xsilvergs
Forum Member
Our Motorhome has a Truma 4E blown air heating system which for the 5 years of ownership has failed to impress. From day one I've thought that no matter what temperature it is set to it doesn't feel right. I have fiddled with the OFFSET, which only goes in one direction, but that didn't work.
A couple of months ago I bought a Ruuvi to integrate with the RPi GX I use. That was dead simple and through the summer I could see how hot it got!
My last purchase was an ET112 power meter. This is a great bit of kit and with Node-Red I can see how much energy we use and how much we're saving being away in the MoHo.
With this cold spell I set the Truma to 6*C to stop things freezing and sat indoors watching the VRM. I was surprised to see that the Truma couldn't maintain the set temperature of 6*C with an outside air temperature of about -4*C.
When set at 6*C the heating came on at about 17:00 with an inside temperature of 6.7*C, heated the van to 9*C before cutting off. The next time it started heating was around 20:11 but not at 6*C but at 7.9*C raising the temperature to 9.7*C at 23:00. The next time it started heating was at 00:00 from 8.5*C to 10*C at 03:00.The last time the heater came on that night was at 03:45 with a van temp of 8.7*C, 2.7*C over the set temperature of 6*C. The graphs above show temperature and when the heater came on.
Does this explain my gut feelings from day one that the Truma wasn't performing?
The Truma temperature sensor is above the hab door in a box which contains the Truma controller and the the van electrics control panel. I think this is the recommended position and similar to many other vans I've been in. The sensor is pushed through a 10mm dia hole in this box, the rear of the box is not subject to any heating as it's partially sealed, in fact it feels quite cold in there this weather.
Yesterday I pulled the sensor on its lead, out of its box by about 100mm so that the cooler temperature inside the box has no effect on the sensor. The results are below.
The van sits much closer to the 6*C set temperature with less than 1*C hysteresis. Compared to the previous results where the heater only came on 4 times during the period, this time it came on 14 times of shorter periods. The night temperatures were similar and a possible contributor to the heater starting later is due to me spending time working in the van.
I am now 3D printing a support to hold the sensor outside of the box so that it is in free air. I hope to update this post later with more results.
A couple of months ago I bought a Ruuvi to integrate with the RPi GX I use. That was dead simple and through the summer I could see how hot it got!
My last purchase was an ET112 power meter. This is a great bit of kit and with Node-Red I can see how much energy we use and how much we're saving being away in the MoHo.
With this cold spell I set the Truma to 6*C to stop things freezing and sat indoors watching the VRM. I was surprised to see that the Truma couldn't maintain the set temperature of 6*C with an outside air temperature of about -4*C.
When set at 6*C the heating came on at about 17:00 with an inside temperature of 6.7*C, heated the van to 9*C before cutting off. The next time it started heating was around 20:11 but not at 6*C but at 7.9*C raising the temperature to 9.7*C at 23:00. The next time it started heating was at 00:00 from 8.5*C to 10*C at 03:00.The last time the heater came on that night was at 03:45 with a van temp of 8.7*C, 2.7*C over the set temperature of 6*C. The graphs above show temperature and when the heater came on.
Does this explain my gut feelings from day one that the Truma wasn't performing?
The Truma temperature sensor is above the hab door in a box which contains the Truma controller and the the van electrics control panel. I think this is the recommended position and similar to many other vans I've been in. The sensor is pushed through a 10mm dia hole in this box, the rear of the box is not subject to any heating as it's partially sealed, in fact it feels quite cold in there this weather.
Yesterday I pulled the sensor on its lead, out of its box by about 100mm so that the cooler temperature inside the box has no effect on the sensor. The results are below.
The van sits much closer to the 6*C set temperature with less than 1*C hysteresis. Compared to the previous results where the heater only came on 4 times during the period, this time it came on 14 times of shorter periods. The night temperatures were similar and a possible contributor to the heater starting later is due to me spending time working in the van.
I am now 3D printing a support to hold the sensor outside of the box so that it is in free air. I hope to update this post later with more results.