I'm not familiar with propane (didn't Eric Clapton do a song about it?!?)

But let's deal with facts, shall we? What is the pressure?
What is the pressure supposed to be?

Gas pressure is usually measured in psi or inches of water, not amount of yellow flame.

Put a gauge on it and then ask your question.

Often the propane tank will have a regulator that reduces the pressure to 10PSI with a line to the house and an additional regulator just outside the house to deliver 1/2PSI inside the house. In some cases with longer lines, the regulator may deliver 2PSI to a regulator placed at the appliance for the final reduction to 1/2 PSI. I have no experience with gas dryers, but it sounds as if yours may have 2PSI supplied to it. And it could be an orfice intended for natural gas, which are larger. Get it resolved before further use.

Here is a link that might be useful: Converter

Call your LP supplier and tell them what concerns you. They will come out and check the regulator and pressure at no charge. By law they have to be certified in LP and are usually more skilled than appliance installers.

Don't run the dryer until this is resolved.

To determine if the pressure is correct it needs to be checked with a pressure gauge. The flame is a good indicator of whats going on to an experienced technician, but only a gauge will tell. You very well may have a dryer that has not been converted to lp gas as well. Call the gas company you buy your gas from.

The overall size of the flame is determined by line pressure and the size of the orifice but the color of the flame is determined by the efficiency of the combustion.

Excessive yellow generally indicates an incomplete combustion which results from an improper air/fuel ratio.

While the gas line pressure is determined by the regulator, the air pressure is a natural function of altitude above sea level.

Standard atmospheric pressure is 14.7psig @ sea level and it decreases by an average of 1psi for each 1000' of elevation above sea level.

In turn, all gas burners have a means of adjusting the fuel/air mixture at the point of setup to compensate for changes in altitude.

I suspect your initial installer either installed the wrong orifice or he/she did not properly adjust the fuel/air mixture.

Thank you all for the fast responses.

I do intend on having the problem resolved before we use the dryer - the question I had was who to call first.

I think I will start with the appliance company to make sure the air/fuel mixture was adjusted properly. This should be zero cost to me since we paid for a white glove service and should be covered under that. The dryer we ordered was LP but they shipped a NG unit. A service tech had to come out and put the converter in - but I suspect that there are adjustments that need to be made.

Once I know that the appliance has been set up correctly - and if the long yellow flames persist - then I will call the gas company. They will gladly come out - but I have to pay for the call if there is nothing wrong with he service.

My house is at 1250 feet above sea level. Perhaps the appliance was set for sea level performance and needs to be adjusted for my higher elevation.

Again - thanks very much for the very quick responses. I will post back once I have the problem resolved.