HVAC system upgrade questions

[danski0224]

One interesting thing about the VS stuff is in some situations it will "fix" bad ductwork .... not leaking and wacky stuff with flex all over the place. But -- there are many houses with undersize ductwork. Modern VS equipment can be zoned very easy ... and by doing so you can often change the main runs in the basement and zone off areas of a house.

You just have to make sure that the smallest zone has a CFM about 25% above the lowest CFM of the equipment. Carriers infinity zoning system is really slick ... it goes through a test of each zone and knows the CFM/ static pressure of the run. When you fire it up it knows what each zone needs and where it has that zones damper. So a hot/ cold second floor can be easily fixed .... same with a great room.

The "ductwork fix" is only within the rated operating range (TESP and CFM) of the motor. In order to keep the amp draw down, the TESP has to be around 0.5" water column and certainly no more than 0.8" wc. That requires that the system (equipment/blower, coil, filter and ductwork) needs to be chosen properly. Bad ductwork can also mean fittings that have bad airflow characteristics, even though the physical size may be OK.

The Carrier equipment you describe is top shelf. The percentage of customers that will choose that level is small, then there is the additional work.

Not so sure on fixing a hot/cold floor or area without some diagnostics first. I certainly wouldn't promise it.

Ductwork problems could be easily fixed if the stuff was installed right in the first place...

 

[u3b3rg33k]

I think the point is some people think the new VS motors will help over come ****** duct work. It might help, just a bit, but crappy duct work is still crappy duct work.

It "works" in the sense that hot or cold air will come out of the registers and the equipment makes noise when it switches on.

The operating costs can increase because that VS motor is trying to deliver whatever it is set for, in that hypothetical crappy duct system.

Then, the repair costs are higher when that hypothetical crappy duct system (or even just the HVAC equipment and filter choices) take out that VS motor due to high amp draw.

The customer is sold on the high efficiency stuff, but then wonders why the utility bills are higher and/or they are uncomfortable after spending buckets of money.

i mean there's always the option to set the motor for the same flow as before. keeps blower power down, and delivers the same fuel efficiency as before.

 

[danski0224]

If you think so.

 

[yeldogt]

The "ductwork fix" is only within the rated operating range (TESP and CFM) of the motor. In order to keep the amp draw down, the TESP has to be around 0.5" water column and certainly no more than 0.8" wc. That requires that the system (equipment/blower, coil, filter and ductwork) needs to be chosen properly. Bad ductwork can also mean fittings that have bad airflow characteristics, even though the physical size may be OK.

The Carrier equipment you describe is top shelf. The percentage of customers that will choose that level is small, then there is the additional work.

Not so sure on fixing a hot/cold floor or area without some diagnostics first. I certainly wouldn't promise it.

Ductwork problems could be easily fixed if the stuff was installed right in the first place...

There are many houses that have poorly designed ductwork for the application. IE -- not enough runs to the second floor given the limitations in the building space -- the CFM may be too small for the room in relation to the other spaces ... but, not too small to send air through it. Common with kitchen/great rooms w/ lots of glass and in the suns path. Most homes have poor returns .

All too often HVAC is installed using simple rules of thumb ... room up to "X" gets one run .... over "Y" with little thought to the fact that many are 2x the length. Zoning can pick those various spaces off and allow them to be properly controlled. With a static system the solution is often to close down areas in an attempt to force more CFM over to others .... it's often just makes more noise.

Sure it's more money to purchase the variable speed unit .... but, you can't easily replace the ductwork in the walls or add more without doing costly damage.

 

[PoorUB]

I dealt with warm rooms in the summer on the south side of my house for years. Not enough duct. The thermostat was located just into the living room so it was trying to cool the living room and the AC ran a lot and over cooled the rest of the house.

Last summer I finally ran another duct into the kitchen and another into the living room. Now I can mess with dampers on registers and keep the whole house within one degree. Before the family room in the lower level would be four or more degrees cooler than the living room above. I remember one hot summer day the two rooms were eight degrees a part!

 

[Learninggal]

Guys - couple of questions if you don't mind helping
1) I have a local mechanic willing to help me with this install as a side gig and he wants to take the exhaust and intake for this 96% efficient unit out the sidewall vs shingles roof. I have a 100 year old stucco home (all interior & exterior walls are stucco) and I know for a fact that our basement wall is 15 inches thick. Do any of you know if it'll be any different in the attic?
2) I'll be ordering the unit online since he doesn't have any local supplier relationships and prices are better online anyways. The unit comes with the line set. Are there any expensive parts that he'd need to procure locally or it's mostly PVC ducts. Just doing the whole budgeting
3) What's the sweet spot for SEER rating for 1.5 ton units. How high a SEER rating should I aim for? As I've mentioned, I prefer higher upfront costs and lower bills over time and we pay some of the highest electric per/kwh rates here
4) Lastly, anybody heard of Tosot comfort making a combination furnace & a-coil?

Thanks

 

[Learninggal]

Anybody?

 

[u3b3rg33k]

tip of the spear SEER ratings are only achievable if everything else in your install is perfect, and those systems are usually inverter at this point. I would focus your money on getting the rest of the install right unless you know what you want with those systems.

 

[PoorUB]

Guys - couple of questions if you don't mind helping
1) I have a local mechanic willing to help me with this install as a side gig and he wants to take the exhaust and intake for this 96% efficient unit out the sidewall vs shingles roof. I have a 100 year old stucco home (all interior & exterior walls are stucco) and I know for a fact that our basement wall is 15 inches thick. Do any of you know if it'll be any different in the attic?
2) I'll be ordering the unit online since he doesn't have any local supplier relationships and prices are better online anyways. The unit comes with the line set. Are there any expensive parts that he'd need to procure locally or it's mostly PVC ducts. Just doing the whole budgeting
3) What's the sweet spot for SEER rating for 1.5 ton units. How high a SEER rating should I aim for? As I've mentioned, I prefer higher upfront costs and lower bills over time and we pay some of the highest electric per/kwh rates here
4) Lastly, anybody heard of Tosot comfort making a combination furnace & a-coil?

Thanks

1. Pretty typical to go out the side wall for furnace venting. My preferred way, less chance of leaks. Stucco can be a ***** to get through. A lot of sand in it and it will tear up a hole saw in not time.

2. What ever works for you!

3. SEER ratings versus cost are all over. There is no "sweet spot". You need to look at the cost of equipment, cost of operation, cost of electricity and do the math. Usually the really high SEER does not pay back in northern states, but it might in southern state where you are condition a lot. About right in the middle for SEER is a good guess if no other information is available. Keep in mind that from, 14 SEER to 20 SEER is a bunch, but from 17 SEER to 20 is not so much. 17 SEER might be the best deal, maybe! Too many variables to just toss out a number.

4.Tosot is rebadged Gree. As far as I know, no gas furnace available, although they do have an air handler with electric resistant heat available. No very many manufacturers make a AC/heat pump that will mount on any one's furnace and make an ARI claim., and you probably can not buy them over the internet. Bosch builds one.

 

[justinjoyal]

x2 for Tosot, rebadged Gree. Never heard of them making a furnace and I sell Gree products (although US could be different from Canada I guess.)