Missing bleed valve knob - cast iron rad

northernsoul

Hi there

We have orginal 1930s iron rads in our house (mostly Corto). There is one small rad (6 single fins mounted against wall) in a utility room that doesn’t seem to be heating. I am wondering if it has air in it - but it appears to be missing the knob to bleed it. Can I just use needle nose pliers to turn it ? Or should I try and locate a replacement knob?

Thanks !

Ironman

It's plugged up with paint. Replacing it may be the best option, but the system would have to be depressurized first.

northernsoul

> @Ironman said:
> It's plugged up with paint. Replacing it may be the best option, but the system would have to be depressurized first.

If I scrape off paint can I bleed it with pliers or is that risky without a knob?

I could just leave it alone since we don’t need that room heated I suppose

JUGHNE

Air in the top of a hot water radiator is one way to avoid overheating a room.
However you want to be sure some water is moving thru the radiator. If the bottom 1/3 or so stays hot it will avoid freezing and damaging the pipes and radiator.
Most of the original supply valves would not completely stop the flow of water for this reason.

If the radiator says too cold and you have to replace the air vent it may be a good idea to replace all the air vents in the system.
The air bleeders are not expensive.
The most time needed is the refilling and air bleeding.
If you have a single story house the water would only have to be drained down below the lowest air vent.

northernsoul

> @JUGHNE said:
> Air in the top of a hot water radiator is one way to avoid overheating a room.
> However you want to be sure some water is moving thru the radiator. If the bottom 1/3 or so stays hot it will avoid freezing and damaging the pipes and radiator.
> Most of the original supply valves would not completely stop the flow of water for this reason.
>
> If the radiator says too cold and you have to replace the air vent it may be a good idea to replace all the air vents in the system.
> The air bleeders are not expensive.
> The most time needed is the refilling and air bleeding.
> If you have a single story house the water would only have to be drained down below the lowest air vent.

This rad doesn’t actually have a supply valve to open or close - only a bleed valve. So unless there is air in the whole rad - it should be working.

It’s completely cold.

This rad is on main floor in 2 story house / in a small supply room that isn’t occupied

Big Ed_4

Originally there was a black wooden knob on the air vent .. It is a simple needle valve . It may just vent though the shaft passage or use a pin to clear out the paint .. Slide a finish nail though the hole for leverage opening or use pilers ...

Leave it alone if you need no heat , vent a little for partial heat or....

JUGHNE

How about a picture of the rad showing all of it and both ends.

northernsoul

> @JUGHNE said:
> How about a picture of the rad showing all of it and both ends.

Thanks

JUGHNE

It probably has water in it but will not move because of being air bound in the top.

How about a picture of working air valve with a good handle, same design?

northernsoul

Thanks -

JUGHNE

IIWM I would open the vent hole with a pin/needle and find a nail or pin to go thru the handle hole to turn open.
It may even come down to the pliers

northernsoul

> @JUGHNE said:
> IIWM I would open the vent hole with a pin/needle and find a nail or pin to go thru the handle hole to turn open.
> It may even come down to the pliers
Thanks . Was worried it snap off or not close again. It’s 80 years old or so

JUGHNE

A back up wrench on the flats where it screws into the rad will help against that.
Do you know where the water shut off to the boiler is and also how to drain down the system? Not to alarm you but these are just prudent things to be aware of.

Maybe not a Sunday project...

northernsoul

> @JUGHNE said:
> A back up wrench on the flats where it screws into the rad will help against that.
> Do you know where the water shut off to the boiler is and also how to drain down the system? Not to alarm you but these are just prudent things to be aware of.
>
> Maybe not a Sunday project...

I do - had to shut it off to drain the expansion thank and refill

northernsoul

> @JUGHNE said:
> A back up wrench on the flats where it screws into the rad will help against that.
> Do you know where the water shut off to the boiler is and also how to drain down the system? Not to alarm you but these are just prudent things to be aware of.
>
> Maybe not a Sunday project...

So I was able to bleed the small non working rad - air came out for about 30 second before very dirty water started coming out - then closed it.

I started up boiler but noticed that the cold pressure dropped about 3-4 PSI and the full heat PSI is down to about 18 from 22.

The prob is now some of the furthest rads upstairs aren’t heating much now.

The set psi is 15 but it seems the system has dropped a bit below that now.

Any ideas how to get it back heating all over?

neilc

when you closed the bleed valve on the dirty water,
was there still pressure there pushing the dirty out?
or had flow(pressure) stopped?

you may have to bleed those other rads now also,
that air bubble may be moving around.

if you bleed the furthest rad upstairs,
is there pressure there pushing the dirty out?
or is flow(pressure) stopped?

Is the auto feed at the boiler on and working?

northernsoul

I shut the valve as soon as dirty water started sputtering out - so maybe I should have let it run till it was a stream?

> @neilc said:
> when you closed the bleed valve on the dirty water,
> was there still pressure there pushing the dirty out?
> or had flow(pressure) stopped?
>
> you may have to bleed those other rads now also,
> that air bubble may be moving around.
>
> if you bleed the furthest rad upstairs,
> is there pressure there pushing the dirty out?
> or is flow(pressure) stopped?
>
> Is the auto feed at the boiler on and working?

I will try another rad upstairs.

The auto feed is working (was replaced in the summer) and the water is on.

neilc

yeah,
you could have waited for a more steady stream,
the sputtering is the air you're looking for.

you're doing this bleeding with the circulator(s) off,
correct?

with the circ off,
you should still have some pressure at the highest and furthest radiator,
bleed there and confirm.

northernsoul

The boiler was off for 2 hours at least and cool so the pump should’not be going right?

neilc

from here i would think the pump was off,
the service switch at the boiler, or ?, at the stairs down there?
would be more certain,
got pics?

northernsoul

I didn’t shut off the power to the boiler. I guess i should have. I figured as long as it was cooled - or would be okay to bleed.
What pics do you neee? Thanks

neilc

hold off on the pics for now,
with the boiler switch off,
go bleed the cold rads upstairs far and highest, or which ever went cold.
as long as you have air or water escaping then you have pressure enough to bleed.
then you could post a picture of the boiler, showing the circulator, and expansion or compression tank,
one or two good wide angle shots,
we can zoom in after if we need to.

northernsoul

Okay will do as soon as the system cools down again.
Thanks

JUGHNE

One method is to run the boiler and pump getting the water up to the max temp....quite hot.
Then shut off the power and let it sit for maybe 20-30 minutes.
The theory is that air will come out of higher temp water and rise to the top of the system.

Then with everything off start bleeding from each radiator.
Some say start at the top floor.....some say start at the bottom floor. I go for the top first.
But the water will be hot, so be careful.
You can hang a washcloth sized rag over the valve with the ends stuck into a container. The air bubbles will spurt and splash, the rag contains that.
I would let it run a steady stream.

You want your auto filler valve on, (assuming it is piped into the bottom of the boiler). You will not be adding that much water and the water temp will mix without shocking the boiler.

northernsoul

Okay bled the upstairs ones - one had quite a bit of air (and was the coldest one) and two-others had a little bit. The main floor ones had none only water.. So will see how that goes when i start it up later. Fingers crossed it heats equally.

For my house size - now that hopefully the air is al out - the pressure should be enough. I don’t think I need 20 Psi plus for 2 floors

neilc

you want your cold fill pressure around 12,
what kind of tank do you have?
expansion or compression?
post a pic, of that and the boiler area.
the 20 you see might be your hot pressure, which will be higher,
something I just learned this past year, thanks calliffee.
you do not want to see up around 30 though.

northernsoul

It’s an old metal expansion tank

Cold fill is 13. Hot is 19

northernsoul

Tank

neilc

pressure(s)
sound about right,
what's the boiler temp get up to?
makes you wanna go kick the thermostat up a degree or 2 and see what's what upstairs,
doesn't it?

northernsoul

> @neilc said:
> pressure(s)
> sound about right,
> what's the boiler temp get up to?
> makes you wanna go kick the thermostat up a degree or 2 and see what's what upstairs,
> doesn't it?

Return temp is round 140. It’s a mid efficiency boiler from around 2001

northernsoul

So all the rads are heating but the main floor ones def are hotter than some of the upstairs ones. As a result our one bedroom (which has a north wall) is 3-4 degrees cooler. Now the house is 80 years old ,so no wall insulation, and the attic has some old loose fill - so prob an R value of like 10 now. I’m assuming since the room has 2 outdoor walls it’s losing heat faster than downstairs.

Would it help to balance the downstairs valves by closing them a bit so they don’t heat as fast? Would that force more water upstairs to heat longer ?

JUGHNE

It sounds worth a try.
Does the valve have multiple turns or only 1/2 a turn.
The 1/2 turn type when closed might still have a small port to always allow some flow for freeze protection.

northernsoul

I’ll have to check they are old school 1930s cast
Iron rads- have never tried

JUGHNE

Gently try both directions at first.
loosing the packing nut might help.
Sometimes the pliers under the knob is needed.
Remember the 1/2 turn possibility.

northernsoul

> @JUGHNE said:
> Gently try both directions at first.
> loosing the packing nut might help.
> Sometimes the pliers under the knob is needed.
> Remember the 1/2 turn possibility.
Will try - think they are wood handles

JUGHNE

Any pliers jaw marks will hide under that knob.
Will look better than a broken knob.