I have a gas furnace and radiator heat. I am getting no heat from radiators on the top floor, but the ones on the floor below are very hot. I was getting pipe knocking, so a couple weeks ago I bled the radiators. They seemed to work after that, but now, about about a week or so later, the top ones are cold. I tried bleeding again, and got a few seconds of air, but not water from the valves on the top floor radiators. Thoughts?

Thanks,
Don

 

Hello Don,

I would check several things:

1) Do you have a master thermostat for the whole house or zone thermostats (separate thermostats for the main floor and upper floors) ?

If you have zone heating, the problem could be with the zone valve or thermostat.

2) One simple thing I would try, is to close completely and open completely several times with the heating on, the valves at the cold radiators. If there is an obstruction, this might help dislodge it.

Good Luck

TheZman

 

First, I assume you mean boiler not furnace. Second is this steam radiators or baseboard? It sounds like you have two zones, two thermostats? if so you have either circulators for each zone or zone valves for each with a main circulator. The TACO and Honetwell have an override lever on the zone valve, if you don't feel the resistance when moving it over it most likely is open, reguardless, read the boiler pressure with the unit off and on. How high is it from the highest point to the lowest?

 

An important statement in your post is that you got some air BUT NO WATER out of the second floor radiators. You will need to raise the pressure in your system to about 15 psi and bleed the radiators again. Either your automatic water feed isn't working, or you don't have one. Can you find out how to add water to your particular boiler? I can give you some pointers but if you can locate the point where the main water system is tied into the heating system, you will be able to figure out how to add water to your heating system. The upper floor radiators must be filled with water before you can get circulation through them. There may be a lot of air in them and you may have to add water several times to get all the air out.

Your original knocking may have been an indication that pressure was low or you have a leak in your heating system.

 

question 1.) Are you bleeding the system with the pumps running?
2.)With the system off, what is the boiler pressure reading ?
3.) how many story building?

 

DWMDC,

As Kfield said, your alimeter gauge should read 12-15 lbs.
15lbs is good for up to a 3 story building. The rule is 1 lb pressure per every 28 inches the water must rise to the highest radiator plus a few lbs extra to facilitate bleeding.

If the pressure is low, locate your pressure regulator. It is found between the cold line and your boiler. If it is a Watts type regulator, you can adjust pressure by unscrewing the quick fill lever on top. Turning the nut below clockwise this will increase the water pressure, counterwise will decrease the pressure.

Good Luck

TheZman

 

Turns out the problem was pretty simple. Someone (the previous owner, most likely) turned off the water feed valve!

After reading your responses, I checked the system pressure, which was low. When I went to adjust it, I realized the the valve feeding into the regulator was off. It has a slight leak in it, so rather than fix it, someone decided to simply turn it off. It's probably been that way for three years or more...took losing heat for me to realize it.

Thanks again for your quick and helpful responses!

Happy and warm in D.C.,
Don