Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
AIR CONDITIONING & HEAT PUMP SYSTEMS
BACKDRAFTING HEATING EQUIPMENT
BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATOR, DAMPER, BOOSTER
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER FLAME & NOISE DEFECTS
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
GAS LP & NATURAL GAS SAFETY HAZARDS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL FILL PIPE LEAKS
OIL SPILL CLEANUP / PREVENTION
PLASTIC PLEXVENT ULTRAVENT RECALL
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
RESET SWITCH, HEATER PRIMARY CONTROL
RESET SWITCH, ELECTRIC MOTOR
RESET SWITCH, STACK RELAY
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: HEATING SYSTEMS
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
ZONE VALVES, HEATING
Leaky hot water heating system vent repairs - how to repair a leaky hot water air vent or bleeder valve: here we explain how to repair or replace both manual heating system air bleed valves and automatic float type air vents that are leaky. Float type automatic vents on hot water heating systems are normally left "open" to automatically purge air from the system.
But a float vent that leaks water will stop working, may leak onto and damage equipment, and is often left "closed" or shut off as a temporary measure. And a manual air vent that is leaky or that no longer vents due to corrosion and clogging is not going to do the job when your heating system is airbound and radiators or baseboards are cold.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
Air Bleed Valve Leak Repair: How to Inspect and fix or replace leaky float-type automatic or manual air bleeder valves (air vents):
Is there a little cap on top of the air bleeder? many air bleeders use an internal float and an air valve stem that is about the same as the valve stem of an automobile tire valve or bicycle tire valve. The cap over these valves looks just like the cap on the valve stem on a tire (it is).
But on an air bleeder the valve cap is normally left loose so that when the valve has accumulated enough air to move the internal float the valve can open to expel the air.
If the valve cover is screwed down tightly, or if the valve cover has become clogged with mineral debris left by leaking water, air cannot be released. Loosen the valve cap.
If air escapes when you loosen the valve cap on the air bleed valve, that's good.
If the valve cap on your air bleeder is badly corroded (photo above left) the valve probably needs to be replaced.
Automatic air bleeders, to work, require that their little screw cap (it looks like and is a tire valve stem cap) be left loose so that the float inside the automatic air purger/bleeder can release air when needed.
Usually automatic float type air bleeder valves are installed at the boiler where it's easy to see and replace leaky ones during boiler service.
I don't recommend using float type automatic air bleeders at heating baseboards inside the building where they may be hidden by baseboard covers and can leak into and damage the building for some time before anyone notices.
Additional automatic air bleeder valves may be installed at other points on the hot water piping, usually at a higher spot near the boiler and sometimes on upper floors in the building.
Look for and check the operation of these air bleeder valves too.
How to Protect the Building from Water Damage from a Leaky Air Purge Vent
If water starts to leak out of the air bleeder valve continuously (photo at left) (it's ok for a drop or so to be expelled if the leak stops quickly) then screw the cap down tight again and ask your heating service technician to replace the valve.
Taco® provides a neat little attachment, the Taco Hy-Vent waste connector (sketch at left, adapted from Taco's product literature), that connects to the company's Hy-Vent air purger. The Hy-Vent waste connector allows the Taco Hy-Vent's outlet to be connected to a suitable drain location so that should the valve begin to leak through its vent opening water will be directed to a drain without damaging the building.
Watch out: Taco warns that while connecting a 3/4" flexible hose to the air vent outlet can suit to protect building areas from water damage, do not solder a connection to the air vent valve. Soldering the air vent outlet will cause it to fail to operate properly.
[Click to enlarge any image]
In our OPINION it would be smart to also inspect for leaks at any and all piping connections, including the threaded air vent mounts, and it would be smart to direct a waste connector vent drain to a location where somebody will notice that the vent is leaking so that proper repairs can be made.
Watch out: reading the installation literature from a variety of air eliminator and air vent manufacturers we observe that instructions about how to leave the air vent valve cap vary. Generally the cap is left loose to permit automatic air purging from float type air vents and partly loose to permit automatic air venting from some models of coin vents. But some instructions such as for the Honeywell EA79 Air Vent want you to leave the vent cap shut, stating
How to Fix or Replace Corroded or Leaky Manual Air Bleeder Valves
Is the air bleeder valve corroded? If the air bleeder is thick with corrosion or mineral deposits (photo at left) it has probably been leaking water when it should not, and it probably needs replacement.
Inspect and use or replace manual air bleeder valves on the heat distribution piping:
Problem spot manual air bleed valves: If a building heating system has experienced previous problems with air blockage in the heating system a technician may have installed a manual bleed valve at a strategic location to get air out of a problem section of piping. Look for valves that resemble the one shown in our photo.
Problem finding all of the air bleeder valves: air bleed or air purge valves on hot water heating piping or baseboards can be hard to find. Usually, in addition to one or more automatic air purge valves found at or close to the heating boiler itself, you will find an automatic or manual air purger at the higher end of a section of heating baseboard that has become air-bound in the past.
Leaky air bleeder valves: I find leaky air bleeder manual air bleed valves as well as automatic or float type air vent valves on heating systems.
Sometimes the manual air vent is leaking just because the manual air bleed valve was left open or was abused by a heavy-handed operator who over-torqued its fittings and damaged screw threads or a seating gasket
Tips for Step by Step Replacement of a Damaged or Leaky Air Bleeder or Vent are
We have a 2 zone hot water heating system that operates off of one thermostat. When calling for heat the 1st zone going to the 1st level of the home works good. The 2nd zone on the 2nd level has 6 baseboards and 3 seem to work good but 3 do not radiate heat at all. each one has a air bleeder on them and when I went to bleed the one off I got a little air but then got nothing, no water either. I it normal to have no pressure on them when not calling for heat or do I have an obstruction in the line such as frozen or some sort of dibree. - K.C. 1/27/14
the heating system is at my moms and I went over there yesterday to take a look at it and couldn't find a pressure gauge or not much of a place to put one with out taking apart some thing.
When I got there I had noticed that the water supply valve was shut coming from the water well going to the make up point of the hot water system and wasn't sure if that was suppose to be left open so I opened it and it sounded like it was taking some. Let me know if that is suppose to be left open or not or will it hurt something if I do. When I did have it on and went to bleed the air I found quite a bit of air but when the air stopped I didn't get water and if I shut it and waited al little bit I could get some more air but no water.
Shouldn't there be enough pressure on the system to keep on forcing the air out until you get water so maybe the bladder is bad or I need to add some pressure to it somehow. I did find out that it is a loop system and there is a 1" pipe looping along side the out side of the house between the floor and ceiling of the upper and lower level and pipes Ting off of it to the baseboards.
That is why we are still getting good heat at 2 baseboards at the beginning of the run and 1 at the end of the run but 3 in the middle you will get the one end of the pipe might be warm to hot but at the other end might be luke warm to cold. could there be a blockage in those pipes caused by sediment from the water? Or maybe the pump that moves the hot water isn't working right. Let me know your thought. Thanks for your time and help. - K.C. 1/28/2014
I cannot give safe advice about operating the controls on a heating system I can't see - there are just too many unknowns.
If the water to the boiler was shut off it may be that the system has ONLY a manual water feed. If this is hot water heat, (not steam heat) and if the boiler is not leaky, it may rarely ever need water added; if you pushed water in you may have overpressurized the boiler, which in turn can make the relief valves leak when the system heats up (another unsafe condition).
If on the other hand the boiler starting pressure was low, you might have addressed the original boiler pressure worry. But unless you bleed air until water comes out of the air bleeder valve, you have left air in the system - which can leave it air bound.
I think I would try forcing water into the system until I got water out at the air bleeder.
Then if I found I had too much pressure in the system, after bleeding out all the air one can always open a drain at the boiler to reduce the water pressure. (of course when you TOUCH an old part that nobody has touched for years it may break, leak or jam).
Watch out: for an old, not-working heating system that does not even seem to have normal safety controls and is in unknown condition, I don't think it's safe to keep fooling with it - you need to figure it's time to call a heating professional. We may try to offer some tips by email or online, but we are limited by your eyes - what you see and report. Often a pro will be able to home in on the no-heat problem almost immediately (that's a benefit of having a lot of experience).
Thank you for your help. The resent info was some good advice. I did shut the water valve off today and it didn't seem to set off any reliefs but I did notice that there was a bleeder on top of the bladder assembly and the cap was on and when I took it off it seem to bleed alot of air out and then seem to bleed it out in spurts like it was an automatic air bleeder and when it did that I could hear water moving through the pipes better and went upstairs and was able to bleed air out of one of the baseboard until it came onto water which hadn't been able to do before and one of the shorter baseboards that she said hadn't been working in awhile was working now. sounds like slowly but surly things are starting to work. I know it is hard to give info when not here looking at it but thanks for the info you have given. At least it gave me some knowledge and will call some one in if can't get things working safely and normal.
Sounds like progress. What's hard to determine from our conversation is to confirm that the system is air-bound (which I suspect) and whether you have found the bleed valves necessary to get that air out without having to call a heating service tech to force the air out of the system (using a pony pump at the boiler).
If you can keep bleeding air until water comes out at a bleeder that's what you want to do.
If you hear water moving through the pipes that was not moving before, you're making progress and we know the circulator must be working.
If you feel piping and it's hot for a ways from the boiler then is cold, that's probably where the air is blocking the system.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website