Rinnai Boiler: Radiators not hot enough or slow to heat
Radiators not hot enough or slow to heat on a Rinnai boiler: Heating performance is poor.
Applies to: E50CRN; E75CRN; E75CRP; E110CRN; E110CRP
Common causes of radiators not hot enough or slow to heat
- Room thermostat or RS100 setting
- Supply temperature setpoint too low
- Wrong installation type in parameter 2
- System resistance too high (boiler cuts load when delta T exceeds 36 F)
How to fix radiators not hot enough or slow to heat: step by step
- Check thermostat / RS100 settings.
- Check PARA parameter 1 and raise if needed.
- Check PARA parameter 2.
- Check and clean the water filter; verify pipe sizing.
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.
If the unit shows an error code, look it up: Rinnai Boiler codes
Models
I-Series Plus 150K and smaller
I-Series Plus 175K and higher
Source: Rinnai E-Combi Series Installation & Servicing Instructions (8U516009 V0116), p.77 (15.4). Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.