Author Topic: HVAC  (Read 876 times)

Offline bmc5733946

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HVAC
« on: August 19, 2022, 09:17:56 AM »
So we want / need to replace our furnace A/C system this year. We are considering a hybrid heat pump gas furnace system. So far the prices are daunting but the reality is that the efficiency is also way up there now. We might realize some savings but not enough to recover costs in our lifetimes. The mini split heat pump in the shop works so well and the energy costs are negligible. We thought that we might benefit from a somewhat similar system for the house but need the assurance of the gas heat for the sub zero degree days we get here. Any thoughts are welcome.

Brian
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Offline dguzzi

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Re: HVAC
« Reply #1 on: August 19, 2022, 09:36:54 AM »
  I'm in the same situation, I'd like to do the right thing but the initial cost is a bit scary.  I'd like to add solar as well, maybe the new assistance will help even it out for us.   (please no politics!)
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Offline czakky82

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Re: HVAC
« Reply #2 on: August 19, 2022, 10:46:43 AM »
An air to air heat pump will only work down to 35-40f. You’ll need geothermal or electric heat if you’re trying to cut your gas off. FWIW.

Offline bmc5733946

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Re: HVAC
« Reply #3 on: August 19, 2022, 11:16:56 AM »
Definitely not cutting off gas, will be staying with some kind of gas heat at the very least as a supplement to the heat pump system. Heat pumps really aren't efficient below about 30 degrees. The mini split heat pump in the shop works down to below 15 degrees but loses all its efficiency below about 20 degrees. The shop area is not critical for heat because it isn't living space, the house is. Insulation is a key factor in both places and we are quite well insulated in both spaces. Heat pumps are not efficient in uninsulated spaces. Boilers and wood heat etc. are not under consideration for a number of reasons not the least environmental impact, access etc. etc.

Brian
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Re: HVAC
« Reply #3 on: August 19, 2022, 11:16:56 AM »

Offline RinkRat II

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Re: HVAC
« Reply #4 on: August 19, 2022, 11:51:01 AM »

       I believe if you go with the mini split, you'll need to keep the gas heat portion of your current system to supplement the days below 30.  I know several people that have installed the mini splits with multiple indoor units running off one or two outdoor condensers. Sizing is the key and finding a competent installer. Good luck with the project.  Also, nowadays with efficiency's up there, your payback time may be less than you think.

      Paul B :boozing:
A Miller in the hand is worth two in the fridge.

Offline bmc5733946

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Re: HVAC
« Reply #5 on: August 19, 2022, 12:00:45 PM »
Mini splits for the house are not under consideration for many reasons. A hybrid system which consists of a heat pump attached to a gas furnace is what we are considering. We get about a week of subzero weather along with some scattered days of subzero therefore mini splits are not under consideration. We have a mini split in operation in my shop area, about 450 soft., it works well but since it is a shop heat is not as critical an issue as it is in the house.

Brian   
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Offline RinkRat II

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Re: HVAC
« Reply #6 on: August 19, 2022, 12:58:53 PM »

      Sorry for the confusion on my end, I currently run a heat pump with electric heat strips for back up. Winter here I need the strips if temps dip below 25 for more than a day or two. I'm really impressed the heat pump works down that far, as everyone told me it wouldn't, but it's been just fine for 12 years now. One major thing I did was to install a humidistat to keep the condenser from "defrosting" every 90 minutes of run time. That was the longest setting on the control board. Now it only defrosts above 75% humidity and won't wear out the reversing valve prematurely.

   Paul B :boozing:

A Miller in the hand is worth two in the fridge.

Offline Mike Tashjian

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Re: HVAC
« Reply #7 on: August 19, 2022, 01:33:41 PM »
I have a forced air heat system with A/C and it is 30 plus years old.  I have been looking at the mini splits for heat and cooling as supplemental to the system I have.  I would like to be able to just install a unit in the existing plenum and not hang units on the walls or in the ceilings.  Prices have not been good for them yet.  I was hoping they will come down in price as time goes on. As long as my unit runs the heat side is 93% and the cooling side is SEER 10 so, I am watching patiently too. 

Offline bmc5733946

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Re: HVAC
« Reply #8 on: August 19, 2022, 03:50:20 PM »
The units we've been seeing are 96% efficiency furnaces and A/C seers into the 20s. Some of the non heat pump versions are also close to those numbers. I think waiting for prices to come down will be fruitless in this situation. Technology prices do usually seem to fall after acceptance of new technologies but in this case I think supply restrictions will quickly overwhelm that awaited reduction. It's just my opinion but I think that the advancements will continue to come in all of the energy hungry sectors, cars, home heating/cooling, industrial heating (induction furnaces) etc.

Brian
« Last Edit: August 19, 2022, 09:54:05 PM by bmc5733946 »
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Offline bumpnstump

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Re: HVAC
« Reply #9 on: August 19, 2022, 07:28:29 PM »
The newer inverter heat pumps can heat effectively lower than when heat pumps first came out, often times negating the need for a hybrid system, or, only needing the hybrid backup less than you'd think.  The advancements in HVAC seem to be moving so quickly, one can hardly keep up with them.  Youtube sites like 'Inverter Always', or, 'Griffin Heating and Air', and others try to keep folks informed with what's new.

When we were in Kentucky a few years back, I, after researching current (at that time) technology, put in a 98% efficient hybrid Daikin unit.  The company that did the work was amazing!  They set it all up to a) run maximally efficient;  b)  be almost silent when it was running.  If you have good A/C contractors in your area, they will catch the details and make sure you get what is the best for your situation-  using a good company is key!

One thing most of us don't think about, but the HVAC guys deal with it every day, is that the EPA standards that are (seemingly) in constant flux-  it is affecting the entire A/C industry, and if you don't have at least a cursory understanding of current standards, a less-than-scrupulous dealer might try to sell you something that might be 'good', but is not 'best'.

Caveat emptor.....

Rick

Offline PeteS

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Re: HVAC
« Reply #10 on: August 20, 2022, 07:12:26 AM »
Curious, how often do you need AC in Michigan? Here in upstate New York, its helpful a few dozen days a year. A couple of window units takes care of that for us. Our 150+ year old home doesn't lend itself to central air. 95% gas forced air furnace takes care of the cold including below zero F.

Pete

Offline bmc5733946

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Re: HVAC
« Reply #11 on: August 20, 2022, 09:45:12 AM »
In Michigan this year the A/C has been running since early April. Temperatures seem to be rising earlier in the year now days. I don't have any objective information to share, just my seat of the pants. 90 to 95 degree days in April and close to 100 in May, and 95% humidity mean that the 30 year old unit is running 24/7 many days. The new units are so much more efficient that they probably can run a 10% or less capacity for much of our needs. Right now we are having much cooler than normal mornings and slightly cooler afternoons than in recent Augusts so things are changing. I would like to be prepared for what comes next no matter what that is. No crystal ball or anything just awareness of coming changes and trying to be prepared.

Brian
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Offline Navydad

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Re: HVAC
« Reply #12 on: August 20, 2022, 02:08:03 PM »
Heat pump with gas furnace here and we are very happy with it. When temps drop to around 25F and stay long the gas will take over. We saw a big drop in our energy bills when we installed this system. Enough of a drop to pay for the system? No, but smaller energy bills are smaller energy bills and it saved us a lot over keeping the old system.

Offline bmc5733946

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Re: HVAC
« Reply #13 on: August 20, 2022, 05:34:07 PM »
Thanks Navydad this is the kind of information I was seeking!!!!  If I'm not prying too much, for curiosities sake what system are you using and how many square feet are you conditioning with your system?
Thank you!

Brian
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Offline ChuckH

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Re: HVAC
« Reply #14 on: August 21, 2022, 06:01:55 AM »
I recently changed out our HVAC system. 

We have been in this well built/insulated house for 26 years, the original Carrier system was a 3.5 Ton A/C (12 SEER) with a 80K BTU (92%) furnace, both units single stage.

I changed to a Trane system with a 4 Ton A/C (18 SEER) with a 100K BTU (95%) gas furnace, both units are two stage.  Warranty is 10 years on parts, two years on labor, 12 years on the compressor.  I worked for Trane for three years back in the day, so have a soft place in my heart for them.  We now have a long-time, family owned, reputable dealer in the area.  That made the decision easier.

We live 50 miles south of Indy.  Our winter weather is not as severe, nor as long, as those of you in the north.  Our summer weather can be pretty warm and humid but we have a lot of days when just a little bit of A/C keeps the house at a pleasant temp.  I'm expecting the two-staging on both systems will make an impact on our heating/cooling costs.
















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Offline larrys

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Re: HVAC
« Reply #15 on: August 21, 2022, 06:14:42 AM »
An air to air heat pump will only work down to 35-40f. You’ll need geothermal or electric heat if you’re trying to cut your gas off. FWIW.

The newest heat pumps don't use R134. They have a new refrigerant that boils at around 5° F. Which means that the unit can pull heat out of the outside air down to 10° F or so.
Larry
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Offline Muzz

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Re: HVAC
« Reply #16 on: August 21, 2022, 05:21:22 PM »
Brian, I see you are not looking at mini splits but here is a  guff sheet that explains what I was talking about earlier.


https://www.mitsubishi-electric.co.nz/heatpump/hypercore.aspx
Muzz. Cristchurch, New Zealand
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Offline bmc5733946

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Re: HVAC
« Reply #17 on: August 21, 2022, 06:29:18 PM »
This is what we have in the shop.

https://www.fujitsugeneral.com/us/products/split/wall/asu15rls3hy.html

I don't find any FUJITSU labeled Extreme marketed in the US.
Basically what I'm finding is that those who make and market mini splits here don't make and market hybrid systems. So far we've looked at Lennox and EnergiAir. Trane is up next. Estimates are from 15 to 25 k$ for hybrids and up to 17k for non hybrid high efficiency furnace A/C units which rival the hybrids for efficiency. They will of course use more natural gas than a hybrid. The real issue is the volatility of the gas vs electric market place and all its inherent vagueries. If gas prices skyrocket where do we stand, same for electric? Hedging my bets with a dual system seem wise but at what cost. Definitely not looking for system to pay us back with savings although there will be surely some payback. The saga continues.

Brian
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Offline Muzz

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Re: HVAC
« Reply #18 on: August 21, 2022, 07:25:09 PM »
I am out of my pay grade with those hybrid units Brian. We just don't have them down here. Guess we are not cold enough and out mini split and ducted systems work just fine. Gas is way more expensive and not much is town supply; most is bottled LPG.
Muzz. Cristchurch, New Zealand
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Life is just a bowl of Allbran
Ya wake up in the morning and it's there

Offline nsmith

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Re: HVAC
« Reply #19 on: August 22, 2022, 08:34:37 AM »
I have seen and installed units which use all three ideas. Air to air heat pump with gas furnace AND an electric heater in the plenum. Using electric or gas as a backup is only the flip of a switch away. There are many power companies who offer incentive programs, they can help you plan a system. You should contact them for any discounts they might have. Also, the right install is absolute key to how well the system works. A poor install can ruin the best system on the market. Choose your heating company wisely, You might pay more now, but it might be worth the premium. 
Neil formally from South Dakota now living it up in Arkansas

Offline Muzz

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Re: HVAC
« Reply #20 on: August 22, 2022, 04:57:34 PM »
A poor install can ruin the best system on the market. Choose your heating company wisely, You might pay more now, but it might be worth the premium.

I can certainly testify to this!
Muzz. Cristchurch, New Zealand
03 Breva

Life is just a bowl of Allbran
Ya wake up in the morning and it's there

Offline bmc5733946

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Re: HVAC
« Reply #21 on: October 16, 2022, 07:49:58 PM »
Just to wrap this up. All Trane equipment, 40k btu furnace 97% efficiency,  2 ton inverter heat pump, up to 20 seer, uv aircleaner and filter, standard humidifier, digital thermostat with wireless capability, can be controlled from any digital device, phone, tablet, computer etc. Got a break on the inverter heat pump because the 2 stage we specified wasn't in stock although the computer showed it was so the contractor bumped us up to the inverter unit for same price as two stage about 3.5k difference. Installed price for everything was @ 22k. Seems to work very quietly and very comfortably. I don't even realize it's running most of the time. The thermostat allows me to set it on automatic and maintain a warm heated temp of 71 degrees and a cooled temp of 75 degrees, overnight heated temp set to 55 degrees. Right now the outside temps are between 40 and 60 degrees. You can hold a conversation next to the outdoor unit even when it is running at 100% capacity.

Brian
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Offline Muzz

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Re: HVAC
« Reply #22 on: October 16, 2022, 11:08:12 PM »
Great upgrade to go from the two speed to the inverter.

In a split system it can cut the power consumption by up to a third.
Muzz. Cristchurch, New Zealand
03 Breva

Life is just a bowl of Allbran
Ya wake up in the morning and it's there


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