Installer has let new cast iron boiler condense for months.

john_james

mattmia2 said:

The issue, at least so far, isn't that the vent is perforated from corrosion (though that will happen eventually), the issue is that it may not be drafting properly, it may not be pulling the products of combustion up the vent but that they may be spilling out the draft hood.

Thanks for making me aware of that.
I will have the new guy look at that too.
I bought a third CO + gas detector and installed on the first floor directly above the boiler.

This morning I put one of the alarms in the basement by the boiler, the specs say it will display CO on the screen at CO above 30ppm. The boiler has been on for 4 hours straight and the display has stayed fixed at 0ppm.

pecmsg

Purchase a Low-Level CO detector not the UL listed version.

Defender is one I like.

john_james

pecmsg said:

Purchase a Low-Level CO detector not the UL listed version.

Defender is one I like.

I'm trying to.

I've searched all the stores in Canada, they were only UL:
- Home hardware
- Home depot
- Canadian tire
- Lowes

We only seem to have kidde and first alert, which can take up to 4 hours at 70ppm to sound. Google nest is available but doesn't actually say when it goes off.

Likewise amazon Canada's top 100 carbon monoxide detectors are not any better; X-Sense is only UL and airthings doesn't even do CO. The rest of the listing are really cheap stuff or handheld detectors like this:
https://www.amazon.ca/Sensorcon-Inspector-Industrial-Adjustable-Vibrating/dp/B08235BSWG/
which ships from the US anyways and is $400CAD.

Anything from the US that isn't upstate New York or Michigan will take a week to get here. Smaller businesses that don't prepay customs and duties are worse; I've had packages from shippers besides USPS (especially UPS) just hold things up for another week at the border.

Ironically the Defender is made in Canada, but searching around all the sellers seem to only be in the US. They have contact info for their US representative, but nothing about Canada.

I am trying to take your advice and appreciate you looking out for my family and I, but I just can't find anything in my country. If anyone has anything in Canada I would appreciate it.

captainco

Problem number one is the boiler is underfired. Doesn't look like there are any holes in the llue for testing. The flue temperature of the boiler, regardless of the water temperature should be over 250 degress and eventually over 300 degrees. These are not temperatures that should condense. No such thing as a flue too big or no water heater would ever vent. By the way water heaters take in much colder water than 120 degrees and only make 120 degrees. Condensate is caused by underfiring and possible venting problems. Almost all induced draft equipment will condensate after the burner shuts down because the inducer turns off before all the flue gases exit the boiler and flue. This can ber modified by someone with some mechanical skills.

Don;t know what part of Ontario you live but I have trained contractors in New Market. If they are too far, they may know someone else that they have worked with.

mattmia2

The kidde nighthawk detectors will at least show if at some point they have seen down to i think 10 ppm if you press the button to look at the memory. unfortunately to be UL listed they can't display continuously.

john_james

captainco said:

Problem number one is the boiler is underfired. Doesn't look like there are any holes in the llue for testing. The flue temperature of the boiler, regardless of the water temperature should be over 250 degress and eventually over 300 degrees. These are not temperatures that should condense. No such thing as a flue too big or no water heater would ever vent. By the way water heaters take in much colder water than 120 degrees and only make 120 degrees. Condensate is caused by underfiring and possible venting problems. Almost all induced draft equipment will condensate after the burner shuts down because the inducer turns off before all the flue gases exit the boiler and flue. This can ber modified by someone with some mechanical skills.

Don;t know what part of Ontario you live but I have trained contractors in New Market. If they are too far, they may know someone else that they have worked with.

I'm reading more about under-fired and might post a question later.

I'm going to DM you with specifics of my location and the contractors.

I probably should have specified condensing from the chimney, as opposed to in the boiler. I have learned the difference now.

---

Venting problems make sense based on my conversation today.

Another contractor, (call him "B" and the original install "A" for clarity), from the next town over spent an hour on the phone with me today, I was sending him pictures and measuring stuff. "B" had me open the physical manual and double check things with him against the manual he had online. In a shorter conversation yesterday, "B" was the one who also suggested opening the bypass valve (as most people here did too; note I said my boiler was condensing, but I cannot remember if I said where the condensation was dripping from). "B" has done this all free of charge so far.

I have next to no knowledge about gas appliances or venting. So I might be using some terms wrong and I'm paraphrasing what he said below:

Contractor "B" pointed out a couple of illegal things that "A" did venting it. "A" used insulated B-vent on the flue, which was also downsized against the manual's instructions (4" ID vs 5" in the manual) to try and fix the condensation.

The vent pipe was also installed the wrong way in one section (the pipe sections that fit together had the larger side towards the boiler). Contractor "B" said a boiler was a 'positive pressure exhaust' (any mistakes with this specific term is my error in memory here), so the larger side needs to face the chimney to avoid leaking.





The chimney length is also on the border of being too long. The chimney is also around 23" wide (external diameter) inside the walls. He said they might have to run a stainless steel rigid pipe down it (it is a 5" diameter flexible duct now) or figure something else out, but he will have to look at the boiler first.


Where the vent goes into the wall. This is probably the liner sticking out here. "A" also cracked the concrete and didn't repair it:



Here's our chimney (brickwork redone from the roofline up in the last 10 years)


Our chimney used to look like this (our neighbours chimney here; our buildings are symmetrical)



Contractor "B" said the boiler temperature (supply and return) was too low and "A" was probably lowering the temperature to try to get it to run longer and avoid condensing as much. "B" said he would install a thermostatic mixing valve for return temperature boiler protection if I wanted.


I'm thinking this guy knows his stuff. He was recommended by the counter staff at the plumbing and HVAC supply store and has spent plenty of time with me on the phone. I'd like to see what people think of him.

john_james

mattmia2 said:

The kidde nighthawk detectors will at least show if at some point they have seen down to i think 10 ppm if you press the button to look at the memory. unfortunately to be UL listed they can't display continuously.

Thanks, that's useful. I just checked and one of my current alarms has that feature too. I'll make sure to check it periodically.

Kickstand55

I haven't read everything posted here, but, insulate those pipes and find a competent contractor who knows your system.
Is the boiler sized for the entire load?
May need a primary/secondary system retrofitted to help combat low return temps with a large water volume . Aquastat needs to be set to prevent condensation. Being a cast iron boiler, it will self destruct in short time.

john_james

Kickstand55 said:

I haven't read everything posted here, but, insulate those pipes and find a competent contractor who knows your system.
Is the boiler sized for the entire load?
May need a primary/secondary system retrofitted to help combat low return temps with a large water volume . Aquastat needs to be set to prevent condensation. Being a cast iron boiler, it will self destruct in short time.

LOAD

- The building requires is about 55k Btu/h at 2F/-16.7C (99%DB)
- If the main attic gets insulated to R60 and air sealed, which needs to get done for preventing ice damming, take off another 4k-5k Btu/h from the building requirements.
- The boiler outputs 100k Btu/h (84% efficient)


EMITTERS

The cast iron radiators, in theory, can emit
AVG TEMP | Btu/h | Good to
110F      | 26,600    | 36F/ 2C
120F      | 44,300    | 16F/ -9C
130F      | 62,000    | - 4F/-20C
140F      | 79,800    | -23F/-30C


The pipe in the basement probably acts as a 25k-30k Btu/h emitter at 130F-140F; around 400ft of 2" and 80ft of 1.5".

The basement loss occurs before the rads, so a 140F supply ends up being about 130F to the rads. The rads usually have a 10F-15F temperature drop. It's probably 55k from the rads and 30k from the pipes right now, but all that water can take a long time to heat since it rarely turns on.


INSULATION
I have been thinking about insulating the pipes in the basement, but I've got some other ideas that involve replacing a 100ft 2" section that only serves two rads with properly sized pex-al-pex and a manifold. I would also like to move one rad in the process.

https://www.grainger.ca/en/product/PIPE-INSULATION,SEMI-SLIT,2-3-8-IN,/p/WWG2CKE1

Getting split insulation costs about $6-$7/ft, so it is maybe $1400 for the single pair of 2" pipes.

It is probably part of another thread for later, unless it relates to my current boiler problems

EBEBRATT-Ed

A thermostat mixing valve is the best way to protect the boiler. You can also use an additional pulp tp blend supply water into the return,
.
Size the pump by taking the boiler output in btus and divide that # by 10000 to get the gpm required. Then you nedd to calculate the head pressure of the longest or most restrictive loop at the flow that loop needs to come up with the head the pump must overcome. The B & G system sizer you can download will do this

hot_rod

Your systems your system is seeking and finding thermal equilibrium at a temperature that is too low to keep the boiler from”sweating”
If you want absolute protection you need to monitor and respond to temperature at the boiler return. A thermostatic mixing valve can do that, or a circulator with a temperature function, properly piped!
A basic primary secondary without temperature function cannot assure protection, see example below

mattmia2

I'd use this type of thing:
https://www.supplyhouse.com/Mr-PEX-5240748-Strap-On-Pipe-Thermometer-for-3-8-1-5-Pipe-0-248F-Pack-of-2

john_james

I had another guy look at it on Tuesday.


VENT HEIGHT
The chimney is 60 feet from the top to the basement flue entrance on the wall. There's about another 8ft or so of flue from the boiler to the wall. About 68 feet total.

The manual says 48 feet is the max length with 2 elbows, 55 feet with one. I think the turn the liner makes from being vertical in the chimney to perpendicular to the ceiling the room counts as an elbow; so two elbows total. So probably 20 feet over.


BUILDING LAYOUT
- The front wall is directly on the sidewalk. Lots of pedestrians. The front is also a historically designated area, so it would have to be somewhat inconspicuous.

- The side walls of the building are shared walls, so it can't be vented out the side.

- The back is our parking lot, any venting here could easily be done


BOILER LOCATION
The boiler is currently on the side wall where the chimney is. It is about 30 feet from the front.
Venting out the front, 7 feet above the sidewalk, would require 3 bends, 30 feet over and 12 feet up. The max length with three bends is 41 feet.

He is looking if any solutions are possible, like using rigid pipe, insulating the chimney and installing a condensate drain, otherwise he said it might have to be moved to the rear of the building. At that point the labour cost to move the boiler is the same as installing a new one. He also said he could do a combustion test like captainco suggested, but the length seems to be worrying him, so he wants to research it first.


OFF TOPIC
I am thinking running it to the back would mean re-piping the first floor with a manifold in a pex home run and attaching to the existing risers to the upper floors (there's two 2" riser pairs with 4 and 5 rads). I'm also looking at air-to-water heat pumps. That's probably off topic, so I'll make another post later.


QUESTION
Is a venting length this much taller than the manual states allowed? Will this probably require moving the boiler or venting location?

mattmia2

You could replace it with a mod con then vent it out the back, that vent can be routed a significant distance. That would also solve your return water temp problem.

I think someone who knows combustion and venting could make your current location work, might mean a different size liner. The rules in the manual are sort of a one size fits all hope it works ok approach to avoid the engineering. It isn't going to work until you solve the return water temp problem because that is going to drive your flue temp down.

john_james

Sorry for the long response time.

I got the condensation to stop by opening up the bypass nearly all the way and turning off nighttime setback. We've had temperatures of -10C/14F since then, but the 99% here is 3F, so it could potentially still condense at that temperature. The balance in the system changed dramatically after opening the bypass, but I used the flow valves on the main 2" lines to balance it more. The third floor is about 2C hotter than the first, but it doesn't bother me. A third contractor thinks it is mostly working off gravity now. This seems, to me, to indicate that return water temperatures were the problem.

The exhaust length I mentioned apparently does not apply to a chimney, according to a third contractor. The second contractor and I were looking at a direct venting section. The old boiler had a draft hood and the chimney worked fine, so this boiler with power venting should work too.

None of the contractors seemed to think a thermostatic mixing valve to protect the boiler was necessary.

The third contractor said the chimney length and lining was fine. The third contractor wanted to sell me a new high flow pump and redo the vent from the boiler to the chimney (9ft) - he was going to charge me nearly as much as the boiler installation cost.

The second contractor wanted to reline my chimney and redo the vent from the boiler to the chimney. He will not redo the vent without doing the chimney.

I have not agreed to either yet.

Paul Pollets

That's one of the worst examples of a boiler installation I've seen and poses a risk to the owner. It needs to be repiped and re-vented per manufacturer's instructions. There's no shortcuts to proper boiler installations that don't pose a risk to the system longevity or to the owner.

hot_rod

The only way a bypass could be set is for one condition. That would be all zones open and at design condition. Setting that valve on a mild day with no load on the radiators will not be accurate, as the return blending with bypass will be higher..

If the boiler at design cannot get up over140 or so SWT, there is no way that bypass can increase the boiler operating condition. Thermal equalibrium, the mass of the system is in charge, not the aquastat on the boiler.

And as zones open and close that bypass mix will change as it cannot respond to varying loads.

If it is worth repiping it is worth doing it correctly

Mad Dog_2

DON'T hire anyone yet...You haven't found the right Guy yet.  Isn't there ANYONE from Find A Contractor near you?  Listen to the Legends here...they will lead you out of the Forest.  The best CO detectors I have found are at Jim Davis' National Comfort Institute in Ohio.  They are on their website.  Store-bought plugs ins are BETTER than nothing but for the highest level of protection for your fambly, there is no other.  $$$ They are almost $200 bucks a piece..I have 4 in my 🏠 house...not cheap but STILL cheaper than even a low-budget, Pine Box Funeral....Mad Dog  

john_james

There's only one zone.
I'm in Canada, so Find a Contractor doesn't work.

The guy captainco recommended wanted to put in a new high flow pump and change the venting from the boiler to the chimney. He said the bypass valve was fine and a thermostatic mixing valve was not needed (he talked to Weil-Maclein). He also quoted nearly as much as the boiler installation cost for a new pump and 9 feet of vent.

There is another HVAC guy in the next town. I personally know someone he has done work for (furnace and AC) and seen the results. I am going to see if he can fix the venting from the boiler to the chimney.

I'm not going to touch the piping this winter, it is working now. I know it might not when it is colder. I have plans to change the system, so the boiler will probably become backup heat or removed anyways.


BUILDING PLANS
I've been reading Joe Lstiburek's stuff on insulating masonry buildings and rubble basement walls. Between that, insulating the main attic from R12->R60 and building some more interior storm windows, I can nearly half the heating load of the building. The coldest day of the year (down to -30C) gave a heating load of 60kBtu/h and my heating load estimate is slightly higher. That can reasonably be brought down to 35-40kBtu/h. I can get a 5 ton monobloc heat pump ($7k CAD) to cover that down to -13F/-25C (99% design load is only 3F) at a water temperature of 113F. Lose 5F to a plate heat exchanger and using a dT=10F across the rads, gives an average water temp of 103F to the rads. Caleffi's idronics 25 gives ~34-42Btu/sqft (65F-70F room) for cast iron at that temp, so the existing rads can cover that. Adding three more panel rads would let me drop the temperatures lower and balance things better. I can manage running oxy-pex or pex-al-pex from each rad to a manifold on each floor.

The first floor of the building has AC that needs replacing. The top two floors do not have AC. I can use that same monobloc heat pump, with three or four thin fan coil units on the top floors, and replace the existing air handler with a hydronic one. That gives me AC too. The cooling load I have partially done suggests the 5 ton pump will be fine (using CLTD method by hand). I still have work to do on that. Cooling loads are much harder to calculate!

This is a system I could manage myself. I'm thinking about learning to solder copper pipe too. After that whether the boiler is worth repiping to use as a backup is questionable vs an electric boiler backup (~$1k to buy, no added customer charges like gas). After all of this trouble the thing I value the most is a system I can manage myself.