I have a UFT-100 boiler installed with an SSU-40 indirect water heater with a Caleffi air separator and a Grundfos Alpha II pump(and pressure reducing valve and expansion tank and other assorted accessories for a complete system). The flow calculations show about 4 gpm and the pump reads 3 gpm. It intentionally has a lower flow to keep the return water temp in the condensing range most of the time. The DHW heating supply is set to 135 degrees and the DHW firing rate is set to 65%. It is using the HTP indirect tank probe and is set to 118 degrees with a 5 degree delta T. A combustion analyzer shows about 8.8% carbon dioxide and no carbon monoxide at low fire. It was running rich for about a month before adjustment. It also was shipped via UPS so it was likely dropped.
I experience a hot plastic or rubber smell that I think is coming from the foam insulation around the boiler vessel in the area above the water line. That area seems to not exceed 190 degrees or so but it is difficult to accurately measure the temperature of a surface like that(this was measured when the mixture was rich and it seemed the smell was worse with the rich mixture). It seems to happen more at the end of a DHW call as the tank approaches the setpoint and delta T of the boiler water falls. If you increase the boiler setpoint to 145 degrees there is significantly more of the smell. It has been running for about 2 months with only the DHW load so it should have had time to remove any manufacturing residues. It is set up in a powered vent configuration and is installed with the included cpvc nipple on the exhaust (but the smell does not appear to be coming from the intake).
Has anyone seen anything like this? The boiler should be operating in its modulating range. I am wondering if there was a material that didn't meet spec used for the boiler insulation. It also seems that 1/8 of foam has so little insulating value that it is pointless anyhow. Is there some component behind the boiler vessel that might be making the smell?
It is planned to also heat some zones of baseboard in my basement but that has not been installed yet.
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