I’ve seen a few posts about this but still not sure which route to go.
We live in PA (outside of Philadelphia) in a ~2700sqft (counting finished basement space) 2 story center hall colonial with a hip roof. Our house is incredibly poorly insulated with the outside walls being cinderblock, what appears to be just two thin layers of stucco on the outside and on the inside of the block furring strips and essentially ~3/4” yoga mat looking insulation between the strips. The house is currently heated and cooled by a single oil furnace in the basement.
We are planning to open up the first floor center walls of the house to give it more of an open concept. That means removing ductwork to the upstairs.
Our thought is to convert the basement furnace to gas if budget allows. Then add a second system to handle the upstairs instead of chasing new ductwork upstairs after the walls are opened.
We had a few contractors over and have had a few different options proposed to us to heat and cool upstairs which is roughly 1,200 sq ft and consists of 4 bedrooms and 2 bathrooms. All the quotes involve putting systems in our unconditioned attic and ducting to room ceilings.
The options given are:
1. Install a ducted 18,000btu Fujitsu mini split
2. Install a Bryant legacy 60,000btu 80% furnace
3. Install a high efficiency unit in an insulated “room” that would need built in the attic.
The attic space is unconditioned though we did have cellulose blown in shortly after buying the house. We also plan to put plywood down in some of the attic area to create storage.
I’ve seen many people post putting a unit in an unconditioned attic being a bad idea so curious about the following.
1. With weather in PA being pretty cold in the winter, is a mini split without gas as a backup for heat on cold days a good idea even if only heating the 2nd floor? My neighbor next door used to have just a heat pump and her stories of $800/mth winter electric bills terrifies me even though that was her whole house not just the second floor.
2. Is having the system in the unconditioned attic a substantially big performance difference from keeping the main unit in a conditioned space and the ducts in the unconditioned attic or are there other concerns we should be weary of with the main unit and ducts all on the attic?
3. Does mini split vs “regular” furnace make a difference in an unconditioned attic space? The 60k btu 80% system recommended by one guys seems really big compared to the 18k Fujitsu recommended by the other but I know nothing about these systems really. The 60k furnace guy also recommended 80% the 80% over the high efficiency because of the cost of building the insulated space in the attic and drain for condensate. He also mentioned with the size of the space and conditions we wouldn’t really see enough savings to justify the cost of the high efficiency.
4. We do have two closets on the 2nd floor we could use some space in to install a system within the building envelope. I’m not sure what type of space we would need for a ducted mini split vs a “standard” furnace though. Also if we use a gas furnace would we need a divider wall between the furnace space and the closet storage space? If we put the system in one of these closets we’d still want to run ductwork through the unconditioned attic instead of creating soffits in each room for the ducts. Will keeping the unit but not ducts inside the building envelope make a huge performance difference versus having both in the attic? We’d really prefer not to eat up the closet space if we can avoid it.
We live in PA (outside of Philadelphia) in a ~2700sqft (counting finished basement space) 2 story center hall colonial with a hip roof. Our house is incredibly poorly insulated with the outside walls being cinderblock, what appears to be just two thin layers of stucco on the outside and on the inside of the block furring strips and essentially ~3/4” yoga mat looking insulation between the strips. The house is currently heated and cooled by a single oil furnace in the basement.
We are planning to open up the first floor center walls of the house to give it more of an open concept. That means removing ductwork to the upstairs.
Our thought is to convert the basement furnace to gas if budget allows. Then add a second system to handle the upstairs instead of chasing new ductwork upstairs after the walls are opened.
We had a few contractors over and have had a few different options proposed to us to heat and cool upstairs which is roughly 1,200 sq ft and consists of 4 bedrooms and 2 bathrooms. All the quotes involve putting systems in our unconditioned attic and ducting to room ceilings.
The options given are:
1. Install a ducted 18,000btu Fujitsu mini split
2. Install a Bryant legacy 60,000btu 80% furnace
3. Install a high efficiency unit in an insulated “room” that would need built in the attic.
The attic space is unconditioned though we did have cellulose blown in shortly after buying the house. We also plan to put plywood down in some of the attic area to create storage.
I’ve seen many people post putting a unit in an unconditioned attic being a bad idea so curious about the following.
1. With weather in PA being pretty cold in the winter, is a mini split without gas as a backup for heat on cold days a good idea even if only heating the 2nd floor? My neighbor next door used to have just a heat pump and her stories of $800/mth winter electric bills terrifies me even though that was her whole house not just the second floor.
2. Is having the system in the unconditioned attic a substantially big performance difference from keeping the main unit in a conditioned space and the ducts in the unconditioned attic or are there other concerns we should be weary of with the main unit and ducts all on the attic?
3. Does mini split vs “regular” furnace make a difference in an unconditioned attic space? The 60k btu 80% system recommended by one guys seems really big compared to the 18k Fujitsu recommended by the other but I know nothing about these systems really. The 60k furnace guy also recommended 80% the 80% over the high efficiency because of the cost of building the insulated space in the attic and drain for condensate. He also mentioned with the size of the space and conditions we wouldn’t really see enough savings to justify the cost of the high efficiency.
4. We do have two closets on the 2nd floor we could use some space in to install a system within the building envelope. I’m not sure what type of space we would need for a ducted mini split vs a “standard” furnace though. Also if we use a gas furnace would we need a divider wall between the furnace space and the closet storage space? If we put the system in one of these closets we’d still want to run ductwork through the unconditioned attic instead of creating soffits in each room for the ducts. Will keeping the unit but not ducts inside the building envelope make a huge performance difference versus having both in the attic? We’d really prefer not to eat up the closet space if we can avoid it.
source https://hvac-talk.com/vbb/threads/2228608-Two-systems-One-house?goto=newpost
No comments:
Post a Comment