As my big garage is very nearly finished (WOOHOO!) I'm now looking at ways to HVAC it. I'm pretty sold on a wall mounted heat pump unit with an outdoor heat exchanger. I even have the location picked out and 220V available.
I live in Chicago, and would like something that can still heat even on the coldest days. Lots of heat pumps are rated with something like "heats up to 5F". Is that the minimum outside temp for the unit to provide heat inside? or is it the minimum difference in temperature between outside and inside that the unit needs to function? I see some come with 'pre-charged lines', which I assume means that you can install the whole shebang without vacuum pumps and gauge manifolds. I don't have those things, but will use them on cars probably so I am not averse to buying them if they are needed. If pre-charged lines get me past the need, then I would lean that way.
I will have an 840 sqft garage (9-13ft tall inside though, so the volume is large) with 2x6 construction walls and ceiling with fiberglass at like R19 or so in both. All finished with drywall, etc. Both garage doors will be insulated, and there are only three small windows. I also don't need the temp to be 70 inside all year. I'd be very ok with inside temps between 55-80.
Recommendations on unit size? Recommendations on brand/type/manufacturer? I'm planning to install myself - should I reconsider that?
Lay it on me!
Most heat pumps give up below 20 degrees. There just isn't enough heat in the outside air for them to move. Some of the mini-splits may do better. In the great white north, I would look for one with a aux heat strip for the coldest days or plan on some sort of supplemental heat.
I've had good luck with Klimaire units. I've installed 4 of them over the years.
900 sq-ft puts you in the 1.5 ton range.
A gas heater by Reznor, Modine, etc would do a better job of heating your space at all temps than a heat pump. You just set a thermostat and it adds heat anytime the temp drops below the set temp. But it seems like most heat pumps or mini splits will cool the air in the warmer months too and you wouldn't be able to cool the space with a gas heater. I'm not sure there's a "do it all in all weather types" option that's also economical.
In reply to STM317 :
Yeah, I like the do it all ability of the hest pump. Plus, I don't have gas to the garage, and that would be a big install.
I'm with not having perfect heat on the coldest days (I can either stop working in the garage or run a portable heater), but if I could get a system that heats when temp is 5 outside that would be a lot better than 30.
mtn
MegaDork
2/15/18 1:49 p.m.
Too late now, but did you get a heated floor?
RossD
MegaDork
2/15/18 1:53 p.m.
You can get commercial heat pumps that will go down to -20°F but its usually an option or an extra to get it down that cold.
Robbie said:
In reply to STM317 :
Yeah, I like the do it all ability of the hest pump. Plus, I don't have gas to the garage, and that would be a big install.
I'm with not having perfect heat on the coldest days (I can either stop working in the garage or run a portable heater), but if I could get a system that heats when temp is 5 outside that would be a lot better than 30.
We have similar weather, and I'll probably end up with a mini split too. Like you, I like that it will be more flexible, and running a gas line to the shop wasn't desirable. Even on the coldest days, it will still be making a little heat, it just won't be able to keep up. But I doubt I'll be working in there on really cold days anyway.
Toyman is right, heat pumps don't function below 20 degrees. The electric aux heat in mine runs a lot below 32 degrees, and the power bill shows it. Mine has a separate 220v line just for the aux heater.
That's why you don't seem them as much in the northern states as in southern states. If you have gas service at your house, then a gas aux heater for the heat pump would be better.
Robbie,
I'm in central Illinois. Put in a new HP and electric air handler last fall. No NG to the house.
1200 SF main floor, 600 SF finished basement, temp set at 68F. Latest power bill was $220. Outside temp was well below zero for much of that month. I would say my average bill over the year would be ~$125/month.
I'm a fan of the heat pump even though they are more efficient in milder climates.
mtn said:
Too late now, but did you get a heated floor?
Nope - I didn't want the bill of an electric system or the plumbing issues of a water/coolant system. We thought about it though.
RossD said:
You can get commercial heat pumps that will go down to -20°F but its usually an option or an extra to get it down that cold.
I'm seeing that the cheaper ones (for 18k units are in the $1000 range) are rated down to 5-15 degrees. There are more expensive ones (more like $2k) with brand names I recognize like fujitsu and mitsubishi that are rated down to -15 or so. The extra $500-1000 puts me off now but may be worth it in the long run. The more expensive units also have SEER ratings around 25 vs 15 for the cheaper units.
Annoyingly, the brand name units seem to be sold mostly through contractors, and not direct, while the cheapos are direct to consumer. Is it worth calling a pro just to get a quote?
SaltyDog said:
Robbie,
I'm in central Illinois. Put in a new HP and electric air handler last fall. No NG to the house.
1200 SF main floor, 600 SF finished basement, temp set at 68F. Latest power bill was $220. Outside temp was well below zero for much of that month. I would say my average bill over the year would be ~$125/month.
I'm a fan of the heat pump even though they are more efficient in milder climates.
Interesting! what brand/size do you have?
In reply to Toyman01 :
I'm seeing some klimaire units, thanks for the feedback!
RossD
MegaDork
2/15/18 2:52 p.m.
Cant hurt to get an over the phone quote.
"Heat pump, shmeat pump."
Some commercials really stick with a guy.
In reply to Robbie :
Lennox 14HPX heat pump and CBX25 air handler.
The average bill estimate is from the old system, which was a 30 year old air handler and a 15 year old heat pump.
Anxious to see what the new system does come summertime.
If they are allowed where you live (hoa or whatever) for a single room space like a garage you might want to look at "package" units too. Basically oversized window units with a supply and return duct from the unit to the room. Pretty much as DIY as you can get for not much more $.
RossD
MegaDork
2/16/18 7:28 a.m.
In reply to oldopelguy :
It's what's in every hotel room. Packaged Terminal Air Conditioner (PTAC)
The PTAC thing is not a bad idea, here's an example:
https://www.ecomfort.com/Amana-PTH153G50AXXX/p58425.html
This one works as a heat pump down to 24 deg then the electric heating element at 5kw comes on below that. Less than a grand for the unit looks nice.
The efficiencies on these things is not so great though. With the listed EER of 9.7 compared to the mini splits which are 15-25. Also, I feel like losing the heat pump at less than 24 degrees will mean the thing chews up a lot of electricity most of the winter.
For SEER to actual dollars, according to this site a difference of 9 to 25 SEER (on cooling alone - in chicago no less) means a $2000 unit pays itself back over the $1000 unit in about 7-8 years.
https://kobiecomplete.com/cool-tips/seer-savings-calculator/
Add in the efficiency of heating, and I bet the payback period is more like 2-3 years, especially if the heat pump can keep heat pumping and not use an electronic resistive element down to nearly 0F outside temp.
This one looks like it goes down to -4 for heating (nice) and is in general over-powered for my area (24k vs 18k). How are LG HVAC appliances in general?
https://www.ecomfort.com/LG-LS243HLV-SD/p80469.html
