Air in heating system headache


  #1  
Old 12-24-22, 03:57 PM
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Air in heating system headache

Hi everyone,

Looking for some help as I am at my wit's end. I needed to shorten a baseboard on my 1 zone baseboard heating system so though the advice I got in this thread I added a combo shut off/purge valve on the return line and a regular shut off on the supply line.

The goal was to give me a way to purge air without having to drain the boiler.

My boiler does not have a fast fill valve so it took many hours to get the water flowing smoothly out of the hose I hooked up to the new drain valve.

Problem is that wasn't enough - heat was insufficient. So I bled at the baseboards again, and again, and again - only one is a smooth stream with no air.

To make matters worse, my circulator pump got very hot and buzzed twice when called for heat. I shut down the thermostat to let it cool. I am thinking maybe it is caused by air not cooling the pump?

Bottom line is I cannot seem to get the air out of the system. I have purged the at boiler through the new drain at least 50 times and the radiators about the same.

Any advice?
 
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Old 01-04-23, 07:15 PM
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I usually agree 100% with Spott's posts except one thing on these posts. If the tank has 12 psi of air the system water pressure should be operated at 12 psi. As Dh stated 12 psi is good for two floors above the boiler (my words) and if the water has to go higher you will need to increase the water pressure. It does not stop there. You would have to change the air pressure in the tank to match your cold operating pressure. If you need to raise the water pressure to 18 psi, you need to raise the tank air pressure to 18 psi. The tank air pressure and cold-water fill pressure must match.
Any air separators in the basement does a far better job of eliminating air than can vents up in the system. With that said, there are applications where can vents are a good practice. Convector heating on mono-flo systems may be the only application.
To improve air elimination using basement air separators is placing the circulator after the expansion tank and air separator. This will allow the circulator to add pressure to the system minimizing the size of the air bubble to make it easier to get down to the boiler for elimination in the air separator.
No matter what some say this style of air elimination have been time tested and proven do a very good job. Air separators come in a basic style to much higher quality. I have seen hundreds of air problem jobs become air free and stay air free for decades. I have changed parts on hydronic systems that required draining and basement purging. All you have to do is get out enough air to get flow and the rest of the air will be removed by basement air separators and supply side circulators.
 
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Old 01-03-23, 09:11 AM
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@doughess - Thank you for your response. I put some comments/questions:

1) Basics of hydronic systems are heated 12 psi water (100% no air) circulated through heating elements. common problems are unvented air, or incomplete, unconfirmed venting haunt heating systems
- Understood. Question, are you saying I should be running at 12 PSI, not 18 - 20 PSI?


2) Expansion tanks raise new problems. Diaphragms may loose 1 PSIG per year. On system with regulator at 12 psi, diaphragm expand, increasing water percentage, tank and reducing expansion to maintain system 12 psig.

A simple easy way to check expansion tanks is shutting off water feed valve to regulator. Then drain small quantity of water dropping system pressure to 8 or 10 psig. Apply 12 psig to tanks tire valve.


If boiler pressure rises to 12 psig, drain more water and fill tank with 12 psig. Repeat until boiler pressure no longer rises. Then turn on water feed valve.
- Do you mean to add 12 PSI of AIR to the tire valve?


3) DH highest priority is reliable heat on cold winter day. Have system with 12 elements/convectors that can not be remotely vented Solved chronic venting problem with Watts auto vents https://www.supplyhouse.com/Watts-05...Vent-3679000-p If a Watts auto vent ever leaked, can swap in a spare while heating is running.
- During this venture it got down to 9 degrees F with no heat. I luckily got it up and running (thanks to help here) and it works. My concern now is that it is not working as efficiently as it can so your input is appreciated.
- I am still concerned about potential leaks on those auto bleeders (as happened in the past) - and how can you swap them with the heat running? I've done that and it results in spraying of hot water everywhere.

4) Air scoop on spata97 boiler uses principal that lower pressure of water passing though larger chamber facilitates release of air. Old timers erroneously thought, that louder sounds when venting with higher pressures improved venting without confirming it.
- Can you explain the air scoop? I do not understand exactly what it means.


 
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Old 12-24-22, 08:14 PM
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Please post picture of work done.
What is the water pressure?
How many floors above the boiler?
 
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Old 12-24-22, 09:05 PM
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S,
Went back to look at pics you posted. New pics of the work you did would be helpful.

In the meantime since you have no fastfill on your fill valve to the boiler you must fill another way to get the pressure high enough to bleed properly. You have a boiler drain on the bottom of your boiler you can use as a fast fill to bleed your system.

Now that you have your shutoff / bleed valve installed you can fill your system through the bottom of the boiler with a washing machine hose if you have a faucet a cold water faucet available. Shut off the manual cold water valve above the boiler fill valve and feed through the bottom off of another faucet to app. 28 psi and open drain on return line until water runs clear. Shut off fill and drain to 18-20 psi. and run at that pressure.

You will do this with your boiler and pump off. Never bleed a system with the power on. Your pump is not air cooled. That thing you are calling a motor is a cannister and has boiler in it which is why it could be hot. If it runs dry you will burn it out.

If you are trying to bleed by going through the pressure reducing valve which is only set for 12-15 lbs. it will never work because as you drain water out you are letting fresh water and air back in at the same rate.

One more thought. You do not need individual hi-vents if you have a loop system. You mentioned radiators once. Do you have rads or baseboard heat. That could make a difference.
 
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Old 12-25-22, 07:04 AM
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Hi All - Merry Christmas and thanks for the replies!

Below are the pics - the red arrow (12 - 15 PSI) is movable if you spin the face of the gauge and a reference to where the boiler pressure was before I started. Now it runs at about 20 PSI. If I open the bleeder valve on the new valve I installed it will get the pressure down temporarily to the red arrow but will climb back up to 20 PSI.

With my current bleeding procedure the hose which is attached is running clear with no bubbles but there are bubbles in the baseboard bleeders.

I have bleeders at all the baseboards and was advised to add one even with this bleeder valve.

@spott - To clarify I have baseboards, not radiators. What you are stating makes perfect sense and I will try that tomorrow. Also, if you are saying the boiler should be 18-20 psi maybe it was low before and it is ok now (as far as pressure)?

Question though, using the boiler drain to fill: I get the PSI up to 28 then close the boiler drain, then open the new bleed valve until it is running clear.

I assume I may have to do a few cycles of this in order to ensure all the air is out? In other words, fill the boiler, bleed, get down to 20 PSI, shut the new bleed valve, and do it again?


New Valves




Boiler Pressure After Work/Bleeding


Shortened baseboard

 
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Old 12-25-22, 01:25 PM
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Unhappy

Questionthough, using the boiler drain to fill: I get the PSI up to 28 then close the boiler drain, then open the new bleed valve until it is running clear.

When you get it to 28 you open up bleed valve while leaving the boiler drain open to continuously feed water through the system and bled. It may take 2 people to work the valves. If it fills faster than it drains close it for a few seconds so the pressure doesn't get to 30 psi but open it back up before it gets to 25. If it feeds to quick close the boiler drain a little to slow the feed down so you maintain that 28 until water runs clear.

With 1 zone it should take about 5 -10 minutes maybe to make sure all air is out..You do not need your baseboard bleeders. They serve no purpose on your system. If you doubt that then try to bleed through them and see what happens. You will continually get water and the system will still have air.

When all bled drain remaining water until 20 psi is reached and then set everything back to normal and test for proper operation.
 
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Old 12-25-22, 02:29 PM
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Awesome Spott! Thanks!

I agree the air valve bleeders at the baseboards won’t work as well. This is great because I have one more baseboard to plumb in which I won’t touch until summer time lol. When I was working on this project with no heat it was 9 degrees outside!

I’ll give this a shot (likely tomorrow) and will post back results or addition questions.

Thank you again for your help!
 
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Old 12-25-22, 10:05 PM
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Spata97 problems are easily solved with Watts auto vents at high points of each zone, $12low cost, reliable, long term way. Watts has black knob to manually check, confirm venting or turn off. valve Keep a $12 spare Watts to swap in if issue.https://www.supplyhouse.com/Watts-05...Vent-3679000-p

Many other brands of vent vents, leak, have to be capped off and impossible to, or cannot be serviced.

Watts are easy to install: turn off power to system, turn off valve under expansion tank, drain water until pressure is zero PSI. Then remove old manual vent on baseboard and replace with a Watts.

Many years ago DH installed Watts auto vents on 12 enclosed heating. elements, that could not be vented at boiler level, On two zones with baseboards also have Watt auto vents. Then retired from manual vent/purge hassle, keep $12 spare to swap in if problem

The old way to manually vent/purge at boiler was with lengthily, complex steps and pressure raising that did not confirm venting of air at high points of zones. After all those manual steps, remaining air still caused problems and had to be repeated.
 
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Old 12-26-22, 07:16 AM
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@doughess - thanks for the info and link. I had previously used auto bleeders and had one fail which caused water damage in the bathroom below after I just remodeled it.

the strange thing is it was intermittent so it took a while to track down the actual cause. The bleeder was dry but I was finding pools of water and couldn’t track it down.

finally I got the idea on here that it may be the bleeder so I took a colored folder and put it near it and after a few days the folder color was distorted so I realized it was the culprit.

when I posted here the recommendation was to replace them with the manual key ones I have now which I did and haven’t had any fail.

perhaps that specific model is better? That technology makes me nervous as I had to redo a ceiling I just did (Sheetrock, spackle, primer, paint).
 
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Old 12-26-22, 10:58 AM
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spata97.: Suggest Install Watts Auto vents, if it leaks turn off black knob on it to stop flow and venting. Is same as turning off your existing manual vent. Best of both worlds, have you cake and eat it, etc

DH bought a 1957 home with hot water oil burner heating in 1969. As problem arose tried to both fix and improve system. After years of time and money on venting issues found $12 venting solution.

On DIY posts see many posts about complex, convoluted tales solving problems. Venting and old leaking auto vent are common. Since 1950’s when hydronic heating systems came into wide use there have been many improvements introduced that ended problem.

Many old time fixes posted do not reflect basic understanding of problem and use ways to avoid recurrence.

Raising temporally pressure to 20 PSI or more, makes for loud venting sounds but does often does not remove air in elements or more important confirm it.


 
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Old 12-27-22, 12:28 PM
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@doughess, thanks again for your input. The leaking I described before was not from the screw cap but from the seam on the bleeder valve as best I can tell. And it was not a little water, ultimately it was in the gallon(s) range.

This all happened while I was away at work and I came home to mushy drywall and a soaked floor. It took me a while to track it down too because it went along the ceiling and finally found its way out about 6 feet away.

Perhaps the particular bleeder valve you linked is improved over the ones I had before but I am scared of them due to damage they can cause. I included a pic of the ones I used to use which had a failure.

I will definitely look into the model you linked though - perhaps they are more reliable?


 
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Old 12-27-22, 02:29 PM
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In New York cold freezing weather auto vent valves are important maintaining heat. If concerned about auto vent leaking install $6 ball valve under it.

Vent in picture at boiler level is worthless. Would remove and plug with 1/8” NPT plug to void future leaks.
Watts are very reliable, easy to open and service. None of 12 Watts in DH home has leaked.

https://www.amazon.com/Metaland-Bras...54626421&psc=1
Vent in picture at boiler level is worthless. Would remove and plug with 1/8” NPT plug to void future leaks.

Watts are very reliable, easy to open and service. None of 12 Watts in DH home has leaked.https://www.supplyhouse.com/Watts-05...Vent-3679000-p


 

Last edited by doughess; 12-27-22 at 02:50 PM.
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Old 01-02-23, 07:56 AM
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@spott - Apologies for the delay but been a little crazy with holidays and the kitchen.

Anyway, I ran through the procedure you indicated for 15 minutes (wanted to make sure it was good). When I finished I set it to 18 PSI but it has not stayed there - it seems to have lost pressure (see pics below).

NOTE: In my haste I forgot to turn back on the cold water supply to the boiler (gate valve) so I'm thinking maybe it lost pressure that way as I ran the faucet for a bit? Should I redo it again?

Interestingly, it stayed at 18 PSI for several hours later and slowly lost pressure as the days went on.

Thoughts?





 
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Old 01-02-23, 12:32 PM
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sp,
First, how is your system heating since your bleeding it. Is it noisy at all or did it get all the air out. If your Blue valve to the boiler is on, feel the pipe between the RED (B & G) auto feed and the boiler. If it is cold that means you have water feeding in which means you have a leak somewhere. If it's warm then there is nothing coming in so fresh feed water is not your problem.

You can check your extrol tank by shutting off the gate valve before the tank to depressurize and remove the blue cap and with a tire pressure gage check the pressure. It should be around 12 psi if it has not been adjusted.

What was your boiler pressure when you remembered to open your boiler feed. The last pic with the gage @ 12 psi is where I have a question. Since your feed valve is set at 12 then when the boiler gets to 12 is fresh water feeding in to maintain that pressure and is a leak causing the pressure drop.

If your tank checks out OK and your pipe between the feed valve and boiler are warm and your heat is working and quiet what I would try is to add a little water to get to 20 and see results and go from there.

Your faucet water has no bearing on your heating water or pressure at all. They are completely separate. Check your auto vent or vents also. They can let air in as well as leak water out which is why I do not use them on a loop system.

By the way Weil McLain design needs and requires that vent on top of the boiler. Eliminating that vent can void the warranty if boiler cracks, especially since you have no air scoop.

If you feel comfortable you can bleed again and set properly to see what happens.
 
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Old 01-02-23, 03:23 PM
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Thanks again for the quick reply Spott.

To answer your questions:

1) First, how is your system heating since your bleeding it. Is it noisy at all or did it get all the air out.
- Heat is working, though I feel like I am getting less heat from the upstairs baseboards/convection heaters. I should have mentioned it before, but the baseboards are just where I installed new. The old ones are those "convection" heaters (think that is what they are called). Not radiators, but have two pipes in them as opposed to one like a baseboard).
- No noise at all

2) If your Blue valve to the boiler is on, feel the pipe between the RED (B & G) auto feed and the boiler. If it is cold that means you have water feeding in which means you have a leak somewhere. If it's warm then there is nothing coming in so fresh feed water is not your problem.
- I just checked and the pipe is warm

3) You can check your extrol tank by shutting off the gate valve before the tank to depressurize and remove the blue cap and with a tire pressure gage check the pressure. It should be around 12 psi if it has not been adjusted.
- I will plan to do this over the weekend.

4) What was your boiler pressure when you remembered to open your boiler feed. The last pic with the gage @ 12 psi is where I have a question. Since your feed valve is set at 12 then when the boiler gets to 12 is fresh water feeding in to maintain that pressure and is a leak causing the pressure drop.
- From what I recall it was still at 18 PSI but I am not positive
- I do not see any leaks and the pipe from the red autofeeder/pressure regulator is warm so hoping it is not a leak.

5) If your tank checks out OK and your pipe between the feed valve and boiler are warm and your heat is working and quiet what I would try is to add a little water to get to 20 and see results and go from there.
- Will do that this weekend

6) Your faucet water has no bearing on your heating water or pressure at all. They are completely separate.
- Good to know, thanks

7) Check your auto vent or vents also. They can let air in as well as leak water out which is why I do not use them on a loop system.
- The only autovent I have is on the boiler. All the baseboards/heaters have manual valves

8) By the way Weil McLain design needs and requires that vent on top of the boiler. Eliminating that vent can void the warranty if boiler cracks, especially since you have no air scoop.
- I thought I would have gotten air out of that bleeder but I haven't heard any - wonder if it needs replacing?

9) If you feel comfortable you can bleed again and set properly to see what happens.
- I'll probably do it again. It all went pretty smoothly with my gf checking the hose but was a two person job. I had to throttle the bleed valve to keep the pressure at 28 PSI during the procedure. Not hard but required a lot of adjustments to keep it in balance.

One additional question, is there any harm of trying to bleed from the top floor at the baseboards/heaters? I just want to confirm that I am getting a nice stream of water with no bubbles.

Thanks again!
 
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Old 01-02-23, 06:30 PM
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sp,
Exactly what do you have for heat emitters. Convectors must be bled individually because they are usually installed either with special tee's called monoflo tees or on a 2 pipe system. Either of these cannot properly be bled from the basement like a loop system.

Can you take pics of your piping where the supply and return go to the convectors and how the baseboard is piped Are you saying you have 2 different piping systems going to your emitters.

What I would do 1st is to pressurize your system back up to 28 psi the way you did before and then bleed your convectors with the coin vent on the convectors making sure the pressure remained at 28 until all of them are bled. Don't be in a rush and make sure you get that good clear stream of water at each one. Do not bleed your baseboard again, only the convectors.

When completed all bleeding, drain excess water again to 20 psi and test for proper operation.

How did you pipe 2 different types of heaters with only 1 zone. By that I mean you said you have a loop system with the baseboards and either a 2 pipe or monoflo with the convectors if I'm understanding you.

Could you take pics of your main piping also.
 
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Old 01-02-23, 09:11 PM
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Basics of hydronic systems are heated 12 psi water (100% no air) circulated through heating elements. common problems are unvented air, or incomplete, unconfirmed venting haunt heating systems

Expansion tanks raise new problems. Diaphragms may loose 1 PSIG per year. On system with regulator at 12 psi, diaphragm expand, increasing water percentage, tank and reducing expansion to maintain system 12 psig.

A simple easy way to check expansion tanks is shutting off water feed valve to regulator. Then drain small quantity of water dropping system pressure to 8 or 10 psig. Apply 12 psig to tanks tire valve.

If boiler pressure rises to 12 psig, drain more water and fill tank with 12 psig. Repeat until boiler pressure no longer rises. Then turn on water feed valve.

DH highest priority is reliable heat on cold winter day. Have system with 12 elements/convectors that can not be remotely vented Solved chronic venting problem with Watts auto vents https://www.supplyhouse.com/Watts-05...Vent-3679000-p If a Watts auto vent ever leaked, can swap in a spare while heating is running.

Air scoop on spata97 boiler uses principal that lower pressure of water passing though larger chamber facilitates release of air. Old timers erroneously thought, that louder sounds when venting with higher pressures improved venting without confirming it.

Am old timer who finds/learns new ways to both fix and avoid repeating/recurrence of old ones.
 
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Old 01-03-23, 09:03 AM
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@spott - Thanks again for the reply. My apologies for not including this info as I did not realize it was relevant:

1) Exactly what do you have for heat emitters.
- I have what I was told were convectors (please confirm - pics below). As I remodel rooms I replace them with regular Slant/Fin 30 baseboards. Right now I have 3 baseboards (kitchen, basement, upstairs bath) and 5 convectors.

2) Convectors must be bled individually because they are usually installed either with special tee's called monoflo tees or on a 2 pipe system. Either of these cannot properly be bled from the basement like a loop system.
- I do have monoflo tees on all heaters. Basically the 1" copper supply pipe out of my boiler goes into a cast iron pipe loop. At each heating element I have a monoflo tee at the inlet and outlet which is connected to the heater (either convector or baseboard) though 1/2" copper pipe on the inlet and outlet.


3) Can you take pics of your piping where the supply and return go to the convectors and how the baseboard is piped Are you saying you have 2 different piping systems going to your emitters.
- Pics below


4) What I would do 1st is to pressurize your system back up to 28 psi the way you did before and then bleed your convectors with the coin vent on the convectors making sure the pressure remained at 28 until all of them are bled. Don't be in a rush and make sure you get that good clear stream of water at each one. Do not bleed your baseboard again, only the convectors. When completed all bleeding, drain excess water again to 20 psi and test for proper operation.
- Will do

5) How did you pipe 2 different types of heaters with only 1 zone. By that I mean you said you have a loop system with the baseboards and either a 2 pipe or monoflo with the convectors if I'm understanding you.
- All I did was cut the copper inlet and outlet to the convectors and connected to the baseboards

Here are some pics - let me know if this clarifies.





 
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Old 01-03-23, 11:56 AM
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spata97 post # 18 Questions and DH answers:

1) Question, are you saying I should be running at 12 PSI, not 18 - 20 PSI?

In most homes the highest heating element is 18 feet or less above boiler, so 12 psi is widely used. Only if elements are higher It is increased Those ignorant of basic principals, raise pressure it for various reason often creating new problems

2) - Do you mean to add 12 PSI of AIR to the tire valve?
Yes

3) I am still concerned about potential leaks on those auto bleeders (as happened in the past) - and how can you swap them with the heat running? I've done that and it results in spraying of hot water everywhere.

If Watts auto vents are installed at all high points, shut off fresh water boiler feed valve, and ball valve under expansion tank. drain a gallon of so of boiler water until pressure is zero. Put towel or pan under vent in case of water drops and remove vent.
Caution: If not vented “ it results in spraying of hot water everywhere.”

4)- Can you explain the air scoop? I do not understand exactly what it means.

Air scoops are one of many ineffective boiler room gadgets that do not confirm or remove at at high points of systems. . https://inspectapedia.com/heat/Air-S...coops-FAQs.php

Finally: Adding to and modernizing system with simple things makes for more trouble free, reliable, lower fuel cost system. Is easier that dealing with repeated fixes.
 

Last edited by doughess; 01-03-23 at 01:14 PM.
  #21  
Old 01-03-23, 12:17 PM
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@doughess - thanks for the responses!

Interesting you mention 12 PSI as that is what my boiler is currently running at (last pic on post #12). That being the case, is it running at the correct pressure now and was high before I started?

I can try the testing of the expansion tank as well.

 
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Old 01-03-23, 08:25 PM
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sp.
That monoflo system has to be bled 1 emitter at a time at about 28 psi if possible and when finished drain to 18-20 psi for operating pressure.
When you tried bleeding from the basement with your system all you were doing was bleeding the main line mostly because water follows the path of least resistance.

If you try to bleed at 12 psi your pressure will continuously fall below the 12 and fresh water which brings air will continuously feed back in to create the same air problems but it's up to you if you want to follow DH down the path of constant air problems which is why he needs the auto vents handy.

As I said I would just close the valve before the tank and put a tire gage on it and if isays 12 open the valve and leave it alone.
 
  #23  
Old 01-03-23, 09:12 PM
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Apparently some do not understand the interrelationships in heating systems.

A widely used practice is keeping fresh water feed valve open so pressure regulator maintains system pressure at 12 psi for several reasons:
1 Leak of water, that is not replenished can make it a steam boiler and bad things may happen.
2.Avoiding pressure drop issues as air is automatically vented
3.Makes practical use of reliable Watts auto vents and ending cause heating problems and need to manually vent.

DH spare $12 Watts kept “constantly” in box on top of boiler is reminder of past problems. Opening 12 cabinets to vent mono-flow elements was real hassle.

Now only read about it on DIY and post to help others avoid complex alternative solutions. i.e. "That mono-lo system has to be bled 1 emitter at a time at about 28 psi if possible and when finished drain to 18-20 psi for operating pressure."
 

Last edited by doughess; 01-03-23 at 09:37 PM.
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Old 01-03-23, 09:50 PM
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DH.....Apparently some do not understand the interrelationships in heating systems.
WHAT DOES THAT EVEN MEAN!!!

DH......A widely used practice is keeping fresh water feed valve open. The pressure regulator maintains system pressure at 12 psi if for several reasons:
1 leak of water can make it a steam boiler and bad things may happen.2.avoiding pressure drop as air is automatically vented
HAVE ALWAYS MAINTAINED THAT FWFV SHOULD BE OPEN. WHAT BRINGS THAT UP!!!!

DH.....Makes practical use of reliable Watts auto vents and ending cause heating problems and need to manually vent.
WHAT DOES THE OPEN FWFV HAVE TO DO WITH THE PRACTICAL USE OF WATTS AUTO VENTS!!!!


DH spare $12 Watts kept “constantly” in box on top of boiler is remembers past problems. Opening 12 cabinets to vent monoflow elements was real hassle. Now only read about it on DIY and post to help others avoid complex alternative solutions. i.e. "That mono-lo system has to be bled 1 emitter at a time at about 28 psi if possible and when finished drain to 18-20 psi for operating pressure."
IF THE SYSTEM IS BLED PROPERLY THE FIRST TIME AND THE SYSTEM, WEATHER IT BE A MONOFLO, 2 PIPE, LOOP, REVERSE RETURN, IS A CLOSED SYSTEM WHICH MEANS ONCE THE AIR IS GONE IT CANNOT RETURN UNLESS THE SYSTEM IS OPENED UP OR DRAINED FOR REPAIRS SO THERE IS NO NEED FOR $12 WATTS AUTO VENTS.

Some suggestions come from people who only do work on their own systems and is satisfied when he thinks he's found the solution and through close mindedness refuses to even consider that something other than his way may work for others. I'm not debating that his way works for him but there are a lot of different design systems out there in the field that may need different procedures.


 
  #25  
Old 01-04-23, 10:56 AM
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@spott - thanks for the additional info. I had some questions though:

1) That monoflo system has to be bled 1 emitter at a time
- In what order should I bleed? Bottom to top? Closest to furthest?

2) at about 28 psi if possible and when finished drain to 18-20 psi for operating pressure.

When you tried bleeding from the basement with your system all you were doing was bleeding the main line mostly because water follows the path of least resistance.
- I assume I will have to bleed a little, then bring it up to 28 PSI, then repeat. Correct?
- The monoflo valves (as I understand them) are just one way valves. I would have thought the water would flow both through them up into the heaters and forward through the pipe, no?



- Since all heaters (both baseboard and convection) have monoflows, I suppose I will have to bleed at the heaters for all (including baseboards). Correct?

- In the future (when I replace another convector with baseboard) is it a good idea to do a flush at the boiler first, then bleed individually? Will that get a lot of air out (it did this time) to save me from bleeding more at the heaters?
 
  #26  
Old 01-04-23, 02:07 PM
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1) When I've had jobs like this I just bled them at random and found it never made a difference.

2) Two people are best for this job. One to work the pressure and one to bleed. The monoflo tees are 1 way fittings with a special insert inside to direct or force a portion of water into the emitter and also allow the water to continue in the pipe to the next emitter and next and finally back to the boiler.
The 28 psi is not carved in stone as long as the pressure stays above what you intend to make your operating pressure so you are not adding fresh water after everything is bled. It tends to remove the air better at higher pressure.

3) As you replace the convectors for baseboard each will have to be bled. When you change the convectors you don't have to drain the whole system every time. You just drain enough water to get below where you are working and that will save you time

4) Whatever works for you. I have the same exact system as you from the same boiler to the monoflow system with baseboard heat. I believe you are going to have a harder time trying to bleed the baseboard than the convectors due to the design of the emitters. Convectors and rads are meant to be bled from the units where as baseboard has that direct flow through pipe instead of sections with a high vent. I had a hard time bleeding my baseboard and I came up with this which also let me do everything from the basement with no furniture moving.

I installed ball valves on the supply and return lines of the emitters and a drawoff on the return lines. To bleed I would open the supply and close the return and with water going through the emitter and back to the main, open the drawoff to bleed the emitter. When done close both ball valves so no fresh water could enter while bleeding the others.
By doing this you can also shut off all emitters and bleed just the main line removing the lions share of the air and if you had to work on the boiler or something where you had to drain water you could shut off the heaters and you would have total control of each emiitter and your system. I put this in in 84 and have never had the overs off of the baseboard and have eliminated all vents in living area no so chance of leaks.
 
  #27  
Old 01-04-23, 02:56 PM
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A sentence in Pos#1 was about purge/vent air “The goal was to give me a way to purge air without having to drain the boiler. “

As often happens many post raised issues that added confusion, rather that positive help finding a solution

spott.IF THE SYSTEM IS BLED PROPERLY THE FIRST TIME AND THE SYSTEM, WEATHER IT BE A MONOFLO, 2 PIPE, LOOP, REVERSE RETURN, IS A CLOSED SYSTEM WHICH MEANS ONCE THE AIR IS GONE IT CANNOT RETURN UNLESS THE SYSTEM IS OPENED UP OR DRAINED FOR REPAIRS SO THERE IS NO NEED FOR $12 WATTS AUTO VENTS."
A wide spread falsehood is that air does not develop in systems that were properly vented at startup.
Those that believe it spend huge amounts of time and money to resolve problems caused by unvented air.
DIY.com has many post that may be partially due to air in system..

Mono-flow feds elements typically receive a percentage of water flow from main line below. Each element is an air trap. Bleeding one, does impact venting of others. so sequence is needless.

Watts auto vents on DH 12 mono-flow elements, vent as needed. Saves wasting time worrying about imagined issues like sequence or following someone’s complex manually procedures, raise pressure to 28 Psi. that might cause safety valve to release.

Other issue:

“spott: DH: WHAT DOES THE OPEN FWFV HAVE TO DO WITH THE PRACTICAL USE OF WATTS AUTO VENTS!!!! “

DH answer is in rela6ionwhips: spott Read DH Post #22 line: 3.Makes practical use of reliable Watts auto vents and ending cause heating problems and need to manually vent.

Finally flushing or draining boiler should be avoided for many reasons, but is OK if replacing it.
 

Last edited by doughess; 01-04-23 at 05:06 PM.
  #28  
Old 01-04-23, 02:59 PM
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@spott - Thanks again, makes perfect sense.

Interestingly, I have never had so many issues when I replaced the convectors before. This time I had an issue with water in the system not allowing me to solder so I stuck a wet/dry vac in the lines to suck out water. I think by doing that I took out way more water than I needed to (and introduced air) which is why the bleeding at the heaters was so difficult. Also, doing it with only 12-15 PSI didn't help matters. I am tempted to have a furnace tech install a new regulator with a fast fill lever but only if I can find a company which is good (not likely).

Thanks again for your assistance - will post back results when I get this done!
 
  #29  
Old 01-04-23, 07:46 PM
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spat97: I am tempted to have a furnace tech install a new regulator with a fast fill lever but only if I can find a company which is good (not likely).
Pressure regulators often need service. Make it easy to remove in future with ½” unions on either side of regulator and ½” ball shut valves.

Is simple plumbing job many homeowner/DIYer can do. Major benefit is boiler keeps heating while serviced.

https://www.supplyhouse.com/Elkhart-...2-Copper-Union

https://www.supplyhouse.com/Bluefin-...eat-Ball-Valve

A Wye strainer before regulator, filters out rust particles in city water prolonging life.

https://www.supplyhouse.com/Bluefin-...-Free-Threaded

Air elimination scoops at boiler level with auto vents are worthless, old school stuff. The more effective modern way is with Auto vents at zone high points. https://inspectapedia.com/heat/Air-S...coops-FAQs.php
 
  #30  
Old 01-05-23, 01:52 PM
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DH thanks for the link. I got a good laugh from it, although he was promoting air scoops etc. He even listed a lot of manufacturers with links. The funniest part is using an auto vent with the old steel expansion tank. I would probably find another mentor to follow that would better knowledge of hydronics.
Here are a few, Dan Holohan books or website, Taco after Dark videos, John Siegenthalers books or articles, and Caleffi's itronic books all of which are great resources.

 
  #31  
Old 01-05-23, 04:17 PM
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After adjusting the expansion tank as described previously above, add enough water to the system so the pressure at the boiler stays at least 5 PSI times the number of stories of the house plus two more PSI, for example 12 PSI for a 2 story house including after the boiler shuts off between heat cycles and is cold.

(This is so the system pressure does not drop to zero at any time in the baseboards in the uppermost floor.)

(copied from another forum) Do the heat pipes within the baseboards have any vertical give that lets the ends bob up and down perhaps an inch each when you push or pull on them manually without using much force?

If so then see if you can prop up the end with the air valve on it and tie down (with the help of a screw into the floor) the other end. (Don't push or move any heat pipes with no valve at either end.)

After this, every day for a few days open the air valve(s) in the radiators one at a time and see if you can bleed out some air.
 
  #32  
Old 01-05-23, 08:25 PM
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AllanJ: A basic law is in closed liquid (water) systems the pressure is basically the same at all points.

Pressure regulator automatically adds water to keep at 12 psi needed.

As boiler heat expands the water, expansion tanks balder stretches/expands space so 12 psi maintained at all places in home.

Usually there is no need to change those settings.

 
  #33  
Old 01-08-23, 07:17 PM
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DH, I believe I misunderstood your last comment. Water pressure does decrease as you gain altitude in the system. 1 PSI loss for every 2.31 feet you go up in the system. If you have 12 PSI at the feeder attachment and measure the system pressure 10 feet higher you would have 7.7 PSI.
 
  #34  
Old 01-08-23, 10:33 PM
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DH tries to keep post simple and not add technical data to substantiate things i.e..
Post#32 AllanJ: A basic law is in closed liquid (water) systems the pressure is basically the same at all points.

Here a definition that might have added confusion and not helped readers:
Pascal's law is a principle in fluid mechanics at a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. https://en.wikipedia.org/wiki/Pascal%27s_law

DH Post #32 was about heating “system” pressure, Not “head of water” in outside earth “atmosphere”

While rbeck in post #33 was correct writing I believe I misunderstood your last comment. “ he may not have consider closed pressurized 12 psi system is not atmosphere pressure
i.e. “What is head? Head is the height difference between where the water enters into the hydro system and where it leaves it, measured in metres.” https://www.google.com/search?client...UTF-8&oe=UTF-8

DH thinks 12 psi at boiler is 12 psi at system high point. If for some reason there is a small pressure drop it will not significantly impact BTU's delivered. Unvented air is more common issue.
 

Last edited by doughess; 01-08-23 at 10:51 PM.
  #35  
Old 01-09-23, 11:34 AM
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DH, not disagreeing but not what I have been taught or experienced. If you have a gauge at a high point and the low point of the system, the pressure in that heating loop is always lower at the high point than the low point. I have seen this with my own eyes. If what you say is true, that would mean the weight of water has no bearing on a gauge reading at the lowest point or the highest point.
Plus, also have seen the circulator change the system pressure both high and low points dependent where it is located. Mounted before the expansion tank will lower the high point pressure and after the tank raise the high point pressure.
Is not the feet of head, more commonly called head in the heating industry, the resistance the circulator encounters, not referring to the water height?
Because this is a pressurized system it takes higher pressure to get the water level higher in a system. IE: 2-story to a 4-story home. The pressure at the top of the system could be the same in any given water height but the pressure at the bottom would be higher in the 4-story then the 2-story home due to the weight of water. Again 2.31 ft equals 1 psi.
Thanks
 
  #36  
Old 01-09-23, 04:21 PM
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rbeck Post #35 raises issue of 1 psi variation on heating but lacks specifics.

BTUs circulated to elements are calculated by simple formula that shows significance of GPM flow and water temperature, but not pressure?

System Delivered Btu = 500 × GPM × System Temperature Change.

Usually slight variations from 12 psi or have little impact on BTU’s delivered.

Can rbeck post way or formula that shows how 1 psi effect BTU delivered?

 
  #37  
Old 01-09-23, 09:37 PM
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Can rbeck post way or formula that shows how 1 psi effect BTU delivered?

It takes 1 psi to lift water 2.31 ft.

If heating elements are installed 5 ft. above boiler there are NO btu's delivered to elements at that pressure.

Contrary to your point of thinking, the only place of no pressure change is the expansion tank. If you put your pump on the return side you will get 12 psi or whatever pressure you run to your elements. If your pump is on the supply side AFTER the expansion tank you will have the benefit of added pressure from the pump to the elements so you can run your boiler at 12 and possibly get may 18 to your elements.

 
  #38  
Old 01-10-23, 11:02 AM
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DH Post#36 read “Usually slight variations from 12 psi or have little impact on BTU’s delivered.”

Has split level home with 18’ elevation from boiler to highest heating element uses 12 psi circulated water.

In 50 years there has never been a circulation problem. Pressure differential between pump in and out is normal … suck water in with lower pressure and push out at higher pressure.

Expansion tanks are to maintain system pressure as water expands and contracts due to temperature changes, not pump differential pressure.

DH cannot explain why that works given Spott’s If heating elements are installed 5 ft. above boiler there are NO btu's delivered to elements at that pressure.

Biggest problem has been unvented air, accumulating in mono-flow fed elements 18” above 1” main line. Permanently ended periodic, manual venting hassle with Watts auto vents on all elements (at boiler there is no air scoop or vent) https://www.supplyhouse.com/Watts-05...Vent-3679000-p

When there is heating system problem look for solution/fix that avoids repeat, makes system more reliable and efficient.
 

Last edited by doughess; 01-10-23 at 11:33 AM.
  #39  
Old 01-10-23, 02:33 PM
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Nowhere do I mention that PSI affects BTU's. I was discussing the fact that Dh stated the pressure is the same at the high point and low point which it is not correct. Pressure does not affect radiation btu output. I referenced 1 PSI = 2.31 ft because I was explaining the difference in pressure is basically due to water weight.
Flow and water temperature affect output. Speed water up get more heat slow water down get less heat.
 
  #40  
Old 01-10-23, 04:31 PM
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When there is lack of adequate heat with circulating hot water, one of first and easiest things to eliminate, as factor, is unvented air. If venting not confirmed at high points the a lot time is needlessly spent on other possible causes.

Spta97 has not confirmed air has been vented from high points. One possible result mentioned in Post #1 is circulator overheating because unvented air in elements, lowers BTU output, so thermostat keeps it running.

Post #3, #4,#5 has lot’s about venting, but describes no way to confirm it. Some are negative about auto vents

Maybe spta97 might end his Air in heating system headache and confirmed venting by opening high point until only water and not air comes out?
 

Last edited by doughess; 01-10-23 at 07:19 PM.
 

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