What is the purpose of having BOTH a bunk heater and an APU?

I meant in his case.

 

I guess depending how you read that it could be misleading. A Tripac uses a bun heater for heat. It is part of the APU set up, buts it’s a separate unit and different manufacturer

 

Thermoking tripacs usually have that set up. AC and cabin fan are powered by the APU and the APU will crank on to top off the batteries but the heat is from the bunk heater. Now the bunk heater does draw on the battery so you might hear the apu kick on but the thermoking does not draw heat from the apu itself.

 

Tell us you've never looked under your bunk, without saying you've never looked under your bunk.

 

I was surprised recently when looking at a friends new Truck. It has an APU, and a separate bunk heater. It’s all wired into the Trucks HVAC controls. Bunk heaters not working. I always wanted a bunk heater. Webasto s are $1200 of more, last time I checked. Chinese knock offs are now available for about $300. I hear they burn 1 gal. Every 10 hrs. They’re all about the size of a narrow shoebox. Tiny 1 cylinder Diesel engine. Only recently found out that they draw down the batteries. APU takes care of that, I guess? Must only run when needed. Seems the APU could just circulate water, and heat the Truck, but that probably costs a lot more in fuel, wear and tear on APU. Webasto also makes a similar size engine coolant heater. Heats and circulates the coolant. They’ve both been around since at least the early 90s. A lot of Canadian Trucks used to have them. Back before APUs were common.

 

My truck with APU & bunk heater was great. The APU provided ice-cold air conditioning. The bunk heater could cook a roast in 45nminutes. The APU provides virtually no heat in sleeper with engine off.

 

The clue is in the name. TRI-pack

1 Diesel fired Bunk heater

2 Ac conventional refrigerant system powered by main unit

3 Apu providing electricity/engine heat

 

The bunk heater is for running down the road, the APU is for when your parked engine off. The bunk heater is standerd on the truck, the PAU is added later to save fuel, nothing to do with drier comfort, about saving the company money.