Cold Room - additional vents or baseboard electric?

I think either one would do it's a matter of what appearance you like

It sounds like who ever put the heat vent in! In the first place! Seems to me they spliced into the nearest furnace heating duct tube and didn't bother to see if enough air flow was coming out of it to heat such a big area! The room that size should have been 2 vented!!! Just like a livingroom does!

One on each end of the longest parts of the room! and even an air circulation vent! A baseboard may help, but it will add to your electric bill too! I would either see if you could resplice into a the smallest room in your house heat duct vent tubing, Like maybe your laundry room heat duct tube!!! or a room that is hotter then the rest of the rooms!!! It may make a huge difference of hooking to a better heat flow furnace heat duct tube!!!!

I would guess who ever put the heat vent in, most likely may have spliced into maybe your living room heat tube, a much smaller room heat duct tube would be a better splicing for the vent in the 15 x 30 room! and in the winter I would keep any interior doors to the room open, closing them will make the room colder if the heat flow to the vent is to low!!!

But if you want to add extra heating source to the room that size, I would say you would be better off with the heater system that looks like the old days welded bent poles, oil filled heating sytem, they come on wheels so you can move it around to a differnet area of the room or a whole totally different room! they take up about the same as a little end table, There white and look like about 7 bent 3 inch wide pipes ! There I'm sure better then a baseboard heater! and probably a lot better on your electric bill!!!

First you need to determine if your heating and cooling system is adequate for the added square footage. It very well may not be.

It is also likely that the contractor that added the addition did not use an adequate duct size for the addition. Also in a room that big it would be nice to have a return air duct run.

If the HVAC system is large enough for the additional square footage and the problem is just undersized ducting you can install a duct booster to avoid tearing up walls. It is better though if you have properly sized duct work.

You may want to hire an HVAC contractor to run some load calculations to see what needs to be done.

What I would do is re run ducting to that area of the house and put in a vent unless it is an upstairs area then you are looking to be more costly. Then I would suggest to getting an Electric heater/ register to put in the room. Granted it will take some time to run the ducting ect to the area of the house if it is on the lower part of the house but then again it would be worth it you can then re run it all if you want to provide sufficiant air flow through the home

i would use forced air "central heat/air" also add a return air vent in the room "this is the vent that sucks the existing air out and heats/cools it you know the one that you need to change the vent on every month" this will ensure that the air gets circulated correctly