DIY Mini Split? Or Pay a Pro? 1100 sq ft home

[dried_mango]

Hello everyone, hoping to get some advice and guidance from those of you who have been down this road before/recently.

My home is 1100 sq ft, the front half of my home is pretty 'open concept'. The back half of my home is split between 3 bedrooms and 1 bathroom - so a lot of walls.

For #reasons that I wont go into, I no longer have a gas line / gas meter. This means my gas powered furnace does not work. It of course been no problem because it's summer now.

Heading into the fall/winter months, I of course, do not want my pipes to freeze. Getting quotes for a heat pump HVAC system, hoo boy the numbers! The lowest quote I've gotten so far is for a 2.5 ton 16 seer Carrier unit for $10,400 (after $300 rebate). The other quotes for 14 or 16 seer units have been between this much all the way up to $15k. A neighbor's friend is attempting to start their own HVAC business and offered over the summer to install a 14 seer unit for $8k.

I've been curiously looking at the MrCool DIY multizone unit, it seems like the cost would be under $4k for at least two indoor heads.

Would it be worth DIYing this myself like I did with my water heater? Or am I just being cheap / penny wise pound foolish (considering I have duct work) and should just go with a local contractor?

Also aware of IRA. I make 130k in the DMV so I doubt I'd be able to get anything. Also, it doesnt lower the upfront cost, which is important because I want to save as much as I can now - if I not for the pipes I wouldnt even worry about heating.

[uniwelder]

I'm currently putting in my 3rd system.  So far there has been an LG wall mount unit, LG central unit, and Fujitsu short ducted unit.  In the first two, I did the all the electrical, installed the physical units, and ran the refrigeration lines.  Then an HVAC tech ($300) did the final connections of the copper lines and vacuumed them.  This time, I bought the equipment needed for the vacuuming.  Since the price for a professional is more than 2x DIY, I can't be bothered with the extra warranty coverage for that price difference.  I'm not sure what Mr Cool's warranty is since its geared toward DIY installs.

I don't have any experience with Mr Cool, but they do make central ducted units https://mrcool.com/central-ducted/ so it is a possibility if you want to DIY and use your ducts. There are losses associated with ductwork-- heat/cold and heavier duty blower.  If you don't want to reuse your ducts, you could potentially install a wall mount unit at the open end and condition the entire house.  I think that would largely depend on how well insulated your house currently is, how many bedroom doors stay closed, and the wall configuration.  I don't know if Mr Cool has them, but there are also ceiling mounted short duct units that can go in a closet, which would then blow into adjacent rooms.  Could you upload a sketch of the layout?

I have been told ducts usually need to be redone because newer blowers operate with less pressure (head) but I haven't looked into it.  I tend to think thats just HVAC companies wanting to pocket more money.  If your old ducts were designed for a single stage blower and gas furnace that comes on at full blast for 10 minutes at a time, it seems logical that an inverter driven heat pump blowing 100% of the time at much lower cfm should be perfectly fine. 

I'm curious of the implication of the Inflation Reduction Act.  If you buy the unit now, would it be eligible, regardless of your personal income situation?  I haven't seen anything clearly written about it.  From what I gathered, it won't be implemented until 2023.

[Uturn]

talk to some AC pros, or even call a supply house and ask about Mr Cool.  My understanding is they are inexpensive and easy to DIY, but you cannot find parts when they break. 

[CatamaranSailor]

There's a lot that goes into making the right call as far as HVAC for your house. Having no idea how insulated your house is, I'll throw a few things out that come to mind.

#1 A lot of gas furnaces can be converted to propane. Since you have a working furnace with ducts in place, converting to propane and putting a tank out back might be an option. Obviously cost of propane vs electric is something to look at. But, it would be quick.

#2 Minisplits are cool and there are some DIY options. I'll echo the other poster regarding parts availability. If you choose that route, I'd go with a reputable brand with a parts network in place.

#3 I'd check out heatinghelp.com. It's actually a site for pros but the techs will answer question (search the forum first before posting. Chances are there is already a thread on the topic). They are generally not fans of DIY but there are some techs on the board with 30+ years of HVAC experience.

#4 My in-laws heated their house with just a wood stove for years (they did have electric baseboard as a backup). A nice pellet stove with an electric auger on a thermostat could work....maybe.

Good luck.

[NorCal]

What is the climate like where you live?

Based on my heat-pump experience, the more extreme your winters are, the more important it will be to get a professionals opinion on placement, sizing, etc.

I expect you’re right that two wall-heads will work for that volume of space, but you’d probably need to keep all the doors open and strategically use fans in order to get good airflow.

I’d certainly have a preference for re-using the ductwork, but only you can answer whether it’s truly worth that cost differential.

If you do go a professional route, I highly recommend the Mitsubishi ones. I have a single outdoor unit powering both a air handler and two wall heads (technically ceiling cassettes), and it’s been an amazing boost to efficiency, home comfort, and noise reduction.

[Jon Bon]

Yes climate is VERY important. Heat pumps in resistance heat mode use an absurd amount of energy. They also go into "defrost mode" so the heat strips will come on to thaw out the machine itself. This is part of normal operation and happens more the colder it gets.

I like in climate zone 4/5 depending on the map and I think I am marginal for a heat pump. We have gas heat below us (1st floor) and the HP struggles to keep up. The electric bill was quite the shock. As for pricing, we had ours installed with brand new ducting during the height of the supply chain issues for $9200.

So a HP with no new ducting for north of 10k feels like a hell of a lot of money. I would also recommend reusing duct work. Dealing with uneven heat all winter sounds like a bummer.

Converting to propane also feels worth looking into.

[uniwelder]

Yes climate is VERY important. Heat pumps in resistance heat mode use an absurd amount of energy. They also go into "defrost mode" so the heat strips will come on to thaw out the machine itself. This is part of normal operation and happens more the colder it gets.

I like in climate zone 4/5 depending on the map and I think I am marginal for a heat pump. We have gas heat below us (1st floor) and the HP struggles to keep up. The electric bill was quite the shock. As for pricing, we had ours installed with brand new ducting during the height of the supply chain issues for $9200.

So a HP with no new ducting for north of 10k feels like a hell of a lot of money. I would also recommend reusing duct work. Dealing with uneven heat all winter sounds like a bummer.

Converting to propane also feels worth looking into.

Zone 4 or 5 shouldn’t be an issue for a good modern heat pump. They can operate at the lowest temps for that area without any backup resistance heat. I think the problem is buying outdated equipment and that gives heat pumps a bad reputation. US companies are about 20 years behind everyone else in hvac technology.

Edited to add- I live around the zone 4-5 border, my units don’t have any kind of backup resistance heat elements, and I’m quite happy with their performance during the coldest temperatures.

[NorCal]

Yes climate is VERY important. Heat pumps in resistance heat mode use an absurd amount of energy. They also go into "defrost mode" so the heat strips will come on to thaw out the machine itself. This is part of normal operation and happens more the colder it gets.

I like in climate zone 4/5 depending on the map and I think I am marginal for a heat pump. We have gas heat below us (1st floor) and the HP struggles to keep up. The electric bill was quite the shock. As for pricing, we had ours installed with brand new ducting during the height of the supply chain issues for $9200.

So a HP with no new ducting for north of 10k feels like a hell of a lot of money. I would also recommend reusing duct work. Dealing with uneven heat all winter sounds like a bummer.

Converting to propane also feels worth looking into.

Zone 4 or 5 shouldn’t be an issue for a good modern heat pump. They can operate at the lowest temps for that area without any backup resistance heat. I think the problem is buying outdated equipment and that gives heat pumps a bad reputation. US companies are about 20 years behind everyone else in hvac technology.

Edited to add- I live around the zone 4-5 border, my units don’t have any kind of backup resistance heat elements, and I’m quite happy with their performance during the coldest temperatures.

Agreed. I’m in zone 5, and just had a unit installed with no backup resistive elements. Newer ones are more capable.  If my estimates are right, it’s breakeven with natural gas at roughly $1/therm for heating only, but will save me a couple hundred in cooking per year (it’s a higher SEER unit).

Natural gas is currently about $1.17/ therm for me now, but was only like $0.65 last year.  So I think it will be cheaper some years but not all years on the heating side.  I’ll should still have an overall reduction when heating and cooling are looked at together.

[index]

I'd go with two separate units. Go with a ducted minisplit installed in the attic for the bedrooms and a single head unit in the living room. Otherwise, go with a central ducted unit.

[Glenstache]

I just finished a fully DIY install of a 27k Mr Cool 3-zone mini split system to heat a similar square footage. Two units went to bedrooms and one for the open living room area. Mine is an upgrade from electric baseboard heat mixed with noisy electric squirrel cage wall fans. I am comfortable with electrical work, etc, and found it to be a pretty easy project on the whole other than having to run lines 3 stories up a blank wall with no ladder access; but that is specific to my house. My total cost was around $5k. The neighbors paid a pro to install a similar system, with similar access difficulties and it was $14k. The lead time in my area from initial call to install with a contractor is beyond 6 months in my area. If you are headed into winter and need heat, you may end up going the DIY route just to have it done in time... or use a lot of space heaters.

If you go the MrCool route, I have a 25ft line set and a coupler leftover that I'll send to you for the cost of shipping (I figured out a more efficient way to set the sysetm up and was outside of the return window by the time I was done).

[Jon Bon]

Yes climate is VERY important. Heat pumps in resistance heat mode use an absurd amount of energy. They also go into "defrost mode" so the heat strips will come on to thaw out the machine itself. This is part of normal operation and happens more the colder it gets.

I like in climate zone 4/5 depending on the map and I think I am marginal for a heat pump. We have gas heat below us (1st floor) and the HP struggles to keep up. The electric bill was quite the shock. As for pricing, we had ours installed with brand new ducting during the height of the supply chain issues for $9200.

So a HP with no new ducting for north of 10k feels like a hell of a lot of money. I would also recommend reusing duct work. Dealing with uneven heat all winter sounds like a bummer.

Converting to propane also feels worth looking into.

Zone 4 or 5 shouldn’t be an issue for a good modern heat pump. They can operate at the lowest temps for that area without any backup resistance heat. I think the problem is buying outdated equipment and that gives heat pumps a bad reputation. US companies are about 20 years behind everyone else in hvac technology.

Edited to add- I live around the zone 4-5 border, my units don’t have any kind of backup resistance heat elements, and I’m quite happy with their performance during the coldest temperatures.

Agreed. I’m in zone 5, and just had a unit installed with no backup resistive elements. Newer ones are more capable.  If my estimates are right, it’s breakeven with natural gas at roughly $1/therm for heating only, but will save me a couple hundred in cooking per year (it’s a higher SEER unit).

Natural gas is currently about $1.17/ therm for me now, but was only like $0.65 last year.  So I think it will be cheaper some years but not all years on the heating side.  I’ll should still have an overall reduction when heating and cooling are looked at together.

Is this new tech or a different style? I was under the impression that every heat pump has heat strips unless its being installed in a place where it does not go below 32 degrees. It has to go into defrost mode at some point, thus using the heat strips. I am not an expert but every heat pump will get to a point where its needs to go into emergency heat. The Seer and the quality of your insulation will determine when that is. I believe the saying is if you own a snow shovel your heat pump has heat strips.

Basically does your heat pump have a single 30 amp breaker, or a 30amp and an additional 30amp or larger for the heat strips?

[uniwelder]

Yes climate is VERY important. Heat pumps in resistance heat mode use an absurd amount of energy. They also go into "defrost mode" so the heat strips will come on to thaw out the machine itself. This is part of normal operation and happens more the colder it gets.

I like in climate zone 4/5 depending on the map and I think I am marginal for a heat pump. We have gas heat below us (1st floor) and the HP struggles to keep up. The electric bill was quite the shock. As for pricing, we had ours installed with brand new ducting during the height of the supply chain issues for $9200.

So a HP with no new ducting for north of 10k feels like a hell of a lot of money. I would also recommend reusing duct work. Dealing with uneven heat all winter sounds like a bummer.

Converting to propane also feels worth looking into.

Zone 4 or 5 shouldn’t be an issue for a good modern heat pump. They can operate at the lowest temps for that area without any backup resistance heat. I think the problem is buying outdated equipment and that gives heat pumps a bad reputation. US companies are about 20 years behind everyone else in hvac technology.

Edited to add- I live around the zone 4-5 border, my units don’t have any kind of backup resistance heat elements, and I’m quite happy with their performance during the coldest temperatures.

Agreed. I’m in zone 5, and just had a unit installed with no backup resistive elements. Newer ones are more capable.  If my estimates are right, it’s breakeven with natural gas at roughly $1/therm for heating only, but will save me a couple hundred in cooking per year (it’s a higher SEER unit).

Natural gas is currently about $1.17/ therm for me now, but was only like $0.65 last year.  So I think it will be cheaper some years but not all years on the heating side.  I’ll should still have an overall reduction when heating and cooling are looked at together.

Is this new tech or a different style? I was under the impression that every heat pump has heat strips unless its being installed in a place where it does not go below 32 degrees. It has to go into defrost mode at some point, thus using the heat strips. I am not an expert but every heat pump will get to a point where its needs to go into emergency heat. The Seer and the quality of your insulation will determine when that is. I believe the saying is if you own a snow shovel your heat pump has heat strips.

Basically does your heat pump have a single 30 amp breaker, or a 30amp and an additional 30amp or larger for the heat strips?

My 2 ton mini split has a 230v, 20 25 amp breaker that handles both inside and outside units. I think the 3 ton unit has a single 30 40? amp breaker for both inside and outside units. There are no resistance heating elements for the inside unit, or outside that I’m aware of. The outside unit defrosts by running in reverse (like summer air conditioning) so cold air blows around inside the house for a few minutes, though the fins direct the air toward the ceiling so it’s not blowing on people directly.

Heat strips for the interior aren’t usually necessary with newer technology because the mini split maintains the majority of its capacity at low temps. This is what I mean by US technology being 20 years behind.

Edited to add- the hvac guy I know will generally only install single or two stage units because inverter types are too complicated to diagnose problems. With the older style, he can usually just swap out a capacitor or at least run in backup heat until a new part comes in. He thinks I’m foolish for liking my newfangled technology because when an issue eventually arises, I won’t be able to fix it and won’t be able to afford a service call. My response is that in the worst case scenario, I can buy a whole new interior or exterior unit for no more than $1,000. Hopefully it’s something simple I can get a replacement piece for though.

edited again- I read the label on the 2 ton mini split and corrected my original post.  Maximum running amperage for the units (inside and outside) is 15.7 amps, but states wiring must be rated to 19 amps, and there is a 25 amp breaker in place.  I think that the 3 ton unit could have a 40 amp breaker then, but probably only draw 25 amps for inside and outside units when operating at max capacity.