Backdrafting Gas Water Heater + Boiler Noise Issue Advice?
Last winter we noticed a buzzing/droning sound with a higher pitched overtone coming from our boiler while it was operating. This sound was really loud and certainly louder than the normal operating noise. Unfortunately it is not making the sound now but I did record it last season and can be heard here:
https://soundcloud.com/christopherjanzen/boiler-noise/s-Z9GMCsV9QkB
The model is a Weil-McLain Gold CGi Series 3 from 2013 (11 years old).
While I had a company come assess the issue, I also brought up a concern with potential backdrafting of flue gas from our atmospherically vented hot water heater as the plastic coverings around the hot and cold water pipes are melted. It seems like our house has a negative pressure (we tested with range hood and bathroom fan and this was enough to create a backdraft). The hot water heater is also from 2013 (11 years old).
For context, we live in Winnipeg where our winters get to -30C/-22F. Our home is a 1000sqft bungalow and was built in 1925. It has an unfinished stone foundation with radiant heating on the main floor with 5 radiators. We purchased it 9 years ago and, embarrassingly, the boiler and hot water heater have not been maintained during that period of time. The heating and hot water have been just fine aside from the loud noise that started intermittently last winter season.
As it relates to the boiler, the technician suspects that it could be the inducer motor is shot and that perhaps we’re hearing a bad fan and/or bearings. They quoted $ CAD for the part before taxes and labour.
The technician recommended a few solutions and I’m hoping to get some other opinions from this community while I wait for another estimate from local companies. Here are the proposed solutions and their respective costs:
- Their first recommendation is to replace the boiler and hot water heater in one go with a new Triangle Tube Instinct Solo 110 boiler along with a Triangle Tube Cardinal 40 indirect water heater. This would include new components and venting holes to bypass the chimney thus solving the negative pressure issue and boiler issue. They quoted $$$ CAD + taxes.
- Second recommendation is to replace the hot water heater with a power vent gas Rheem PROG40S-36N hot water heater installed for $$ CAD + taxes. This would include new venting holes to bypass chimney and circumvent the negative pressure issue. This solution of course does not solve the potential boiler issue.
In either case, the electrician that came along felt confident that we could fit these solutions on our existing electrical panel.
As someone who is quite ignorant about all of this, comparing a $ + $ + $ Labour = ~$$ solution to a $$$ is giving me a lot to think about and obviously quite a large spread.
When the technician came, for some reason they were under the impression that the boiler was about 15 years old instead of 11 years as I discovered after the fact. I could see 15 years (especially with 9 of those years being unmaintained) being easier to justify replacing the boiler altogether, but considering it has otherwise run just fine and is only 11 years old, I am having a hard time wrapping my head around this.
Ultimately I am willing to pay the $$$ if that’s the right solution, but what advice do you all have? Let me know if more information is needed to help inform your advice!
Comments
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@cijanzen We don't allow pricing information on this forum as it can lead to unfair practices. I replaced your price numbers with dollar signs instead.
Forum Moderator
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Two possible sources of the buzzing: one is the inducer fan/motor which would run before the boiler fired.
The other is the gas valve, but only when it opens and the boiler fires…..after the fan does a pre-purge.
You can add a "Fan in a Can" which will pressurize the boiler room with fresh outside air, whenever the boiler or water heater fires.
11 years is not very old for a cast iron boiler
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Hi, Speaking only about the water heater backdrafting; either there is a negative pressure in the room where the water heater lives, or there is an obstruction in the vent. I would look at the vent cap on the roof and see if it's damaged, to start. Check out as much of the vent pipe as you can. Any damage? Next, make sure the door to the room the heater is in, is open. If there is a window to the room, open it. Make sure no fans are running in the house. Now, fire up the water heater and see how much it backdrafts. You can hold your fingers close to the the draft hood, or use a stick of incense to see which way fumes are going. When things operate correctly, backdrafting should only happen for a few seconds after the heater fires up. Time it and let us know what you find.
Yours, Larry
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thanks @HeatingHelp.com, didn’t mean to break the rules! Suffice to say that the option to replace the boiler and hot water heater is a little over 2x the cost to potentially replace the boiler induced motor and hot water heater.
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there’s definitely a negative pressure in the house. One crucial detail that I should have mentioned is that we have two portable air conditioner units in the house running at this time. Now, that won’t be a problem in the winter, but even then the range fan + bathroom fan was enough to create a negative pressure that prevented the gases from escaping normally. When turning off these fans it does exhaust normally, but it should perform as expected with those everyday fans.
if I’m not mistaken, we tested with those fans running and had a window open right next to the hot water heater and it still was backdrafting. I’ll perform that test again though just to double-check.
the basement is unfinished and totally open so there’s a lot of space to pull air from. I don’t see any blockages in the vent cap at a glance from ground level and unfortunately don’t have the means to access it myself at this time.0 -
A new water heater of the same design will not fix the problem.
A power vented WH might not either…..it than could back draft the boiler.
IIWM, I would try to sell you the Fan in a Can and fix the boiler.
But then I am old school…….
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If the power vented water heater had a 2-pipe installation, wouldn't that have 0 impact on the boiler? I ask this earnestly because I have no idea! I'm possibly leaning towards the repair and add a fan-in-a-can solution or explore HRV (don't know much about that either) to help offset negative pressure.
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Hi, If there is no reasonable way to fix the air pressure, how about going with a direct vent heater? These don't need power or have a fan. There is less to go wrong. 😊
Yours, Larry
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thank for the suggestion, that type of water heater hadn’t been recommended to me so I’ll definitely look into it!
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Hi @cijanzen, This type of heater will need to be close to an outside wall, but if you can do that, I've seen very few problems with them.
Yours, Larry
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After seeing a video of someone else's boiler with a bad gas valve, I feel quite confident that this is exactly what mine is doing.
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If you gently "thump" the side of the valve with a rubber handled screw driver the pitch may change.
The same screwdriver can also be used as stethoscope by putting the tip against the valve and the handle pressed to your ear. You could listen to the inducer motor also.
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The only thing is that the issue is very intermittent and I don't know what factors are involved to trigger the issue! Certainly this information will help though when it inevitably does come back.
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Thanks everyone for your support so far. Here's a problem statement and question based on what I'm discovering so far:
Because the house seems to create quite a strong negative pressure when range hood and bathroom fans are running, with it getting worse if dryer is running or portable air-conditioners, I think I need to replace the hot water heater with something that will not be affected by negative pressure. It's getting up there in age anyway so I think it could make sense to do something like direct vent or power vented.
In addition, my boiler is 11 years old, seems okay except occasionally hearing a noise that sounds an awful lot like the gas valve failing in some way. Sounds exactly like this:
Now, that should be repairable, and assuming everything else is okay despite the neglect the boiler has received over the last 9 years, would it possibly make sense to install a high-efficiency boiler with indirect tank that would intake and exhaust directly from outside or does it make more sense to keep existing boiler and try to get the water heater vented outside? Again, this would avoid the negative pressure.
I'm just trying to think of the most economical solution but at the same time determine what would make most sense in the long run.
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The hrv or the fan in a can make the most sense. The other appliances that vent outside like the dryer and the exhaust fans won't work well if they are under negative pressure either. The main maintenance to perform on a cast iron boiler is to make sure it is burning properly and that the safeties work. There is little reason to replace an 11 year old boiler unless it is leaking.
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They're upselling you. And they might not even fix the problem.
As has been suggested: Fix the negative pressure issue, and inspect the flues. And then fix the boiler. At 11yrs old you could get another 30 out of it easily. That water heater might live another 5-10 years.
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