gas flame starts out full flame, then as room heats up dies to a trickle???

[big bear]

hello and thanks for any help on this conundrum. i have a ndv 3630I natural gas fireplace from hearth and home. when i initially turn the fireplace on, the flames are tall and perfect, then after about 15-20 of running, the flames drop down to barley visible and mostly blue. i had given up hope on solving this situation and resigned myself to having a low heat/no flame fireplace. i had my installer as well as another local fireplace tech come by and no one could trouble shoot this. then, last fall i left the back door to the house ajar for a few hours and wala, the flames shot right back up when the room was cold!! i have been able to repeat this situation and sure enough, when the room is cold the flames and perfect, the warmer the room, the smaller the flames. is it possible that there is a temp sensor that no one knows about? thanks again for any assistance you can provide

 

[DAKSY]

How are you controlling this unit? Remote? Wall thermostat? Wall switch? Tech switch?

 

[big bear]

How are you controlling this unit? Remote? Wall thermostat? Wall switch? Tech switch?

i am using the on off/remote switch that is part of the unit. i found that the included remote was not reliable. and since it does not heat up well, i typically just turn it on and let it run all night and day if it is cold. thanks!!

 

[big bear]

i am using the on off/remote switch that is part of the unit. i found that the included remote was not reliable. and since it does not heat up well, i typically just turn it on and let it run all night and day if it is cold. thanks!!

 

[Vsipusic]

My fireplace has thermostat on remote itself, so if your remote has it also this could be your problem, if you have remote near fireplace it picks up heat and turn down temp.