Cold weather and Boiler Vibration

Leeman7957

I have an HTP boiler for my house in Minnesota and when the temperature dips into the single digits the unit will occasionally vibrate and then spit out a burst of exhaust. Once it warms up to about 10 degrees F the issue no longer exists. Initially service agent thought there might be a freeze up at a junction site so I put hot water over these areas but it did not solve the problem, plus at 10 degrees water should still be frozen if it was indeed restricting gas flow. Any ideas on what might be going on here? It only happens when we get into the single digits or lower. The noise is very loud outside but I live in a pretty secluded area. The gas type is propane.

Leeman7957

Additional info the system is only 2 years old now and we did not see this last winter when it was also extremely cold. When I say it bursts out exhaust the exhaust has a constant flow thats visible then when it vibrates it seems to spit out a large ball of exhaust then constant flow again. Its not continuous vibration but rather a build up you can here starting then it vibrates a second or two then stops ... rinse and repeat. I am able to stop the vibration though when I inserted a few fingers into the intake air line to see if anything was blocking the air flow however by doing so I blocked a bit of air flow and the situation stopped.

EBEBRATT-Ed

First stem would be to check and make sure bot intake and flue pipes are clear and unobstructed. Sometimes a bird or something can get inside them.

Then have you technician do a combustion test on the system and see what shows up

Leeman7957

The pipes all seem to be clear. My question though on that would be if there was an obstruction wouldnt that cause a constant issue regardless of temperature, and not only present itself in very cold weather?

Jamie Hall

Leeman7957 said:

The pipes all seem to be clear. My question though on that would be if there was an obstruction wouldnt that cause a constant issue regardless of temperature, and not only present itself in very cold weather?

The vibration from an obstruction or even from slightly off piping could well be temperature sensitive. The piping could resonate and vibrate only over a rather narrow range of temperatures.

That said, have you checked for the possibility of ice forming in the intake in cold weather?

Leeman7957

Jamie Hall said:

Leeman7957 said:

The pipes all seem to be clear. My question though on that would be if there was an obstruction wouldnt that cause a constant issue regardless of temperature, and not only present itself in very cold weather?

The vibration from an obstruction or even from slightly off piping could well be temperature sensitive. The piping could resonate and vibrate only over a rather narrow range of temperatures.

That said, have you checked for the possibility of ice forming in the intake in cold weather?

We will be experiencing single digits to sub zero temperatures starting thursday so I will definitely look to see if there is any build up and get back to you. Its been unseasonably warm right now so there has been no vibration of the boiler.

Leeman7957

https://photos.app.goo.gl/YixwZXurXpZrDxJA7

This is a short video of the noise it is making but only when it is very cold ... below 10F

Leeman7957

https://photos.app.goo.gl/4sv6CrFgCjWUPufs9

This is a video of the exhaust and what it is doing when the vibration of the boiler occurs.

neilc

nobody is going to like that turned up 45 on the exhaust,

is the inducer fan condensate drain clear?

neilc

and what's that icon on the panel represent?
it's flashing in time with your noise

Brent H.

@neilc I think the blinking indicator is due to there being no outside temp. sensor. I dug around on the HTP site and think the poster has an Elite boiler. Picture below of what different indicators mean from the manual.

Jamie Hall

I wonder... I just wonder... if under certain unusual conditions that boiler is trying to modulate in response to an outside temperature signal which isn't present. it shouldn't, of course -- it should just ignore tha absent signal and default to something, but it wouldn't be the first time I've hit a control system which has an odd response to a missing input.

Leeman7957

https://photos.app.goo.gl/YixwZXurXpZrDxJA7

Leeman7957

neilc said:

nobody is going to like that turned up 45 on the exhaust,

is the inducer fan condensate drain clear?

The turned up 45 is actually on a lot of houses in the area. I havent found any obstructions in either the intake or exhaust line. The blinking light is (as the poster above notes) the absence of a outside temperature sensor. My neighbor has a similar HTP and hers has the same blinking icon. It doesnt seem to cause any issues with hers so I am thinking it doesnt have anything to do with my issue.

Leeman7957

@neilc We should be getting low single to negative numbers tonight and tomorrow so ill update if I find anything forming. I am expecting the system will resume vibration tonight when we are to hit around 3 degrees

Leeman7957

So to update we have had several days now of negative degree temperatures and the vibration in the system just isnt constant. Its pretty reliable that it will start in the morning when the furnace kicks on but it vibrates for a bit then stops. If I were to describe it in terms of humans its like someone is clearing their throat over and over and then it gets clear and works flawlessly from there on out. When it seems to sit over night not running then wakes up it starts the throat clearing again. So I am just baffled by this situation. Is it possible there is ice build up in the exhaust pipe and backing up the exhaust in to the system until the heat melts the ice away? Is that a possible reason for the vibration?

Jamie Hall

In one word, yes.

neilc

I still don't like that turned up 45,
unless you show me it in the manual somewhere,
don't you see how it could collect and trap condensate there,
and it would freeze back to your machine?????
Do Not Keep Up with your neighbors on this one, LEAD.

but back inside the machine,
are your condensate drains clear ?
the trap also?
the port under the collector and the inducer fan ?
these are annual maintenances in your manual,

post a picture inside the boiler cover

Leeman7957

neilc said:

I still don't like that turned up 45,
unless you show me it in the manual somewhere,
don't you see how it could collect and trap condensate there,
and it would freeze back to your machine?????
Do Not Keep Up with your neighbors on this one, LEAD.

but back inside the machine,
are your condensate drains clear ?
the trap also?
the port under the collector and the inducer fan ?
these are annual maintenances in your manual,

post a picture inside the boiler cover

I will take some pictures of the inside. I am not a boiler technician. Maintenance was performed in October and levels checked at that time. Technician is the one who piped the exhaust. Should it point down or just straight out?

Leeman7957

Question ... someone also mentioned low gas pressure into the house. Could that also cause this vibration?

neilc

I'm gonna say straight out until I see the freshair intake,
pointing it down might start an exhaust gas recirculation,

low gas pressure, yeah, sure,
are you saying none of your techs have put a manometer on this yet ?
job one,

can you see your burners and their flame,
is it throbbing with your sound ?

do you have your manual ?

HVACNUT

The exhaust should rise towards the termination. That horizontal run looks like its pitched down towards the 45. Not good.
Some manufacturers spec an inline Tee on the exhaust with a drain in the bull.
It sounds like the inducer fan is making crushed ice. Get your guy back.

kcopp

Im not wild about the upturned 45 but it is a common practice by some Mfg to ask for this. They are concerned about cross contamination.
A coupling and a properly pitched vent will work.
i am wondering if the house regulator is getting sticky when it gets that cold and messing w the gas pressure.

neilc

the fan is shuddering on the condesate puddle in the inducer shroud

Leeman7957

Here are some shots from the inside of the boiler.

To add to the situation this is actually only happening at night.  I ran it for a good portion of the day the last two days as temps where low in the negatives all day but the system never acted up.  Why does cold at night affect it yet not colder temps in the day?after 

Leeman7957

neilc said:

I'm gonna say straight out until I see the freshair intake, pointing it down might start an exhaust gas recirculation, low gas pressure, yeah, sure, are you saying none of your techs have put a manometer on this yet ? job one, can you see your burners and their flame, is it throbbing with your sound ? do you have your manual ?

I have the manual and here is the section on vents.  I sent a request to see if pressure was checked I'm waiting to hear back but it's the holiday season so may take a few days.  However the tech comes in the days when nothing seems to act up of course.  Today though it did display an er:10 code of flame extinguished 5 times see picture.  The propane tank is also down below 30 percent if that means anything.  Probably will get a refill this week or next.

Leeman7957

Leeman7957

https://photos.app.goo.gl/Mvmn6hNEwcsCauV76

Here is a clip of what's going on inside as the vibration goes

kcopp

A couple observations.
>Even though the Mfg shows the upturned 45 on the termination I would remove and see what a coupling does. There may be built up ice in there.
> there is a fair amount of CSST gas piping there. That has been known to cause harmonic vibration noises as the gas flows through and into variable speed gas valves.
> is the LP gas tank in the sunlight? Sun warming that up may make a difference in the day.
> I would consider treating the condensate from the boiler....maybe have it go to a trap vs. just letting it drip into a floor drain.

Leeman7957

kcopp said:

A couple observations. >Even though the Mfg shows the upturned 45 on the termination I would remove and see what a coupling does. There may be built up ice in there. > there is a fair amount of CSST gas piping there. That has been known to cause harmonic vibration noises as the gas flows through and into variable speed gas valves. > is the LP gas tank in the sunlight? Sun warming that up may make a difference in the day. > I would consider treating the condensate from the boiler....maybe have it go to a trap vs. just letting it drip into a floor drain.

Thanks for the insight.  I'm not sure though what a trap would do rather than just having it go down the drain?  What does treat it do?  

I've checked the 45 several times before operation and snaked some poles through and not found any blockage at any point.

The tank is in the sun which would make a lot of sense but however how can it be corrected for night time?  Of course temps will be above 10 today and tomorrow so there won't be any issues I'm sure.  

realliveplumber

Its amazing, the cheapest and fastest suggestion offered by experienced professionals gets discounted by the op.

The most valuable thing I have learned on this site is "what are you going to next, after what you've just done, does not fix the problem. [thanks for that]

Leeman7957

realliveplumber said:

Its amazing, the cheapest and fastest suggestion offered by experienced professionals gets discounted by the op. The most valuable thing I have learned on this site is "what are you going to next, after what you've just done, does not fix the problem. [thanks for that]

Honestly I'm not sure what you're trying to say.  I haven't discounted anything.  I'm merely looking for explanation and reasoning.  

Leeman7957

neilc said:

I'm gonna say straight out until I see the freshair intake, pointing it down might start an exhaust gas recirculation, low gas pressure, yeah, sure, are you saying none of your techs have put a manometer on this yet ? job one, can you see your burners and their flame, is it throbbing with your sound ? do you have your manual ?

Speaking of exhaust recirculating I did take some video this morning of what was going on outside.  
I'll look to remove 45 but it's stuck on their real tight

https://photos.app.goo.gl/73F67xYJkydXgWth8

Leeman7957

So interesting enough I was able to mimic the vibration from the boiler.  By slowly closing gas inlet to the boiler it started to make the familiar vibration sound.  

So I'm starting to lean that it is low gas pressure from the tank being down below 30 percent, only happening at night when sun is not on the tank, and temps below 5 degrees.  I'm going to see cenex tomorrow about a delivery to see if the increased lp brings pressure back up and the issue goes away.  I'm on auto delivery and not sure how low it needs to be before it triggers their arrival.  I'll keep posted

Daveinscranton

How big is your propane tank?  It is possible that your tank is not big enough if throttling back the gas replicated the noise.  In extreme cold, the liquid propane still needs to evaporate into vapor.  The heat of vaporization has to come from somewhere.  At 5 degrees, it could be that there is not much propane evaporating into propane gas.  If this is the case, you may need a bigger tank.  (At 50% fill it may work better than 90% full.)

Just a thought.  Old physical chemistry major. Not a pro so take with a grain of salt.

Daveinscranton

BTW.  Long tanks (horizontal) should give move evaporative area than tall cylindrical ones of the same volume.  

Daveinscranton

Further looking for Zebras, could be in your tank or house regulator too.  Or piping.  Something external to the boiler itself.

At one time, I had a gas well.  Free gas.  Downside was the maintenance.  I miss that house every winter.  

neilc

so I was wrong about the turned up exhaust 45,
I'll be wrong again,

I am back to gas pressure, and I think your on it,
answer the tank size and orientation questoins

you did show one picture of the condensate trap inside the case,
small clearish plastic jar, mostly full of water, bottom right,
check that in your manual,
but not your problem either I don't think

EBEBRATT-Ed

The first thing I would do is get rid of the upturned 45.

The fact that water snow & ice can block the vent is rediculous.

If it won't come off cut it off. Extend the pipe with a coupling and put a 45 deg whistle cut on the pipe (cut the pipe on a 45)

Get rid of the csst flex gas pipe that stuff is no good and may be causing the noise.

Post your location and the size of your propane tank (above ground or below ground) and BTU of all appliance's connected to it so we can check the vaporization rate.

Make sure the propane company is treating the propane with additive to keep the propane from freezing

moisture can cause a regulator to stick

PC7060

This is unrelated to your problem but I noticed you are dumping your condensate directly into a floor drain.  The acidic condensate needs to be neutralized before dumping into drain or it will eventually eat up any metal it runs across including the floor drain cover. 

Quick question: is that rectangular unit under the air extractor the compression tank?

Leeman7957

My tank is a 500 gallon horizontal above ground tank.  It's exactly like everyone else's in the area. 

I'm not home so I'll get the btu information when I do.  I know the only things on gas are the boiler, stove, and dryer.  I wanna say the tech said it was 140000 btus on the boiler but I'm not committing to that.

I'm in northern Minnesota near Canada border.

I'll need to consult manual regarding if it's compression tank.

I'm discussing with gas company in regards to tank and regulators.  It's just very difficult when during the day there is no issues and they certainly aren't coming out at 4am to listen to it vibrate.

I'll keep you posted