Radiator is cold--anyone willing to walk me through it?

Dan_15

Its two pipe; valve is brand-new and seems to be working properly; yes, all the other rads work fine. I guess maybe I have a pressure differential problem as said above. Time to call back the plumber. Why cant everyone be like you guys at the wall and do it right the first time? I do NOT want to be ripping up new marble floors. Ugh!

Dan_15

Had bathrooms remodeled over the summer. Kept both wonderful cast iron Burnham radiant radiators in place. Both needed to be disconnected because the piping was not codeworthy. They were both wrongly piped on top of the subfloor and bedded into the mortar for the tile floor--although it did make the floor nice and warm . Both were repiped below the subfloor.

Something is amiss. Just ran a cold-weather test and one of the rads is stone cold--cant get it to heat. The other one took a long time to heat, seems like longer than it used to take, but it did eventually get quite hot. Both seem to be piped correctly--i.e., supply on the left, return on the right, bleed tapping on the top right. Both were repiped with ball valves to help throttle the flow when they get too hot (they are very oversized). The hot one has a ball valve on the supply. The cold one has a ball valve on the return. The cold one doesnt seem to be getting any flow. I can feel with my hand that the supply pipe is cooking hot but the return is cold to the touch. I can manually induce some flow by bleeding lots of water out of the tapping on the top right. Ive tried the ball valve in both positions already. Seems like something is blocking flow on the return side.

All other rads in the house are working fine. The system is converted gravity. Both rads are piped with 1/4" copper to the risers.

Could the cold one be airbound? Are ball valves flow directional? Could the ball valve have been installed backwards? Does it matter if the ball valve is on the return? What is preventing flow through this cold rad? They both worked fine before.

Any advice is greatly appreciated. Thanks, Dan

Unknown

how many more

How many more elbows did u put on the repiping, below the main and 1/4" size? Sounds like u lost the pressure differatal between the supply and return.. U have pressure,no flow...

Dan_15

Wish I could take a photo of it, but my wife has the camera. To be honest, the piping to the rad looks kind of tortuous. It looks like there are possibly a bit more turns directly under the rad than used to be, but I dont think really a ton more. I cant tell about piping from the risers because they are now covered up. But nothing was drastically moved; everything follows generally the same path as before. A master plumber did the repiping, not me. The warm rad is piped the same way, and it seems to get hot fine. Could the cold one have airbound issues?

Unknown

I reread ur

I re read ur 1st post, u said u have bled the radiators so.. Unless u have a hellva loop in return line, maybe be air bounded... Still gotta have pressure differtal between the supply and return to make any radaitors to work.... Again, 1/4 " pipings? Or 1/2"?

Dan_15

Sorry my mistake, I meant 1/2" copper. Is it possible to be air bound somewhere in the return or in the rad itself, even if I am bleeding tons of water? How do I remedy? Should I just keep bleeding water? Thanks.

GermanPlumber

Hi Dan,

ball valve direction does not matter. Do you have a one or two pipe system? If you bleed the system as you wrote I do not think we have a air problem at this point. Take off the handle on the ball valves and make sure your are turning the valve and not only the handle, depends how old the valve is. All the other radiators work fine?

Unknown

if ya bled

If ya bled, bled water... Then its not the air plm... As I said before, if u have more fittings, valves installed on the line, u may have lost the pressure differatal,, meanings, water not moving between the 2 points... Wait til u get that camera and post some pixs...

Rodney Summers

Just a thought....have you bled the radiator with only the return valve open until hot water comes out and the return pipe is hot/warm to the touch.

try that before ripping up the marble...

good luck Brendan

Unknown

why did ya

Why did ya call the plumber? Insteand of the hot water heating pros which he have to know the system and differental, etc... Most plumbers will think that pipes are just pipes...

Dan_15

I'll try bleeding till hot water comes out, but correct me if I am wrong, since the valve is on the return, I think the hot water will be coming from the supply--I have no way to isolate the return. How do I do that? Thanks.

Dan_15

Too true indeed. I had no choice; this project was managed by a GC with subcontracted plumber. HVAC issues were unexpected; only when the floor was demolished did we discover the need to repipe the heat to code. I guess this will test if the GC stands by the work.

Unknown

to code?

In ur 1st post, u said the pipes were in the floor and keeping it warm... Oh noooooo, those million feets of radaint tubings have to be taken out to codes... This GC gonna take the "beating" from the rest of the wallies

Rodney Summers

Dan... It is imposible to properly bleed both lines with only one valve! you could install a tap-a-line bleeder valve on the boiler side of that return valve.

you may already have valves downstream where the 1/2" tubing originates if so you need to alternatly close them as you bleed the radiator...You have to draw water from both pipes to make sure no air is lurking there.

hope this helps Brendan

Dan_15

Well, I bled a lot of water and I have gotten both rads to heat now, but it seems to take a really long time. Seems longer than usual. How long should the rad take to heat up under normal circumstances with 1/2" pipe? Does 25+ minutes sound like a long time from a cold start? Could an unacceptable pressure differential cause it to take longer to heat up? Thanks.

Weezbo

heres a easy way to see whats what.

go close off the other rads leaving the one in question wide open....the pipe should "brighten "up rather swiftly*~/:)

probably 4 mins tops:)

Ron Schroeder

Could an unacceptable

Could an unacceptable pressure differential cause it to take longer to heat up? Absolutely, but so could air in the lines until it clears itself, if there is not a proper way to bleed both sides. Think of it this way water is going to go the easiest route it can, the harder you make the run the slower it will be.

Bruce

Unknown

on a properly installed

On properly installed system, radiators heat up within a minute, whatever the temps and pump u have on the system. Where are u located?

Weezbo

maybe... depends on just what length that supply

pipe is from the boiler....the pump and pipe size of the main and the boilers ability to ramp to that magic ..OK! You Got Heat! level:)

Dan_15

Well it is heating now, but it does seem like it takes a lot longer than it used to. I'll try doing some more tests from a cold start and see if maybe I had air trapped, or if there is really some pressure/flow problem. I am in then metro west Boston area.
Dan