Bleeding baseboard heater until water feels hot?

rog2e

I have a gas boiler and all my baseboards heaters work fine except for 2 rooms on my second floor. My house only has 1 zone for the whole house (it's a small house). I had an incident 3 days ago and someone turned off my boiler by hitting the wrong switch on the coldest day of the year. Once I turned it back on I had to thaw out a couple of the baseboards to get the heat flowing again. Now the only problem are the 2 baseboards on the second floor. When I bleed the valves I could hear air coming out but then the water comes out is cold. I tried bleeding out the cold water for a good 10 min. and stopped because I had to leave but maybe I just didn't do it long enough. My question is should I bleed the baseboard until the water feels hot? I always thought you just needed to do it until the air stops hissing.

hot_rod

If you have large air bubbles in the system that is stopping flow, really good power purge back at the boiler is the best way. The small bleeders can take some time, and mess to get an air locked system working.

Hopefully there are some isolation valves at the boiler that allows for purging, forcing flow in one direction and a full port purge cock.

In addition a good air purger properly placed will keep working at air removal after a purge.

STEVEusaPA

Are you also adding water to the system-either manually or with an auto water feeder, while you bleed?

JUGHNE

Obviously it takes a supply and a return pipe to these heaters.
Is it possible that only one of them would be have frozen and block the flow thru the baseboards?
The water you are getting could be coming from the pipe that is not plugged. Just a long shot.

rog2e

Thanks for the comments. Steve yes there is an auto filler. Jughne it's been 3 days and the house is warm so any frozen pipes would have de thawed by now so I really think it is just because I have air in my pipes.

rog2e

How do you tell if the boiler is low on water? will the pressure drop?

hot_rod

Make sure the gauge on the boiler or system is in fact working and accurate. You can buy temporary test gauges that would screw not a boiler drain or any other connection into the system.

Air removal is directly related to system pressure. A good rule of thumb is determine the highest point in the piping circuit above the boiler.

Say 15 feet elevation X .433, then add 5 psi.
About 11-12 psi at the boiler gauge is correct.

The expansion tank pre-charge needs to be adjusted to the determined fill pressure.

Lastly the circulator pump should be piped to pump away from the expansion tank connection point.

This assures the addition pump pressure shows up throughout the system.

Start by getting an accurate pressure reading and determining fill pressure.

Brewbeer

Yes, pressure will drop.

Can you post photos of the piping near the boiler?

mikemc

yes, JUGHNE is correct about possibly one of the two still being frozen. just because its warm in house doesn't mean piping thawed. these pipes are on outside walls. also, do check as someone else mentioned the pressure while bleeding. VERY important to have enough pressure to properly bleed air, especially when doing it for awhile and NOT raising boiler pressure while doing this.

ChrisJ

I can't add anything to the bleeding, but you may want to buy and install one of these.

My wife used to accidentally hit the boiler switch instead of the basement light switch. Not anymore.

https://www.amazon.com/Wall-Switch-Cover-Lockout-Red/dp/B01AOHCUPQ