Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Warm air comfort

Brad White_9
Brad White_9 Member Posts: 2,440
is 130 degree supply water but like any rule there are exceptions/circumstances.

The general concern which I am sure you know is that the space tends to be dryer in winter hence more skin evaporation, hence the actual supply air temperature has to be warmer to compensate. IOW: If you humidify you can get away with cooler supply air temperatures than if you do not.

What you have going for you is using what is normally a cooling coil: More rows typically, therefore a given water temperature will perform better than in a coil with fewer rows.

As a footnote, watch your leaving water temperature (return water to the boiler) should it not be of a condensing type. Multiple row coils can sub-cool that water in a hurry, to below dewpoint. If you have a condensing boiler, go for it.

The advice you got on trying it and adjusting it is the best way to go, all things said. You might get a table from the coil manufacturer, but in the end, you are going to play with valves anyway, aren't you? :)


  • Simply Rad_2
    Simply Rad_2 Member Posts: 171
    Quick heat and comfort

    I have a project where I am supply heat(hot water) to a fan coil unit. The primary use of the unit is for cooling. This is a 2nd home and will be turned down when it is unoccupied(60 degres). The owner would like a quick heat source to bring the home up to temp. So I am supply heat to the fan coil. What my question is how low of supply temps can I provide to the fan coil and not lose comfort-blowing cool air. I am installing a condensing boiler so I would to keep the supply temps as low as possible, I spoke with the HVAC contractor and he said the unit needs 140 to operate BUT can be adjusted lower if needed. I am just concerned about comfort.
    Thanks Jeffrey
This discussion has been closed.