After using my system for a couple of days, I think I've undersized the emitters in one of my rooms. All the circuits are getting plenty of flow, and after running some additional heat loss calculations I think the room just loses more heat than the emitter can provide.
I have two home runs in the room, each feeding a radiator that is rated to put out 3,480 btus at 140* water temp. I would like to add a second radiator to one of the home runs that is rated for 3,120 btus at the same temp.
The current piping is 1/2" fostapex to each home run. The 1/2" should have no problem carrying the btus at a 20* delta t (each radiator needs only about 1/3 a gallon/minute of flow to meet the btu demand). My question is the best way to pipe in the new radiator:
- Pipe both radiators in series with a single TRV controlling flow to both radiators based on the temperature of the room where they are located.
- Pipe both radiators in reverse return configuration with 1/2" legs from the 1/2" mains supplying and returning to each radiator, with each radiator controlled by a dedicated TRV.
- Pipe both radiators in direct return configuration with 1/2" legs from the 1/2" mains supplying and returning to each radiator, with each radiator controlled by a dedicated TRV.
- Add a new home run.
Option 1 is the cheapest and easiest, but I read that a single TRV piped in series can cause problems because the temperature will drop too much in the first radiator and under power the second. Running parallel piping will be easy for me, and the cost of the additional TRV isn't so bad. Running a new home run would be a pain, and I would like to avoid doing it if any of Options 1--3 will work.
Thanks for your thoughts in advance.