Heat Loss from a Patio Sliding Door?

wanttolearn

I am trying to figure out why my den has such large amounts of heat loss.  Here is some background.

The den has two exterior walls, and a slanted ceiling that is also exposed to the outside.

My den has a large patio sliding door leading to the outside.  It measure approx 8 feet wide by 7 feet tall.

My den is primarily heated by a hot water baseboard heater.  During the depth of winter, the baseboard heater is running most of the time (probably 70% to 80% of the time).  The thermostat is set at 72 degrees, and the heater struggles to get the room to that temperature.  Because the unit is running so much, I suspect that it contributes a LOT to my heating bill.  There does not seem to be anything wrong with the heater as it gets nice and hot when it is running.

But for some reason, the heat does not stay in the room for long, and the unit kicks on again shortly after turning off. 

My first suspicion was that the room is not adequately insulated, so I had a company blow insulation into the ceiling and exterior walls.  It helped somewhat, but I still feel that the baseboard unit is working much too frequently, and hence wasting too much heat.

My only other guess is that the heat is escaping through the sliding door.  I cannot feel any obvious breezes when I hold my hand around the edges of the door, so it is not a question of "plugging" any cracks around the door.  Also, the door does appear to be double-glass, not single.  But if the sliding door is old and not insulated to modern standards, could this be the source of my problem?  Is it worth spending a few thousand dollars to get a new door, or will the improvement be fairly minor?

Just for curiousity, I took a thermal reading of the glass door the other night.  The outside temperature was around 30 degrees, the interior wall was in the den was at 72 degrees, and the inside of the glass door measured at 55 degrees.  Does this give a clue as to whether the door is at fault for my heating problems here?

Any thoughts are greatly appreciated.  It is a large expense to replace this door, and I dont want to do it, unless I can be sure that I will get a significant benefit.

rlaggren

Sometimes it's easier/best to test things

Do a mock-up when possible.



In this case you have a 7x8 surface that's in question and you're thinking about making it's R-value better. What would it take to do a quick-dirty R-value fix? Two pieces of 2" 4x8 rigid insulation from HD, a big kitchen knife or a hacksaw blade, and some masking tape; maybe don't even need to cut the boards. It'd look like a mess for a few days while you considered the affect, but it would tell you sure as shooting whether that door is making the difference you fear. Use the blue or green masking tape so's less chance of lifting any paint.



The whole kit would run you about $80 or less and maybe 6 hours of your time. Weigh that against $1000's for doors and grief and it might be worth it. If the door is a big heat sink you then need to figure if a new door would be that much better. Might want to try things like heavy curtains at night.



FWIW.  Rufus

Alan (California Radiant) Forbes

Den

What are the dimensions of the room? How many feet of baseboard are there?



I've seen too many rooms that don't have enough baseboard to properly heat the room. 



And you want to heat the room to 72 degrees?  Sheesh, that's too warm.

Gordy

heatloss

First off is this a new development? Or is something that has gotten worse over time?  Have you always lived in this home, or are you new to it?  What is the dimensions of the den?  How many feet of Baseboard, and what type?  What water temps are you running through the baseboard?



The patio door is surely a source of heatloss just to the fact that its glass. Vaulted ceilings do not help much in keeping the heat down at the occupants level. Is there a ceiling fan to help push heat down, but then of course you are creating a cooling effect from air movement. Two exterior walls is another strike. Does the room face south,north, east, west? wall orientations to that?



I have found that a standard thermo pane window is not much better than a well sealed single pane double hung with a gasketed storm window. glass temps are about the same with in a couple of degrees.

Windows do not start being noticeably different until you add low e glass, and argon or krypton in between the panes, and triple glazing



If you want to improve your run time on the baseboard either add more of it if possible, or run higher water  temps 180* is usually what baseboard output is rated at.



Just some starter questions.



Gordy

Gordy

Sorry Alan

Must have been posting at same time.



Gordy

icesailor

Heat Loss:

You have two outside exposed walls and an exposed cathedral ceiling. With a 7' X 8' slider. That's a lot of loss. If it is running as you say, it isn't too far off in my opinion. But, I think that a room like this should be on a zone of its own.

But, lets talk about that ceiling. You have no idea how much loss is going out there. Get a infra-red heat thermometer gun and "shoot" the ceiling. If the ceiling isn't in the high 60's or low 70's, you are loosing a lot of heat. Do you have any recessed ceiling lights in the ceiling? You have a vacuum cleaner connected to your ceiling sucking heat out of the room. How thick is the rook panel structure? Is there an air space over the insulation where air is allowed to ventilate the roof? Forget it. I'll bet the designer didn't allow for what he/she was dealing with. I'm sure that "I" wouldn't have designed that radiation for that room the way that it was done. I've seen folks burned badly by these rooms. Not enough infiltration was allowed for this room. There are too many air changes per hour.

But you're not too far off by what you say.

Declan

Re:

I solved the problem with heat loss from my glass sliding patio door by having it covered in some heavy curtains– this is an efficient and affordable solution for stopping draughts in doors and windows. You will be surely satisfied with the result.

Gordan

Another marketeer heard from.

I hope this forum doesn't turn into a haven for spammers.