Air-bound heating baseboard or radiator repair FAQs:

Frequently-asked questions about 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 valveOn a heating boiler.

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.

FAQs on How to Diagnose & Fix an Air-Bound Hot Water Heating System

Discussed in these FAQs: How to diagnose and fix cold heating baseboards or radiators, and how to diagnose and fix heating circulator pumps that won't stop running.

These questions and answers about air bleeders and air removal valves used on hot water (hydronic) heating systems were posted originally at AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE - be sure to see the diagnosis and repair steps given in that article.

Also see AIR BLEEDER VALVES - found at various hot water heating system locations

Also see AIR BOUND HEAT SYSTEM REPAIR by PUMP - a repair process used if you can't bleed air out of an airbound hot water heating system.

On 2019-10-02 by Don

Thanks for your feedback.

On 2019-10-02 by (mod) - recurrent airbound heating system

Because the problem is recurrent, I'd

1. be sure that the air purger at the boiler is working - or replace it; also be sure it's properly located (high on the outlet side above the boiler)

2. install automatic or manual air vents higher in the building- at high end of high runs or rads or baseboards

3. take a close look at all accessible boiler connections and hot water heat piping for corrosion or other signs of leaks out - that might also be air-leaks-in when the system cools.

On 2019-10-02 by Don

There are just circulator pumps and no zone valves. There is some gurgling in the pipe/radiator system but goes away when individual radiators or baseboards are bled.

The 2 times that the circulator was air bound the problem was remedied by purging the system right at the circulator. This seemed to get water into the circulator and hot water would then pump through the system.

On 2019-10-02 by (mod) -

Don:

A couple of diagnostic questions:

- are there zone valves or just circulator pumps on your system? (a zone valve could be stuck closed)(

- do you ever hear gurling water or burbling bubbling sounds in hot water heating pipes, radiators, etc?

- how has the problem of no-heat been resolved before?

On 2019-10-02 by Don

I have a 2 year old boiler using Taco circulators for 2 heat zones and hot water storage tank.

Each of the last 2 years when the thermostat called for heat for the first time after not having run all summer (except for personal hot water), the first floor circulator would run but not pump water.

I bled each (cast iron baseboard and radiator) on the first floor, which immediately spouted water, not any air. I then went to the boiler, closing off the first floor return, connecting a drain hose and opening the drain petcock while opening the cold water quick fill valve.

Water flowed right away, seemingly without air. There is a Spirovent brass microbubble resorber on the supply line right out of the boiler and just before the first floor circulator.

There is no noticeable leak or corrosion of any of these lines. Any thoughts?

On 2018-12-29 by (mod) -

Indeed that sounds as if your heating system maybe are bound. Take a look at the suggested procedures in the article above.

On 2018-12-28 by darryl

1 baseboard is hot the other four is cold . Check the system and water to the baseboard is coming in hot . The boiler and thermostat work fine

On 2018-09-29 by (mod) -

I think the difficulty is the we're talking about are that is actually dissolved in the water. When you heat the water is when the air is likely to return to a gas form. So it may be more difficult and more expensive to try to do something about that with the incoming water.

On 2018-09-29 by Orville

Wouldn't it be best to prevent/remove air from the fresh water entering the heating system where it is connected to the home cold water system?

On 2018-06-08 by (mod) -

That's something to try first but keep in mind that the system needs to be at normal operating pressure and up to full temperature.

On 2018-06-08 by Jeff

Then is the best way to purge air maybe just out of the radiator bleed valves on the second upstairs loop as I fill it or should I open the boiler drain and/or the loop outlet spigot to purge air as it fills? Thank you.

On 2018-06-07 by (mod) -

Jeff,

I may have misunderstood your situation, bit if you keep the inlet valve closed to the boiler, NO water can enter the system and it will have too-low water pressure in the system, and it won't be able to purge air.

On 2018-06-06 by Jeff

I have a 1991 New Yorker coil hot water boiler to cast iron radiators. I had to empty and repair the second story radiator and empty that loop. I am going attempt to refill the loop. Should I keep the inlet valve closed to the boiler on the loop and bleed the air out of the spigot right before it goes back into the boiler and then open it to the boiler when air free? I understand all I have to do to refill the loop is turn the water back on to the boiler which is now off. The boiler is off too. Is there anything else I should know? I have my bucket and towels ready. Thank you!

On 2018-01-01 by (mod) -

Brenda

Let's start by finding the brand and model of furnace you have in your attic, then find the installation and operation manual for it. There we will find a specific guide to error lights and codes.

On 2018-01-01 16:23:24.550898 by Brenda

I have 2 zones for heating. I have two thermostats - one upstairs and one down. The upstairs is nice and warm. Downstairs is freezing and not actually heating when heat is being called for. I have Honeywell TH421D thermostats. The furnace is in the attic. It has some sort of sensor thing on it and it shows zone one with a blinking amber light and zone two is greensand the heat shows green as well. Is there something i can do myself to get zone 2 to work?

On 2015-12-13 by (mod) - bleeding my radiators (two zones) about every three or four days but air keeps returning.

Will

Search InspectAPedia.com for AQUASTAT SETTINGS for the best advice I can offer; let me know if questions remain.

On 2015-12-06 by Will

I've adjusted the HT to 200, should I do something with the LT ?

On 2015-12-05 by (mod) - difficulty getting all air out of an air-bound radiator

The boiler temperature - but don't set above 200F

Then call for heat and keep the boiler running long enough to reach max temp and pressure.

Use our page bottom CONTACT link to send me photos for comment or posting

On 2015-12-05 by Will

When you say pushing the temperature up a bit do you mean the boiler temperature or the thermostat temperature ?
I pushed the pressure to 20 psi and that hasn't helped.

I've isolated the 1st floor zone (turned off the basement and 2nd floor and closed the shut off valves) to see if the first floor on its own gets air introduced.

Is there a way I can post a picture of my set up ?
In the meantime I will try to describe it.

Cold water in :
Cold water from outside goes straight down into the furnace. There's a valve that is wide open right above the furnace. Just above that valve there is a T that leads to another valve that is closed.

Beyond that closed valve is the "no return" valve then after that is the pressure regulating valve and after that it tees into another large pipe that goes down into the furnace and up to the zone valves.

Between the t into that main pipe and the zone valves is a t off to the expansion tank (brand new).
Question....the valve that is closed (the one between the cold water and the pressure regulator (not the one right above the furnace that is wide open), should that be closed or open ?

Seems that it should be open if that is there to "auto fill" - is that the auto fill ? Should I have an auto fill ? I don't know. If I could post a picture it would be easier to describe.

On 2015-12-04 by (mod) -

Sometimes pushing the temperature and pressure up a bit can help purging air. Just watch you don't dump the TPR valve. Scalding hazards.

On 2015-12-04 by Will

Unfortunately my setup doesn't have service drains on the zone valve side, only on the returns where I have been purging air to date.

On 2015-12-04 by (mod) -

Yes Will,

scroll up just a bit to see the live link in capital letters at

Continue reading at AIR BOUND HEAT SYSTEM REPAIR by PUMP

On 2015-12-04 by Will

I closed the two automatic bleed valves and still got air in the system. Whats more, when I opened them up again and ran my heat one of them is now leaking constantly. It drips every few seconds.
I purged a lot of air, ran the water for a full 5 minutes. It will be ok for a day then will be full of air again.
I don't see any evidence of water loss other than a small damp patch under the pipe that leads to the non return valve. It just kind of hangs down close to the floor and must drip occasionally.

Is there a more effective way to purge the air ?

I shut off the valve just past the purge spigot, connect the hose and run it to bucket over a drain. Then I turn on the outside water supply and open the spigot. I run the water pressure reducer wide open until I reach 30 psi then shut it off again so as not to trip the pressure release valve. When the pressure drops I open it again until 30 then off again and so on. I keep doing this until I see no bubbles in my bucket that I have the other end of the hose in.

Should I have the purge spigot wide open, partially open maybe ?

If I have an inward air leak how can I possibly find it ?

Thanks

Will

On 2015-11-29 by (mod) - I've been bleeding my radiators (two zones) about every three or four days but air keeps returning.

Will, in AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE click on the capitalized link you see in the text reading

Or see AIR BLEEDER VALVES - 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.

to read about the type of air bleeder you are describing.

The problem you describe may not be in the air bleed valves but rather I suspect one of the following:

- you have not successfully purged a large volume of air from the heating system and it is making its way slowly in doses to the radiators where you are bleeding it

- there is a water loss out of or air leak into your heating system

It is normal to put the circulator pump on the return side of the boiler, as lower temperatures there may extend the life of the circulator pump and its motor.

The lift capacity of circulator pumps on residential buildings is very modest - the pump circulates rather than lifts, and relies on the boiler pressure to enable the necessary lift or elevation of hot water through higher heating pipes in the building, so suction or negative pressure is not normally a problem on residential hydronic systems.

However there might be an odd case of a system leak (such as a defective air bleed valve) that DOES let air back into the heating piping.

If that's happening, however, I suspect the root problem is the presence of the leak, not the placement of the circulator pump.

The boiler pressure ranges from just under 30 PSI when the boiler is at full operating temperature down to 12 psi when the boiler is cold. That pressure change itself (30-12=18 psi) is more than enough to draw air into the system piping during cool-down cycles.

Start by temporarily tightening the (normally left loose) valve caps on your air bleeders and making sure that no other bleeders are leaking. Keep us posted.

On 2015-11-29 by Will:

WIll said:

I've been bleeding my radiators (two zones) about every three or four days but air keeps returning. With the New England winter fast approaching I want to get this under control before I get an airlock when I am away and my pipes freeze.

My boiler is in my basement, the zones are 1st and 2nd floors. There are two bleed valves above the furnace, just below the ceiling in the boiler room, one for each zone. Both valves have the caps undone on top, loose.

The system has a circulator pump right before the boiler on the return pipe....I read somewhere that this could cause negative pressure in the system and air could be sucked in through the bleed valves or the pressure relief valve. They look like this -...

Should I just replace them or is there something else more likely the problem ?

On 2015-11-29 01:17:05.223818 by (mod) -

Will I'll check out the link you posted before replying

 

On 2015-11-10 by (mod) - the whole heating system blew up in my basement

Teri

I must be missing something here. I don't understand how a neighbor's activity - turning water on or off - would affect your property - a separate building - by making your faucets leak.

Only if you actually shared water supply piping and plumbing might one persons actions affect fixtures in another area. In that case search InspectApedia.com for WATER HAMMER as that is a possible explanation.

On 2015-11-10 by Teri

I rent a place that had these types of heaters.

Last year the whole system blew up in my basement send water all over (had to much pressure) it's been fixed but since then it purged the whole house anytime the neighbor turns on their water all my faucets leak and I have only 1 heater in my whole house that won't work the rest work great.

Any idea as to what maybe wrong?

Comment: this site saved me time and money and aggravation

(Feb 18, 2015) Anonymous said:

This site saved me a lot of money time and heartache as a new/first time home owner! I always look things over here before calling a technician. Having this knowledge at hand with pictures and some basic tools and mechanical skills saves time and money.

This site [explains how to do] things you wont be able to accomplish [without these procedures and this advice]!

Question: help fixing cold radiators

(Feb 19, 2012) John said:
I tried to follow your procedures listed at AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE but I am thrown off by the fact that even without a auto fill valve the cold water feed does not refill the system thru the fitting at the amtrol tank? I have a weil-mclain #68 boiler used for heat and hot water.

The gurgling noise in the baseboards has slowly gotten noisier until its now a bang/clang on cooling off. No vents on the baseboards and there is no auto fill valve.

Three drain valves on boiler 1 on the the ( 2 zone) return line above recirc pump, one at the base of the boiler & one off the cold water feed below the mixing valve. the amtrol tank is mounted high and the vent over it occasionally vents but the noises have not improved.

I shut the boiler down and after the temp dropped I ran a hose from the cold water fill below the mixing valve to the drain at the base of the boiler.

I had both zone valves open and cracked the valves while watching the gauge.

I then tried opening the valve on the return line but did not notice any air bleed.

The pressure stayed around 15+ psi. I am going to recheck for the noises and just want to make sure that the lines are properly filled ( I assume more efficient and minimal to no noise) and to find out why the gauge is usually on 0-5 inspite of being professionally installed (1993) and serviced continually by the same shop.

Please let me know if I should run more water out of the return line while feeding the boiler drain until I hear air coming out. Thanks John

(Nov 4, 2012) sarah said:
all my radiators are cold just one gets hot in the bathroom i need help to fix it

Reply:

John, and also Sarah,

Manual air bleeding at a radiator or other valve or vent only works if the bleed opening is at a high point in the system and is where or uphill and just past where the air blockage is located.

Take a look at the air bleeder valves article and the air bound heat rpair method 2
Both links are in this aricle.

Often it helps to locate the air blockage by turning up the thermostat, and when the boiler is hot, feel piping to see where heat stops.

Question: how much draining of the boiler is needed before opening the water feed bypass

(Nov 4, 2012) Alex said:
I am not sure - do you drain the system entirely prior to opening the water feeder bypass?

Reply:

No - none.

Alex, we are not draining water out of the heating system when purging air, we are pushing water in and air out.

Question: Can't figure out how to drain system to stop the boiler air noise

(Nov 19, 2012) Todd said:
I have an older system (Boiler gas fired 77) Can't figure out how to drain system to stop the noise. I checked expansion tank and no water came out. The system seems backwards. Water from hot water heater to vertical piping and 3 zone valves off that each with a drain valve and then looks like into cirq pump than boiler.

This seems backwards to me. on the output side of boiler has 3 branches off and expansion tank with auto relief valve. I can send photos if needed. Any advise would be great! I'm just trying to make it through the winter then I will replace the system, but I would like to get some sleep in the mean time.

Reply:

Todd,

I would like to see some photos of the system and piping arrangement.

But too, our article may have confused you. In general, we don't try to stop air bubbling noise in a hot water heating system by draining water out. Quite the opposite. We want the system piping to have no air in it at all - filled with water.

Draining an expansion tank to get air into that component is correct for non- bladder type tanks, but is a separate topic.

Question:

(Nov 28, 2012) OsK said:
Hi, I have a hydronic boiler with lots of zones one of which is for the indirectly heated hot water system. When the flame goes off and all zones are off, the boiler which operates at about 55C or 110F starts heating up and sometimes vents at the overpressure valve.

What could be causing this "latent" heat? I suspect either air in the top of the boiler or gunk in the bottom but I have tried to get rid of both, if there was any. If I could add a "run-on" or "cool-off" time to the water pumps (of which there is 3) then the problem would be solved. OsK

Reply:

OsK,
Thanks for the helpful comment on radiator & piping temperatures. I agree.

It is also helpful to feel comparable temperatures. For example, I (carefully as surfaces can be quite hot) touch and compare pipe temperatures on the inlet and outlet sides of a zone valve or a (quiet) Taco circulator to see if the valve has opened or the circulator is running.

Indeed for some applications we need to read temperatures more accurately, or we may even need to use thermography or other large area scanning tools (like finding where there is a break in readiant heat tubing in a floor), but just to see if something is open or working, the simple temperature comparison should be enough.

Finally, at least with some themographic equipment such as my Exergen scanner, the temperatures given on the digital readout are NOT accurate unless you are reading at the proper distance and from a flat black surface. Exergen even included a black crayon we use to make a mark on a shiny surface when we're looking for more accurate numbers.

We appreciate your helping-out OsK - together we are smarter than any individual.

Editor

Question:

(Nov 29, 2012) Craig said:
Exactly how "hot to the touch" should radiators get? Do you define hot to the touch as can't touch them for more then 5, 10 seconds? My radiators get luke warm (not "hot" to the touch)after the boiler has been running.

Reply:

Craig, your definition of hot to the touch seems about right. Luke warm is ok if it is the last radiator in a long series chained together. If the input side of the radiator is warmer than the output then the radiator is doing its job radiating heat.

If the output of the boiler is too hot to touch and the return is cool, then the heat is being transferred to the radiators and hopefully making the rooms warm. If the return on the boiler is also hot while the radiator remains luke warm then there is a problem. I go around and check the radiators with my hand but I also use this temperature tool

- Mastercraft Digital Temperature Reader available from Canadian Temperature

Reply from moderator:

OsK

About that odd hot boiler, I thought I answered this question on another page. I agree that it's an unacceptable condition, and regular spilling of a TP valve can be dangerous for some reasons beyond the obvious.

Is it possible that the boiler in question uses a tankless coil that is leaking into the boiler, increasing its pressure or even causing it to cycle on?

If not, check
- using our pipe feeling discussion, is there actually hot water from somewhere draining back into the boiler? (A bad check valve or zone valve?

- the primary control temperature sensor - is it properly placed, using the manufacturer recommended thermal grease, and working?

- the primary control itself

- or of course the problem might be something we haven't though of or can't see via just e-chatting

(Nov 29, 2012) Craig said:

Hey Dan, Thanks for the response. The output is "Warmer" then the input, so I can say with confidence that it is circulating. However, the output right at the boiler, but I can hold it indefinately (its not too hot). I also came across a post regarding the expansion tank (old big steel kind above boiler), if it has water in it to empty it (about 40+ gallons removed) and it would recharge about 11 gals.

I then ran the boiler for 2 hours now and the output is still not very hot to touch. So recap- 1.burners are working fine, 2. the circulating pump seems to be working, 3. the expansion tank has "air cushion," and the thermastat at the burner control is on max.

Here it is really bizarre, I can touch the cast iron heat exchanger on the sides no problem, you would think that all the cast iron on the exchanger would be red hot when being cooked for 2 hours???? In the end the room temp maintains 68, I just have a gut feeling it isn't working they way it is suppose to be. BTW thanks for taking the time with managing this site, very helpful!

The output pipe is hotter then the input, I can say for certain the circulating pump is working, but even right at the boiler the output pipe isn't that hot, I can grab it right at the boiler for any amount of time. Crazy is the burners are working and the thermostat is on close to max

. Further, the cast iron heat exchangers aren't that hot on the sides. You would think the anywhere on the exchanger would be red-hot after cooking for hours. Today I emptied the 40+ gals. of water from the expansion tank, when I turned on the water again, the tank filled w/ about 11 gals. (watched water meter).

So pump works, burners work, expansion tank has "air cushion" but the output pipe and radiators are not that "hot" to touch. Thoughts? Thanks for maintaining this site, very helpful!

Reply:

Craig a waterlogged expansion tank causes relief valve spillage, not indequate radiator heating.

A radiator that is just warm is probably not getting enou heat delivered

Partially air bound or piping uninsulated or temps set too low, or rad valve partly shut
Etc.

Figure water leaving the boiler is 180 and maybe 140 at a radiator - bllpark,
It would feel quite hot, not ... Warm

Question:

(Dec 9, 2012) debbie said:
I have replaced the zone valve, the thermostat and the pressure release valve and 2x purged the pipes getting full stream water coming thru. This 1 room is still not getting any heat and it is on its on zone?

What have I not thought of doing?

Question: Modine convection heater operating problem diagnosis

(Dec 11, 2012) Tom c said:
Purged the boiler short loop that got hot to the modine convection heater BUT a few min later the supply a the heater would get cool and the aqua stat at the unit shuts d

Purged the boiler short loop that got hot to the modine convection heater BUT a few min later the supply at the heater would get cool and the aqua stat at the unit shuts down waiting for the loop to circulate warm water to the loop as the thermostat calls for heat

There are 2 other loops that circulate with no problem and are longer loops in floors above?
What could be stopping the loop after bleeding it.

Reply:

Perhaps a

Bad check valve, bad TT wire or TT, (TT = thermostat)

Bad circulator relay, air in the system

Question: leaks due to puncture in heating line, trouble getting heat, noise complaints

(Dec 29, 2012) marlo said:
i am purging the baseboards they get hot for 10 minutes then go cold again...whats going on?

(Jan 2, 2013) A. Khan said:
The hot water only runs through finned-tube baseboards located in the dining room and living room, however, it does not run through the baseboards located in the guest room, bedroom and the washroom. I have to zone valves (one for the basement and the other one for the upper level).

The pressure gauge on the boiler reads 25psi (seems reasonable). It is an oil fired boiler. I did some purging (by opening the knob and trying to drain some water from the pipes). It did work for a little while, however, it stopped working later.

Please comment. I am trying to figure out the system as I go. I am new to this type of system, but keen to learn.
Is it an issue of air in the line or something else?

(Jan 5, 2013) Keith C Lenox Mass. said:
I purge my baseboard heating system but now I do not get any running hot water from any of my taps , The cold water is fine (( when i say no hot water I mean no water at all when i turn on the hot water handles ))Not sure what to do next

(Jan 25, 2014) hearty said:
Last week I had a leak through the light fixture on the first floor which turned out to be caused by a puncture on the heating line running to the second floor (right underneath the baseboard) that piece was replaced.

first we couldn't get heat on the second floor. After bleeding it for a long while, finally heat came out. Now I hear strong bangs on the pipe (there was always this noise but it was mild before). I was told that baseboard needs to be bled when that happens since that is caused by air.

However, the noise continues and I have bled it for quite sometime. I went to the basement and have open and close the breathers as well but I didn't hear any air coming from there (although early today it did expel a lot of air) I bled all baseboards and for a bit the noise diminished; however, the bangs increase from time to time. Can you please help how to fix this problem?

Reply:

Hearty:

It is possible for individual radiators or baseboard sections to remain partially air-bound once air has leaked into the piping system. If your air bleeders are located somewhere lower in the piping system it can be difficult to get that air out. In a severe case no hot water circulates. But it's possible to get *reduced* but not totally-blocked hot water flow from air in the system too.

The options are to use a pony pump to force water around and try to force air out of such locations or to identify the problem sections and install additional air bleeders at high points that will solve the problem.

Question:

(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!

Reply:

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?

Reader Comments:

Re-posting without link:

Sophia Castella said:

A few day's before i have join a service of cooling heater, gain many thinks about that but its post is really fantastic.

(Oct 1, 2014) Jacob Lineberry said:
Thank you for such a useful website - it's saved me so much money and prevented more cold nights ;)

Question: one roof is much hotter than any others

(Oct 6, 2014) Billy said:
I have gas boiler with water based board heating.

One room is significantly hoter than any other room in the entire house. All base boards have been bled and the boiler was serviced last year. Do I need to get into the crawl space to shut off one of the base boards water supply? Is that even the answer? Thank you.

Reply:

Billy

Take a look at the heating system distribution piping. Sometimes one baseboard loop is much shorter than others, or closer to the boiler, and can be hotter than wanted IF it is on the same thermostat as other heating pipe loops

If that's the case you can have your plumber install a flow balancing valve to slow or restrict the excessive hot water flow to the too-hot loop.

If the too-hot area is on its own thermostat then that's were to go to adjust the temp.

Question: water leaking from "furnace" then oil leaks at steam boiler

(Oct 8, 2014) samuel G said:
Hi, i started my furnace and some water started leaking, it stopped and then was oil, so i replace that pump and got a news circulator with a maintenance free design. i purge all the radiators, and the old expansion tank but i still heard some banging in the pipes. all the radiators are hot.

am not sure what else to do. am thinking about replacing the old expansion tank. i don't know if that will solve the problem. any help will be very well appreciated.

Reply:

Samuel there are two articles to review that should help

inspectapedia.com/plumbing/Water_Hammer_Noise.php

and

inspectapedia.com/heat/Banging_Pipes_Radiators.php

Question: isolate and purge just problem piping loop in air bound system

(Oct 22, 2014) Alan said:
I have three zones: two on te first floor and one on the second. The second floor zone is made up of two loops. One comes up and around the "front" rooms and one for the "back" rooms. The loops leave the boiler as one pipe and then "Y" before traveling vertically to the second floor

. They rejoin as one before returning to the boiler. The front loop heats well but the back loop is not heating at all. I think it is air bound. Do I need to drain all three zones to purge the air or can I isolate it and just purge the second floor zone?

Using air bound heat remedy one if the boiler is off how can the valves stay open so the water can forcefully run out. As soon as I shut the boiler off the valves feeding the pipes close. What am I missing in this scenario?

Reply:

If the zone valves have a manual lever, latch it in the OPEN position. Else you have to power the zone valves and thermostats.

Question: loud air release at boiler and steam in the boiler room

4 Jan 2015 ken said:
so holiday company shows , we run our oil burning boiler more for heat/hot water....then after a few days , the upstairs radiator still carry heat but then we get significant loud air valve release in boiler room filling it with steam , and the floor by the boiler relief is wet ....

we turn off system, restart. later and still within 1/2 hr get a another air valve release and a room full of steam . ? what next

Reply:

Ken what valve is releasing steam: if it's a pressure/temperature relief valve then the system is unsafe and should be shut down for repair.

Question:

8 January 2015 Fred said:
I have a split with one zone for the upstairs and one for the basement. No problems in the basement.

The upstairs feed off the boiler splits off in two direction, one fro the front of the house and one for the back. The back baseboards are hot, but the front are cold. The return to the boiler is again split, and one of the pipes is cold. What could be the problem. The furnance is oil forced hot water.

Reply:

Fred

I'd look for air bound piping in the cold zone or a zone valve that is not opening properly.

Question:

(Feb 18, 2015) AL said:

I have tried closing the gate valve to the boiler and feeding water while trying to remove air to the system ...Lots of air ,,,have tried feed ing water into system while bleeding ,cannot get above 72 degrees unless i run t stat at80 allday ,,later its back to72 again
Any suggestion

Reply:

Often air in long horizontal piping runs is difficult to remove by the method you tried. Check out

AIR BOUND HEAT SYSTEM REPAIR by PUMP

Question:

(Feb 19, 2015) Bill said:
I have a steam/hot water heating system. Originally the system was all steam, than added upstairs extension to house that is running gravity feed water from the boiler. So I'm running steam in one section and water in the other section from the same boiler.

When hot water starts to run through the extension, it hammers through most of the pipes, but I do get heat. Question; is it air or cold water sitting in the pipes and how do I fix it?

Reply:

I'm not sure, Bill, but typically banging pipes in a steam system is traces to a condensate return blockage or a clogged steam trap.

See BANGING HEATING PIPES RADIATORS for more detailed help.

Question:

(Mar 3, 2015) Donny said:

I changed out the pressure relief valve today, after all the work was done let the boiler fill back up, everything fired up got to temp and pressure but, found the return side (I believe) with circulator pump on it was ice cold, but supply side (expansion tank side)was super hot.

Tried to bleed out air but nothing seems to work. Still in same mess..Any suggestions ?

Reply:

You may find that just manual bleeding of air doesn't remove the air from long horizontal runs.

Try the procedure at AIR BOUND HEAT SYSTEM REPAIR by PUMP

...

Continue reading at AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Articles on Fixing Air-Bound Heatiing Systems

• AIR BLEEDER VALVES
• AIR-BOUND HEATING SYSTEMS - home
  • AIR BOUND RADIANT HEAT
  • AIR BOUND HEAT SYSTEM REPAIR by PUMP
  • AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE
• AIR SCOOPS PURGERS SEPARATORS

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