|
Sanctuary Cold Weather Heating Test
Last week we had a cold spell here in mid-Michigan with a nightly low forecast around 7 degrees F, so we decided to try camping in the Sanctuary to see how it performs in cold weather. We camped in the driveway so we could dash inside just in case it didn't work out!
I pulled the van out of our pole barn around 4PM and the temperature inside the van indicated 17F on the BMPro panel, which is the A/C control so it's not exactly the same as the Truma Combi thermostat sensor but should be close. I started the Truma heater and set it to 60F. The propane tank was completely full, but the gauge on the panel didn't show a reading and I presume that's due to the cold. After about an hour the temp reading was 45F and the propane gauge was working again, indicating a full tank.
By 6PM the temp reading was 57F so we gained 28 degrees in the first hour and 12 degrees in the second hour. The Truma fan sounded like it was running with lower output by then. At any rate I'd plan on 2 hours to heat the van from the upper teens to somewhere around 60F.
We slept fairly well, and the Truma ran all night as far as I know but the fan speed decreased so it wasn't particularly noisy and not disruptive. I prefer to sleep a bit warmer than 60F but this was entirely tolerable and not unpleasant when getting up at night. The water system is winterized but we used the cassette toilet during the night and emptied it in the morning.
Propane Consumption
I shut the heater off at 9AM, and the propane gauge read 7/8 full. After I had emptied the potty and parked the van back in the barn, the gauge was reading 3/4 full. This is not unexpected as it is not a super precise gauge and can be affected by temperature plus how level the van is parked. Based on the gauge reading my best guess is that we used between 1/8 and 1/4 tank of propane.
We have a 24 pound propane tank so if we pessimistically assume that we used 1/4 tank that's 6 pounds of propane. It provides 21,548 BTU per pound so that's 129,288 BTU consumed in 17 hours, or 7,605 BTU/h. The Truma Combi Eco operates at 7,500 (low) and 14,300 (high) BTU/h so that consumption is consistent with it running on low for the entire 17 hours. Based on listening to the fan I think it ran on high for about 2 hours and low the rest of the time, and probably cycled on and off a bit in the evening before it got really cold outside.
Battery Consumption
We ran entirely on the 200AH AGM battery bank that started fully charged, and it was reading 12.4V in the morning indicating approximately 75% charge so we used approximately 50AH in 17 hours for an average consumption of 3A or about 36W. That included running the inverter to watch TV in the evening and running a CPAP all night. The Truma has a specified average consumption of 1.6A and the CPAP takes about 1A so this adds up about right. The battery voltage is not a very accurate way to measure state of charge though, and at some point I plan to upgrade to a real battery monitor such as the Victron BMV-712.
Conclusions
I would feel confident to camp 3 or 4 nights in cold weather like this if we started with a full tank of propane and didn't use the heater much during the day. I wouldn't use the generator but propane for cooking is minimal in comparison so I wouldn't worry about using the cooktop, except for the need to bring in very cold fresh air for ventilation. The battery bank should be adequate for up to 3 nights like this without any recharging, but it would be preferable not to run it below 50% so we should expect to recharge it every 2 days one way or another.
__________________
|
Linear Mode
