I am getting low CO emission readings (40 to 60 PPM) from the gas fired boiler. It is power vented. The vent fan shuts off when the boiler cycles off. My question is do all these power vent systems incorporate a Time Delay Purge Relay to remove the last of the exhaust ? I ask because I've gotten 2 different opinions, one saying the vent fan is running correctly and the boiler needs to be cleaned of soot build up and another that says the control box needs to be replaced.
there is only one answer for this question,,call a Professional,,,ALLLLL boilers should be serviced at least every 2 years,it may be dangerous and running inefficient
The short answer is that power-venting does not necessarily mean you have a condensing boiler. It means that you have a power-venting option so that you may vent the boiler directly to the exterior via a short vent line. A simple power-vent option runs the vent only when the boiler is firing - when the boiler shuts off so does the fan. With a condensing boiler, the fan will *typically-but-not-always* run for some preset period after the boiler stops firing to remove the last of the moisture from the secondary heat-exchanger. I suggest that you look at the installation manual for that boiler and determine the operational sequence. From that you can determine whether the system is operating correctly. Or contact the manufacturer. But in any case, not every power-vent system will continue to run after firing stops.
