Heat Reclaim Coil After Gas Heat??

[MeÐiC]

Most of our stores have air heat reclaim. None of those stores have a relcaim coil after gas heat. I have a HVAC contractor wanting to install a HR coil in the SA duct of an RTU. HR coil would be 10-15' from gas burner. Applying 90+ degree heat to a reclaim coil will reak havoc on the rack???

[VTP99]

Most of our stores have air heat reclaim. None of those stores have a relcaim coil after gas heat. I have a HVAC contractor wanting to install a HR coil in the SA duct of an RTU. HR coil would be 10-15' from gas burner. Applying 90+ degree heat to a reclaim coil will reak havoc on the rack???

Seems backwards if you ask me. All the ones i have seen were before. Just guessing but would you not have less thermo transfer ?

[Dowadudda]

well think about it. Heat Reclaim is redistribution of the heat picked up from the removal in the cases. That heat is recycled to use as comfort heat and or de humidifcation.

But what is actually happening is your de super heating the discharge gas. The temperature of the air entering the HR coil has to be lower than that of the Discharge Gas to desuperheat it, or you defeat the purpose. There is a rejection of heat from the gas to the air passing over the HR coil.

So the minute you need additional heat after were heat reclaiming to start, you turn the gas fired burners on. The dishcharge air temperature off them heat exchangers is going to be too high for then the air to travel down to the HR coil and desuperheat the HR coil to extract the heat out of the discharge gas.

Is that not common sense?

[MeÐiC]

Indeed it is and that was my thinking. Just wanted confirmation from the experts here.

[VTP99]

This is a classic case of were a HVAC guy should not be doing RACK type work.:gah:

[MeÐiC]

Seems like they were thinking dehumidification only and not space heating.

BTW what is so difficult in making a lower tonnage RTU with a heat reclaim coil?? Seems Carrier is the only manufacturer that will even touch the subject.

[Dowadudda]

for de humid only, it's not that bad of an idea. But, why would you go through the expense to do it for reheat for dehumid only.

[MeÐiC]

The foremost reason for installing the HR coil is gas savings on space heating. Dehumidification capability is a plus.