Appreciate the various ideas. Our
Razor has the cold weather package (heated rails, blowdown and weep) so not really worried. 99% of the time the
doors help keep the bay temp fine (lowest is usually in the 40s even when below 32 outside). When we had zero degrees outside for a few days during xmas we closed down the bay to preserve the heat at 32 inside the bay (actually the
Razor shut itself down by design). Thinking that if ER is at 60 if we blow in some air when bay temp reaches 35 we can keep the place running when we have several days of extreme low temps. Perhaps it is wishful thinking, worst case is that we install the exhaust vent and do not use it if ineffective. We have an open square in the ER ceiling to access the attic so it can get new air form the attic if necessary. I am a bit concerned as the WIFI CO2 monitor is showing a higher than expected CO2 level (948ppm) so the exhaust may be necessary to vent the ER.