New AC unit

[oleRocky]

I need some advice on which type of unit to install. I live in North Central texas and just finished adding 700 sq.ft to an old farm house I bought. It brings the total footage to about 1900 sq. ft. I had an AC company come out and give me a quote and they said I needed a 4 ton unit. The kicker is that they quoted me 11K. That seems way high to me so I thought I would try the install myself. What I am wondering is should I go w/a heat pump, furnace or electric heat. I have talk to three different AC people down here and all three have give me a different answer. So I thought I would come to yall for some advice.

Thanks for you help.

[rabadger]

Don't buy anthing or install any ducts without performing the load calculations first. The days of guessing by square footage ended in the early 1980's with the advancement of engineering and application standards.

Are you certified in CFC handling and usage :?: If not don't let the EPA find out!

Are you replacing the old unit to take care of the old part and new part? If so what is the ductwork like? You can purchase a gold plated unit but if the air movement is not right it will not work.

11k :?: OUCH :!: I am must be working in the wrong part of the HVAC industry. Exactly what were they going to do for 11k?

[VALENT]

That is definitely high. Talk to some more installers in your area. I would definitely get the most efficient(price considered) unit available.

[oleRocky]

Yeah, I kind of thought that was a high price.

The house currently doesn't have any duct work. There has never been an AC unit in the house.

I have a friend that used to be in the AC business and he help me size the duct work if I choose to do it my self.

I was just wondering what yalls thought are when it comes to choosing between a heat pump, furnace or just electric heat.

I had an individual last night call me and he said all I needed was electric heat. He said the heat pump wasn't very effecient, which is just the opposite of what I've heard in the past.

Thanks

[rabadger]

A heat pump is as good as the whole system design. Discharge temps are low so you have to make sure the ducts are right for the air volume needed into each room.

Here in northwest Indiana the heat pump is turned off at about 35 degrees and the fosil fuel furnace comes on. It just boils down to how much you want to pay for the monthly heating bills.

If you get the equipment sized correctly and the ducts sized correctly they are all good. But with a heat pump it is much more critical.

Remember one thing. With todays equipment weather heat pump electric or gas, Rule of thumb 6" round to every room really does not apply. The air discharge temperatures are lower and proper air volume is the key to comfort.

Have you or will you be remodeling the old part of the home?

[oleRocky]

The older part had been remodeled in the past. I am not sure about the wall insulation. It has vinyl siding w/1" foam insulation but I am not sure if the walls have insulation behind the sheetrock or not. I am going to blow the ceiling w/insulation after I am thru w/the AC work.

Thanks for all the input.

[rabadger]

The A/C MUST be sized for the building after insulation. If it is to small before you insulate thats ok. But size it for the building after insulation.

It must be a room-by-room calculation. Thats the only way of figuring the duct sizes. If someone tells you the old story about how they do rule of thumb and have never been wrong it is because rule of thumb guesses oversize the unit. Thats why people have humidity problems. Whatever you do - do not guess at it.

If you have to work from scratch and install the ducts also, do it right. That 11K can be spent more wisely.

[rabadger]

How long did the company take to come up with the 11k price?

When they came to the home did they measure every room and the windows, doors?

What did the quote say they wre going to do, and did they show you the calculations?

[Cole]

and did they show you the calculations?

Fat chance here in Texas.

[rabadger]

It got so bad in Kentucky they passed a law. You can't get a building permit without HVAC load calculations and an engineer's drawings. Now they are years ahead of the other states.

[oleRocky]

Cole is correct, they didn't show me a calculation sheet but they did come out and measure each room and the windows and doors.

Thanks again for yalls help

[VALENT]

Now, it is definitely possible that 11k might be the cost if they are going to remodel and put in ducts. There is no way I would go with just electric heat- a heat pump is definitely more efficient and part of the air conditioner. It sounds like they want to use a separate ac and separate heat system(still the same ducts but different units) In your location, air conditioning is going to be more important than heat. If you are relatively handy, you probably can install the ductwork yourself and it is quite possible that the ac company would be glad to help you with calculations if you have them do the system installation. Most ac folks I know would rather not add ducts to existing homes because there are so many chances to mess something up.

[HVACTexas]

It being a "farm house" and with todays rising prices of materials $11,000 is a very reasonable price for a quality job. No doubt you can find a cheaper price but you normally get what you pay for in this business. If you hire any portion of this job done the initial design work would be most beneficial to you. Once you have a good road map it greatly reduces your chances of making a big mistake. If you call out three companies for "free" estimates that is all you will get. If you are really serious about the quality, utility costs, and life span of the system you should pay someone to give you this information. Sorry, but doing a whole house room by room calculation does not fall under the scope of a free estimate in my opinion. It is design work and needs to be compensated for.

A heat pump uses about 1/3 the elect. than straight electric heat (winter only). In the summer there is no advantage.

Gas furnaces are noisy compared to elect/heat pump.

Gas furnaces are safer fire hazard wise than elect/heat pump.

If the house is two story and you want the indoor equipment on the first floor or under the house then gas heat is difficult because there isn't much of a place to run the flue. O by the way I can't believe New Texas Homes are being built with 80% furnaces. Why not offer the customer a 96% AFUE? This way only 4% of the heat is lost through the flue instead of 20%.

Other quality upgrades to shop for are:
1. Good air filtering system (a dirty unit is a dead unit)
2. Indoor TXV refrigerant control is a must
3. Hard Start Kit on compressor
4. Thermostat on each level of home (if two story)
5. Safety switches that typically builder model units don't have
6. Secured/poured concrete outdoor pad to keep unit level when dirt settles