Help if you can.

bgmz05

So I have these old radiators in my house. They aren't what you would think of when you think radiators. They are built into the wall with a metal casing. It looks like cast Iron and on the side it says, AERO CONVECTOR. My problem is that some radiators in my house heat wayyyyy more than others. I wanted to ask is anyone knew of how to adjust then to distribute the heat more evenly. Some have knobs on the covers some dont.thanks in advance. 

EBEBRATT-Ed

I think the missing knobs may have controlled a sheet metal damper so that you could control the amount of heat coming through the front of the convector.

You should post pictures of your boiler and air vents so w can see the whole system

bgmz05

So here are some pictures. Thanks for the tip on the knobs. I checked all my radiators and only 2 have knobs who seem to work(turn) as opposed to the others who turn but just spin with no resistance. 

JUGHNE

In your first picture of the convector there is a small copper tube from the top going down....where does that tube go to? Can you show us the end?

EBEBRATT-Ed

@bgmz05

It looks like the knobs can be moved in the slotted holes. Are there dampers attached to the inside of the covers

fnmnjim

Some of the cast iron convectors may need to be bled ( air trapped in the top of the cast iron), there should be little bleed ports at the top of each one.

Steamhead

JUGHNE said:

In your first picture of the convector there is a small copper tube from the top going down....where does that tube go to? Can you show us the end?

That's probably the air bleeding device. The bleed valve is at the bottom of the tube.

JUGHNE

That is my thought also, though it might go to the basement.
Usually they are bent over to access without removing a panel.

I added one in an attic so as to avoid that trip up there.

EdTheHeaterMan

Two things.
1. You must bleed all the air out of each radiator. If a radiator is heating only at the bottom, then there is air in the radiator. If that is a room with less heat, then air is your problem.
2. Assuming all air is out of the system, then you can regulate the room airflow across the hot radiator with the damper designed into the original design. If the dampers are missing, any SheetMetal man can make you an operating damper for each cover This altered photo of your radiator cover illustrates the concept.


I hope this is helpful
Yours Truly,
Mr.Ed

Justin0101

Found this thread. I happen to have the same Aero Convector radiators in my home. They've been reliable however tonight I ran into an issue. Heard a hissing and upon removing the vented cover saw water coming out of what appears to be the air bleed valve on the unit. Luckily it happened in the same room I was in so I was able to shut the heat off and turn the quarter turn valves from the boiler off to prevent any additional water from passing through this zone (house has 2 zones total).

Can anyone who has worked on these units before confirm if these generic replacements will fit the bill? Something tells me @EdTheHeaterMan will know. Also awesome idea on those vented covers - I have many similar style covers but they are without the adjustable damper slot in the center - not to say they couldn't be modified.

https://www.homedepot.com/p/Coin-Key-Hot-Water-Air-Valve-A957/202306131#overlay

Some pictures of my actual unit attached.




And some nostalgia, found this in my search for info on these units on eBay.

mattmia2

looks like a standard 1/8" coin key vent.

actually i'm not so sure now that i look more closely, kind of looks like a plug that mounts with a screw.

Justin0101

@mattmia2 Better shot from the side I just took.  I used my caliper to get an idea of thread size assuming the whole thing screws into the cast iron and it does measure very similar to the coin key vent I grabbed from HD.

Big Ed_4

They are convectors , the amount of air flowing though the cabinet picking up the heat from the element heats the room .The dampers controls the air flow . With out the dampers you can use tinfoil to cover part of the element to control .. If the cabinet is made of steel , a sheet of magnet material can be cut to block part of the opening for adjustments .

Intplm.

Justin0101 said:

@mattmia2 Better shot from the side I just took.  I used my caliper to get an idea of thread size assuming the whole thing screws into the cast iron and it does measure very similar to the coin key vent I grabbed from HD.

It's what @mattmia2 said. A coin vent.

Bleed the air from there.

Justin0101

Thank you @Intplm. and @mattmia2 - will swap this over to a new coin vent later today since the one here failed yesterday, I'll inspect it once I unscrew as I am curious where it failed.

Best practice just some thread sealant/dope on the threads?

Intplm.

Justin0101 said:

Thank you @Intplm. and @mattmia2 - will swap this over to a new coin vent later today since the one here failed yesterday, I'll inspect it once I unscrew as I am curious where it failed.

Best practice just some thread sealant/dope on the threads?

Yes to the best practice. Be careful not to plug the inlet with dope or tape.
I would also take precautions when removing these. They can brake off and leave threads in the rad.
Might want to have a pipe tap ready just incase.

Alan (California Radiant) Forbes

Those are 1/8" threads.

Good luck removing it. I've never had one break off, but there's always a first time. Even though it's corroded, it seems that there's still plenty of material to hold it together when forced to de-thread.

mattmia2

If you have a 6 point socket that size it will increase your chance of success.

Justin0101

@mattmia2 The 6 point suggestion did the trick, great idea to keep the removal of this old piece straight on.  The old failed one came out clean but I did still chase the threads gently to get out any old tape etc.

To pay it forward and help the next guy/gal:

16mm deep socket, 6pt for old unit removal

1/8 NPT tap

7/16 wrench for new replacement (Plumbers Choice brand from HD)

And some tape/dope

Hopefully my last question till it's back to business -

To bleed air out start with valve closed and then crack loose until air is gone and water is present and close (this is logical, have bled many varying systems)- I am curious if the other radiators (same style) in this zone will also need to be bled?  Maybe it's a your mileage will vary type of thing but curious your take to set some expectations.  I do have a Taco auto hy-vent mounted in the Taco air scoop, but that's in the basement and the rads are upstairs (single level house w/ basement) and not sure if this will assist with overall bleeding once water is flowing again.

Thank you everyone who replied, I am grateful.

EdTheHeaterMan

I just noticed this post. I have not seen anyone post that the original vent is an automatic hygroscopic air vent, that can also be used as a manual air vent by using a screwdriver. I can not find the original information on that brand/model but Caleffi has a similar vent here https://s3.amazonaws.com/s3.supplyhouse.com/manuals/1346229298166/78227_PROD_FILE.pdf on page 3... it is model 5080.


I was never a fan of this vent as they would eventually wear out and leak. Then corrosion would build up on the vent. Then they would get stuck. Then you would try to remove them with channel lock pliers. Then they would break off, Then you would need to drill out the core. Then you could get an easy-out in there to try to twist out the broken core. Then end up buggering up the threads on the radiator. Then you would need to drill and tap a 1/4" pipe thread in the radiator. Then you would need to put a 1/4" x 1/8" bushing in there. Then you could put a standard coin air vent or lose key air vent in its place. But I’m glad that never happened to me!

Justin0101

@EdTheHeaterMan I have to give you credit for identifying the unit even though it's in tough shape from all the years of use.  I bought enough of the standard replacements so I have them ready if I have any others fail on me, may proactively change them once heat is no longer needed (this summer) just in case I run into any 'fun" removals. 

Did a little research and I think bleeding from the burner is the best move (burner off of course), but open to suggestions vs just trying to eliminate the air from the new air valve I installed.  I've got 4 radiators in this zone and just like a brake system the air might move from my newly fixed radiator that had this fault to another radiator in the zone.  I've got your standard hose output  at the burner that I can run outside and try to push the air out this way using the city water as the assist.

Is there an ideal pressure range I should try to stay within between bleeding off air/water and allowing some city water back in to perform the bleed?

Thank you for the knowledge everyone who has replied!

bburd

Purging from the boiler works for series loop systems like baseboard. Those convectors must be bled from the top, which is why they each have a vent.

Good air separation at the boiler will help prevent air from accumulating in the convectors, but it cannot remove all the air from the high spots after the system is refilled.

Justin0101

Thanks @bburd

I have learned more about these radiators in the past couple days than in the past decade of ownership because of everyone here.  In this zone I've got only 4x Aero's, it's in smaller section of the house.  In the other zone I've got a mix, 4x Aero's plus cast iron baseboards in the living room.

On the unit I just repaired it is adjacent to another at the same level, and the other two are technically one step lower in the other room.  Is it possible to bleed this loop of convectors via the one I just repaired or must they all be done individually?

Also compared to bleeding at the burner (where the burner is off) using water pressure to push out any air pockets of the looped system, is the procedure different for convectors or is it the same where you're bleeding from the top of the convector rather than running a hose outside from the spigot?

I'm close, just want to do it once, do it right 🙂

EdTheHeaterMan

Each of the radiators must be vented individually. Think of it this way: the air in the top of each radiator can not find its way down from the top of a radiator to the pipe on the bottom of the radiator in order to get to a vent that is open in a different high point.



And purging with a high pressure flow of water is not possible, since the large cavities in the cast iron convectors have more than one path. Water is lazy and will take the path of least resistance across the bottom so the journey the water takes to the bottom pipe connections will not include the air from the top.

A series loop of 3/4" pipe with some aluminum fins attached has only one path, and that path is only 3/4" nominal diameter inside the pipe. There is no other path and flushing water under higher pressure will entrain the air in the high spots to travel down the small diameter pipe to cause high pressure flushing to remove the air.

Justin0101

Thank you @EdTheHeaterMan

I am picking up what you are putting down and I appreciate you for literally helping paint that picture.  It makes sense that the vent is at the top considering the inlet/outlet for the supply and return are at the very bottom and your comment about water being lazy made it click.  Also your comparison to a baseboard of just a single pipe's path with fins to radiate the heat makes sense.  Plain copper pipe, fins or not, simpler by comparison, no cavities or extra paths except the pipe itself.

Now here's my followup question.  Knowing I need to bleed the convector(s) in this zone to remove the expected air, my goal like with any system I've bled is to replace the air with liquid via positive pressure.  As part of the mad dash to the basement when I had experienced the failure I was quick to shut the burner off and the quarter turn valves on both my supply and return side in an attempt to isolate the problem so I could troubleshoot, they're still shut now.  My plan is below.

-Leave burner shut off as it currently is

-Open zone valve manually where I had the failure and replaced the coin/key valve (currently closed since burner power is off)

-Open return only? (Zone valves are on return side) or Open return AND supply?

-Crack open the coin/key valve and bleed air until water fills the void and spits out briefly, close

-Assuming both Return and Supply are open, turn burner back on and test

I can see the finish line for this repair but I need to confirm two items.  The city water Watts pressure regulator is set to be within spec as nothing has changed here, so when I crack open the coin/key on the convector(s) I expect pressure to drop temporarily and the regulator to allow more city water in to back fill the system thus replacing the air gap with water.

What I don't know as I have never seen a circulator pump torn apart is if water will pass through it regardless of direction - which is why I want to confirm if I should open both return and supply valves or just one side to perform the bleed?

I took a picture of my setup and marked up the items I talked about.  Thank you!

neilc

don't think of this as a purge,
think of this as filling the system, from the bottom up,
turn all electricity off to boiler and circulator, the service switch,
set all valves for normal operation, open,
use the reduced pressure fill valve to set the water system to 12 psi, leave it open and feeding, maintaining the 12,
go to each radiator and bleed the air at each one,
still have 12 psi at the boiler ? you should,
start the circ for a moment or 2 minutes to move any other air and water thru the system,
shut off service switch again and go check the radiators one more time,
turn it all back on and enjoy heat

how is your expansion/compression tank?

EdTheHeaterMan

You definitely need at least one valve open to the zone that you want to vent the air from. Both the supply and the return open are fine. Then, to make your job easier, I like to have 2 people do this step. One will be in the basement watching the water pressure on the gauge. The other will be at each radiator (one at a time) to vent the air. You see the higher the pressure at the top of the system, the faster the air will leave the radiator vent. I like to make that the customers job since any dirty boiler water that is spilled on the white carper is not your fault. Then lift the fast fill lever on the water feed valve. Watch the water pressure on the gauge and make sure it does not exceed 25 PSI. As the boiler pressure drops below 20 PSI, lift the fast fill lever. As the pressure gets near 25 PSI lower the fast fill lever.


If I am stuck doing this job myself, I increase the pressure setting on the auto feed to about 18 PSI and vent each radiator until the job is completed. After you finish the job, reduce the pressure setting on the auto feed back to 12 PSI and let the extra pressure out of the boiler at a boiler drain valve in the basement.

ALSO, you are correct to do this with the burner off. You want the cold fill pressure to be 12 PSI when completed, and you can't be sure of that cold pressure if the burner is operating and the water is hot.

Justin0101

@neilc

That makes sense.  The ~12psi to the open loop from the city water feed being my positive pressure to fill the convectors bottom up.  As Ed explained to me, water is lazy so the purge methodology with a hose  on the return's service spigot would not solve my issue of air introduced from my failed bleeder. If the pressure drops below the target, pressure regulator valve opens to allow more water in, idea being to get the air out of the top of the convector(s). 

@EdTheHeaterMan thank you for the run down.  You have a talent in explaining things extremely well and have helped me understand the system much more than prior to a few days ago. I am the type of person who likes to know how everything works, knowledge is power.

Thank you to everyone here that's helped me with this repair.  I ended up mapping out my homes system for my own knowledge and now have more confidence for when I work on the garage this summer - the garage is heated (has the plumbing and radiant heat) but the pipes were burst in a few spots when we bought the home.  There is a cutoff at the supply and return for this section and now I'm confident I know what to do when it's time to solder in a few repair sections and tie this back in to my homes heating system - so here's to future heat in my workshop for 2025!  (I'll play with this in a few months, already bought the supplies I needed but I need heat in the home for the time being haha)

I'm almost done getting things back up and running thanks to you all, you have all put positivity into the universe over the past few days.  Even though things breaking are never welcomed, the knowledge gained is.  I also got a kick out of the original Aero Convector advertisement I found "how long will they last?" "You'll have to ask your grandchildren" It was fairly accurate timeline wise 😅

hot_rod

The Caleffi 5080 is both a manual and auto vent with hydroscopic discs inside. It is recommended you change the top every 5 years or so, it depends on how often it is used.
The lower part stays in the radiator, it has a ball check so you can remove and replace the top portion with out loosing a drop of water.

Or just use it as a manual valve.
Realistically the air should be 100% gone at some point and you should not need constant air purging? If so look in the mechanical room for a better or purger upgrade and location. Pumping away, for example.

Unless you have a mis-applied compression tank

Justin0101

We have heat!  It was in the mid to high 50s with the heat being off during the repair and tstats set to 70.  I got the pressure dropped to 12psi and let it run until it got to operating temp.

Now since it had to warm a cold house the burner ran for a while as you'd assume, pressure and temp raised, higher than where it currently sits where it's maintaining the set temp.  It's sitting at 20psi and 180def F as we speak.

I checked every convector/baseboard in the house and all were nice and hot other than one baseboard, I'll try to bleed this one in case there is an air pocket that made its way to it along the way but other than that it's in good shape. I picked up enough replacement coin/key bleeders to change them all out this summer while I also work on getting the garage heat fixed as well in prep for next fall/winter.

I have one final question on expansion tanks to extend my knowledge.  I understand their purpose and internally what they look like with the bladder above the air space and Schrader valve.  I have probably the most common model/size I've seen in my research.  Since this gives room for the expansion of water as heat rises is there an easy calculation to figure out what kind of headroom this gives you?  Example, if you have an expansion tank that's set at 12psi from the bottom Schrader valve, does this give you 12psi of expansion when water makes it to the bladder?  Then when cool, it returns the 12psi back to the system so you can always stay within an ideal pressure range?  This one I am just curious about and this is the best place to ask. 

Thank you everyone