Q&A on selecting & installing air eliminators, air bleeder valves & automatic air purging valves.

This article series provides a detailed guide to installing & using air bleed valves to get rid of unwanted air in hot water heating systems: fix cold or noisy hot water heating radiators or baseboards.

FAQs on How & Where to Install Automatic or Manual Air Bleeder Valves on Hot Water Heating Systems

These questions & answers about how to install air eliminators, purgers or air bleeder valves used on hot water heating systems were posted originally

at AIR BLEED VALVE INSTALLATION - please check the advice given there.

Question: Where to Install extra air bleeder valves: Advice for installing remote or secondary air bleeder valves

When installing an automatic air bleeder on a system is it possible to install a tee at the high point then run a line to a different location and install the auto air bleeder in the secondary location, and will it work if that secondary location is lower than the tee in the main line? - Steve

Reply: the high point air bleeder valves are most important on hydronic heating systems but air bleeders in other locations work also

Steve you will sometimes see automatic air bleed valves at various heights and locations on heating system piping, and all of them will work to release air that finds its way to each of those locations. However it's most likely most important to include an air bleeder at the highest point in system piping where air may be found.

You can run a tee at a high point, as in your question, and then add a more remote air bleeder, provided that all of the piping slopes horizontally or better, uphill from the tee.

Small amounts of air in a hydronic heating systems are sometimes pushed around by the circulating water and may reach even lower air bleeders. But the circulator can't push large amounts of air - the system can become air bound unless means are provided for getting rid of it.

Also see AIR BLEEDER VALVE FUNCTIONS

For eliminating air from potable water, cold water or hot water supply systems see AIR ELIMINATORS for POTABLE WATER SUPPLIES

Question: Does the air eliminator at the boiler mean I don't need vents at the baseboards?

Does a Spirovent™ eliminate the need for baseboard vents? - plw65 11/18/11

Reply:

No. While an automatic air eliminator at the heating boiler will usually avoid an airbound heating system, leaks or work on the heating system or even bacterial growth can cause air accumulation along heat piping runs, particularly in longer horizontal runs without much pitch.

We usually need at least one air bleed valve at the high end of the heating piping, and we often need to add a bleed valve to remove air from tricky or long baseboard or piping runs. You can install a new system with no air bleeders involved, and the heating system may work perfectly for many years. But sooner or later the system will need air purging.

A properly located manual air bleeder makes this job quick and trivial. Without it there are still ways to fix the problem

See AIR BOUND HEAT SYSTEM REPAIR by PUMP

and AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE)

but with more trouble and at a greater cost.

On 2018-11-18 by (mod) - boiler runs but house doesn't get heat - why?

Leo

In the ARTICLE INDEX at the end of the article see the diagnostics at COLD RADIATOr

On 2018-11-17 by Leo

Have baseboard heat the furnace runs and just heats the hot water and shuts off but don't heat up the house not sure what is going on

On 2018-01-25 by (mod) - I bled some air - could the system still be air-bound?

Yes the system could still be air-bound.

Try the procedure at AIR BOUND HEAT SYSTEM REPAIR by PUMP

On 2018-01-23 by jim kaiser

Just removed a bell and gosset pump from heatinging system to replace coupler when i reinstalled it my zone will not heat higher than 63 degrees.

I flushed the line to bleed trapped air still wont go past 63. Ihave an auto vent on top of return line 7 feet above pump.

Could it be bad and still trapping air and not letting temp rise to over 63 but water is circulating because it will go from 58 to 63 but no higher.

On 2017-11-25 by (mod) - steam radiators converted to hot water, now air bound

Phineas,

I agree that it seems likely that your warehouse was originally heated by steam, later converted to forced hot water - something that's possible in a two-pipe steam system.

I speculate the same as you that if the air bleeder is at the bottom of the radiator, probably right on the radiator valve, that might actually have been a condensate drain or bleeder for servicing a steam radiator.

It is impossible to bleed AIR out of a hot water (hydronic) radiator from the bottom of a radiator. Air wants to be above the hot water in a radiator, and is pushed out by incoming water.

You might get help from::

1. if there is a tapping at the rad top you can add an air bleeder there

2. you can add automagic (or manual) air bleeders elsewhere in the piping system including if necessary at riser pipes off of the radiator outlet pipes that, combined with forcing water through the system can push air down and out of the radiators - not easy but doable.

See our article series on this at AIR-BOUND HEATING SYSTEMS

On 2017-11-08 by Phineas

I have an old warehouse-converted to house with a 4-zone hydronic heating system installed (converted?) in the 90's, long before we got the house.

The radiators upstairs are the classic, old, cast radiator style.

These radiators have their supply and return lines, in addition to their bleeder valves, all mounted at the bottom ends of the units.

Two radiators (each in a separate zone - one is its own solo zone) suffer from the classic air lock situation with them staying cold at the top and warm at the bottom halves of the units. The other units work fine.

Opening the bleeder valves on these two bum ones does not let air out - of course, because they are mounted at the bottom, right?

- Am I to assume (for curiosity's sake) that these all bleeder-valve-bottom mounted units were meant for steam heat? -

And so then, how do I purge air from these two if the bleeders are at bottom?

On 2017-09-04 13:54:32.382227 by Art

I have 3 copper bleeder elbows installed in the hot water baseboard heating system that weep from time to time. I want to eliminate them without unsoldering them. I understand there is a plug I can install if I remove the cap. Where can I find that pug?

On 2017-01-23 by Holly

So, I've tried to arrange for this heating contractor to come and pick up payment and to return my house key. He refuses to return my key (guessing I can press charges for theft among other things here), and wants payment in full, refusing to guarantee his work, even though his contract states he will.

In addition to the air in the lines, my plumber found a leak in one of the pex lines, so the heating contractor had not done an air test. I'm paying him as agreed, excepting the payment I had to make to my plumber to fix his work...is that not reasonable under the circumstances?

On 2017-01-14 1 by (mod) - heating job guaranteed until truck gets out of the driveway

Holly

Boy do we both hate this. It's one of those jobs characterized by "guaranteed until my truck reaches the end of your driveway".

Sometimes letting the sun of publicity shine on bad doings is the last recourse before hiring a lawyer, getting nasty, and making everyone including yourself still more miserable. You might want to post specific details about your contractor as a comment here, then send them the link.

Once when I had a problem with a plumber who left pipes leaking all over a home I called the company owner.

I said Hey Mike, my check to pay your bill is right here in my hand. I'm ready to send it to you - but I can't until the job is finished: your guy left leaks all over the customer's house.

Mike came over himself and repaired the leaks. And I think he had some things to say to his employee too.

It can't be good business for someone to work on a home, leave it with no heat, and fail to respond. Or else we're missing something here.

If it were my home I'd let the service manager know that in OUR OPINION it's not appropriate for a contractor to leave their work incomplete, improper, not functioning, perhaps even not safe. I would add that you have no choice but to hire a third party to fix the problem immediately and that you'll be sending the original contractor the bill.

I would not disparage nor make comments about the first contractor when hiring a second, hopefully more-responsible repair company since doing so may scare them from working for you.

InspectAPedia is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information provided free to the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

We are dedicated to making our information as accurate, complete, useful, and unbiased as possible: we very much welcome critique, questions, or content suggestions for our web articles. Working together and exchanging information makes us better informed than any individual can be working alone.

On 2017-01-14 by Holly

Mod: , that was my approach. They told me they had no idea when they could get back out to look at/correct the problem, which I found grossly unprofessional, considering we've been in sub-zero temps this past week. It's now over a week since I made that call, and they've not gotten back to me.

To be honest, I'm not sure I want someone telling me I need a new pump and disagrees my system needs the air bled out is someone I want to have back, since it appears he hopes to get me to install a new furnace, not do what I hired him to do.

With all this is mind, my plumber has offered to resolve it for me by no later than next Tuesday, and since I trust my plumber, who has always been upfront and straightforward about things, I think this is a better way to go.

Since I am having to have him come in to essentially clean up the heating contractor's mess, and since it seems the heating contractor had no intention to guarantee his work or rectify the situation, I'll be adjusting his payment accordingly.

I think a phone call to notify and a week for him to respond/fix is more than reasonable. I've lost a week on my overall project since I could not have plumbing or flooring installed due to a lack of stable heat. Out of patience.

On 2017-01-13 by (mod) - getting the service tech back to fix the job

Try a non-threatening, polite, telephone call to the service manager at your heating company. Explain your concerns to the heating manager and ask him to send an experienced technician to help correct the previous work that has left you without heat.

On 2017-01-13 by Anonymous

thank you for your response. Would it be out of line for me to ask him to correct his improper installation?

I have invested too much time and money at this stage to be comfortable with leaving one of the most important systems in my home subject to potential issues from this error. If you think I should request this, how do you think I should go about it, and

how can I get some assurance he will bleed the lines before making further assumptions that parts are needed? Or, do you think I should just fire him and get someone else to correct his errors?

On 2017-01-13 by (mod) - how did office assistant know you need a new circulator pump?

Holly,

I am really impressed that an office assistant, based on a phone conversation about a home I suspect he or she has never seen, could tell you that you need a new "pump" - presumably a circulator pump.

And I'm disappointed that the installer/technician didn't either adequately remove all of the air in the system or install automagic air bleeders wherever needed to assure that the air would leave voluntarily or that he or she didn't stand behind their work, return to the job, and fix the problem.

But then I've been disappointed in my own corner-cutting heating contractor who installed pex-plumbed baseboards in my office too.

A search of InspectApedia using the search box just above will return several articles that show how to force air out of the system by using the water feeder valve or by using a separate pump.

See https://inspectapedia.com/heat/Air_Bound_Heating_System.php - diagnosis

See https://inspectapedia.com/heat/Air_Removal_Valve.php - air removal using existing controls and valves

See https://inspectapedia.com/heat/Air_Removal_Pump.php air removal using a pony pump

See https://inspectapedia.com/heat/Air_Bleeder_Valves.php - where those bleeders were wanted

See https://inspectapedia.com/heat/Air_Separators_Scoops.php - the main air-scoop air purger that ought to be over your boiler

On 2017-01-13 by Holly

I am in the final phase of a whole house renovation. As part of the renovation, I wa ted to replace all my hot water baseboard slantfins with new ones, split my heating into two zones (upstairs/ downstairs), and new pex line was run for this purpose when the walls were open

. My heating contractor returned last week to connect/install the slantfins, connect up all the lines/manifold in the basement, and fill and restart the furnace. Since he did this, the heating does not rise to the set temperature (70 degrees), and the pipe is knocking (definitely air in the system).

I called the contractor and described the problem, and asked of the lines were bled out after the restart. His office assistant phoned me back, and told me he said I needed a new pump.

My radiators upstairs get hot, so I'm fairly certain I don't need a new pump...the problem is on the main floor, where radiators at the start of the run get hot, but the rest do not.

After having my plumber take a look, he told me there was no bleeder valve on my system, and I'm fairly certain, give the speed with which they were installed, that there are not bleeders on the slantfins.

There are also no shut off valves that could be used to isolate the two loops, which my plumber thought would have been a good idea, certainly convenient if you're only having an issue in one zone. My question is, how to I get the air out of the system when there's no bleeder valve?

Seems like my heating contractor cut some corners here, and I'm not sure how to proceed. He said the pump needs replacement sight unseen, so what if he replaces it and I still don't get hot water flowing to those slantfins? Guess he'll tell me I need a new furnace. Any help greatly appreciated.

On 2016-09-23 by Imran Mahmood

Very nice and easy to understand article.

Question: Installing air bleeder valves: Is it ok to install an air bleeder valve by just drilling and soldering into an existing copper pipe elbow on the heating line?

Hi Dan,
I've hired a HAVC guy to put replacement slant-fin baseboard heaters. because some of the stubs are coming from the wall, he claimed that he can't install a regular bleeder but have to drill a hole on the elbow and solder one in place. Is this the right way to do it? thanks. - Lily

Reply: not recommended

Lily

My OPINION is that drilling and soldering a bleeder valve into an existing copper elbow is an unreliable "fix" to add an air bleeder - the risk is that the soldered fitting is not strong enough and that you have a leak, worst when no one is home - and a flooded building and costly repairs.

Drilling a standard copper or bronze elbow to try to tap in a 1/8" diameter vent is likely to lead to leaks and maybe costly damage to building later on.

If it were my house I'd cut away the wall and solder the necessary fittings (called a baseboard tee and illustrated at the top of this page) in place, or I'd look a second time to see if there is not another location that will do.

Question: Installing air bleeder valves: which end of the heating baseboard gets the air bleed valve

Should the air vents be installed on the inlet or outlet of the baseboard heater? - Ron Thompson

Reply: at the outlet end or at both ends of the baseboard

Ron, if I were installing only one manual air bleed valve I'd certainly place it at the end of the heating baseboard so that I could force air out of that baseboard section.

On difficult or long baseboard runs I like to install bleed valves at both ends of the baseboard run. In that case I might install an automatic air bleed valve at the input end of the baseboard and a manual air bleed valve at the end of that baseboard run. In that manner, as long as the automatic air purge or air bleed valve keeps working air shouldn't enter the baseboard run.

But if air does get into the system, from a bad valve or from a sudden large surge of air, some of which gets past the front end air bleed valve, I can still purge the problem air from the system without having to follow other more complicated, lengthy, and expensive procedures.

Question: installing heating piping air bleeder valves: do I need air bleed valves at both ends of the piping run?

My home has several zones with base board hot water radiator. the problem zone is divided by a stair case between two rooms. The plumber installed no bleeds. he simply made a 90 degree rise 7 feet to the top of the landing then across 10 feet to 90 degree 7 foot drop to the other room.

This makes the 7 foot stair case landing the highest point for this zone. I now have an air lock. Do I put a bleeder valve on both the right and left side of the landing? (PS. .I am now very proficient at complex copper sweating.) Is there a rule dictating how short or long a run need to be before needing to add 2 bleeders. melvincoke@yahoo.com

Reply:

Melvin, I don't think you need two bleeders if you can get one at the end of that high point in the piping - by "end point" I mean that for that high horizontal run, put a bleeder at the end of the run (where the pipe heads back down) that is more distant from the boiler feed side.

That is, it's on the "return" end of that high leg.

Then with the bleeder in place, when the system is up to operating temperature and pressure, if you open the bleeder, the system pressure should push the air out.

Recapping: I like bleeders at both ends of high runs myself, but in truth you should be ok with just a bleeder at the far end from the feed side of the boiler.

Let us know how it goes - the results will help other readers.

Follow-up comment:

A [lumber friend came by said the same thing you said Dan. However, we both feel sometimes saving $6.00 costs hundreds or thousands. So we ended up just placing bleeders at both ends of the high point. I tested your theory by filling the system and only bleeding system using the valve installed at the return side bleed and the system worked.

So thanks very much for your help.

Reply: plumber shortcuts on heating piping diameter and air bleeder valves cost plenty later

I agree with you completely. The owners and contractor were disgusted when Paul A., somewhat of a bully plumber in Poughkeepsie, saved himself some labor time and "saved" the customer essentially nothing by installing smaller diameter hot water heat supply piping to and from a building addition.

Paul also saved himself labor time by refusing to install two air bleeders on the high loop in the system even though we bought the bleeders and left them on the floor at the locations where they were to be installed. When questioned he explained that "half-inch heating piping is just fine, and you don't want those bleeders anyway - they're a liability - they always leak".

The smaller heat supply piping he used failed to consider the design specifications for the heating system - an assumed hot heating water flow rate through the baseboard, combined with a high-output heating baseboard design had permitted the use of about half the normal linear footage of baseboard in the room.

Now if the heat is found to be inadequate the owners will have to either ruin their design by adding baseboard, or they'll have to rip out ceilings to install larger diameter heating water piping.

And about leaving off those air bleeders: sooner or later over the life of the building, when that high heating pipe loop becomes airbound, the occupants will have to hire a heating or plumbing tech to go through a more troublesome (and costly) procedure to fix the airbound heat problem. If Paul had taken the trouble to make a first-class installation, one could have just opened a screw and bled out the air in minutes.

Question: I want to shorten a 24-inch air bleeder valve

I have a bleeder valve that is 24 inches tall and would like to shorten it to 12 inches. Can a plumber specializing in hot water heating do this job or do you advise against? Thank you - Thierry Neubert 4/20/12

Reply:

Theirry I'm not sure it's safe for us to diagnose and prescribe for your heating system with so little specific detail. In general you're talking about a simple plumbing job, changing out a length of pipe for a shorter one. But check with your heating service technician to be sure that there is no specific need for a 24-inch tall riser pipe.

Question: what about adding air vents at baseboards - is that a good idea? What about using Sharkbites for fittings?

I noticed that you said automatic air bleeders are typically installed at or near the boiler/expansion tank and that you only mention manual set ups at the baseboard.

Do you advise against installing automatic air bleeders at the baseboard?

Second, my install is nearly all pex, have you found a source for 3/4" pex x 3/4" pex x 1/8" female npt tees? I've ben unlucky thus far. Finally, I'm planning on using sharkbite push/fit connections anywhere possible, they max out at 200 degrees, while my system will generally be about 170 degrees.

Do you advise against using sharkbites in this application? - Bobbito 1/23/13

Reply:

Bobbito,

I like to install manual air vents (automatic ones are nice but I've seen a few leak complaints) at the highest run of heating baseboard as well as at the start or more often the end of any runs of baseboard with a history of becoming air bound.

We have used sharkbite type fittings on heating systems as well as PEX tubing with no problems, operating at 180F.

Question: how do I add an air vent if there is no room for a vertical pipe at the boiler

how install auto air vent if no 18 inches horizontal pipe possible? - Air Vent Installation 3/31/2013

Reply:

Air


I've seen people try drilling, tapping, soldering, gluing an air vent right into a pipe - that's not a reliable plumbing connection and I DO NOT recommend it.

I DO advise installing air bleeders at some critical baseboard locations, especially if there has been a history of particular hot water baseboard sections becoming air bound.

If I didn't have a specific problem hydronic heat baseboard section I would still like to see an air bleeder vent installed at the start or end of the highest baseboard section in the building or on each heating loop.

There are automatic air bleeders that work unattended, but because some have reported leaks at those devices you might install a manually operated bleeder at the baseboard start or end elbow - the necessary fittings are a completely common part available at all plumbing and HVAC suppliers.

...

Continue reading at AIR BLEED VALVE INSTALLATION - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Radiator Air Bleeder & Vent Articles

• AIR BLEEDER VALVES - home
• AIR BLEED VALVE INSTALLATION
• AIR ELIMINATOR / FLOAT VENT REPLACEMENT
• AIR BLEED VALVE LEAK REPAIR
• AIR BLEED VALVE SOURCES
• AIR BLEEDER VALVE FUNCTIONS
• AIR ELIMINATORS for POTABLE WATER SUPPLIES to remove air from water supply systems, piping, fixtures.
• RADIATOR PLUG REMOVAL
• RADIATOR VALVES & HEAT CONTROLS

Suggested citation for this web page

AIR BLEED VALVE INSTALLATION FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING RADIATORS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Or see

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING BOILERS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

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.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---