Weak heatercraft air flow

I installed a 4 outlet heater. 2 euro vents 2 hot tubes. Just about everyone that trys the heater almost immediatly mentions that the flow is pretty low. With two euro vents closed, one hot tube closed, and one open it's decent, but open 2 tubes and one euro vent and you can barely feel any flow if you put your hand 6 inches from the tube.

On the other hand i have no heat output issues at idle speed. It actually keep cranking 5 mins after i shut the engine off!

Any thoughts, is this weak flow normal? Their 40,000 BTU claim seems to be complete crap. I used a 15 amp fuse as required and actually hooked it up to a dedicated accessory wire that supplies 20 amp.

Oh yea, and the hoses carrying the air aren't pinched or anything. They have a couple 90 degree turns, but it doesn't look like airflow is being restricted. The hose runs aren't long maybe 1.5 feet max for the longest one.

Heatercraft heaters have 3 speeds. Are you sure that your connected the hottest wire, I think it is the orange one. The other two wires are yellow and red.

(Message edited by alans on September 03, 2009)

So if you were just using an on off switch, and not a 4 way switch, you would just hook up Ground(Black) and High(Orange), then just tape off the red and yellow.

From the Manual...

that was my guess. sounds like you only have the slow speed wire hooked up

I definitely used their switch and have 3 different speeds. I only run it on high as low/medium is almost pointless.

It is sandwiched behind my drivers footboard and the back bulkhead pretty tight. But there is several inches of clearance on both sides and there's about a foot of clearance from the top of the heater to the botton of my dash.

(Message edited by Antoddio on September 03, 2009)

The only other thing would be a faulty fan motor. I've got two of the three outlet units and they usually work great on medium but my kids run them on high. One on medium will inflate three kids shirts easily.
It sounds like you have enough clearance for air intake.

BTU stands for British Thermal Unit and relates to the amount of energy required to raise one pound of water one degree. So this only relates to the size of the heater core used and not the size of fan. Just states how many degrees above ambient temperature the output of the heater is, i.e. how hot is the air coming out of the heater compared to how hot it is outside. Fans are rated in CFM Cubic Feet per Minute or how much air they move. Sounds to me like for some reason your fan is not running at full speed.