Drawing combustion air from elevator shaft?

JUGHNE

If your furnace is on the top floor, then it is possible you could vent up thru the roof deck for your furnace.
It takes some time and talent and money but is possible.

Hopefully the clothes dryer is not vented out of one of those terminations we see.
Water heater....gas or electric.....picture?

unclejohn

That might be a local code. The installation manual does not show a drain.

piluso

Thanks for the manual.
Jughne, the water heater and dryer are both gas and I would assume the are vented out through those terminations, but not sure.

piluso

Jughne, do you still think that modifying the pipes along the lines you suggested is worth trying?

DZoro

Keep the exhaust drain, it's not needed in the manual but. Trust me you will be creating another issue.

That series of furnaces don't handle condensate well. Also check the interior condensate hoses for cracks they also had issues.
I believe that furnace is capable of a single pipe arrangement. But must be done according to your codes, room size, indoor ventilation must be adequate. Yes you could run the two pipes together. If Payne said you are close on your venting, by going with 3" as far as you can you will be gaining, how much is a guess at best.

As noted before all the furnaces are vented wrong........They should all be corrected sooner the better for everybody.

Yes l hope the other vent is NOT the dryer......

JUGHNE

The PVC tee might make it work, but after seeing more it would be only a band-aid.

Does it seem that each apartment unit has it's own 5 wall terminations?
2 for furnace
1 for WH
1 bath fan (only one?)
1 maybe for dryer?

If so then the furnace would be inhaling the WH exhaust and maybe its own......not good.
Bath fan......not a major concern.
Gas dryer........real bad. IMO

How about kitchen range hood....vented to the outside or recirculation thru filter into the kitchen?

Some condensing units allow an "unbalanced" 2 pipe venting system. This would be where the combustion air is drawn in thru the side wall pipe and the exhaust air pipe goes out the roof.
It might be possible that you have some configuration or combination of the above.
There is probably a roof hatch that perhaps your HVAC person could gain access to for checking this out. Often the AC units would be up there.

You own your apartment....who owns the roof?

piluso

Yes, all apartment units have the terminations you describe. I think I'm the only one with issues. There are like 8 combo units! The builder said something about maybe more tees but who knows.
Just got home, turned the unit on and it is working. I'm going to try the pipes first.
As you can imagine the builder is not responding quickly. The whole winter without consistent heat...
I will look into the roof.
Thanks again

Leonard

Would think elevator shaft would either be slight pressure or vacuum depending on direction the car moves and that would create problems with your firing. Also possible HOT exhaust out the plastic intake pipe if strong enough.

In a restaurant 60 gal gas water heater the vacuum in building from kitchen exhaust fans ( even with kitchen makeup air) is strong enough to suck outside air down the chimney. Seen the spilling hot exhaust scorch plastic dielectric unions on top of tank to brown color.

Zman

The furnace is likely 3X oversized. I would plan a new one in the future.

What makes you so sure the issue is with the vent?

I work more with high efficiency boilers, some of those models allow you to turn down the max firing rate within the controls.

If the furnace will fire with no second stage, I see no harm in running it on 1 stage.

I see the foil tape on the vent. Has anyone done a combustion test?

Zman

Back to the elevator shaft question.

Elevator shafts have a very specific fire and smoke construction and rating. The fire marshal would give birth to a small heard of cows if you stuck a pipe through that assembly and shaft. Not to mention what would happen if a fire broke out. A fire in the shaft would mean a fire in your unit.

The contractor who suggested it has very little knowledge of commercial construction.

piluso

One of the contractors did a combustion test. I forgot the numbers. The conclusion was that it was borderline. They predicted what is happening . It works kind of randomly. The foil tape covers holes the contractor drilled to show me that the problem was the pipe. Thats why i think that trying a different pipe installation might help but i agree that the furnace is really oversized. The cheapest thing down the road might be to replace it with a smaller one. I spent $700 already with 2 visits and replacing the switches.

unclejohn

Most likely the five pipes are all vent and air in from some where else. If not you should call a lawyer. Also where does the drain on the bottom of the vent pipe go? Hopefully right to the pump or open drain and not connected to the internal piping anywhere.

piluso

what would it take to run it in just one stage?

mikeg2015

100k is a huge furnace. I’d start there. I can heat my 3500sqft 2 story 1907 Victorian brick home with lots of big original windows with 100k down to about 5f outside on a windy winter night.

Most condos rarely need over 40k because of shared walls. 60k because you might need a 3 ton AC and hence bigger fan in a larger condo. But I’d bet money the AC is way, way oversized too. Typical

piluso

That's the basic problem. It's a shame to have to look into replacing a relatively new and nice furnace, but the size is ridiculous. How much would replacing it with a 60k BTU furnace cost me? Rough estimate

Brewbeer

Wouldn't surprise me if the cost to downsize the furnace was on par with the cost to upsize the vent pipe when you include the cost of repairing the finish work.

Just a guess, but even 60k is probably oversized. My 2,000 sq.ft. 50+ year old house has yet to use more than 35k per hour, even at -10F and windy.

JUGHNE

IIWM, I would figure out what the 5 wall terminations are all about.
If the situation is as bad as we guess it might be, then your new furnace may meet an early death.
The roof exhausting/inlet may be the best bet.
If that is where the AC units are then there are already roof penetrations.
The wall punch outs were the easiest and quickest on new construction.

piluso

I was looking at the terminations, they are not that close together, there is a lot of wind up there, and we rarely use the dryer can the terminations really be the main problem? Especially given that it is clear that the exhaust pipe is too small.

unclejohn

what would it take to run it in just one stage?

Not much. There is a dip switch on the board that sets up furnace as one or two stage tstat. Set it too two stage operation and don't connect any thing to W2 and you are all set.

piluso

What would running it in just one stage do? How much of a compromise is it? Seems straight forward should i do it with a contractor or it is easy to figure it out?

JUGHNE

I just read thru the Payne PG9YAB install book....that is what you have? It shows a simple single stage set up. No mention of 2-stage.
Often in a low bid job this would be installed.
The 2 stage system is a fair amount more money.

With the door off could you post a picture of the gas valve with inducer fan shown?

piluso

I will

piluso

One more thing. Assuming this is a two stage model. Moving to single stage would definetely solve the problem? I have been reading about the difference and i think im ok with one stage.

Also. The problem cannot be the thermostat no?

Thanks

Zman

JUGHNE said:

I just read thru the Payne PG9YAB install book....that is what you have? It shows a simple single stage set up. No mention of 2-stage.
Often in a low bid job this would be installed.
The 2 stage system is a fair amount more money.

With the door off could you post a picture of the gas valve with inducer fan shown?

I think you are correct. Must have been the wrong manual.
It is strange that a single stage unit would fail only in cold weather. The air density would be greater on cold days. Knowing the combustion numbers would help.

piluso

Here is the picture. When I turn the thermostat on you hear a chip/chip/chip the contractors told those where the switches but that the numbers where not good enough to fire the furnace.

Thanks

JUGHNE

If you open the lower door, there would be a board with the thermostat connections. How about a picture of that board.
Especially showing the terminals R W G Y C etc. That would be where the tstat cable is connected. Thanks

piluso

Here are a couple of pictures, they are not great

ratio

Single stage.

It looks like they used more pipe dope than they had budgeted for & tried to make up the difference on the flue sizing.

It's vanishing unlikely to be the thermostat causing the problem, especially with what we know about the flue. Flues can be strange beasts. I've had problems with as little as two tablespoons of water standing in a horizontal-ish pipe keeping a unit from firing. The ΔP that the pressure switch looks at will tell you.

I did have one instance of a cracked HX causing a similar issue (on the edge of the ΔP, sometimes the switch would make, sometimes not). I solved that by a process of elimination, starting with reworking the flue to be juast what the mfgr wanted.

piluso

Good info. I think that's what needs to be done. Rework the flute, maybe in pieces, and see if it works. When they looked for a blockage the line they put through the pipe came out wet.

DZoro

Ratio is correct that is a single stage furnace. There must not be any water in the venting, if there is the venting must be corrected. No matter what furnace is there.
There is a 1/4" pressure switch hose coming from the left going to the lower pressure switch. Take the hose off and check for any condensate inside of it. It must be dry. Re route the hose up and over the venter with slope to the condensate box, no sags.

Strongly suggest getting the proper size furnace installed with the venting corrections.

piluso

I will look into the hose issue.

piluso

I shouldn't be asking this but what is the difference between dual pressure switches and two stage furnaces? If it's long don't worry I'm ok just learning that they are different things.

piluso

Another question
The manual has the following guide lines for upflow installations venting through the side




but the install is more like this but venting through the side



the first picture has a Tee Trap at the end of the exhaust pipe. The current installation has the drain. Is that a problem?

ratio

The "tee trap" in the first illustration would allow the flue to be drained separately, whereas the other drain must go into the furnace trap to keep flue gas from escaping. It's possible that the tee trap could flow more condensate, but I wouldn't expect that to be a significant issue without other problems, such as a low spot holding condensate until the inducer stops & the it comes back & overwhelms the little drain.

piluso

ok, thanks

DZoro

The 1/4" hose is drawn in your diagram the way it should be installed in your furnace.
Dual pressure switches in your case mean one for your venting and one for your condensate box/drain management system.

unclejohn

Carriers web site came up no results when PG9YAB entered. Not familiar at all with what I'm seeing. Why two stage pressure switch if single stage? May be a door off switch. Have never seen that inducer motor or gas valve on a Carrier/ Payne product before.

JUGHNE

I found the I&O manual by googling the model number.
Some single stage furnaces have double pressure switches.
The 2 stage I use have two sets of doubles.

piluso

Thanks. I was confused about the issue. I hope to get started with the flute soon

piluso

Follow up. A contractor suggested maybe installing a two stage burner. See if it works. If no running it single stage. He didnt give me a price yet. Would that work? Thanks