Home & Garden

Why you DONT want to buy a variable speed Furnace.

  • Last Updated:
  • Dec 27th, 2019 5:14 pm
[OP]
Deal Addict
User avatar
Aug 12, 2007
4685 posts
808 upvotes
Waterloo

Why you DONT want to buy a variable speed Furnace.

tl;dr: because you're going to be locked into a inferior thermostat.



Buying a Variable speed ( this is different from a multispeed Furnace ) mean that the you have to buy a Thermostat from the Manufacturer for about $500. In addition, you are *forever* bound to this specific thermostat. Manufacturers cite that this gives greater efficiency, but this has to be proven ( Since they dont actualy say that a 96% efficient multispeed furnace is less efficient than a 96% variable speed furnace ).

Whats wrong with the Manufacturers Thermostat? Well for starters , it costs $500. For another Furnace manufacturers are just starting to arrive in the 90s technology and are discovering touchscreens and schedules beyond basic schedule programming. And they are not doing this willingly, they are infact being dragged into this screaming by the new entrants such as Google, Ecobee etc.

The life a Furnace is expected to be around 15-20 years. In the old days , when you retired the furnace you changed the thermostat. Those were the days of bimetal and mercury thermostats. Electronics has changed all that and a thermostat can add new features your old thermostat didnt have. Infact the entire market for third party thermostat was born because the furnace manufacturers have fallen behind and are stagnant and arrogant. Have they changed? Not at all!

Why is it locked into the manufacturers thermostat. because the Variable speed furnace communicates with the thermostat , with a protocol (method) which only that specific manufactuere uses. Well, in fact a single manufacturer might use several different protocols which are not compatible across their product lines. Also During that life of 15 -20 years, the manufacturer will upgrade the protocol, but it still means you cant get a newer thermostat from even the same manufacturer.

What about if you want to keep the same thermostat? with a network connected ( WiFi) thermostat this is also not really an option. Since with New Security Vunerabilities in your network being discovered here and there. Its absolutely imperative that those be patched. Do you think any manufacturer will maintain their equipment for 15 years. ( will your cell phone manufacturer main the code for 15 years ? ). It guarenteed this will not happen. Already the first generation( released about 5 years ago) of Manufacturer thermostats are Not being maintained actively. ( and yet those products are still being sold ! )

What about new features that are yet to come. Yes you will forever have to forego them.

Sure if you have, complicated setup with multiple zones you have to buy the manufacturer thermostat, But I'm willing to bet that in the next 3 years most third party thermostats will also pass the stagnant manufacturers in this aspect.

When will this change? When Google or Apple buys a Furnace manufacturer and brings a uniform standard to the Furnace communication.


p.s: A Similar analogy would be, Would you prefer a smart TV or would you prefer to have an external media player/ media box?
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35 replies
Jr. Member
Feb 9, 2006
163 posts
48 upvotes
This isn't true.

Unless you have a communicating control, a thermostat is simply a switch and you can use any one you want. Even if you have a communicating control, you can always swap it out for a downgraded thermostat.
[OP]
Deal Addict
User avatar
Aug 12, 2007
4685 posts
808 upvotes
Waterloo
Hexavalent wrote: This isn't true.

Unless you have a communicating control, a thermostat is simply a switch and you can use any one you want. Even if you have a communicating control, you can always swap it out for a downgraded thermostat.
True. You can Downgrade your furnace to work with a third Party thermostat. but then why pay extra for the Variable speed.

Also true , in the minds of the HVAC Manufacturers the Thermostat is a "simple switch", thats exactly why they are left behind.

A two speed and three Speed Furnace will work Better with ANY thermostat. Hence to prevent the downgrade, dont get it at all to begin with and save yourself $1000.
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Pay it forward.
Deal Fanatic
Feb 4, 2015
6433 posts
2828 upvotes
Canada, Eh!!
We got our communicating tstat for free [not from installer or manufacturer] and it does have a few features like less wires to connect and 6 speeds for fan vs the Ecobee 3 presently using... use whatever works for you but agree not worth paying extra unless you really want to control fan speed to 375 vs 550 vs 750, etc.
.......
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Deal Expert
Mar 23, 2009
18863 posts
4955 upvotes
Toronto
I will never go back to a single stage furnace. 2-stage blower is not good enough either. Variable capacity is totally awesome.

The ability to run at very low capacity means total quiet and better temperature control. Now I never hear the furnace but the temp is always maintained perfectly.
Last edited by EugW on Dec 22nd, 2019 9:16 am, edited 1 time in total.
Newbie
Jul 10, 2013
63 posts
43 upvotes
Oakville
I feel like you’re speaking to me directly OP. I bought a Lennox furnace (EL296V) in 2016 and it came with the iComfort Wi-Fi thermostat. It wasn’t even the latest one from Lennox at the time (I should have pushed for a newer version at time of purchase but I didn’t know - my bad). It gets zero development from Lennox.

Can anyone definitively say if upgrading to a Nest or Ecobee will “downgrade” the performance of the furnace?
Jr. Member
Sep 23, 2019
156 posts
248 upvotes
OP,

I completely disagree with you. About 1 month ago I bought variable speed furnace (Lennox, Elite series) and I use it with Ecobee 3 lite thermostat. Just to be absolutely sure, we are talking here about BLOWER variable speed, and NOT modulating vs single stage vs 2 stage furnace features, this is just about blower variable speed. Here are my comments, but I want to make it very clear - I am not HVAC specialist, I am just regular homeowner.

1. I can change continuos fan or/and first/second stage fan speed using switches on main board of the furnace. It is not the same as changing them from specialized thermostat, but in any way there is a way to change a speed that better matches your house environment. In my case, I increase speed for first and second heat stages so that more air is pumped into the rooms further away. As you would normally adjust these speeds just once, I do not see a need for me to have these settings on the thermostat. On the furnace motherboard there are limited amount of changes I can do, but I want to make it very clear - I CAN DO THAT!

2. My understanding variable speed motors could be (in most cases!) more efficients - usualy they are DC motors and use less electricity.

3. My understanding (And I could be very wrong here), that "variable speed" means a bit more that just that blower can have multiple speeds. My furnace is set to have continuous fan on 540CFM, 1st stage heat at about 1025CFM and second stage heat at 1280CFM (numbers are approx). When my furnace runs, it always shows current CFM. To get exactly that CFM, my furnace blower runs at specific speed for my environment and uses just that much electricity. So depending on air duct static preasure, in my house to achieve 540CFM blower fan might use 70W of electricity, but in your house to get the same CFM fan might have to work harder and use 100W of electricity. So some of the energy effiency comes from ability to control fan speed.

I would not buy a furnace without variable speed motor.
Deal Guru
Feb 9, 2006
12160 posts
6702 upvotes
Brampton
Putting in a Nest isn't even an upgrade.
I would rather have the Honeywell AirIQ system or the carrier infinity system
Deal Expert
Mar 23, 2009
18863 posts
4955 upvotes
Toronto
tebore wrote: Putting in a Nest isn't even an upgrade.
I would rather have the Honeywell AirIQ system or the carrier infinity system
I really dislike the Nest. I also consider it a downgrade.

Anyways for my other furnace (weird house setup so I have two furnaces), I have a Carrier furnace with 2-stage burner and variable speed blower. With my ecobee thermostat it lets the furnace decide how to run the burner. It starts out on low first but if necessary it will change the burner to high. The thermostat also doesn't control the variable speed blower, but the furnace can control that itself. So, yeah, the control is not as fine grained as with a dedicated thermostat, but the ecobee can still run the variable speed blower in variable speed mode. However, the ecobee isn't actually controlling the speed here, as the furnace is doing it itself. This is fine, since the vast majority of the time, the furnace stays very quiet, and temperature control is very good.

BTW, the main reason I bought the ecobee is because it was on sale and because it had an auto fan circulation setting which allows the fan to run even if the burner is off. A lot of the cheaper thermostats out there don't have this auto fan circulation setting, which is annoying. The furnace had originally been installed with a previous relatively dumb programmable thermostat without that circ setting, so I just upgraded it with one with the circ setting which happened to be the ecobee.
Deal Guru
Feb 9, 2006
12160 posts
6702 upvotes
Brampton
EugW wrote: I really dislike the Nest. I also consider it a downgrade.

Anyways for my other furnace (weird house setup so I have two furnaces), I have a Carrier furnace with 2-stage burner and variable speed blower. With my ecobee thermostat it lets the furnace decide how to run the burner. It starts out on low first but if necessary it will change the burner to high. The thermostat also doesn't control the variable speed blower, but the furnace can control that itself. So, yeah, the control is not as fine grained as with a dedicated thermostat, but the ecobee can still run the variable speed blower in variable speed mode. However, the ecobee isn't actually controlling the speed here, as the furnace is doing it itself. This is fine, since the vast majority of the time, the furnace stays very quiet, and temperature control is very good.

BTW, the main reason I bought the ecobee is because it was on sale and because it had an auto fan circulation setting which allows the fan to run even if the burner is off. A lot of the cheaper thermostats out there don't have this auto fan circulation setting, which is annoying. The furnace had originally been installed with a previous relatively dumb programmable thermostat without that circ setting, so I just upgraded it with one with the circ setting which happened to be the ecobee.
I have the nest as well.
It's such a dumb "smart" thermostat.
Their claim to fame was to be a Automatically programable thermostat. But the learning is terrible. So I use it as a programmable.
It still doesn't have a Hold for those odd times you need it.

It doesn't integrate well with the Nest Protects. I mean I does detect motion to extend the home away function but that's it.
There's the safety stuff but there's little to no quality of life improvement.

Still no automated humidifier control like the Ecobee. I had to hack one up.

It collects tons of data but I can't easily access it. Just get stupid emails once a month.

It's like After Google Bought them and Fadell left, Nest was lost.

Get a nest if you want to pay for the privilege of having google mine your data
Deal Expert
Mar 23, 2009
18863 posts
4955 upvotes
Toronto
tebore wrote: I have the nest as well.
It's such a dumb "smart" thermostat.
Their claim to fame was to be a Automatically programable thermostat. But the learning is terrible. So I use it as a programmable.
It still doesn't have a Hold for those odd times you need it.
It doesn't have hold? Really, WTF? I was not aware of this. I didn't like Nest for other reasons, but that takes the cake. That's bizarre.
Deal Addict
User avatar
Oct 9, 2010
2751 posts
912 upvotes
Windsor
tebore wrote: I have the nest as well.
It's such a dumb "smart" thermostat.
Their claim to fame was to be a Automatically programable thermostat. But the learning is terrible. So I use it as a programmable.
It still doesn't have a Hold for those odd times you need it.

It doesn't integrate well with the Nest Protects. I mean I does detect motion to extend the home away function but that's it.
There's the safety stuff but there's little to no quality of life improvement.

Still no automated humidifier control like the Ecobee. I had to hack one up.

It collects tons of data but I can't easily access it. Just get stupid emails once a month.

It's like After Google Bought them and Fadell left, Nest was lost.

Get a nest if you want to pay for the privilege of having google mine your data
I got my Nest for free from some government program, and I fully agree with this entire post. I don't mind the look of it, otherwise I'd just install my old Honeywell 7-day programmable thermostat, which is functionally identical (... given I use Hubitat presence sensing to do various adjustments).
One who is offended by truth, has no place among those who seek wisdom.
Deal Fanatic
User avatar
Mar 31, 2017
6729 posts
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what is the OP talking about when he says proprietary protocol? Does he mean weird wires, or 120V systems that aren't compatible with nest and ecobee?
Sr. Member
Jan 19, 2013
519 posts
305 upvotes
Ottawa
Multi speed ecm and variable speed ecm is one topic
Shouldn’t mix in communicating stat vs standard stat into the same topic.
You can get a variable speed ecm furnace hooked up with a standard thermostat. Variable speed ecm is still advantageous for comfort.
Sr. Member
Jan 19, 2013
519 posts
305 upvotes
Ottawa
badOne wrote: what is the OP talking about when he says proprietary protocol? Does he mean weird wires, or 120V systems that aren't compatible with nest and ecobee?
On communicating capable furnaces. You can get the communicating thermostat. Usually 4 wires. And with 4 wires you can have full control of your eintire hvac system. No extra wires needed because it 2 way communication.
Those furnaces always have legacy wiring for standard stats.

Some manufactures do update/release new communicating stats and are backwards compatible.
Banned
Nov 17, 2014
942 posts
752 upvotes
Ontario
tebore wrote: I have the nest as well.
It's such a dumb "smart" thermostat.
Their claim to fame was to be a Automatically programable thermostat. But the learning is terrible. So I use it as a programmable.
It still doesn't have a Hold for those odd times you need it.

It doesn't integrate well with the Nest Protects. I mean I does detect motion to extend the home away function but that's it.
There's the safety stuff but there's little to no quality of life improvement.

Still no automated humidifier control like the Ecobee. I had to hack one up.

It collects tons of data but I can't easily access it. Just get stupid emails once a month.

It's like After Google Bought them and Fadell left, Nest was lost.

Get a nest if you want to pay for the privilege of having google mine your data
Eco-mode can be used as a defacto hold mode, so long as you don't want to hold above 21C.
Deal Expert
Mar 23, 2009
18863 posts
4955 upvotes
Toronto
Copper1212 wrote: Eco-mode can be used as a defacto hold mode, so long as you don't want to hold above 21C.
Will eco-mode auto revert to regular mode? Hold on most thermostats can be set to automatically revert to the regular mode, either after a period of time or else at the next program schedule change, depending upon what you choose.

I have eco mode on the thermostat for my electric baseboard heaters, but it's a fixed mode, and to go back to the normal schedule you have to manually switch out of eco mode, which is annoying. Luckily, it is a fully programmable thermostat so it has a normal hold mode as well, which I prefer to use. Eco mode in this context is not a very good substitute for hold mode.
Deal Expert
User avatar
Dec 12, 2009
19937 posts
8041 upvotes
Toronto
RedFlagAlias wrote: OP,

I completely disagree with you. About 1 month ago I bought variable speed furnace (Lennox, Elite series) and I use it with Ecobee 3 lite thermostat. Just to be absolutely sure, we are talking here about BLOWER variable speed, and NOT modulating vs single stage vs 2 stage furnace features, this is just about blower variable speed. Here are my comments, but I want to make it very clear - I am not HVAC specialist, I am just regular homeowner.

1. I can change continuos fan or/and first/second stage fan speed using switches on main board of the furnace. It is not the same as changing them from specialized thermostat, but in any way there is a way to change a speed that better matches your house environment. In my case, I increase speed for first and second heat stages so that more air is pumped into the rooms further away. As you would normally adjust these speeds just once, I do not see a need for me to have these settings on the thermostat. On the furnace motherboard there are limited amount of changes I can do, but I want to make it very clear - I CAN DO THAT!

2. My understanding variable speed motors could be (in most cases!) more efficients - usualy they are DC motors and use less electricity.

3. My understanding (And I could be very wrong here), that "variable speed" means a bit more that just that blower can have multiple speeds. My furnace is set to have continuous fan on 540CFM, 1st stage heat at about 1025CFM and second stage heat at 1280CFM (numbers are approx). When my furnace runs, it always shows current CFM. To get exactly that CFM, my furnace blower runs at specific speed for my environment and uses just that much electricity. So depending on air duct static preasure, in my house to achieve 540CFM blower fan might use 70W of electricity, but in your house to get the same CFM fan might have to work harder and use 100W of electricity. So some of the energy effiency comes from ability to control fan speed.

I would not buy a furnace without variable speed motor.
+1. I am happy to let the furnace controls run the show and use the thermostat was an on/off switch.
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Deal Guru
Feb 9, 2006
12160 posts
6702 upvotes
Brampton
Copper1212 wrote: Eco-mode can be used as a defacto hold mode, so long as you don't want to hold above 21C.
That totally defeats the purpose of Eco-mode.
Using a work around indicates that the design has failed basic user cases.

I mean I actually use it as a programmable and also use eco-mode when I'm out.
Banned
Nov 17, 2014
942 posts
752 upvotes
Ontario
EugW wrote: Will eco-mode auto revert to regular mode? Hold on most thermostats can be set to automatically revert to the regular mode, either after a period of time or else at the next program schedule change, depending upon what you choose.

I have eco mode on the thermostat for my electric baseboard heaters, but it's a fixed mode, and to go back to the normal schedule you have to manually switch out of eco mode, which is annoying. Luckily, it is a fully programmable thermostat so it has a normal hold mode as well, which I prefer to use. Eco mode in this context is not a very good substitute for hold mode.
In eco-mode it will not revert at the next schedule change, but in a scenario like that you wouldn't put it into eco-mode, you would just set your temperature (overriding the scheduled one) and it will revert at the next schedule change. In terms of having it change back at a set time, I do not believe that is possible.

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