Cold weather and Boiler Vibration

Leeman7957

So interesting information.  The gas company noted they have had some issue with some models of regulators they installed on houses... I have just such a regulator.  This may hopefully fix the issue!!! 

Daveinscranton

I had a gas well.  Natural gas.  600+ pounds at the well head.  First regulator.  Dryer.  Second regulator as I recall to drop to 12 pounds.  1” tubing for 400’.  Then a pancake regulator at the house to cut the pressure further for the gas main in the house.  Had fairly wet gas, for what ever reason.  

Water would cause freeze ups.  Before I developed a maintenance schedule, cold weather (really cold) and the furnace would go out (standing pilot cast iron boiler).  A bit of methanol worked wonders.  

I doubt that the gas (propane in your case) company wants you drizzling anything into their plumbing.  In my case, I was the gas company.  I think that the gas company would (or should) bend over backwards to help.  Assuming that tank size and cold are not causing your problem.  If the rest of the neighbors have similar tank size, and orientation (horizontal), and have zero problems, might be water (ice) causing your problem.  Which has been mentioned.

This is not the project on which  to learn the intricacies of of propane tank near piping and regulators.  In my opinion.  Again, not a pro.  Just an old guy.  

You could check propane pressure when it is acting up.  I have a manometer, dial gauge type, on a valve, plumbed into my current house (propane) line.  I like lots of added diagnostics.  Faster to get to the bottom of things.

Best wishes 

Daveinscranton

To the original poster, I just saw your last post.  

Swapping out the regulator sounds like a plan. Even better if it is on their dime.  Depends on who owns the regulator.

I would still add a dial gauge (mechanical) on a valve near the boiler.  Assuming that it is allowed.  Nice feature.  You can watch the static pressure.  And watch it drop as the boiler first fires.  On mine, it drops a bit as the boiler gas valve opens and then goes back to near the static pressure.  Gives me peace of mind that my propane piping is big enough.  I have to admit that I like overkill.  And I hate a cold house.  Hate a cold house even more if I don’t know or understand why I have a cold house.

Timco

As a former tech manager for HTP I can say the single most common issue I saw was undersized or failing reg. If it’s only at night the sun is not hitting it possibly. Have a manometer on it when it vibrates or watch the flame as it does this. As to ER10 that’s failure to ignite, which can also be low gas pressure. Be sure your igniter is the type with a metal base not the older all white porcelain type. That solved many ignition issues. There was also a “double perforated burner” that Kiturami sent us for combustion issues but they never really gave us any exact scenarios for when to use it besides “try this”. Since yours is intermittent then that likely won’t help. If it’s strictly temperature related I’m betting it’s a reg or fuel delivery. 

Smitdy

That looks to be the UFT model from HTP.  I've installed a number of HTP boilers and to be honest those uft's were the worst. There's a reason they are priced way cheaper than the EFT's and now the new ELU's.  I only put two of the uft units in and they gave me me nothing but issues. That being said sounds like an air gas mixture issue, have you had someone put a flue gas analyzer on the unit and adjust the gas valve while it is running?  Also just a heads up there is a rubber flap inside the burner that is going to break off on you at some point and stop the unit from running, the two units that I installed I just removed the flap and did not replace. If the gas mixture is off and needs to be adjusted you may need to have the heat exchanger cleaned out it should be done once a year anyway. When I service boilers I clean them out with a product called RydLyme it seems to do the best job, even better than CLR at getting rid of scale. The water trap on the bottom of the boiler also should be flushed out and refilled. If you have the install manual there is a page in there somewhere that will give you the correct CO, CO², & O² values that the boiler should be at when running, you can adjust these values at the gas valve, again you need a technician with a flue gas analyzer to do this. Also is the venting 2" or 3"? it looks to be a short run, if it's 3" you may need to choke the exhaust vent down with a three by two reducing coupling at end of the termination, sometimes those units need the back pressure.  Just a personal choice as it may not be regulated by code in your area yet but many places do not allow PVC to be used for the vent, it's okay for the intake but the vent should be made out of CPVC or another product that is made to take the temperature. Even though the manual will tell you you can vent it with PVC the pipe manufacturers do not want their product being used for that purpose. Many areas have started to change their codes as to disallow PVC for the venting of high efficiency heating equipment. Best of luck -Chris

4Johnpipe

These units have an adjustable Venturi on the intake side of the fan motor where the rubber tube connects with the brass squeeze clamp.
Squeeze the clamp and pull back the rubber hose…this will allow combustion air from the room. Just inside the fan housing you will see the Venturi it should gradually open with fan speed. There may be something stuck or it may be jammed.

The other possibilities are clogged condensate at the bottom collector or a defective fan.

I’m not impressed with the blemish on the fan casting something is pointing me there.

Nutjob

I viewed the video of the flame window; flame flickers in synch with the vibrating noise. Is this due to lower than minimum gas pressure in single digit temps starving the system of gas followed by a momentary flame out then reignited, creating the combustion noise? Is the gas regulator faulty (indoors or outdoors?)?

Voyager

Given your description, videos, boiler error code, and no obvious installation errors, I would do some troubleshooting before making modifications to the exhaust, gas piping, etc. I have NG and am not familiar with propane delivery systems, but it certainly sounds like you are getting an interruption in gas flow and the flame in your boiler is going out, or very low, and then coming back on full again in short succession. This suggests interruption in gas flow causing loss periodic loss of pressure.

I would want the tech to start by ensuring that pressure is within the range at the gas valve. If they can’t measure pressure while the noise is happening, you may have to buy your own gauge or meter. You can buy gauges for less than $100 and have your tech plumb it into the feed line so you can monitor it when the noise is happening. You don’t need an expensive and super accurate gauge, just something where the needle will move if the pressure is varying quickly or trending low at certain times.

A combustion test never hurts, but I really doubt you will see any issue unless the boiler acts up during the test, which is unlikely. It sure seems like a rapid variation in the burner flame.

Lance

I briefly read above and may have missed a few details. But starting from zero, I would do the following: monitor the gas and vent pressures looking for fluctuation. This is a pulsing combustion pressure effect. It can be caused by a propane vaporization but I would like to rule out, gas regulators, water in the combustion chamber that when heated is changing in to a vapor as it heats up. What shows up than goes away when heated? A leak, condensate puddle, and in variable unit, oscillation that overreacts to minor changes from controls. Voltage drop can cause motor changes which can affect blowers. What is the combustion test showing?, and how does it compare to the commissioning report? and of course the usual problem of combustion adjustments are set wrong. An interesting factoid. Propane tank size and orientation affect its ability to provide a steady vaporization especially when temperatures dip. But even a pipe can have a spider web in it, tests good statically, but not with flow. If the vent termination is a question, remove the 45 and if it goes away... But I doubt it is a factor. But again, could there be two things that are causing this. The more complex we make it the more difficult the diagnosis and more frequent the failures. Also the stupid can occur, correct orifice?, Engineering? It will be in the last place you look.

MadecksMechanical1

It sounds like a regulator problem. Have someone check the pressure (static pressure) when its cold enough outside to make that noise. It could be the regulator especially when the propane tank is low. I don't know about what your codes are there but here in Jersey even if the directions say turn that 45 up code won't allow it here. For the I would cut the pipe right  before that coupling add another piece of pipe with a 45 facing down you don't have to glue it for now. That can cause extra condensation facing up. 

Daveinscranton

Being a curious sort, and recovering physical chemistry major (long time ago), I plumbed a nice glass lab quality differential manometer with 3 way valves into my (now deceased at age age 14) HTP Munchkin mod con boiler.  Stainless fittings on the exhaust gas side and valved at the pvc exhaust.  Brass fittings on air intake pvc.  It could be used as a simple nanometer on intake or exhaust.  Or as a differential manometer.  I wanted a baseline of what normal function was.  Steep (for me) metal roof.  You could diagnose a birds nest, or the lack of one, in the intake or exhaust from the basement.  Or look at blower/fan health.  I don’t recommend all this gadgetry routinely but I had the stuff so I put it in.  It actually came in handy.  

Stet

Two Things, I have delt with, both with a boiler with negative pressure gas valve.

One was with a sudden drop in temperature. This particular case was the regulator sticking.

The second problem was beyond frustrating. This boiler had been installed for five years. Customer said boiler was howling. Not all the time. Went to check. Of course, no noise. checked the gas pressure, OK. low fire, high fire, normal. a few days later I get the call again. Go back. NOW I have the howl. I had a replacement gas valve. ( I always have service parts for what I install) Changed the valve. Still have the howl. Found a break in the intake venturi. There you go. Found it. I replaced the venturi. Nice and quiet. All fixed! (So I thought) I few days go by. Get the call. Noise is back.****! I go over again! No noise! High Fire, Low fire, DHW, Central Heat! Nothing! and then the basement door blew open and there was the howl. We were getting a strong wind from an odd direction those few weeks in New England. Blowing right at the exhaust and intake. I changed the direction of the intake and exhaust. Howl never to be heard again.

Wind was messing with the mixture. The howl (vibration) I am sure it was caused the venturi to crack.
And this problem will be more prominent with propane than Natural gas.

Additional Note: This was a Slant Fin CHS Boiler. I have installed dozens of them over the last 10 plus years. The first in my own home. They are all running fine. Minimal problems. And if there is, the factory (AND FACTORY SUPPORT) is right in Long Island, NY. I have been in this business for over 50 years. You won't find better factory service ANYWHERE! When I had this problem, factory service support was right there every step of the way. Can't say enough for their service team.

Darrell_4

Alaskan Serviceman here…two things to check. 

Propane loses its vaporization the colder it gets…meaning that in single digit temps even a full propane tank will not develop sufficient pressure to float the regulator.  If you heat the tank even a little the pressure will rise…I have customers with heat tape wrapped around their propane tanks that comes on to keep the propane at 30 degrees. 

But…more likely the gas valve needs to be tuned by somebody who can use a combustion analyzer really well.  When the temps drop to single digits and below the air is much denser and will mix differently resulting in a fluttering burn and often a harmonic in the flue piping.  You want to do the test just like the book says but make sure you go above the mid-scale reading.  For instance, if the book calls for a CO2 reading of 9-11…you wanna get at least 10%.  It doesn’t seem to matter what the temp is when you do the test as long as you get over mid-range. 

Sufficient gas pressure with no dip at light off or 100% burn. 

Above mid-range combustion test at minimum fire and maximum fire. 

And, absolutely the vent can get blocked with snow, frost and ice. We seldom use the factory vent face because it frosts over.  If you have no wind and low ambient temps, the exhaust (relatively wet and heavy) will hang in the air and be sucked back into the intake…where it accelerates and will make hoar frost and choke the boiler.  We turn the intake down at least 24” and turn the exhaust up with a 45 (cut at 45 on the end so it doesn’t collect rain) so it blows the heavy wet exhaust up and away from the intake.  I make a lot of money knocking frost off of vent intakes…

Smitdy

Someone on this thread recommended looking the 45 down I do not recommend you do this you're going to end up with cross-contamination as the flue gases tend to hang around and swirl. I look the 45's up in a similar manner on every installation I do and I've never had an issue.  If you look the 45 down and end up with flue gas is coming back in your intake you're going to have a whole new list of issues. I've seen cross-contamination cause heat exchangers and burner Motors to fail on multiple installs on all different types of high-efficiency heating equipment.

Leeman7957

So the issue didnt go away at all. The Gas company came out and replaced the regulator, filled up the tank, and checked the pressure which was perfectly fine. Fire back up the boiler and the noise and vibration come back instantly. At least the gas guy was able to hear it this time as he was there after 4pm. It has to be in something with the intake line as restricting the flow makes the system run fine. Please review the following video links. I have a different tech coming in today to take a look and I will mention all your suggestions.

https://photos.app.goo.gl/5ViupXmQW3sPzPSo6

https://photos.app.goo.gl/ehjV9GGpoHtetdWJ8

Daveinscranton

Wonder what would happen if you burned indoor air as an experiment.  Should be easy enough to try.

Best wishes.

Daveinscranton

You could try adding a 90 (not glued)  or two to the intake.  Another experiment.  Maybe a harmonic related to flow.  Assuming you have the combustion analysis anywhere near close to the factory specs.

Daveinscranton

Could it be that 5 degree air is more dense leading to a lean mixture?  The boiler may not adjust for air density.  I don’t know how it was made.  If this is the case, perhaps more intake piping in a heated space, a heat exchanger of sorts, to warm your 5 degree air would help.  This experiment would be cheap to try.  I would think that the factory or tech support would have seen or heard everything.  Including your problem.  Excellent science experiment.  (Certainly not what you wanted to hear).

Daveinscranton

Seems like a mixture problem.  When you choked off the gas supply valve, you got a lean condition.  And noise.  When it was roaring, you choked off the air intake with your hand, richening the mixture.  And the noise went away.  Pretty sure that you will have this one sorted out soon.  I found the comments of the gentleman from Alaska fascinating.  You are in about the same climate it seems.  Or close.

klong

Have experienced this same issue.  It was the proximity of the intake and exhaust.  The install looked similar to yours.  Moved the exhaust up and away from the intake.  The issue went away.  Seems as the air is colder the issue was worse. Thinking the exhaust air must fall and somehow mix with the intake air throwing off combustion.  

Tried so many things and tried to tune the issue away.  Just could not get it to change until we changed the exhaust.  Good Luck!

jeffl2019

I'll go out on a limb and say the mixture is off.

When it's cold out, the air is denser thus more gas is needed to be fed to make the mixture correct. Recognizing that cars use a MAF/sensors to adjust the mixture for this reason, and furnaces don't, it might just be set too low. (or have marginally low gas pressure that only shows up when you really need just a little more gas to make the burn correct.)

I say this because someone once (by mistake) installed a gas valve that came on in 2 steps onto a furnace I owned. When it lit off, the vibration and hum was really noticeable for a few seconds before the full gas flow was released by the valve.

(fyi, my furnace required a gas valve that 'ramped' up linearly, which they eventually found and installed.
They were trying to solve another tech's mistake of installing a single 'all or nothing' valve. Guess what happened when that valve came on? Big pop and band when it flooded the tubes and lit off....)

maddog1950

first of all get rid of the 45 and install a tee, that way the hot exhaust will rise and an condensate will drip down and won't collect any rain water or snow in the exhaust vent when idle. Second are there any other appliances drawing gas when the vibration occurs, also at lower temp. there is more oxygen per cu. ft of air then at higher temp. that extra oxygen could be cooling the flame enough to effect operation. It definitely sounds like a gas/combustion issue.

Leeman7957

So it was a mixture problem.  The gas mixing with the air was WAY to low and as it got cold it could not stay lit constantly and was causing this sputter.  Had a new tech come in who has actually installed these and he knew exactly what was wrong and increased the gas mixture.  We've now had -32 and no issues other than frozen regulators we need to keep thawed but the boiler operates normally now.  They're going to adjust the exhaust next time they are out.  Thanks for all the input.

Daveinscranton

Done.  I love it.  Few odds and ends to clean up.  

Best wishes.