2 Stage vs Variable Stage

[max_w]

I posted earlier concerning my search for a new gas furnace and heat pump to replace my aging furnace and A/C. What advantages do a variable speed furnace offer vs. a 2 stage furnace? Plus are there any differences between Carrier and Trane products?

I live in Omaha, NE and have a 2 story house with 1600 sq ft above grade + a finished basement. HVAC reps have recommended 90K - 100K BTU furnaces w/ 3 ton heat pumps.

Thanks for your help!

[Big]

varible speed is my choice . Both Trane and Carrier are fine (the best) equipmemt . I'm a dealer for both . Carrier infinity system is outstanding .

[coolguysfl]

Max - you're mixing up the equation here:

Our heating guys can offer some guidance, but break it down like this:

1) Is a HEAT PUMP more effective in terms of BTU p/ watt than a GAS furnace for my market given KWH cost vs Therm

2) The term variable speed applies to the BLOWER not the heating source, heat pumps & gas furnaces are available with and w/o variable speed. Variable speed will help keep electric cost down, make up for poorly sized duct work and have some inherent benefit for dehumidification and circulation.

3) The TWO stage you're speaking of address's the firing rate of the GAS furnace. Two stage offers better temp control, better economy and less temp swing than a ONE stage

4) In many markets in makes sense to invest in a dual fuel system employing both a HP & GAS where the HP handles the load down to IE: 30 degrees then the GAS takes over - this "balance point" depends on fuel cost and product design

5) Note - even heat pumps have two stage options --- 1st the best have 2 speed compressors IE: Carrier Infinity, and ALL HP's will cycle conventional strip heat to supplement the demand in low temp applications.


Have you sought out a competent contractor yet? Have they performed these calcs for you?

[max_w]

Thanks for your help. I have 4 bids from contractors. Whether they are all competent is a matter of opinion. I believe the heat pump / gas furnace combo makes sense and will save me on natural gas costs during mild fall/winter weather which we have a lot of in Omaha. We also get a fair amount of very cold weather, so I need the furnace.

Concerning the variable vs dual stage blower, I'm not sure the variable is worth the extra money. Plus I'm concerned that it's too confusing and variable speed blowers are prone to problems.

You mentioned "calculations". I'm not sure any of the reps performed calculations to support their reccomendations. What kind of calculations should they have done.

Thanks!

[Big]

A variable speed is the blower motor , than run on 3 phase DC . All of the magic is done inside the motor . The saving , is that the V/S motor runs on approx. 1 amp.of electric , were a PSC motor could use up to 9 amps. Put in simple english its like running 1 lamp as to 9 lamps. THe saving is in the cost of energy used.

[gcook]

Max,

The calculations that these guys are referring to are called load calculations. These calculations determine that exact size of equipment that your home requires. What these guys want you to realize is that if the 4 contractors that you've gotten proposals from didn't spend time measuring your home (measuring square footage, window & door area, ceiling height, attic & sidewall insulation amounts, color of roof, brick or vinyl siding, etc) then they don't really have any evidence to back up their proposals. They may have looked at your current furnace and air conditioner size and basing the proposal off of that, but that's not really providing you a quality service. Moral of the story... get another contractor if none of these four didn't do a load calculation.

Variable speed furnace - is it worth the extra cost? YES! The variable speed system will enhance the comfort of both the heat pump and furnace and improve the energy efficiency of each as well. In addition, if you've purchased any indoor air quality products (i.e. electronic air cleaner, humidifier, ultra-violet light, etc) the variable speed blower will improve the performance of these products as well.

Hope this helps,

[housepoor]

Originally posted by gcook
Max,

Variable speed furnace - is it worth the extra cost? YES! The variable speed system will enhance the comfort of both the heat pump and furnace and improve the energy efficiency of each as well. In addition, if you've purchased any indoor air quality products (i.e. electronic air cleaner, humidifier, ultra-violet light, etc) the variable speed blower will improve the performance of these products as well.

Hope this helps,


How about a 2-stage 80% furnace (with variable speed blower) Vs. a modulating 90+% furnace (also with a variable speed blower) Vs. a 92% single stage furnace with a non-variable blower. All backed by a single stage 13 SEER heat pump. Considering RUUD equipment in Louisville KY.

[max_w]

I don't think it gets cold enough in Louisville to warrant a 90% or above furnace. 80% should be good enough for you. I'm still not convinced that a variable speed blower is worth the extra money. I do think the heat pump makes sense. No need to go with anything above the 13 seer, the payback could be longer than the HP will last.

Good luck!
Max

[mayguy]

Originally posted by max_w
I'm still not convinced that a variable speed blower is worth the extra money.


What or how can we convince you?

The pro of what I like about the Variable Speed.

-Able to run the fan 24/7 for comfort in the home, Temps both upstairs, and basement is the same.

-With then fan ON, the air flow is very soft and quiet.. don't feel any draft in the winter.

-Quiet ramping in heating and cooling.. No sudden start up/blast of air.

-Better control of humidity in A/C mode with a use of dehumidstat.

-Able to set CFM per ton set up to match the A/C and your region humidity

-Use less power, with less power, I am able to run the fan and not worry about my meter spining faster.


These motor been around since late 80's and pretty well proven by now. A good install will make this last just as long or longer than a standard PSC blower motor.

Only down fall it if you don't get the extneded warranity, it can be expensive to replace... I'd suggest, and I know lot of us here say get the 10 years parts and labor warranity.. It's a good peace of mind for the next 10 years.

[gcook]

Housepoor,

I live just above you in Indiana and it gets pretty cold in our area just like yours. I really like the idea of the duel fuel heating system that you're considering. Duel fuel gives you the best of both worlds, if the electricity gets out of hand you can always switch back to gas and visa versa.

If you're going to use a 13 SEER heat pump (hopefully you're looking at a R-410A refrigerant heat pump) then I would choose either the 80% variable or the 90% variable furnace and forget about the single-stage furnace.

I know that you might be thinking that you don't need the 2-stage or modulating gas heat since your utilizing a heat pump but if you look at the improved efficiency that the variable speed system gives the heat pump, it's worth the cost of the variable speed. When you look at any ARI certified HVAC system, the highest efficiency system always utilizes a variable speed system. I believe the RUDD/RHEEM modulating qualifies for a $200 US Tax Credit (I think it reaches a 95% AFUE).

If I was you I'd consider how long I would probably live in the home as a basis for choosing between the 80% and 90% variable speed furnaces. If I'm going to be in the home over 7 or 8 years then I'd go with the 90% furnace, if not then the 80%. Either variable speed furnace will provide added indoor comfort to your home.

[max_w]

What is R-410A refrigerant? Does this differ from regular freon?

Thanks!

[gcook]

R-410a is an environmental friendly refrigerant that is being phased-in by the government. R-22 can harm the environment and starting in 2010 no new equipment can utilize R-22.

What this means to homeowners is since R-22 in being phased out the cost of repairs dealing with R-22 will drastically increase. It will be just like the R-12 phase out with the automotive industry - try to get R-12 in today's market and you either pay an arm and a leg for it or its illegal!

R-22 this past year alone has more than doubled in price and the other factor to consider is equipment quality. R-410a operates at higher pressures and this means that the sturdiness of the equipment has to be able to handle it. If you read most of the manufactures equipment articles, they feel like their R-410a units are the best units they've ever produced.

[dshoffman]

I live just across the river from Louisville. I just installed a new system about 3 months ago. I'd be glad to give you a contact for a system. I'm a consumer not a dealer, so no sales pitch here, but just from recent experience.

[housepoor]

Originally posted by dshoffman
I live just across the river from Louisville. I just installed a new system about 3 months ago. I'd be glad to give you a contact for a system. I'm a consumer not a dealer, so no sales pitch here, but just from recent experience.

That would be nice, if you could do that.

[housepoor]

Originally posted by gcook
Housepoor,

I live just above you in Indiana and it gets pretty cold in our area just like yours. I really like the idea of the duel fuel heating system that you're considering. Duel fuel gives you the best of both worlds, if the electricity gets out of hand you can always switch back to gas and visa versa.

If you're going to use a 13 SEER heat pump (hopefully you're looking at a R-410A refrigerant heat pump) then I would choose either the 80% variable or the 90% variable furnace and forget about the single-stage furnace.

I know that you might be thinking that you don't need the 2-stage or modulating gas heat since your utilizing a heat pump but if you look at the improved efficiency that the variable speed system gives the heat pump, it's worth the cost of the variable speed. When you look at any ARI certified HVAC system, the highest efficiency system always utilizes a variable speed system. I believe the RUDD/RHEEM modulating qualifies for a $200 US Tax Credit (I think it reaches a 95% AFUE).

If I was you I'd consider how long I would probably live in the home as a basis for choosing between the 80% and 90% variable speed furnaces. If I'm going to be in the home over 7 or 8 years then I'd go with the 90% furnace, if not then the 80%. Either variable speed furnace will provide added indoor comfort to your home.


Modulating furnaces are fairly pricey, so we are thinking of using that only one for the firstfloor and basement. On the second floor we are thinking of going with an 80% 2 stage (2-stage has the variable speed blower). Both backed by 13 SEER heat pumps.

We are also thinking of zoning the basement and the first floor into two zones. Is that a good investment. The way I was explained, it only controls some dampers to change the flow of air. I have also heard that variable speed blowers are difficult to set up with zones. How true is that?

[gcook]

Housepoor,

A variable speed system shouldn't be a problem when using a zone system. With a zoning system you're going to have a static pressure regulator (either a balanced by-pass damper, electronic switch or even oversizing the ductwork) and this will help with the pressure buildup in your ductwork system when not all of the zones are calling.

Their is a lot of talk in the industry that variable speed blower systems will overcome ductwork problems (so this might figth with the by-pass damper). Some people think that's true and a lot of others don't. Every zoning system our company has out in the field in utilizing a variable speed blower system and we're not having any problems (8 systems in 2006, 11 in 2005, etc). Most of our zone systems also utilize a heat pump so there shouldn't be a problem on that end either.

Hope this helps.

[dshoffman]

Originally posted by housepoor

Originally posted by dshoffman
I live just across the river from Louisville. I just installed a new system about 3 months ago. I'd be glad to give you a contact for a system. I'm a consumer not a dealer, so no sales pitch here, but just from recent experience.

That would be nice, if you could do that.

If you give me your email address I'll send you the information, or I can just post it here. Your call.

[housepoor]

Originally posted by dshoffman

Originally posted by housepoor

Originally posted by dshoffman
I live just across the river from Louisville. I just installed a new system about 3 months ago. I'd be glad to give you a contact for a system. I'm a consumer not a dealer, so no sales pitch here, but just from recent experience.

That would be nice, if you could do that.

If you give me your email address I'll send you the information, or I can just post it here. Your call.
just post here. I don't think that would be a problem.

[mayguy]

Originally posted by housepoor

Originally posted by dshoffman

Originally posted by housepoor

Originally posted by dshoffman
I live just across the river from Louisville. I just installed a new system about 3 months ago. I'd be glad to give you a contact for a system. I'm a consumer not a dealer, so no sales pitch here, but just from recent experience.

That would be nice, if you could do that.

If you give me your email address I'll send you the information, or I can just post it here. Your call.
just post here. I don't think that would be a problem.

Don't post the @.com e mail on here.. Just do at dot com or put the e mail on your profile.