Big Radiator is Starving!

Marcus Mead_3

Hi!

This radiator, 15 sections long and one of the tallest, widest, biggest radiators I have ever seen was recently installed in an old home we just purchased and are renovating. I named it Big Daddy. It lives in our 400 sq foot living room, with two much smaller radiators, which is also the room where our thermostat is.

The problem is, it almost NEVER heats up past the second or maybe third section. When the outside temp is 40 or so, the other two smaller radiators kick out enough heat to heat the room, and by the time that Big Daddy here gets started the work is done.

However, we just had our first REAL Michigan winter day. It was probably 10 degrees outside, and we came home after having the heat shut off for the day while we were at work to find our inside temperature around 50 degrees or so. Not a big deal, so we turned up the heat.

The boiler fired up, and ran for five hours straight. It’s never had to work so hard, and the inside temperature in the living room crawled upward at a snail’s pace. Eventually, 14 of Big Daddy’s 15 sections got very hot, and the living room reached 70 degrees. Every other room in the house was 80 +, as they had been heating for hours.

The vents on the three radiators in the living room were set for very fast heating, the rest of the house for much slower.

I think our problem lies in the fact that this monster is hooked in to a 1.25” ID pipe that branches off a 1.5” pipe in the basement.

To get it heating up faster, I am assuming we need a bigger pipe! I could move it to another spot in the room, and either:

1. Tie it in to a 1.5” pipe (branching off a 2” in the basement) that is presently reduced to 1.25” for the smaller radiator. But will a 1.5” pipe make enough of a difference?

2. I could also replace the 1.5” section that runs up through the floor with a 2” section, and feed it into Big Daddy. I am painfully aware that re-piping an old system, even a small part of it, involves risks, like breaking pipes. (I also wondered if this would allow all the steam to go into this Big Daddy, starving the two downstream from it…)

Which of these options would allow Big Daddy to heat up quickly so that the living room is comfortable, switching off the thermostat so the rest of the house is not baking and the boiler isn’t eating us out of house and home?

Thanks, sorry for all the extra details, but who knows what might be important!

Marcus

john_27

Marcus...check your venting on that large radiator..."Lost Art" has a really good section on double venting a large radiator.....I wonder...if you shut off the radiator...would your boiler run for 5 hours?...also, have you vented your mains(again see Lost art)...let us know...john

[Deleted User]

Assuming that the

pictured radiator has 3 columns & is 38" tall, it has 75' EDR. An 1 1/4" horizontal runout (not dripped) can carry 55' of steam. The vertical riser could carry 98', if it could get it. There is no valve to reduce input. Good thing. If you dripped (3/4")the 1 1/4" horizontal runout to the wet return, the supply of steam increases to 144'. The 1 1/2" main the radiator supply is connected to is probably not a problem.

So, if the runout is not dripped, you are limited to 73% of the radiator's capacity. That said, better venting might alleviate the problem. Since the rest of the home seems to heat OK, concentrate on the living room radiators, & their steam main. Vent the main well. Then double vent the large radiator. The new vent should be installed in a new drilled & tapped opening just below the existing vent.

If you really want to make your living room more comfortable, & you want to use the wrenches, take that radiator out. Replace it with 2 smaller ones. They vent quicker & don't tend to overshoot. Very important in the room w/ the stat. Also, don't fall into the "bigger is always better" trap on radiator vents. Large vents that respond quickly can close off before the radiator is full of steam. Then nothing enters until it opens again. Remember the rabbit who lost the race to the turtle. Turtle just kept moving along.

Good luck.