Odd radiator pipes setup

jjjessek

I've got a 70 year old house and 70 year old radiators.  The radiators downstairs work fine, but the upstairs radiators will not get hot, and they are also noisy - I can hear the pipes banging in the ceiling at night.  Which brings me to my main concern: the pipes for the upstairs radiators are in the ceiling, which means that the highest point (where the air would accumulate) is not in the radiator, which I can easily bleed, but in the crawl space which I have no access to. 

Is there any way to get the air out of these pipes?  Has anyone seen this setup before?  Hopefully I can figure something out, or else it's going to be a long winter.

Charlie from wmass

I would guess

If they were installed for 70 years someone put some sort of bleeder up there, if it is hot water. Get a flashlight and trace the pipes in the crawl space. Is this hot water or steam?

jjjessek

Hot water

1. It is a hot water system.  I've gotten a look at the pipes through a vent in the crawl space and I didn't see any bleeders, but I would like to take a closer look.  The problem is that I am going to have to cut a hole in the ceiling to get to it, but I guess that's going to have to happen one way or the other.

If there are bleeder valves, that would take care of the problem, but if not, then what?  Could I tap threads directly into the pipes to screw a valve into?  Or would I have to take some of thepipes apart?

Thanks for the advice.

Alan (California Radiant) Forbes

First

Before you start cutting holes, I would check the pressure on your system.  If I'm understanding your set-up correctly, your boiler is in the basement and the piping for the top floor radiators is in the ceiling of the upper floor.  That means water has to be lifted about 30'.  The water pressure gauge at your boiler should read at least 20 psi.



If your pressure is good, check for air bleeders on the roof or back in the boiler room.  Many installers were very crafty and they would pipe a ¼" copper line from the highest point in the system back down to the boiler room and then put a valve on the end for easy purging.

jjjessek

Almost there

OK, I found the bleeder in the wall in the second floor, and I've spent a few days bleeding the air out of it with  no end in sight.  Some of the second floor radiators have started working, though, so I will keep at it.

The water pressure is only 12 psi, but if the rads upstairs all work I probably won't worry about it.  I was wondering, though, about the need for greater pressure.  Since the water is flowing in a loop (with as much coming down as going up) should we really think of the pump as pushing water up three stories?  Or is it just circulating the water around? 

Thanks for the help.

Gordan

Rhetorical question for you:

How do you GET the water all the way up there, so that the air can be bled out, so that the pump can then circulate the water?

Jamie Hall

You have to distinguish

between the static pressure in your system, which is supposed to be maintained by your expansion tank, and the head generated by the pump, which just circulates the water around.  The static pressure has to be enough to get the water to the highest point in the system and keep it there, with the pump off.  12 psi is good for about 24 feet, more or less -- but no more than that.  On the other hand, there's no point in having too much pressure!