[Slicster]

Hi,
I'd like some help on making a decision. I have to chose between two companies that will offer me two different replacement furnaces. I'm switching from oil furnace to electric and replacing an old Lincoln LBO-125DA in a hybrid configuration with a Goodman thermopump outside. The system is very old and needs constant maintenance so I want to switch to electric to save space and remove the oil tank and also for the safety of my family. The choices they gave me are...

Stelpro sfe18 - 18kwh - 5 year warranty
Amana mbvc1200 - 15kwh - 10 year warranty

One says he can even give me the Stelpro sfe1821 variable 18\13kwh

My house is about 2200sqft so normally they say 15kwh is enough but I really know nothing of this and if variable is good or bad? Plus warranty, sometimes doesn't mean everything right? Was also told variable is bad in terms of long term.

Thoughts? Suggestions?

Thanks.

 

[user_12345a]

You need a load calculation to see how much heat the house needs.

Not only to size the backup heat* but also determine the balance point of different heatpump sizes. Below the balance point, the electric heaters come on to supplement and jack up the electric bill.

*Depending on the house and climate, could need anywhere from 10 to 25kw of backup. Granted if you need 25kw, heatpump smaller than 4 or 5 tons won't do much for you and you would be too dependent on straight resistance heat.

To top it off the ducts need to be checked to see how much airflow they can handle at a reasonable pressure level as larger units need more airflow.



You've just provided air handler models and no other info.

The contractor is the most important aspect of the job, not the brand.

 

[roughneck]

Are you doing just an electric furnace? Or a heat pump with electric backup?
Agreed with above, the contractor is the most important part of the job and without a load calculation you don’t know what size furnace is needed.
Equipment isn’t sized off square footage. No sizing chart exists that shows what size equipment is required for certain square footage.

 

[Slicster]

Are you doing just an electric furnace? Or a heat pump with electric backup?
Agreed with above, the contractor is the most important part of the job and without a load calculation you don’t know what size furnace is needed.
Equipment isn’t sized off square footage. No sizing chart exists that shows what size equipment is required for certain square footage.

Hi, like I said I know nothing of this. Now I see mentions of 25kwh and you're scaring me. I can give the model or what I currently have if you tell me what's missing from the model I provided.

Yes I am trying to stay hybrid with thermopump mostly and furnace to assist and be used only when below -10c.

Both contractors have good reputation in my neighborhood. When I asked why one was at 18kwh,he says he always upsizes and if it's too much an element can be removed to bring it down to 15kwh and be more efficient. Both assured me 15 is enough for my house.

Thanks.

 

[Missouri Bound]

First of all, get more quotes.
Lennox, Carrier even York are reputable companies.
Shop around. Ask each contractor what they suggest as far as tonnage.
When you get ALL the information you can better make a decision.
And don't let pricing make up your mind. When you get all the information you can ask each one about their pricing.
Personally,....and this is just my opinion, I would stay away from the two brands you mentioned. Both Stelpro and Amana can be bought by anyone and do not require professional installation.

 

[sktn77a]

What model is the Goodman heatpump and how old is it? The Amana (Goodman) may be the better match.

Where are you located - that may determine your backup heatstrip needs.

 

[Missouri Bound]

You need a load calculation to see how much heat the house needs.

The contractor is the most important aspect of the job, not the brand.

Hmm.

I don't agree with your first comment. If you are replacing an existing unit and it has warmed and cooled you to your satisfaction then it was sized properly.
Comfort is the key to homeowner satisfaction.

And you are completely correct with last statement.

 

[roughneck]

Hmm.

I don't agree with your first comment. If you are replacing an existing unit and it has warmed and cooled you to your satisfaction then it was sized properly.
Comfort is the key to homeowner satisfaction.

And you are completely correct with last statement.

Not necessarily.
Often a unit can be downsized and will result in additional comfort for the occupants.
Equipment, more often than not, is oversized.

 

[user_12345a]

Hmm.

I don't agree with your first comment. If you are replacing an existing unit and it has warmed and cooled you to your satisfaction then it was sized properly.
Comfort is the key to homeowner satisfaction.

And you are completely correct with last statement.

For a heatpump application, it's really important to know the heat loss and gain for sizing it.

Have to balance not oversizing for cooling with reducing the need for electric backup heat.

Also going from an oil burning furnace, very likely its btu output is way above what 15 kw can provide.

Some 2200 sq ft homes may need more than 15kw/51 000 btu/hr.

May need closer to 20 or 25 kw. Depends on surface area of house, windows, climate, insulation.

 

[udraft]

Hmm.

I don't agree with your first comment. If you are replacing an existing unit and it has warmed and cooled you to your satisfaction then it was sized properly.
Comfort is the key to homeowner satisfaction.

And you are completely correct with last statement.

............................................ I'm switching from oil furnace to electric and replacing an old Lincoln LBO-125DA in a hybrid configuration with a Goodman thermopump outside.................................

But sizing should not be an issue. Any tech who knows what they're doing can walk in a house and have a good idea of what size.

 

[roughneck]

But sizing should not be an issue. Any tech who knows what they're doing can walk in a house and have a good idea of what size.

That is incorrect.
Manual J and S for sizing.
Equipment cannot be sized via someone’s opinion.

 

[user_12345a]

The ones who have so much confidence abilities they think they can just eyeball/approximate and not take measurements should be avoided.

This is applicable to much more than sizing.

It's true that if there's a lot of experience doing heat loss/gain calcs on a certain type of house in a certain climate, can get very close but in all likelyhood most who say they can just tell by walking into the house have just been oversizing and not getting complaints. there will always be exceptions.

 

[Missouri Bound]

That is incorrect.
Manual J and S for sizing.
Equipment cannot be sized via someone’s opinion.

So if a persons says their current HVAC system keeps them comfortable you tell them they are wrong?:vs_laugh:

 

[user_12345a]

There's maintaining setpoint and then there's optimal.When spending a lot of money on new equipment, the idea should always be to improve on what was there, not just do a direct change-out because it seemed to work before.

The owner may not know what normal operation is and think having a unit cycle off after 5 minutes is okay. May set cooling to 68 because at a more normal temp like 75 it doesn't run enough to take the humidity out.

There can be problems that cover up for eachtoher; for example, undersized air ducts for a/c or heatpump size, poor airflow and the
capacity is reduced, dehumidificaion improved, covering up for being oversized. On the heating side, a furnace can be cycling on limit due to being oversized for the ducts and it's not noticed because it's keeping up.

In this case, the oil burning furnace could easily be 80 000-100 000 btu/hr output.

That would be 25 kw to 30kw of heat strips!

 

[roughneck]

So if a persons says their current HVAC system keeps them comfortable you tell them they are wrong?:vs_laugh:

No.
You stress the importance of proper sizing, and how it’s able to make a more comfortable environment.
Most average consumers relate comfort to equipment size and how quick it pulls the temperature down, or how cold the discharge air is.
Give them a proper sized unit that keeps indoor humidity in check and all of a sudden they don’t need to turn the temperature setpoint to 68° anymore.

 

[beenthere]

Yes I am trying to stay hybrid with thermopump mostly and furnace to assist and be used only when below -10c.



Thanks.

A heat pump with electric aux heat. Is not a hybrid system.
So depending on both your electric rate and price per gallon of oil, it could cost more to heat with than your current dual furl unit does.

Hmm.

I don't agree with your first comment. If you are replacing an existing unit and it has warmed and cooled you to your satisfaction then it was sized properly.
Comfort is the key to homeowner satisfaction.

People often become use to the conditions of their house(temp and humidity), and become comfortable in thise conditions. But a new resized system often makes them feel even more comfortable, and works better to maintain the homes soundness.

But sizing should not be an issue. Any tech who knows what they're doing can walk in a house and have a good idea of what size.

Some have a good idea, others have no idea at all. So load calcs done properly are better then a tech's guesses just based on the sizes of units he has seen in other houses that may not have the same orientation, or glazing.

So if a persons says their current HVAC system keeps them comfortable you tell them they are wrong?:vs_laugh:

Not wrong, but paying more for it than they need to.

If a person is comfortable with their 120,000 BTU furnace. It just means the new one doesn't need to be larger than that.

Doesn't mean that the furnace isn't short cycling when it -10°F outside, and a 70,000 BTU would be the correct size at those same conditions. And instead of keeping their thermostat at 75 or 76 to be comfortable, they can set it at 70 or 72, and save a lot of their heating bill.

Works pretty much the same with heat pumps and A/C only units.

 

[Slicster]

First of all, get more quotes.
Lennox, Carrier even York are reputable companies.
Shop around. Ask each contractor what they suggest as far as tonnage.
When you get ALL the information you can better make a decision.
And don't let pricing make up your mind. When you get all the information you can ask each one about their pricing.
Personally,....and this is just my opinion, I would stay away from the two brands you mentioned. Both Stelpro and Amana can be bought by anyone and do not require professional installation.

I got another quote for Lennox from Costco...

CBA27UH-030
ECB-15

The price is about 500$ more but matches again the same kWh as the others so I guess the capacity is at least right.

So now my question is between my three quotes, in which would you choose?

The thermopump is Goodman GSZ130301.

I attached the quote comparison. The w/discount field is the final price.

 

[roughneck]

15 or 18 kw? How did either come to that conclusion?

 

[Slicster]

15 or 18 kw? How did either come to that conclusion?

The thermopump is 2.5 tonnes and I have a 2000 sqft home with 3 floors, one being a basement. So the last qu'y told me this...

You don't count the basement so you calculate over 1326 sqft x 10w/sqft = 13kWh

So says at 15 we're more than enough plus because the thermopump is 2.5 tonnes they should put the same so it's even.

The 18kw one is variable between 13 and 18 apparently. So I guess it will use less electricity most of the time since in reality I should only need 13.

 

[roughneck]

That’s not how equipment is sized.
I’d move on and explore a different contractor that knows proper sizing calculations.
Are you getting a whole new air handler? If so will it be a matched system to your existing heat pump?