I am looking at heating and cooling options.

[WyrTwister]

Originally Posted by Xringer

Since you live in the south, an ASHP might be less costly than a GSHP.
Cost of the hardware for buying a few mini-splits might be a bit higher,
but the install cost can be pretty low for a DIY guy with an HVAC buddy.
The time it takes to do a mini-split install is likely about 1/20th that of a GSHP.
But, if you are doing 90% of the labor, you might not care how long it takes.

I'm using two Sanyo Mini-Splits at my house (heating and cooling),
and they are very cheap to run.

Multiple mini splits also give you the capability of turning off HVAC in rooms or at times of the day , that HVAC is not needed .

This too can be a cost saving feature .

God bless
Wyr

[NiHaoMike]

Originally Posted by WyrTwister

I am running a 10 - 15 year old Goodman 92% two stage gas furnace . It never need to go to high flame , unless I monkey with the Tstat .

Classic sign of an oversized system. That can happen as a result of poor selection or if the house had its insulation upgraded over the years.

[WyrTwister]

Originally Posted by Xringer

It's nice to have the tools needed to DIY repair a system.
Repairing the old unit (that was replaced under warranty)
wasn't really that hard, and it's still working like a brand new unit.

However, the older indoor unit has started to act up in cooling mode.
(Seems to be speeding up and slowing down).
So, I'm half excepting it to fail when the 24/7 heating season starts..
I may be hauling up the AC tool kit again, soon..

I have zero experience with the inverter mini splits . Mine is a 13 SEER unit that simply cycles 100% on & 100% off .

But , thinking about this , I have a few suggestions you might try .

Totally disconnect the power . Check every electrical connect . Tighten screws . Carefully un-plug and re-plug electrical connectors . Ant sensors that measure the temp of copper piping , make sure they are making 100% contact for adequate heat / cool transfer / sensing .

Check your refrigerant pressures and super heat & super cool temps .

Make sure the air flow of fans is OK .

Then turn the power back on and let the unit " reset " . You never know , that in itself might help . As I under stand it , your unit is microprocessor controlled ?

And thanks again for all your help ! :-)

God bless
Wyr

[stevehull]

Mike,

There are situations where you need a unit with say, a 2 ton heater and a four ton cooler. Areas south of me (I am in Oklahoma) have almost twice the number of cooling degree days as heating DD.

In that case, an "oversize" AC unit works well.

Sizing heating and cooling loads is an art . . . . Manual J is just the start and then you need to look at family size, age of kids, etc, etc, etc. Sadly, the "new" computerized manual J does not adequately take into account infiltration and has only barely addressed solar gain (through windows).

In the old days AC installers here said "1 ton per 500 sq feet of living space". Even some of the ground source heat pump installers would oversize units and then put in electric resistance block heaters for emergency heat. I still hear that ratio touted!

I generally do the opposite and slightly undersize - trying to get the AC unit to run 100% on the days of highest demand. This is not just the day of the hottest temps, but a day when washer/dryer is in use a lot, is hot, kids are home never shutting doors and dinners are made in the oven . . . . Dual compressor speeds are a very good option and the new continuously variable scroll will make this MUCH easier.

It is frustrating to educate installers when the client says "put in the biggest unit, so it will cool down fast". Cooling/dehumidification is not like heating and trying to describe sensible and insensible water loads is just too much for many of them.

But you ARE correct that if both heat and AC never leaves stage 1, then the unit is likely oversized (and a classic sign as you say).

Steve

[WyrTwister]

Originally Posted by pinballlooking

This is exactly what I have in mind. My office is the smaller room it will get the 9,000 but unit. The other unit will go in the great room blowing toward the breakfast nook it will get the 12,000 but system. That is where my wife works.

Can anyone have any advice on where the placement should be?
Has anyone mounted one above there bed?

First of all , a mini split is simpler if installed on an outside wall . Is your bed against an outside wall ?

I have a window unit ( wall shaker ) in our bed room . This allows us to shut off all other HVAC , in the house , when we go to bed and only pay for the energy usage for the 6,000 BTU window shaker .

If it was not for the cost , I would replace it NOW . With a Mini split . It would be significantly quiter .

And I would position it right over the head of our bed .

God bless
Wyr



But it is still working and I will probably keep it until it gives up the ghost .

[WyrTwister]

Originally Posted by NiHaoMike

Classic sign of an oversized system. That can happen as a result of poor selection or if the house had its insulation upgraded over the years.

I am told all furnaces in our area are over sized , in order to have enough CFM air flow , for the needed A/C capacity .

So , you are 100% correct , the furnace is over sized , when in heating mode .

I personally love the dual heat / flame / stage of the furnace . It is a 92% furnace & is pretty energy efficient unit .

God bless
Wyr

[WyrTwister]

Originally Posted by stevehull

Mike,

There are situations where you need a unit with say, a 2 ton heater and a four ton cooler. Areas south of me (I am in Oklahoma) have almost twice the number of cooling degree days as heating DD.

In that case, an "oversize" AC unit works well.

Sizing heating and cooling loads is an art . . . . Manual J is just the start and then you need to look at family size, age of kids, etc, etc, etc. Sadly, the "new" computerized manual J does not adequately take into account infiltration and has only barely addressed solar gain (through windows).

In the old days AC installers here said "1 ton per 500 sq feet of living space". Even some of the ground source heat pump installers would oversize units and then put in electric resistance block heaters for emergency heat. I still hear that ratio touted!

I generally do the opposite and slightly undersize - trying to get the AC unit to run 100% on the days of highest demand. This is not just the day of the hottest temps, but a day when washer/dryer is in use a lot, is hot, kids are home never shutting doors and dinners are made in the oven . . . . Dual compressor speeds are a very good option and the new continuously variable scroll will make this MUCH easier.

It is frustrating to educate installers when the client says "put in the biggest unit, so it will cool down fast". Cooling/dehumidification is not like heating and trying to describe sensible and insensible water loads is just too much for many of them.

But you ARE correct that if both heat and AC never leaves stage 1, then the unit is likely oversized (and a classic sign as you say).

Steve

I am south of you and may or may not need more cooling than you do . ( I have family near OKC , just spent a week vacation there . )

But dehumidification is rarely an issue / need , where I live .

We are currently enjoying some cooler fall weather . :-)

God bless
Wyr

[NiHaoMike]

A furnace and A/C system are separate so each can be sized just right. A heat pump can indeed end up oversized in one of the modes. In that case, it makes sense to go with a multi stage or variable speed.

[WyrTwister]

Originally Posted by NiHaoMike

A furnace and A/C system are separate so each can be sized just right. A heat pump can indeed end up oversized in one of the modes. In that case, it makes sense to go with a multi stage or variable speed.

My central system is gas heat - cool only A/C . The A-Coil sets on top of the furnace as part of the supply air plenum .

The way it is done , in this locality , is the furnace is chosen , to have a fan , with enough CFM , to serve what ever size cooling system is needed .

That is just the way it is done , here . And , the gas furnace - A-Coil ends up being one assembly . Connected to the same ducts & return .

As I am said , I was told , the furnace is always over sized , in terms of BTU output .

The 2 stage furnace helps mitigate this , to some extent .


I am not saying this is right or wrong . I do not know anything else to tell you ?

God bless
Wyr

PS De-humidification is rarely a concern / issue . Where I live .

[NiHaoMike]

In climates where heating and cooling requirements are highly asymmetrical (which would be most of them), I'm surprised they don't make furnaces designed just for that climate zone. Multi stage does mitigate it, but then you end up with what is effectively an expensive single stage.