All Forum Posts by: Garrett Dilley

 Its gotta be a dual zone system, then the FAU actually operates as 2 separate HVAC systems. 2 thermostats etc. The challenge with a single zone is dampening raises the static pressure across the fan coil. It literally affects the design of the system and shortens the life of various components.

Interestingly enough I'm getting dual zone units like Bryant/Goodman for almost the same price and disabling the 2nd zone for future needs, plus the fan coil/fan & capacitor are better quality. To note they have bearings instead of bushings which is better.

The small non sexy things that affect the envelope are easy DIY type items, but it's slow going.

A hole behind the thermostat is a big deal because its sensing unconditioned wall space as well as the envelope.

Every single gang electrical box passes around 1 cubic foot per minute of air, 6 in recessed light even more. Its death by papercuts lol.

I've got 2 houses that maintain 25 degree splits without any conditioning, BUT they rely on night temps to affect heat saturation. 100 degree nights in AZ would still need more conditioning.

To note; mini splits certainly do have applications but there's distinctions. I think the DIY splits folks are mentioning are Mr. Cool's, they come with precharged line sets that can be goofed up if not careful. They also have pre-set lengths, so sometimes the line sets are too long, now a coil of extra length has to be "stashed" somewhere.

Samsungs, Fujitsu's etc still require purge and charge. Personally I think their quality is better.

For the lurkers keep in mind the higher the voltage, the lower the amps. Current i.e. amps is what people pay for. Also higher voltage circuits allow for lower gauge wire. Ohm's law.

Don't run mini's without a dedicated circuit! I'd also make sure the circuit is rated at 80% RMS.

All of the above is also variable when considering that landlords have to weigh out, cost to purchase/install and operating costs (may not care) equity, permits (if done) and occupant comfort plus class of property.

Thank you @Alan F.  There is a lot of valuable info here, thank you for that.  The input from all of those that have graciously provided valuable input and insight above taken together with the considerations of your last sentence provide the framework to make necessary decisions.

If you have a 3 bedroom or more the amount of zones could make a condenser more economic negating install.  When I had mine installed it was about 50% labor don't know if that's the case for mini split.  Also wonder what other costs would be associated like the coil and the heat pump itself and not just the zones which can add up on a large enough place.

  Furthermore if you replace the furnace with a heat pump what sort of actual heat will it produce.  I have seen mini splits work great here is Maryland.  The thing is they only work great in upper unit apartments with a high level of resonant heat from a lower unit.  If there is no heat source from below I would not recommend them as this time if year you will have issues and need to provide additional space heaters.  They do work great for ac or supplemental heat.  If you really want to do that maybe add additional baseboard heaters on the lowest finished level.

Furnaces in my opinion are a lot more durable and have a longer life than ac and especially since the old freon is so expensive these days.  My furnaces are old 20 plus years old and doing very well and many of the units I manage have ones from the 90s or earlier.  You can tell from the color of the flame.  The gas valve might need to be changed.  If it absolutely needs changing the replacement should last longer than the mini splits.

Mini splits certainly have their place but not in a  larger ducted unit.  More a smaller unit with ductwork preferably with either supplemental heat from below or in an area of the country that's warmer and I don't think Denver qualifies.

mini split systems are great and a fraction of the cost.

Mini splits are cheap if you DIY and expensive usually if you don't. They are like 300-500 for AC only models and 400-700 for ones that do heat (1 ton). They come pre-charged and are pretty easy to install.

I can tell you if it's already ducted if there is enough space between the plenum and furnace it mi gght be economic with a condenser.  Last time I did 1 was 5 years ago.  It was just $3500 per unit here for that including the coil.   I'm sure now it would be 4 or 4.5k but not bad.  This assumes you have suffice power at 100 amp service per unit.  

If not that will cost you.  Remember that new code requires arc faults if you need to change your breaker location if you go the permiting route.  That could lead to a complete home rewiring of all old wiring of the preromex era as the arc faults trip on old wiring.  Now its probably 20k unless you are an electrician.  Without ductwork I recommend the mini split and as has been stated it's going to cost serious money well over 10k or you can go with ductwork which will be close and then your dealing with more drywall, painting, low lying ceilings, etc.

 Yeah the renta paradigm makes it more challenging, but more info makes it better for you to decide what's best for your application.  Yep HP (really just exchangers) will need electrical heater strips for supplemental) Enthalpy calculations tell that story but resi HVAC guys rarely know this.

 They are being implemented in new construction, albeit slowly and dependent on volume of builders units. Local AHJ'S are a component of implementation. To wit some builders are mandated a KW max per square foot & left to their own volition. Unfortunately energy efficiency is slow to adaptation in residential. Cost to build, region etc creates a complicated mosaic to navigate. The old school is also highly resistant. Most C20's still perpetuate the arcane tribal formula of 1ton per 500sq ft. I'm not as proficient in Colorado, that being said CO looks to CA for the future. 

Oh BTW make sure your new electrical panel has extra spaces for the future, is equipped with breakers that trip on both thermal and magnetic overloads and is permitted.  You may also (depending on what code cycle the AHJ is on) need it to be "solar capable) best of luck. That building is worth "the love" lol