Drained system to replace valve - can't refill

Blvd

• 3 story (2 main floors plus attic with two rads), 1920's house
  
• 14 total hydronic radiators
  
• Single zone
  
• Gas-fired Crown boiler (see pic below)
  
• Manual (?) cold water refill (see pic below)
  
• Has expansion tank on return line (see pic below)
  

I had a leaking rad valve on the first floor. I drained the system and replaced the valve. Now, I'm trying to refill the system and I cannot seem to get the heat past the first floor. By the time I get the last of the (5) first-floor radiators bleed and shooting water instead of air, the pressure in the system is so low that the next radiator I open starts sucking air (see gauge pic below).

Here's the order of operations I'm following:

1. Turn the system off, let it cool down
   
2. Turn on the manual cold water refill to bring the PSI up to ~12 (the gauge half-works on the boiler, but the expansion tanks starts spitting water at some point)
   
3. Open the bleeder on the first-floor radiator furthest away from the boiler and work towards the radiator closest to the boiler
   
4. [Lost pressure]
   

Is this where I should have more patience and just go back to step 2 and open the manual cold water to refill and start over? At this rate, it will take me like 5 hours to get all three floors bled — there's 10 more on floor two and three!

Full boiler setup:


Expansion tank on return line:


Gauge after bleeding first-floor radiators:


Cold water refill setup:

Jamie Hall

Your comment "the expansion tank starts spitting water"...

Say what? The expansion tank should never spit water. If it does, it's shot and needs to be replaced.

OK. That's out of the way. You are using basically the correct procedure -- assuming that the only fill valve you have is manual (it's much easier with a pressure reducing and regulating valve connected and open). However, you will need to get the pressure high enough -- and stay that way -- to bleed. Which means, without an automatic valve, you bleed a radiator, go downstairs, bring the pressure up, bleed a radiator, go downstairs, bring the pressure up... rinse and repeat. If your pressure tank is properly charged and is working, you may be able to get two or three radiators at a time.

GW

Ideally, you need two people if you don’t wanna be there all day and all night. One person hitting the feed valve, keeping it between 20 and 25. That’ll make things go faster. When you get down to the last Radiator, have the person stop feeding, let the regulator do its job

Blvd

Jamie Hall said:

Your comment "the expansion tank starts spitting water"... Say what? The expansion tank should never spit water. If it does, it's shot and needs to be replaced.

Yeah, when I was pressurizing the system (via the cold water refill), the expansion tank started shooting water out of the valve on the top. No good?

Jamie Hall said:

You are using basically the correct procedure -- assuming that the only fill valve you have is manual (it's much easier with a pressure reducing and regulating valve connected and open).

yeah, the setup seems totally manual — i.e. Like you said, I think I have to open up the cold water fill valve and bring the pressure up, then shut off the valve, go upstairs, bleed, so on and so on.

Blvd

GW said:

Ideally, you need two people if you don’t wanna be there all day and all night. One person hitting the feed valve, keeping it between 20 and 25. That’ll make things go faster. When you get down to the last Radiator, have the person stop feeding, let the regulator do its job

When you say "let the regulator do its job", you mean the blow off regulator on the back of the boiler? i.e. I can just keep adding water until the boiler decides to blow off the extra PSI?

I'm worried that A. The gauge is (mostly) broken and I'll over pressurize and B. The blow off on the boiler is frozen and won't release when it should.

Jamie Hall

"Yeah, when I was pressurizing the system (via the cold water refill), the expansion tank started shooting water out of the valve on the top. No good?"

Um... yeah, no good. Unless you mean the air separator fitting on top of the assembly from which the tank is hung. It still shouldn't spit water -- but that would be a problem with the air separator rather than the tank. How much pressure did you get up to?

Dave T_2

@GW is correct. And if the spitting expansion tank is from the vent on the top you should change it (the vent) before you get the system full of water.

Your bottom picture shows a pressure regulator feed valve. If it is working it will automatically feed water to about 16 - 20 psi. If thats the case; change the vent (we usually add a 1/8" isolation valve to the vent to allow easy vent change in the future) and turn on the water and let the pressure regulator feed water to the system as you bleed it.

Blvd

I just went down and checked - technically, the thing that was spurting water is the valve that the expansion tank is attached to — circled in pic below:

Blvd

Dave T_2 said:

@GW is correct. And if the spitting expansion tank is from the vent on the top you should change it (the vent) before you get the system full of water.

Apologies, I'm a real dumby here... when you say (the vent) - you mean the expansion tank itself, or the thing that it's mounted to?

Dave T_2 said:

Your bottom picture shows a pressure regulator feed valve. If it is working it will automatically feed water to about 16 - 20 psi. If thats the case; change the vent (we usually add a 1/8" isolation valve to the vent to allow easy vent change in the future) and turn on the water and let the pressure regulator feed water to the system as you bleed it.

woah, that changes things. I could just leave the cold water feed open while I go around and bleed the radiators?

Blvd

Jamie Hall said:

"Yeah, when I was pressurizing the system (via the cold water refill), the expansion tank started shooting water out of the valve on the top. No good?"

Um... yeah, no good. Unless you mean the air separator fitting on top of the assembly from which the tank is hung. It still shouldn't spit water -- but that would be a problem with the air separator rather than the tank. How much pressure did you get up to?

Based on your comment, I meant the air separator fitting on top of the assembly — that was shooting a big arc of water.

I don't know exactly what the pressure was because the pressure gauge on the boiler is finicky. I can tap on it to increase and decrease the pressure reading. I'm guessing it was getting up to around 20PSI?

Jamie Hall

@Dave T_2 means the vent on top of the fitting the tank is mounted to: https://www.supplyhouse.com/Watts-0590716-1-4-FV-4M1-Auto-Air-Vent?utm_source=bingad&utm_medium=shopping&msclkid=4b5b8d974f911e9bd0cfd251bd366055
And indeed, if the pressure regulator is working you can just leave the cold water feed open while you go around and bleed.

You may find, even so, that it will take more than one trip around to get the air out... until you do, if the regulator is working, just leave it open.

EBEBRATT-Ed

@Blvd

The first thing you need is a gauge you can trust. If you don't have one your working blind. You can get one at a big box or hardware store. You can get an adapter and screw the gauge onto the boiler drain with a garden hose adapter for now.

Raise the pressure to 25 or so. Bleed the top floor with the circulator off. After you bleed the top go down and check the pressure and get it back to 25. Work your way down and when your done lower the pressure. Keep the pressure at 15

Blvd

Ok. Reporting back. I used the collective advice and made it a 2 person job. I had someone watch the gauge pressure and kept the water open and went through each floor and finally got water at every valve.

That vent Dave and Jamie mentioned is definitely oozing water at 20PSI so it's likely needing to be replaced.

So now — what's the easiest way to drop the pressure back to around 12PSI? It's currently still sitting at ~20.

Dave T_2

Try tightening the little cap on the vent to stop the leak. 18 - 20 psi would be a better choice than 12psi. look around the base of the boiler for a drain and let enough water out to lower pressure.

@Blvd is right on when he said put a good gauge on or your going at it blind. Get a good gauge and new vent and get this job done right.

Blvd

Dave T_2 said:

Try tightening the little cap on the vent to stop the leak.

The little black plastic cap? Seems super fragile and frozen up.

Dave T_2 said:

18 - 20 psi would be a better choice than 12psi. look around the base of the boiler for a drain and let enough water out to lower pressure.

Just the regular drain valve will lower the pressure?

Dave T_2 said:

@Blvd is right on when he said put a good gauge on or your going at it blind. Get a good gauge and new vent and get this job done right

Good gauge is probably a little debatable, but I do have a cheapo I attached to the drain valve. It's reading about half of what the boiler gauge is reading. (Any recommendations on an actual good gauge? Seems all the ones I see at the big box stores and the big online stores are poorly rated.)

Jamie Hall

Ah... um... the little cap on the Watts air vent has to be open so that it can vent air... which is what it's supposed to do... the vent has a float inside it, and it it's leaking water it needs to be replaced.

psb75

Get a pressure gauge that goes from 0-30 at a plumbing supply house.

hot_rod

Three stories plus an attic? Boiler in basement? You need about .5 psi for every foot of elevation above the boiler, so you may want to run 20 psi.
Ideally a Caleffi Autofill would allow you to set 20 psi and walk away to purge, it would fast fill and stop at 20. You could get one and connect it with a washer hose to the boiler drain valve if you do not want to pipe it in.
Shouldn't require two people to fill and purge a boiler. Any other purge points to speed up the process?

EdTheHeaterMan

Blvd said:

Ideally, you need two people if you don’t wanna be there all day and all night. One person hitting the feed valve, keeping it between 20 and 25. That’ll make things go faster. When you get down to the last Radiator, have the person stop feeding, let the regulator do its job

When you say "let the regulator do its job", you mean the blow off regulator on the back of the boiler? i.e. I can just keep adding water until the boiler decides to blow off the extra PSI? I'm worried that A. The gauge is (mostly) broken and I'll over pressurize and B. The blow off on the boiler is frozen and won't release when it should.

RED FLAG HERE

You MUST determine that the relief valve is operational.  Allow the boiler pressure to go to 30 PSI on a working gauge and be sure the valve releases pressure.   If it does and it closes properly after the pressure is released, then and only then can you be sure that it is safe to operate the system. If the valve does not release or it leaks after release, REPLACE IT. 

The instructions that come with the valve say the owner MUST operate the valve at least once a year to be sure the passageways are clear. 

Wow. I can’t believe that no one else here picked up on that comment

SERIOUSLY?

JUGHNE

Ed, I noticed that this AM also.
However, I think the OP doesn't understand the operation of the pop valve. He might be assuming that it is an auto relief valve that opens when hitting 15-20 PSI.........

RATHER THAN CRITICAL SAFETY RELIEF VALVE THAT SHOULD PASS WATER WHEN LEVER IS LIFTED.

Also if these are cast iron rads that exp tank looks small for the water content. It is possible that some upper floor rads are acting as "air head" expansion vessels. IMO

EdTheHeaterMan

@JUGHNE Agree. But still needs to be operated annually and replaced if defective.

Without a functioning relief valve, the boiler is not only a heating system, it is also a potential bomb.

WMno57

EdTheHeaterMan said:

You MUST determine that the relief valve is operational.  Allow the boiler pressure to go to 30 PSI on a working gauge and be sure the valve releases pressure.   If it does and it closes properly after the pressure is released, then and only then can you be sure that it is safe to operate the system.

Ha Ha. I'll share with you how dense and impulsive I am. When I first read this, I thought gee, that's a good Idea. I flip the lever every year, but a better test would be to raise the psi to over 30 and observe that the valve actually works. Then I thought, I like the idea of an actual test, but I don't like the idea of running the boiler that long and hot to get the psi over 30.

Yes, I read too fast, and somehow interpreted "Allow the boiler pressure to go to 30 PSI" to "run the boiler over 30" (my thoughts).

Then I thought, there has got to be a way to do this cold. Maybe a Schrader valve and air compressor could be employed.

Then, a couple minutes later the light bulb went on. Duh, change the setting on, or bypass the Filtrol and do this with hydrostatic pressure.

In fairness to myself, I was thinking about a handful of other issues, and taking phone calls, at the same time.

I'm a morning person, and it has been a very loooong day. There are old pilots, and there are bold pilots. There are no old and bold pilots. I'm done for today. It's Miller Time.

JUGHNE

I would not run the pressure up to over 30 PSI with water or especially air.
The best test IMO, is to just lift the lever at standing pressure for a good flush and then make sure it snaps shut for a good seal.
It should be done every year for flushing the seat.

Every service tech is probably reluctant to lift the lever because if not done on a regular basis it may have crap under the seat and drip and require replacement....."That thing never leaked until you messed with!!!" may happen.
Sometimes you have to drain down entire system and bleed air after refill...as Gordo says "your day just got longer".

I just today changed a high dollar valve on a commercial water heater. The boiler inspector asked the owner to lift the lever and it flushed out but would not reseat completely. (You notice that the inspector did not touch it, he knows )

I had told the owner to flush this several times a year, but "sure we will". Good money for me.

SuperTech

Reading this thread I think the best things to do would be to replace the air vent on the air scoop, its obviously shot. I would also definitely replace pressure relief valve while the boiler is drained. The relief valve and air vent are both inexpensive, the relief valve also being an important safety device.  Might as well replace the tridicator gauge while you're at it, this way you can safely raise the boiler pressure to purge the system and bleed the radiators without worrying about opening the pressure relief valve.  I always like to leave the water on to the fill valve, but I also like to see a backflow preventer installed before it.  

WMno57

JUGHNE said:

I would not run the pressure up to over 30 PSI with water or especially air.

After a good nights sleep, I decided that I'm OK with subjecting my boiler to 35 PSI of hydrostatic pressure, but not the 100 year old radiators. No good way in my system to isolate the radiators. Lifting the lever will have to do.

mikeg2015

JUGHNE said:

I would not run the pressure up to over 30 PSI with water or especially air.
The best test IMO, is to just lift the lever at standing pressure for a good flush and then make sure it snaps shut for a good seal.
It should be done every year for flushing the seat.

Every service tech is probably reluctant to lift the lever because if not done on a regular basis it may have crap under the seat and drip and require replacement....."That thing never leaked until you messed with!!!" may happen.
Sometimes you have to drain down entire system and bleed air after refill...as Gordo says "your day just got longer".

I just today changed a high dollar valve on a commercial water heater. The boiler inspector asked the owner to lift the lever and it flushed out but would not reseat completely. (You notice that the inspector did not touch it, he knows )

I had told the owner to flush this several times a year, but "sure we will". Good money for me.

I never test the relief unless I have a replacement on hand and I'm prepared to drain the system and bleed it if needed to fix it.

I never open a boiler drain unless I have a cap to go over the end if it doesn't close.

In winter I typically carry a boiler fill pressure regulator, a 350mbtu relief, a dual pressure/temp gauge, a boiler drain, and a air vent.

It's common that I replace all 5 on a boiler that hasn't seen any or proper service in maybe 10 years. All have often failed.