Delta T for heating applications.

[redif]

The design room temperature inside the room is 5 DegC. Outside temeprature is sub zero deg C( around -20DegC). The room should be heatde suitably. In general what is the good engineering practice between supply air air temperature and the room temperature ( Delta T)for heating applications. Is it mentioned any standards like ASHARE????

Thanks

 

[walkes]

Building codes may indicate the maximum supply temperature for a system with air heating. 110°F (43°C) is usually a reasonable supply air temperature.

 

[redif]

Dear Walkes Thanks for your response.

But dont't you think that off coil temperature of 43 deg C will make the delta T across the coil to 63 deg C which it seems is a very high delta T for a heating coil. Heating coils are generally not more than 2 rows deep.

Also the temperature difference between room design temp of 5 deg and supply air temperature at 43 deg C will be around 38 deg C.

Dont you think that such a high temp difference can cause stratification in the room.

It seems some thing is given in ASHARE Standard 55 but I dont have a copy of it. I hope someone can tell us what is the ASHRAE recommendation for supply air temperatures for heating.

This is an offshore platform application and heating is to be provided in mechanical areas. The installation location will be some where in North Sea. I am not sure we can apply building codes to an offshore platform.

I have checked the applicable offshore design codes but nothing is stated in this respect.

 

[walkes]

I was actually thinking of a dedicated gas fired air handling unit for air supply.
Stratification in the room would be dependant on the means of air distribution and the size of the room.

The delta T of the coil would be dependant on the airflow required for the space. If you were introducing approximately 1 CFM per square foot(5 l/s per meter squared), your delta T may be considerably less.

I think also that you are outside the bounds of comfort conditioning as it would appear that you are just preventing things from freezing, so your discharge temperature may not be as great a concern.