Furnace vs cold weather

[Urban Cowboy]

Does anyone know why my furnace room has a 6 inch air duct through the wall? It's an empty metal pipe. Is this because a furnace room needs some sort of ventilation? My house was built 30 years ago. It sure brings in a lot of cold air this time of year!

Fresh air intake.

It's required by code. Code requires it for safety.

To vent the exhaust the furnace pulls air from inside the house. If your house is well sealed, the furnace won't vent properly. Furnace not venting properly = risk of CO poisoning.

It's inefficient. Modern code requires the use of a heat exchanger for this purpose or the cold air is brought straight into the combustion chamber/box instead of mixing with the warm air in the house.

Don't recommend blocking it off unless you have a drafty home OR you get the equipment to measure air pressure inside and outside of the home while the furnace is running to establish if the furnace can vent properly without the duct in place.

Okay I have a question then, I see an air duct about 4" in diameter for cold air, but water heater is electric, and furnace/heatpump is electric, house doesn't have gas, so why the need to bring in cold air?

I'm of the mind that there's enough fresh air getting in around doors, windows, electrical outlets, and the fireplace, based on what I saw when the guy was sucking all the air out of the house during an energy assessment.

[77TA]

If your house is well sealed, range hoods and bath fans can cause negative pressure and won't operate well. Unfiltered air will be drawn in from wherever it can. A fresh air intake ducted to the return air of your air handler will compensate and also make sure the house has a continuous supply of fresh filtered air. Old days it was just a vent. Now they have make up air systems with heat recovery ventilation-HRV

[Glacier]

Seems like a waste of energy to be running an HRV all the time! Those things are loud too. You don't really notice it too much until the power goes out and then suddenly it's quiet!

[TylerM4]

Okay I have a question then, I see an air duct about 4" in diameter for cold air, but water heater is electric, and furnace/heatpump is electric, house doesn't have gas, so why the need to bring in cold air?

I'm of the mind that there's enough fresh air getting in around doors, windows, electrical outlets, and the fireplace, based on what I saw when the guy was sucking all the air out of the house during an energy assessment.

Good question. Assuming you don't have a home build in the last 10 years (or built with an HRV) If you don't have any gas appliances in your home, I see no reason why that fresh air intake would be required. Best guess is that it was included in the design by accident via copy/paste or included later by someone not aware that NG appliances were not being used.

[rustled]

You can get some HRV models with controllers that allow you to run them occasionally instead of all the time, and some kick in if the humidity gets above a set %. Much more sensible, IMO.

[77TA]

Seems like a waste of energy to be running an HRV all the time! Those things are loud too. You don't really notice it too much until the power goes out and then suddenly it's quiet!

They don't use a lot of energy but it does seem kind of counter productive using electricity to recover heat from the fresh air intake. We used to install a mini HRV which was just a passive heat exchanger (not powered) before primary fans fell out of code but they weren't very efficient and I'm not sure if they're still available.

[BC Landlord]

How much more is your furnace cycling per hour with this cold weather?

Not sure how would you get that "# of cyc/hr", unless you are sitting there every day and every hour counting furnace runs, or having some specialized diagnostic equipment.

I do have a device installed in my house that monitors power consumption on multiple circuits individually, including the furnace (fan) circuit. I would probably be able to indirectly tell you that information, providing that I go down to 1 min resolution of data, which I don't have from that far back (Jan 12-13 cold snap).

But really, what's the importance of knowing that? Newer furnaces are multi-stage, often with heat recovery units installed. They all take care of "cycling" by modulating the output, not just turning the furnace full-on and full-off.

What you really need to look at is you gas consumption and correlate it with temperatures (i.e. outdoor and thermostat setpoints).

[BC Landlord]

You can get some HRV models with controllers that allow you to run them occasionally instead of all the time, and some kick in if the humidity gets above a set %. Much more sensible, IMO.

On my HRV, there is a push-button where you could choose different settings, anywhere from off to low, medium, and high. The problem I have with mine is that anytime there is a power outage, the unit defaults to "off" afterwards. So I have to go back and reselect the setting again. Not very smart!

Are these "controllers" you are talking about something like an add-on? I know, a workaround on mine would be to use an UPS, but that's awkward in my mind.

[Bigbacardi]

Many thermostats will give data on number of cycles, as well as run time.
No furnace mfg today has a HRV/ERV built in.
A HRV/ERV exchanges fresh air from outside to the inside. The air passes thru a heat exchanger which transfers the energy.
Don't want to dump -9C air into a heated space.

The reason for multistaging a furnace is obvious.....the outside air temp is always fluctuating, however the inside air is relatively stable.
Also to ad.....NEST is the worst "smart' tstat out there.
Carrier Infinity is probably one the top.

[rustled]

You can get some HRV models with controllers that allow you to run them occasionally instead of all the time, and some kick in if the humidity gets above a set %. Much more sensible, IMO.

On my HRV, there is a push-button where you could choose different settings, anywhere from off to low, medium, and high. The problem I have with mine is that anytime there is a power outage, the units default to "off" afterwards. So I have to go back and reselect the setting again. Not very smart!

Are these "controllers" you are talking about something like an add-on? I know, a workaround on mine would be to use an UPS, but that's awkward in my mind.

I don't think it's to code for them to default to off. I don't know much about the controllers, just what I figured out when I was trying to ensure we weren't wasting energy with ours. It's a Venmar/VanEE. Their website demands cookie agreements so here's a link to their "main and auxiliary wall controls" for all of their units. https://www.vanee.ca/DATA/DOCUMENT/115_ ... 3714333423

For ours, we didn't install a unit that will work with the advanced controllers so we're stuck with fewer options. The advanced ones let you program the HRV more specifically to your needs which is likely more energy efficient than attempting to do it manually.

We can set ours to one of these options:

• suck in fresh air constantly at high speed
• suck in fresh air constantly constantly at low speed
• suck in fresh air at low speed for 20 minutes and shut off for 40
• suck in fresh air for 20 and recirculate at low speed for 40
• recirculate the air at high speed
• off

There are humidity settings on it, too. Depending on the settings, it can respond to too much humidity in the air it's drawing from the house.

After a power bump ours goes back to doing whatever it was doing before the power went out.

We've used ours long enough to be reasonably sure that leaving these units on all the time, even in the low-speed 20-minute cycle, has a measurable impact on increasing our heating bills. There's no way to know how much the air quality in the house actually benefits from this, though. It's now off more than it's on. We do monitor humidity - it hasn't been a problem.

Also, we know people who were unaware they had to clean the filters quarterly and the heat exchange core annually. Homeowners really need to know how much maintenance these require, particularly if they have pets or live in an area where the outdoor side filter gets clogged quickly.

[BC Landlord]

Many thermostats will give data on number of cycles, as well as run time.
...
Also to ad.....NEST is the worst "smart' tstat out there.
Carrier Infinity is probably one the top.

Not aware of any thermostat that would give you that information, let alone "many". Just looked at the "Carrier Infinity's" user manual, and nowhere could I find "# cycles/hr" info.

No furnace mfg today has a HRV/ERV built in.
...
The reason for multistaging a furnace is obvious.....the outside air temp is always fluctuating, however the inside air is relatively stable.

HRV is a separate unit, but a part of the heating system in most newer houses. Also, my understanding is that furnace's "multi staging" feature is about modulating the air flow, probably some other things as well. I am far from being an expert in this field, but I've observed my furnace running at different fan speeds.

[Bigbacardi]

I am an expert, the infinity stat does exactly that.

It registers cycles, & run times.
It does a whole pile more as well.

You are correct that most late model houses have an ERV/HRV. But it is secondary, not part of the furnace, but part of the HVAC system.

[Urban Cowboy]

I am an expert, the infinity stat does exactly that.

It registers cycles, & run times.
It does a whole pile more as well.

You are correct that most late model houses have an ERV/HRV. But it is secondary, not part of the furnace, but part of the HVAC system.

What do you feel is a good wifi smart thermostat, that will work with Trane heatpump, is NOT Nest, and will work with Google Home?

I've been looking at a lot and some stuff confuses me. For example if it says it is Google Assistant capable, does that mean it will work with Google Home too?

Currently have Ecobee/Nest and don't like it. Reviews also seem terrible.

[Bigbacardi]

Ecobee is a decent choice, however the best is the systems that use proprietary tech.
ie....communicating
Only a few mfg make communicating stats.
They use a different signal, other than the basic terminals of Y R G O C W.
The com. style usually is only available on the hi-end gear.
Unsure of your level?
Also....most "smart" stats are not very smart. So don't get "hung up" on the verbiage.
Carrier was the first to come out with communicating, Lennox 2nd.
I'm not fluent in Trane.
Also note.....the stats you buy at Home Depot are NOT the same as the professional ones, usually they have less options available, as well as a lesser warranty.
I have removed many, many Nest stats.(pure garbage)

[Urban Cowboy]

Ecobee is a decent choice, however the best is the systems that use proprietary tech.
ie....communicating
Only a few mfg make communicating stats.
They use a different signal, other than the basic terminals of Y R G O C W.
The com. style usually is only available on the hi-end gear.
Unsure of your level?
Also....most "smart" stats are not very smart. So don't get "hung up" on the verbiage.
Carrier was the first to come out with communicating, Lennox 2nd.
I'm not fluent in Trane.
Also note.....the stats you buy at Home Depot are NOT the same as the professional ones, usually they have less options available, as well as a lesser warranty.
I have removed many, many Nest stats.(pure garbage)

Ecobee is what was installed, but the reviews on it are not good, people even saying they can ruin the furnace.

It's also Nest.

We were supposed to get Carrier, but there's no stock and wait time was too long, so ended up with a 3 ton Trane unit.