Stage 1 and (2) medium-low (yellow wire) for Stage 2.

So, if you use the low tap for cooling mode, would you just use medium low and medium high for heating or do you have to change the taps between seasons? (Or is there a way to use the low tap for both cooling and heating at the same time -- I suppose this is possible in theory)

[BaldLoonie]

You can bump the heat speeds up a notch OR just wirenut yellow from the stat to the outdoor unit and not connect to Y at the board. When G calls, it brings on the low heat speed which is perfect for the 2 ton. You do lose the capability of the fan-off delay but few know to turn it on anyway.

[JoeSix]

Thanks. Does the XL80 board have any protection circuitry for the compressor (e.g. short cycle time delay, etc.). I'm somewhat leery of going straight from the T-stat to the outdoor unit.

[BaldLoonie]

The board has no time protection against short cycling. Only thing it can do, if you turn the correct DIP switch on, is delay the blower going off for maybe 80 seconds after you lose the call for Y. That is factory disabled which is why I commented that virtually nobody turns it on.