New Home HVAC System

[Sergei1]

The FLIR is build into my CAT S60 phone, I'm really hard on phones and I need a phone that could take it and could help me find issues with the house, this phone fit the bill. The house is a story and half refurnished 3 bedroom farm house that we brought and they didn't or couldn't run duct work to the main bedroom above the two car garage they added, they installed two baseboard heaters and no air. The rest of house is covered by regular ducts and heat and air by a Trane system using propane.
I did make an error in the temperature setting of the room last night, wife had turned the remote down to 65 during the day. I wish I could see what the outside model number is, but to much snow and right now -8 and heading for -20+ over weekend and not covering the wind chill.
Most of the time we keep the rest of the house at 68 degrees and at times it'll get bumped to 70 like now. To warm and wife asthma can be a problem.
In your case I'd think it would be a perfect fit for him, we mounted ours up high and out of the way and best of all its quiet.

 

[Sigarms]

In your case I'd think it would be a perfect fit for him, we mounted ours up high and out of the way and best of all its quiet.

It would be a perfect fit for him I know, but my dad is stubborn. He doesn't want to spend money, and if I did it, he'd pay me or they're would be haydes to pay. Thing is, he doesn't want it, and if I did it, he'd be pissed at me because he'd feel like he has to pay me. Keep in mind, my dad lived with a 30 year old T87 dial thermostat in his old home, and that's ALL he needs LOL

Ironically enough, that 2 system 9 indoor head job I laid out was for an older refurbished farmhouse. As mentioned, ductless can be a perfect fit for certain applications.

Issue is, most bedrooms in NC above grade are only 8' high (7-7.5' if you're lucky enough to have a basement). You need clearance off the top of the indoor unit to the ceiling, and depending on the install instructions per height off the floor and and how tall the indoor unit is, well, if it's 6.5' or 7.5' off the floor you're lucky. My dads bedroom basement ceiling is only 7.5' high.

What I'd really be curious about with that older FE unit you have is if you set the indoor remote to 70, at zero or below outside air, what does the indoor temp maintain at? (in the previous pic where the thermometer was 66, was the indoor remote set at 65F? The other variable is what size is the bedroom and if you have a master bathroom, the size of the bathroom and how is conditioned air brought into the bathroom (another potential headache to deal with on mini splits).

Is the master bedroom the one with the baseboard heat? Assuming if it is it's electric and how ofter do you run it with the mini split? (if my assumption is correct).

Every house is laid out differently, and it that reguard, this is where ductless systems can really come into play.

Thing is, if a new house is built and heating and air is taken into consideration in the design and build, a ductless system is rarely needed. Ductless manufacturers are aware of this, which is one reason why they are teaming up to offer ducted systems with American HVAC manufacturers. If building a new home and you can afford it, Geothermal is the way to go IMO. At least in NC, majority of new builds are not geo.

 

[jk96]

If your pre-construction regardless of the system you go with you should really focus on air leaks and insulation. When we built ours we used closed cell spray foam for insulation for both walls and ceilings including basement walls. The underside of our roofline is sprayed as we have almost no attic space. All of the ductwork is in conditioned space. We also did a blower door test to locate all possible air leaks into and out of the home. Make sure you blower door test before the sheetrock goes on so you can address any problem areas. One additional thing I did during the blower door was a fog test. We did it on calm day with little wind. I used a theatrical fogger to fill the house with fog then reversed the blower door to pressurize the home. You could walk around the outside of the house and easily see everywhere that fog was escaping through cracks. A well sealed home with an air exchange system will return benefits year after year. Just make sure your HVAC hits the mark on your load calc. Ours missed it by a mile and we spent a lot of extra money on HVAC we didn't need and had to make adjustments for short cycling. We are heating and cooling 4,500 sq/ft including the basement. Our contractor used a standard load chart without factoring in closed cell insulation and air sealing I had done. He installed two 4 ton units, one on each end of the house along with backup heat strips for the geo. I ended up having to adjust the units so they never go into stage 2, only run in 1st stage to prevent short cycling which reduces them to about 4.8 tons total. Heat strip breakers have never been turned on. Even with this mornings temps at -3 the units are still cycling on and off in a reduced stage 1 only.

 

[Sigarms]

Ours missed it by a mile and we spent a lot of extra money on HVAC we didn't need and had to make adjustments for short cycling. We are heating and cooling 4,500 sq/ft including the basement. Our contractor used a standard load chart without factoring in closed cell insulation and air sealing I had done.

I would guess at least 75% of HVAC contractors for retrofit applications do not do a full manual J load (at best, perhaps a block load).

On new constsruction homes, you hit the nail on the head if you don't do a full manual J load per the actual insulation material and build type. The insulation/build type (along with window footage/type) can have a huge effect on load changes.

Biggest issue I've seen is builders don't like the subs (such as HVAC) deal directly with the homeowner, and a lot of important information can get missed or overlooked due to lack of communication. HVAC contractor gets one set of plans, it's changed 3 times after the fact, and the HVAC contractor doesn't have the update plans.

That said, for whatever reason, on a new build, the homeowners ALWAYS wants to ensure they are getting what they want in a bathroom or kitchen, but when it comes to ductwork and HVAC equipment along with controls, nobody seems to gives a rat's butt because it's something you generally do not see. People just assume the HVAC is done right, but got forbid if the tile in the kitchen or bathroom isn't what you wanted LOL

On a sidenote, even though blower door tests are technically required in NC, the reality is few actually do it. The issue comes down to time and money and no one wants to do it. If you have a 30-50 year old home, no one wants to update their ductwork. This is why if you have a 30 plus year old home, at the end of the day, a new 20 SEER system may only be 15 -16 SEER if you're lucky, because the ductwork could cost as much as the HVAC equipment.

 

[jk96]

I would guess at least 75% of HVAC contractors for retrofit applications do not do a full manual J load (at best, perhaps a block load)./QUOTE]

Ours actually did a manual J. Came out to 7 tons. Upgraded to 8 he said for airflow. After the fact he did admit he had not done many homes with spray foam. Also the cathedral ceiling (26 ft) and all the windows throughout the home threw him off as well. He seemed shocked we were only running stage 1 and no backup heat in zero temps the first winter. In reality we probably needed 5 tons without heat strips or 3.5 to 4 tons with heat strips on sub zero temps.

2021-02-12_11-19-09

 

[ponytug]

If your pre-construction regardless of the system you go with you should really focus on air leaks and insulation. When we built ours we used closed cell spray foam for insulation for both walls and ceilings including basement walls. The underside of our roofline is sprayed as we have almost no attic space. All of the ductwork is in conditioned space. We also did a blower door test to locate all possible air leaks into and out of the home. Make sure you blower door test before the sheetrock goes on so you can address any problem areas. One additional thing I did during the blower door was a fog test. We did it on calm day with little wind. I used a theatrical fogger to fill the house with fog then reversed the blower door to pressurize the home. You could walk around the outside of the house and easily see everywhere that fog was escaping through cracks. A well sealed home with an air exchange system will return benefits year after year. Just make sure your HVAC hits the mark on your load calc. Ours missed it by a mile and we spent a lot of extra money on HVAC we didn't need and had to make adjustments for short cycling. We are heating and cooling 4,500 sq/ft including the basement. Our contractor used a standard load chart without factoring in closed cell insulation and air sealing I had done. He installed two 4 ton units, one on each end of the house along with backup heat strips for the geo. I ended up having to adjust the units so they never go into stage 2, only run in 1st stage to prevent short cycling which reduces them to about 4.8 tons total. Heat strip breakers have never been turned on. Even with this mornings temps at -3 the units are still cycling on and off in a reduced stage 1 only.

That's great! I think that your construction process is definitely the way to go.

If you are going to be in a home for any length of time, rather than flipping it, going with extra insulation and air tightness is the way to go. It makes homes more comfortable and less costly in the longer term. Often, not so longer term for payback. Don't forget to add a system to cycle in fresh air though.

I have had both ductless mini splits and central HVAC, and I agree that they both have their uses. My preference is to use the mini splits in retrofits, where they can be very cost effective and efficient. I do think that many homeowners don't appreciate how little heating capacity most mini splits have, or the cost of using heaters to get the heating capacity. I do think that central HVAC, especially with zoning, has real advantages in terms of air quality and servicing. As others have mentioned, over sizing the evaporator will give additional gains in efficiency at a cost in humidity control. For most people the difference is humidity control isn't an issue, but it may matter to you. I love that our central air system virtually eliminates dust in the house. Even with filters, the mini splits we had didn't remove much from the air, and changing/cleaning the mini splits filters are a pain.

In your home design, you might also want to consider energy efficient wiring (oversized), energy efficient windows, solar water heating, and roof overhangs to allow winter sun, but not summer sun, for passive heating / cooling gains. Personally, I am a huge fan of in floor radiant heat, but that is a whole other discussion.

All the best,

Peter
P.S. that's a gorgeous great room.

 

[Sergei1]

The outside unit is a single R410A . The bedroom is build above the garage, peaked roof with 4' high knee walls on both sides so its about 25 feet long and about 12 feet wide and ceiling is about 7 1/2 feet. Wife had set the remote at 65 yesterday afternoon down from the normal 68 and the outside was between 2 & 3 degrees for the high, last night the bedroom was at 66. The unit doesn't run all night she likes it turned off about 1am, benefits of sleeping on a waterbed and two cats. The bathroom has a single floor register. They took the attic and converted it into a living area, sitting area and bathroom. Then added the garage which makes the bedroom not at the same level as the other part, about 2 feet higher.
I removed both baseboard heaters completely when the Mitsubishi was installed, ir really depends just depends on the weather and this month has been unusual as normally the unit only gets turned on in the evening but being this cold had wife keep it on longer. This morning outside was -3 and before the unit was turned back on the bedroom was at 56.

 

[Sergei1]

This picture of the backside might help total footage is around 2500.

 

[jk96]

Don't forget to add a system to cycle in fresh air though.

Personally, I am a huge fan of in floor radiant heat, but that is a whole other discussion.

We do have an air exchange tied to the ductwork along with humidifier for winters. Nice thing about duct inside the conditioned space is there is no loss into unconditional attic areas. I would have loved to have installed radiant however my wifes feet get hot easily and puts her in a bad mood. That idea was quickly axed. Lol.

 

[herm0016]

my boiler and hot water baseboard cant quite keep up below 0 in our house, the Mitsubishi is running and heating to keep up. you can still use a mitsu heat pump and have a combination of forced air and wall or ceiling units. This is what I would do in a new build. very effecient, keeps some air circulation and integrates nicely with a proper ERV.