New Radiators for Master Suite - would like opinions on heat loss calculations

JimmyNJ

Hello everyone,

Put on an addition a couple of years ago. Original house has 1 pipe steam heat. At this time I knew very little about Steam heat other than that I liked it and that I wanted to have steam heat in addition. During bidding process, etc all heating contractors said "your boiler looks small, think you would need a larger one if you wanted to add radiators" - of course, no one bothered (or more likely, even knew how) to look at the EDR output of the boiler and calculate existing radiator EDR load. Long story short, I've learned a TON from this awesome website in the past couple of years and via Dan's book (homeowners guide to steam heat), and I am now looking to add radiators to our master bedroom suite (I have attached the construction drawings). According to my slant/fin calculator, I have calculated the following heat loss (indoor temp: 70):

Master Bedroom: 3921 BTU/HR (16.3 EDR)
Master Bath: 1169 BTU/HR (4.8 EDR)
Master walk-in Closet: 1077 BTU/HR (4.5 EDR)

Question 1: Do these calculations appear okay? It's new construction so walls are insulated and so is attic space above (between attic floor joists) , Andersen 400 series windows.

My current Utica PEG150C Boiler is rated for 375 EDR, my current connected radiator EDR load is 341.5. I have a spare 3 column, 5 section, 38" tall (25 EDR) radiator I had planned on putting in the Master Bedroom (which is more than the calculated 16.3 EDR's needed) which would bring the connected load up to 366.5 (giving me 8.5 EDR's to play with if the 33% pickup factor is not accounted for)

Question 2: If I put the 25 EDR output radiator by the wall just outside the walk-in closet - what is everyone's opinion on also putting in a radiator in the closet? Is it needed? If door is kept open to room, should that radiator be able to heat up that space or would be better off putting in a small (19", 4-tube, 4 section slenderized radiator rated at 6.4 EDR) in the closet as well as the master bath? Since I already have the radiator I am hoping to just use it. If I do use it, that would put the connected EDR load slightly over the boiler rating (over by 4.3 EDR) but with my Mains and radiator supply-take offs insulated in the basement, would I still be okay since I know there is a built-in 33% EDR pickup factor.

Opinions are welcomed! Thanks.
-Jimmy

vr608

I recently renovated my attic and had a lot of the same questions, so hopefully I can provide some input.

Regarding the heating load, hard to say with accuracy but based on my experience, the Slant/fin calculator gives a reasonable ballpark figure, assuming you provided the needed input values.

As to the placement of the radiator, I can't say that I've seen any radiators in closets, although in principle it would make it useful in your application since there is a window in the drawing, which will obviously impact your heat load.

If it were me, I would just leave the closet door open and just use the existing radiator to minimize the additional piping requirements. Along with the bathroom radiator, that would keep you under your boiler's rating.

Also, from my understanding it would be better to place the (large) radiator close to the windows. The experts on this forum may be able to speak more on that, but from what I've heard it makes them much more effective. In your case, the west wall in between the two windows would be where I would place it. If you're worried about circulation, you could always add a ceiling fan to move the air around.

ChicagoCooperator

Since there are windows in the closet you might think about a radiator there, though perhaps not necessary. I've seen forced air/central AC systems with registers in large walk in closets - this keeps the temperature balanced over the entire space, or so I've been told.

What about a radiator in the window seat enclosed in an appropriate built in?

vaporvac

I have a large walk-in closet to which I prefer to close the door. It gets COLD in there. Stick a small rad UNDER the window if you have one.
I like the window seat idea, especially if the lid can be raised. I'd put the rad as near to the window as possible other wise.

vr608

My master bedroom also has a walk-in closet with a window. The door usually remains closed, and it does get a bit chilly. The previous owner reduced the chill factor in there by adding some acrylic sheeting over the frame (window is always closed), and it hasn't been an issue for us (I live in northern NJ). Your situation may be vastly different, however.

What type of door are you using for the closet? If its louvered, that may solve your ventilation problem.

Looking back over your original post, however, you could use the large radiator (25 EDR) in lieu of the one specified in your slant/fin calculations; I think a 4 EDR difference over your boiler's rating is not going to cause issues, but perhaps someone else can comment. I think the pick-up factor should be able to account for the minor difference.

j a_2

Do this, if you think your additional radiators are going to exceed the boilers capability...Do a heat loss on the existing radiators and you will probley find them oversized..replace the ones that are grossly oversized because of new windows and such...my guess site unseen you will be fine

JimmyNJ

Thanks for the input guys. We are currently using the built in bench for storage and I am not sure if I could get a radiator small enough (height wise) to fit in one of the compartments (but it's an interesting idea). The walk-in closet door is solid wood, if I wanted to circulate warm air there I think I would just need to keep it open (it is 99% of the time anyways). Maybe the low cost option is to get a small floor fan to blow warm air from the bedroom in there. Thanks again for the input!

vaporvac

Rads were made specifically for under window seats. There's one at my Restore at the moment so they're available if you look around. Depending on the length you could still use some of it for storage.

vr608

JimmyNJ said:

Hello everyone,
Put on an addition a couple of years ago. Original house has 1 pipe steam heat. At this time I knew very little about Steam heat other than that I liked it and that I wanted to have steam heat in addition.

Question; when the addition was built did you run new pipe for the steam lines? Or is your consideration ripping up the floor to pipe new ones?

JimmyNJ

vr608 said:

JimmyNJ said:

Hello everyone,
Put on an addition a couple of years ago. Original house has 1 pipe steam heat. At this time I knew very little about Steam heat other than that I liked it and that I wanted to have steam heat in addition.

Question; when the addition was built did you run new pipe for the steam lines? Or is your consideration ripping up the floor to pipe new ones?

No pipes were run at the time of the addition. I wouldn't need to rip up any floors per say, just drill a whole in the floor for the steam pipe. There is a family room underneath the master suite and a full basement under that, so pipes would be coming up from basement and run either exposed (or tucked into wall) in the family room up to the spots in the Master where I am contemplating putting in the new rads.

vr608

Gotcha. I was just wondering whether that was a consideration (price-wise) for what you were trying to do. I had a wall and floor open for plumbing when I did my project so it was a no-brainer.

Sounds like you have it mostly figured out!

JimmyNJ

vr608 said:

Gotcha. I was just wondering whether that was a consideration (price-wise) for what you were trying to do. I had a wall and floor open for plumbing when I did my project so it was a no-brainer.

Sounds like you have it mostly figured out!

I only wish I knew then what I know now! Then there wouldn't even have been an issue.

vr608

My piece of advice; when they do run the piping, insist on threaded pipe over press-fit fittings (i.e. Viega Megapress). While the jury is still out on their longevity, I'd rest easier knowing it was threaded pipe.

If I had to do it over again I would have insisted on threaded.