Low temps with Runtal UF radiators and efficiency

moral212

i believe i am losing efficiency with my current heating setup (but maybe not?).

Setup:
IBC hc series boiler
1 zone of the house is on radiant under floor heating (wood floor staple up)
1 zone is using Runtal hydronic UF radiators
Controlled with a taco relay srp

Notes:
The temp curve is set lower due to the radiant.
Runtal UF states they can be used with low temp heating
The Runtal heaters may be a box undersized for the spaces at low temp.

Q’s-
Am i burning more fuel running the boiler at low temps for longer than say high temp for shorter?
How to alter the system to provide higher temps to the radiators without buying and installing lots of expensive and complicated components? Should I just raise the temp curve?

Jamie Hall

If the Runtals are giving you satisfactory heat, and the boiler is intended for low temperature operation (a mod/con), then no -- the lower temps for longer will give you better efficiency. However, if the Runtals are not giving you satisfactory heat, you'll have to raise the temperatures (the temperature curve) to accommodate them, and mix the boiler water down (which isn't that hard to do).

moral212

Got it! Ok, thank you. Guess I am running efficiently then!