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Airbound heating baseboard or radiator repairs: Here we explain how to remove un-wanted, air from noisy or air-bound hot water heating system pipes, radiators, convectors, and baseboards using the automatic water feed valve on a heating boiler.
If a hot water heating system develops too much air in the piping you may hear bubbling or gurgling in the heating pipes when the heating system is operating, or worse, so much air may be in the heating piping, radiators, or baseboards that heat may simply not circulate at all.
The article series beginning at AIR BLEEDER VALVES explains how to locate, inspect, use, or replace automatic and manual air bleed valves on hot water heat to fix cold radiators or baseboards caused by air trapped in the heating system. If necessary there are additional methods used to remove air from air-bound hot water heating systems using two different service procedures to force air out of airbound pipes in a hot water heating system.
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If some heating radiators or some sections of heating baseboards of your building are not getting hot, or if your building circulator pump runs continuously but heat is not being delivered to the heating zone served by that circulator, the discussion beginning at AIR BLEEDER VALVES (just bleed air out of the system) and continuing here (how to forcer air out of the system) can help diagnose and cure that problem.
If you cannot bleed out un-wanted air and if using the water feed valve method described here do not work, you'll need to see AIR BOUND HEAT SYSTEM REPAIR by PUMP.
Readers should also see Diagnose Oil Heat Noises for diagnosis and repair of other heating system noises on both oil and gas fired heating equipment. This article series answers most questions about central heating system troubleshooting, inspection, diagnosis, and repairs. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
If you don't know what kind of heat your building uses, we explain how to figure out the answer at HEATING SYSTEM TYPES.
If your heating system is not working properly, see NO HEAT - BOILER or NO HEAT - FURNACE. This article series answers nearly all questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
Question: Why does my heating circulator keep on running?
Here’s the problem, I have a one pump three zone hot water baseboard heating system. The circulating pump keeps running even though there is not call for heat. This happens even in the summer, so I just shut the emergency switch off, but now, it’s getting cold and I want to turn the system on. One of the zones does not get heat, so I replaced the TACO zone valve head thinking that was the problem.
Well, the pump is still running, and no heat even when the thermostat is set to 90. The furnace does not fire up either. I plan on eliminating the thermostat to see if the furnace would turn on by touching the two wires together, but saw your email and decided to write to you first.
The other two zones do heat up when heat is called. This is an American Standard system that was installed new in 1960. The pump has been changed a few times over the years. Any suggestions? - anonymous, Union NJ
Your heating system baseboard, hot water piping, or one or more radiators may have become airbound if:
Your thermostat for the heating zone(s) involved is calling for heat, the boiler is hot, the circulator pump is running, but all or part of the heating zone served by that circulator pump is not getting hot. More than one problem could cause this symptom but below we list possible causes in order of probability:
In this article we explain how to locate, inspect, diagnose problems with, use, or replace automatic and manual air bleed valves on hot water heat, and we explain methods used to remove air from air-bound hot water heating systems by finding and repairing or using automatic or manual air bleeder valves, or by using two different service procedures to force air out of air bound pipes in a hot water heating system. This article is divided into these main sections:
Service Procedures: How to Fix an Air-Bound Hot Water Heating System
Here we describe the procedure that a heating service technician may use to remove un-wanted air in a hot water heating system in order to correct noisy gurgling pipes or to correct loss of heat due to an air-bound radiator, heating convector, or section of hot water heating baseboard.
If your hot water heating system has become air-bound (one or more sections of heating radiators or baseboards are staying cold even though the boiler is on and the circulator pump is running), and if your system does not have an air bleed valve to remove air blocking water flow, you probably need to call a heating service technician who will use one of the methods we describe here.
If your heating system does include both automatic and manual air-bleeder valves it is possible that you can correct a noisy or airbound heating system yourself. See AIR BLEEDER VALVES and then How to Open Manual Air Bleeder Valves.
We use this procedure to remove air blocking heating water flow through baseboards or radiators when there is no convenient air bleed valve already installed on the airbound section of heating baseboard or radiator.
Of course if your heating system already has air bleeder valves (see AIR BLEEDER VALVES) installed on high sections of baseboard or radiators (higher hydronic heat delivery baseboards or radiators are the more likelyi ones to become airbound as air naturally migrates upwards to highest piping in the heating system) you should try opening one or more of those first to see if you can bleed out the air.
The following procedure is the more simple of the two we describe for correcting an air-bound hot water (hydronic) heating system, and it avoids the need to use pumps or to install extra service drains that may have been omitted on the heating system.
While this is the easiest and simplest procedure to remove air from an airbound heating system, you might not want to use this method if
In these cases see Procedure #2 at AIR BOUND HEAT SYSTEM REPAIR by PUMP.
Here are the steps in airbound heat remedy #1
How Do we Know That the Air Bleed Valve Operation Has Been Successful?
Contact us if you have other suggestions for improving this procedure. We are pleased to give credit and links to contributing reviewers, authors, or critics.
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Frequently Asked Questions (FAQs)
(Jan 25, 2013) Circulator pump running and red- said:
From what I've read in your site, it would appear that my system may be airbound. I replaced the circulator pump 2 weeks ago and periodically I could get heat to circulate through the system, but the system would stop working shortly after I'd leave the property. I checked again the other day and found the boiler was heating up the water to temperature as called for by the thermostat, and the circulator (taco) pump was running, but neither the supply side nor the return side pipes were hot. The housing of the pump was red hot, but wasn't moving any heat!
I agree that it makes sense to check for an air-bound heating system. Start by feeling pipes leaving the boiler. Are they hot? Where does the hot piping stop?
Questions & answers or comments about fixing an air-bound hot water heating system
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