Where to bleed air from boiler?

Forumjp59

Hey guys, I've had 3 contractors over now to inspect a 1yr old boiler for some loud banging. They give the boiler a clean bill of health and leave. I've ruled out delayed ignition, and am now wondering if it's air in the system. I have 3 zones. Upstairs and downstairs are baseboards, and the main floor is radiant. Can anyone advise on where to bleed the air from judging by the photos? It seems like the random banging (once every few hours while running) has gotten worse after the hvac contractor flushed the hot water heater. Thanks for any help! 


Pressure 12-15psi
Temp 180
Pump set to low
House heats well, maybe a little short cycling. 

hot_rod

What size is the boiler? Any heat load numbers?
Is there another circulator in the system for the low temperature radiant? Maybe at the manifold?

I would guess with low loads or just the small zone calling it may short cycle. Low mass boilers can overshoot when small loads keep cycling on/off constantly.

Outdoor reset control might help modulate supply temperature on milder days.

Forumjp59

I agree with you as for the small downstairs zone calling for heat which causes the short cycling. Not sure there's much I can do there. 

I need to do some research on all that terminology as I'm still learning. Do these pictures help answer those questions? Thanks so much for your help! 

hot_rod

That is a two stage boiler, so that helps. Low fire is still around 37,000 btu/hr however.

Is there an outdoor sensor connected, on a north facing wall outside somewhere? Page 30 in the manual goes over the outdoor reset control and settings. If so that boiler supply temperature should be modulation based on outdoor temperature. 180 should only be on the coldest days.

If all this is correct it could just be coasting up to high temperature after excessive short cycling.

Still ned to know if there is another pump somewhere that pulls from the mix valve? If not, if the radiant is a separate zone, you will not have flow through the system when that is the only zone calling.

If the boiler over-heats, boils, that could be the cause of the reoccuring air or banging noise.

Get a comfortable chair, sit in front of the boiler, turn on the smallest zone, and then just the radiant zone and observe temperatures and when the noise starts. Once you determine what condition caused the noise, you can identify the fix. We need more data.

Too busy to sit in front of the boiler? some people rig up a video camera, GoPro, to let it record the system operation

Forumjp59

I don't think there is an outside sensor but I will look later today l. I've kept an eye on the temp guage quite a bit and during start up it does seem to pass 180 and go more towards 200. I don't see another pump, would it be another Red Grundofos if there is one? 

I'm planning to set up a gopro tonight! I sit in front of the boiler too often and my SO thinks I'm crazy haha 

leonz

Lower the high limit to 160 degrees Fahrenheit.

Did your plumbers check the pressure of the Extrol tank by draining the system a little to remove the Extrol tank to check the air pressure in it?

Forumjp59

I don't think they did. 

Can I just change the high limit Temps on the fly and see how the system reacts? Does anything else have to be changed with that? Will that change the pressure? 

leonz

You can lower the high limit temperature without doing anything else.
Your pressure will drop a little but it will not hurt anything other than
making the cat angry about not having a hot seat to lay on.

I have one question though, is anyone drawing water at the same time??
you can have banging when the hot water or cold water tap is closed suddenly.

Forumjp59

Okay thanks. 

So that is another question I have and have been doing research on. During the service the overflow valve blew twice and lost some fluid. How does the boiler refill? The Hvac tech who installed the system mentioned the auto fill valve was broken, but there was no need to replace it and can leave that valve off since we dont use it. I've attached a photo of this valve showing the tip broken off. 

Do I have to refill the boiler? I've looked for a water level monitoring system but cannot find one. 

JUGHNE

Assuming that this is a change out for the boiler, are the zone valves installed backwards or has the water

flow changed directions thru the system?

Forumjp59

JUGHNE said:

Assuming that this is a change out for the boiler, are the zone valves installed backwards or has the water flow changed directions thru the system?

That's a good question. I don't know as the system was changed out November 2022 and we didn't take ownership until June 2023. 

EBEBRATT-Ed

I looked in the boiler manual and your piping looks to be all wrong. You need to look in the boiler manual.

This boiler needs to be hooked up primary /secondary. You only have one circulator pump and you need 2 of them

There are more things wrong than I can list. See the manual about page 29 are the piping instructions.

Either I am blind and cannot read or the person that installed this has no clue as well as the three 'contractors" you had look at it. As far as I can see you have no flow through the boiler

EdTheHeaterMan

I can't tell if anyone has given instructions on how to purge air yet, so here goes.
Oops I forgot one of the valves you need to close... here is the edit: I added a step #4 valve to close just above the circulator pump.


Best I can come up with based on the photograph. Hidden check valves may change this because it appears that you are purging in reverse.

EdTheHeaterMan

Forumjp59 said:

I don't think there is an outside sensor but I will look later today l. I've kept an eye on the temp guage quite a bit and during start up it does seem to pass 180 and go more towards 200. I don't see another pump, would it be another Red Grundofos if there is one? 

I'm planning to set up a gopro tonight! I sit in front of the boiler too often and my SO thinks I'm crazy haha 

She may not be wrong about that!

EBEBRATT-Ed

@EdTheHeaterMan
Can you take a peak on pg 29 of the manual I attached above? Looks like he is missing a circulator and that this thing is all wrong

hot_rod

The boiler has its own pump, it comes mounted on it on it. Below the piping header . I think it is controlled as a return protection logic

Forumjp59

EBEBRATT-Ed said:

@EdTheHeaterMan Can you take a peak on pg 29 of the manual I attached above? Looks like he is missing a circulator and that this thing is all wrong

Man if this wole thing was installed wrong, how do I even go about telling that to the contractor when he's "supposed" to be the professional. 

Also, if it was backwards and there was actually no water flowing through the boiler at all wouldn't it have more problems than just a random bang? Or is this system just a disaster waiting to happen...

JUGHNE

The zone valves look to have been soldered in previously, rather than press fit connections.

There are arrows on the body of the valve which show the direction of flow.

If flow is wrong they can hammer when closing.

Forumjp59

Here's an image of the direction of flow from the valve, towards the boiler. The arrow points towards the boiler. 


This also shows the main level/in floor radiant with a separate line. 

EdTheHeaterMan

EBEBRATT-Ed said:

@EdTheHeaterMan
Can you take a peak on pg 29 of the manual I attached above? Looks like he is missing a circulator and that this thing is all wrong

Hard to see, and I did not notice it until you mentioned to look for it, but look at the bottom of the boiler

Forumjp59

EdTheHeaterMan said:

I can't tell if anyone has given instructions on how to purge air yet, so here goes. Oops I forgot one of the valves you need to close... here is the edit: I added a step #4 valve to close just above the circulator pump. Best I can come up with based on the photograph. Hidden check valves may change this because it appears that you are purging in reverse.

This is awesome. Thanks so much for putting those instructions together. If lots of water comes out with some of the air, do I have to refill the system? 

Forumjp59

EdTheHeaterMan said:

@EdTheHeaterMan Can you take a peak on pg 29 of the manual I attached above? Looks like he is missing a circulator and that this thing is all wrong

Hard to see, and I did not notice it until you mentioned to look for it, but look at the bottom of the boiler

Here is a better close up of that area. 

Forumjp59

Also, doesn't this valve need to be open for the system to regulate properly? All I was told is that it's broken and to leave it off because I'm assuming it won't auto regulate...

EdTheHeaterMan

That manual ball valve with the green handle can be left open or closed on your system as long as the auto fill (pressure reducing) valve is working. If the Auto Fill is defective, the leave the valve closed until you get a replacement auto fill valve

Forumjp59

EdTheHeaterMan said:

That manual ball valve with the green handle can be left open or closed on your system as long as the auto fill (pressure reducing) valve is working. If the Auto Fill is defective, the leave the valve closed until you get a replacement auto fill valve

Okay that was my assumption as well, in your opinion does this valve need to replaced for the system to operate at 100%? Could the random banging be from the relief valve releasing fluid and not being replaced because because auto fill valve is defective? 

KC_Jones

EBEBRATT-Ed said:

I looked in the boiler manual and your piping looks to be all wrong. You need to look in the boiler manual. This boiler needs to be hooked up primary /secondary. You only have one circulator pump and you need 2 of them There are more things wrong than I can list. See the manual about page 29 are the piping instructions. Either I am blind and cannot read or the person that installed this has no clue as well as the three 'contractors" you had look at it. As far as I can see you have no flow through the boiler

I think you might be onto something. Here is a quote about the supplied pump on the boiler.

” These units are equipped with an integral performance loop, which is designed to provide efficiency optimization by maintaining a constant flow through the unit’s heat exchanger loop when building system flow is reduced. The performance loop assembly is standard equipment and is NOT to be used as a system or boiler pump.”

So there should be a primary and secondary pump for this to be correct.

EBEBRATT-Ed

@hot_rod & @EdTheHeaterMan

I see the pump now in the latest picture he posted. But the boiler manual I downloaded and posted specifically said no boiler pump comes with the boiler.

The flow on the secondary loop doesn't look right though.

KC_Jones

@EBEBRATT-Ed see my reply just above yours, the supplied pump is not to be used as a boiler pump.

hot_rod

I believe they mean it is not intended to flow the heat emitters. It should be able to flow the piping from the boiler through the closely spaced tees.
Otherwise you need 3 pumps to make that boiler work?

EBEBRATT-Ed

@KC_Jones if you look at page 29 of the boiler manual this thing needs 3 pumps.

I think the one mounted on the boiler only pumps through the HX to the boiler mounted manifold and that is all it does. I still think he is short a pump

KC_Jones

hot_rod said:

I believe they mean it is not intended to flow the heat emitters. It should be able to flow the piping from the boiler through the closely spaced tees. Otherwise you need 3 pumps to make that boiler work?

The wording is quite clear to the point they capitalized NOT and bolded the entire sentence.

Forumjp59

Thank you all for the time you've spent reviewing this system. 

It seems as though I need to find a way to call this company and kindly tell them the install wasn't completed to spec? 

Forumjp59

Does this info about primary and secondary piping hold any weight to explain they way they installed it? 

EBEBRATT-Ed

@Forumjp59 Yes you need the contractor to come back and pipe the boiler loke the drawing on page 29 in the manual.

It will not work right until that is done

Look at the Grundfoss circ mounted above the boiler and see which way it is pumping there should be an arrow on the pump body

Forumjp59

EBEBRATT-Ed said:

@Forumjp59 Yes you need the contractor to come back and pipe the boiler loke the drawing on page 29 in the manual. It will not work right until that is done Look at the Grundfoss circ mounted above the boiler and see which way it is pumping there should be an arrow on the pump body

It is pointing down towards the boiler 

EBEBRATT-Ed

@Forumjp59

You're only getting some gravity circulation between the boiler manifold and the heating pipes which is why it does not work right.

hot_rod

Looks like you do need a boiler loop pump, and possibly boiler protection valve on some installs

Forumjp59

@hot_rod and @EBEBRATT-Ed Thank you! I'm going to call the original installer and try to relay this info to him. 

Forumjp59

@hot_rod @EBEBRATT-Ed to make matters more fun, I set up a camera to capture the boiler noise and the hot water heater now makes loud swooshing/banging noises after the contractor flushed it a couple days ago. It was quiet before that service...this was while the washing machine was running a cycle...this is getting fun! 

EBEBRATT-Ed

@Forumjp59

Don't know about the water heater. Are you getting some water hammer? Does it happen when the washing machine starts filling and stops filling?

Forumjp59

@EBEBRATT-Ed it did not sound like water hammer, more like a jet engine. Yes it happened when the washing machine started and finished filling...seems like an odd coincidence that something has gone bad in that system.