Coleman manual why do i have low fuel flow, blue flame, not yellow.

Question edited for clarity.

Those boilers only work if they sense water flow. Try opening the tap fully and see if it will stay alight. Then after a 5 minutes, see if you can reduce the flow, which will increase the temperature of the water.

A blue flame is good.

Don't forget if it is only a couple of months old, it is under warranty, call the seller, Coleman or the installer.

Sorry I know nothing about the model - just wanted to say a yellow flame isn't right.
When a heater burns with a yellow flame it is inefficient, producing an excess of soot or carbon and producing an excess of carbon monoxide, a dangerous poisonous gas.

A blue flame is correct and efficient and ideally there should not even be yellow tips to the flame.

may be low fuel flow video below have some suggestions.
https://www.youtube.com/watch?v=L5UNAvPWXNE
https://www.youtube.com/watch?v=JU8dS8XNU7k
https://www.youtube.com/watch?v=VLbA_DFlqoQ
https://www.youtube.com/watch?v=s58YeeyD0zE
https://www.youtube.com/watch?v=kdnOhjev3BU
manual below troubleshooting starts page 13
https://www.mrheater.com/downloads/dl/file/id/275/mr_heater_20_30k_btu_propane_vent_free_manual_2016.pdf

lack of air causing yellow flame burners need cleaning . Burners are blocked or injectors are .

check all burner holes are clear . also check air mixture is right you can adjust this on the burner by the injector .

Should be a damper which can be moved cutting back and increasing the air intake

can you tell me more about your model?

Orange or yellow flame is usually an indication of too much fuel, or not enough air mixture. Make sure all areas where burners would receive air from, are cleaned of spider webs, debris etc., and be sure when set up, nothing is close to it that would block that air flow from entering.

The pressure drops and so you have to pump it up a little every now and then. What I do is pump it up a hair. Reset the flames to a pretty blue. Yellow flame is too much fuel to air ratio. An air shutter adjustment is needed. Also dust in the burner can cause the secondary air to have an improper mix

If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

does the same burner flame turn blue if other burners decreast in flow-with that burner on high and others low-is it still yellow? if so Gas Valve needs to be replaced.