Tube-type Radiator Question

rjtolly

I have a small tube-type radiator (the rest are column) on a one pipe system. The vent is on the same side as the valve approx. 10" above it. I've noticed that this radiator tends to stay cooler on the bottom. Is this just the nature of a tube-type radiator or is this because the vent is on the wrong side. Would it be advisable to move the vent to the other side? How hard is it to drill and tap cast?

JohnNY

I don't have a thermal image of a radiator with a vent on the shut-off valve side, but I have several images of 1-pipe radiators with vents at the top tappings.
It's very consistent. The top of the rad gets hot and forms this weird triangle of not-hotness.
Look at the scale at the bottom of the image. The hottest part of that radiator is 213° while smack-dab in the middle is only 105°. That's barely warm to the touch. It's like a 22-section radiator giving off the heat of a 6 or 8 section radiator. Not cool.

I'd bet a good buck that your vent setup is causing more than half the radiator to remain cool.

Fred

Is there a hex head plug at the bottom of that radiator on the opposite side that would allow you to turn the radiator around and change the spud to that side? May be another option if you are concerned about drilling and tapping for a vent on the other side.

rjtolly

Thanks for the comments guys. That thermal image is very interesting. I haven't had the system running long enough yet this year to really get a good handle on how consistent it is across the whole radiator but I'm guessing your right.
There is a plug at the other end of the radiator so changing things around could be done but not sure which would be the lessor of two evils. Also I'm afraid to see what the other side of that radiator looks like!

rjtolly

Followup: I added a vent on the correct side of the radiator. Drilling and tapping was a piece of cake. The rad now heats much faster and is more uniform. It is also quiet now - no gurgling or sloshing. I left the original vent on the valve side. I have a nice warm bathroom now.

nicholas bonham-carter

Use a center punch to make a small dimple in the surface of the rad, before drilling. This will help the bit to not wander. Starting with an undersize bit helps as well. When you buy the tap, it will tell you what size bit should be used for the final hole.--NBC

Fred

Great. I'd take that vent off of the valve side and put a 1/4 inch plug in there. That vent closes so fast it really does nothing and it may fail open one day.

rjtolly

Thanks Fred, that's a good suggestion. As far as the drilling and tapping, fortunately the rad casting had a thick spot with a large dimple (I assume made for a vent) that made it easy to start the bit. I debated whether I should start with an undersized bit or not but decided to just go for it. I used a "Q" bit (.332") and it worked out perfect. I'm sure it helped to use a brand new drill and tap.