You could do it with 101º water if the coil had enough rows, static pressure would need to be higher to push the air thru' this 20-40 row coil. Truthfully, there is not enough info to answer the question, need airflow, coil size and rows etc.
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You can run your rtu discharge temp at a higher temp as long as it will not hurt other zones in the building. I have a building that has a combination of vav and cav zones and if I don't run the discharge @ 60 deg in middle of winter, the cav zones won't reheat enough.I think that is what your asking.
I would try increasing the DAT setpoint until I got complaints from interior zones then back it down. Is your boiler on a reset schedule? Turn the water temp up. I have a VAV system that was converted from a old constant volume system and with the increased volume of air I have problems getting enough heat out of some coils. You will probably have to lower the temp again next summer. Ken
drop the box on that 3 zone perimeter area and install a fan powered VAV...when you call for heat the VAV 55F will damper off and the fan will pull rturn air to supply the zones plus your wet coil temp. then without touching the rooftop and effecting the other interior zones on the cooling side.maintain your 55F on that rooftop and work the space heat generated within especially on the perimeter where it is missing baseboard.
Originally posted by flange you would need much more info to get the correct answer. you dont necessarily need 100 degree air to heat that area. design supply air temp? hot water temp? cfm, heat loss, type of box? etc.
Flange is right, we need more information. If the system is designed right, you shouldn't have to change th DA-temp. Don't know if you system is pnuematic or ddc. Your vav box should have heating cfm setpoint. Typical boiler water temps are from 160-180 degrees, should vary if based on a outdoor air reset schedule. Make sure your reheat valve is opening fully. Need to fully test out vav box, check all the above mentioned by flange.