Sizing a ductless min-split for basement

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airahcaz
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Re: Sizing a ductless min-split for basement

Postby airahcaz » Mon Mar 20, 2017 11:05 am

Most recent HVAC installer is suggesting a 3-4 zone unit, vs. single zone, as if we need to heat bedroom (bathroom, future office, etc.) later, we'd have to replace the outside unit? This will double initial costs, materials and labor, but worth considering?
1) Invest you must 2) Time is your friend 3) Impulse is your enemy 4) Basic arithmetic works 5) Stick to simplicity 6) Stay the course. (Plagiarized, but worth stealing)

Valuethinker
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Re: Sizing a ductless min-split for basement

Postby Valuethinker » Mon Mar 20, 2017 5:26 pm

airahcaz wrote:Most recent HVAC installer is suggesting a 3-4 zone unit, vs. single zone, as if we need to heat bedroom (bathroom, future office, etc.) later, we'd have to replace the outside unit? This will double initial costs, materials and labor, but worth considering?


Hi, is this if you subdivide the basement space?

I am generally for zoned because of the flexibility, but I don't know on this point whether it is worth it.

airahcaz
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Joined: Sat Oct 31, 2009 3:37 pm

Re: Sizing a ductless min-split for basement

Postby airahcaz » Mon Mar 20, 2017 5:33 pm

Valuethinker wrote:
airahcaz wrote:Most recent HVAC installer is suggesting a 3-4 zone unit, vs. single zone, as if we need to heat bedroom (bathroom, future office, etc.) later, we'd have to replace the outside unit? This will double initial costs, materials and labor, but worth considering?


Hi, is this if you subdivide the basement space?

I am generally for zoned because of the flexibility, but I don't know on this point whether it is worth it.


Yes it will be subdivided meaning a bedroom and an office. Yes it will cost maybe double but would cost even more if we did it later.
1) Invest you must 2) Time is your friend 3) Impulse is your enemy 4) Basic arithmetic works 5) Stick to simplicity 6) Stay the course. (Plagiarized, but worth stealing)

iamlucky13
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Re: Sizing a ductless min-split for basement

Postby iamlucky13 » Mon Mar 20, 2017 6:10 pm

So how many total BTU/hour is he trying to sell you?

A single unit generally heats a single floor fairly well when the doors are open - maybe a couple degrees difference if the outside walls are reasonably insulated. If that leaves a couple rooms too cool, I'd turn the basement heat up just enough to compensate, or or have a baseboard or in-wall forced air heater installed to turn on in those rooms when occupied. They are significantly less efficient than the heat pump, but will not be running enough to make up the cost difference.

I don't see why you should need a system big enough to heat your entire house just to boost your basement temperatures 15-20 degrees.

Where this might make sense to me is if your upstairs heat is electric baseboards or an electric furnace. If those are the primary heat source upstairs (as opposed to supplemental as I suggested they might be used downstairs), then installing one or two indoor units for a multi-zone system upstairs may be economical.

airahcaz
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Re: Sizing a ductless min-split for basement

Postby airahcaz » Mon Mar 20, 2017 6:27 pm

iamlucky13 wrote:So how many total BTU/hour is he trying to sell you?

A single unit generally heats a single floor fairly well when the doors are open - maybe a couple degrees difference if the outside walls are reasonably insulated. If that leaves a couple rooms too cool, I'd turn the basement heat up just enough to compensate, or or have a baseboard or in-wall forced air heater installed to turn on in those rooms when occupied. They are significantly less efficient than the heat pump, but will not be running enough to make up the cost difference.

I don't see why you should need a system big enough to heat your entire house just to boost your basement temperatures 15-20 degrees.

Where this might make sense to me is if your upstairs heat is electric baseboards or an electric furnace. If those are the primary heat source upstairs (as opposed to supplemental as I suggested they might be used downstairs), then installing one or two indoor units for a multi-zone system upstairs may be economical.


Ah so you'd use multi zone to satisfy two floors but not necessarily just a basement with some rooms?
What's an in-wall forced air heater?
1) Invest you must 2) Time is your friend 3) Impulse is your enemy 4) Basic arithmetic works 5) Stick to simplicity 6) Stay the course. (Plagiarized, but worth stealing)

iamlucky13
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Re: Sizing a ductless min-split for basement

Postby iamlucky13 » Mon Mar 20, 2017 9:21 pm

That would definitely be my inclination. Multi-zone seems like overkill for what you're doing. I won't rule out that the installer might have good reasons for his suggestion, but he might also just be trying to sell you a seriously oversized system for his own profit.

By in-wall, forced air heater, I mean this style:
http://www.homedepot.com/p/Cadet-Com-Pa ... /100012248

They're quite cheap and unobtrusive, although the fan does make audible noise just like similar plug-in space heaters. They require wiring run to their location, but so do mini-split indoor units. I believe they can usually be controlled by a separate thermostat - potentially even smart thermostats - so you don't have to bend down to adjust the temperature.

airahcaz
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Re: Sizing a ductless min-split for basement

Postby airahcaz » Mon Mar 20, 2017 10:13 pm

iamlucky13 wrote:That would definitely be my inclination. Multi-zone seems like overkill for what you're doing. I won't rule out that the installer might have good reasons for his suggestion, but he might also just be trying to sell you a seriously oversized system for his own profit.

By in-wall, forced air heater, I mean this style:
http://www.homedepot.com/p/Cadet-Com-Pa ... /100012248

They're quite cheap and unobtrusive, although the fan does make audible noise just like similar plug-in space heaters. They require wiring run to their location, but so do mini-split indoor units. I believe they can usually be controlled by a separate thermostat - potentially even smart thermostats - so you don't have to bend down to adjust the temperature.


These in-wall units seem perfect for the occasional need for heat! Thanks so much. I guess this is the replacement and preferred over baseboard?

I've sent them an email asking about their Energy Plus and their new Apex 72 models to see if there are any distinct advantages over this regular ComPak unit!
1) Invest you must 2) Time is your friend 3) Impulse is your enemy 4) Basic arithmetic works 5) Stick to simplicity 6) Stay the course. (Plagiarized, but worth stealing)

iamlucky13
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Re: Sizing a ductless min-split for basement

Postby iamlucky13 » Tue Mar 21, 2017 1:49 pm

To be clear, I've not really given much of a look into the pro's and con's of in-wall heaters versus baseboards. I just know the in-wall heaters are very low cost and easy to find a location to fit them into the room because of their small size. Because they do make some fan noise, a baseboard might be preferable to a forced air heater in the bedroom.

The key to using the electric heaters cost-effectively is to leave them turned down when the rooms are unoccupied so that most of the heat comes from the more efficient heat pump in the adjacent room. The whole reason I'm suggesting them at all is because it is likely those rooms will be 2-4 degrees cooler than the room the heat pump is in. It's up to your preferences whether to accept that difference or install supplemental heaters.

My reasoning is I expect the cost of a single zone heat pump in the main room and electric heaters in the other rooms (including the cost of running wiring to the heaters and their higher energy use for the amount of heat delivered), will be lower than the cost of a multi-zone heat pump.

airahcaz
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Re: Sizing a ductless min-split for basement

Postby airahcaz » Tue Mar 21, 2017 1:57 pm

iamlucky13 wrote:To be clear, I've not really given much of a look into the pro's and con's of in-wall heaters versus baseboards. I just know the in-wall heaters are very low cost and easy to find a location to fit them into the room because of their small size. Because they do make some fan noise, a baseboard might be preferable to a forced air heater in the bedroom.

The key to using the electric heaters cost-effectively is to leave them turned down when the rooms are unoccupied so that most of the heat comes from the more efficient heat pump in the adjacent room. The whole reason I'm suggesting them at all is because it is likely those rooms will be 2-4 degrees cooler than the room the heat pump is in. It's up to your preferences whether to accept that difference or install supplemental heaters.

My reasoning is I expect the cost of a single zone heat pump in the main room and electric heaters in the other rooms (including the cost of running wiring to the heaters and their higher energy use for the amount of heat delivered), will be lower than the cost of a multi-zone heat pump.

Have done some research today and emailed and chatted with the manufacturer: Cadet. This is their newest model
http://thd.co/1MVRLk4 and has a digital thermostat that regulates output.

Everything you mention seems to fit our bill. Single zone in main living space and an in-wall heater (or even electric fireplace) for the bedroom and office which will have infrequent use when there's a need for additional heating in those winter months that guests indeed sleep over.
1) Invest you must 2) Time is your friend 3) Impulse is your enemy 4) Basic arithmetic works 5) Stick to simplicity 6) Stay the course. (Plagiarized, but worth stealing)


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