Most techs I get from companies have been very poorly informed and almost hopeless at "debugging" any performance or functional problem. The operating model seems to simply be to replace parts in a pre-determined "likelihood of failure" model.
I don't blame the techs - I liked most of them but after casual conversation it seems clear that most of them don't get much training.
I guess my main complaint is that while I definitely want to "call a pro" my experience finding a good professional in HVAC (and plumbing for that matter) has not been particularly successful.
And don't get me started on part pricing - I am very happy to pay for knowledge (with high hourly technician costs) but more than once I have had easily purchasable OEM parts massively marked up by HVAC companies in what seems just like price gouging.
Case in point, a few years ago when I was a new homeowner I converted to natural gas from oil and got three quotes from three highly rated companies. All three companies recommended the exact same boiler. A few months ago I started to research the outdoor reset functionality that allows it to change the water temperature based on the outdoor temp. Well, I discovered that the feature is basically useless for me because both of my zones are too small to generate the minimum number of BTUs at lower temperatures. So I have a (up to) 96% efficient boiler that will never be able to reach that efficiency. I either would have needed a smaller boiler and or a buffer tank to be able to work correctly.
In trying to fix it, I had multiple techs come out and none really fixed the issue. These are basically some notes on the experience: - First tech stayed for 6 hours. Cleaned the system, replaced a high pressure switched, and readjusted the PVC in and out takes. The pressure switch alone costed over $500 dollars. He did the PVC for free. The problem persisted after he left. - First tech sent a second guy out the next day. This guy comes in and within 10 minutes recommended replacing my Nest with their "preferred" smart thermostat for a cost of $500. He also wanted to redo my humidifiers water setup ($200), and redo the elbow joint in the condensation output of the furnace ($200). After he quoted me all of that I asked him to leave. I redid the condensation output myself ($15 in parts), and humidifier ($15 in parts). I looked up the high pressure switched they replaced, and was shocked to learn it only costs $150. - I wrote my first Yelp review ever because of this company. They contacted me a day after I posted my review asking me to take it down in exchange for a partial ($300) refund. I agreed. - I had two family friends who do HVAC come out afterwards to look at it. After seeing that it was a high efficiency unit they basically wouldn't touch it. They are older and basically said they never retrained for high-efficiency units. It was never needed because they have more work then they can handle with older units. All they were able to offer was to give me a good deal on replacing it with a less efficient unit if I wanted.
At the end of the day my issue was never fixed. Luckily we haven't had as cold of weather as that week, so the issue hasn't manifested again. If it happens again I honestly will cross my fingers and hope the next company that I use is more helpful then the previous.
If you Google your furnace model you may find you tube videos with similar issues or things to check.
+1 on the rapid change of filters, much better to change a filter frequently even if it is a bit lower performance than to let one sit for too long, but keep an eye on your electricity cost, that is the factor that should decide the quality filter that you purchase and frequently you replace it.
Ground rule: the better the filter, the more it will absorb, the better the chances that something you really don't want lodges there and starts spreading if the filter gets overloaded. Fiberglass filters are a good compromise between energy efficiency and cost, they have excellent working surface compared to their physical size and tend to have a relatively long working life before they 'join the other side' and become a source of contaminants rather than a filter of contaminants.
I live in a highrise in SF and this bit me during the wildfires this year. The air conditioning would pull in smoke from outside. I ended up turning it off altogether on the worst AQI days, and buying lots of replacement filters for both the furnace and some off-the-shelf air purifiers.
That's it.
Somewhere there is a reservoir and something to heat the water. It can be anything, and indeed most older homes have been converted a few times already but nothing changed in the water system itsef. (For a house to have started with a wood furnace, then oil, then electric, then municipial heating or solar or whatever, is completely normal.)
The water either circulates by convection (very old systems), or with a pump. If the pump fails, convection typically still works, just less flow.
But even chilled water systems start to get complicated because of humidity and condensation.
And if you're already installing a forced air HVAC system for the 'AC' part, then installing radiators for heat is usually superfluous.
>should be able to cheaply add networked sensors, fans, filters, and vents
Sensors can be ok... But your homes's AC design, even if based on simple building code lookups, is based on some fairy complex engineering which rely on certain assumptions.
If those assumptions aren't met, the design usually must be approved by a licensed engineer. This is why you don't see more independently controlled vents on the market. No professional is going to install products that don't meet code, unless an engineer has stamped the plans. (Which includes operational logic.)
Ignoring regulations, you shouldn't just add controlled vents to a system (or manually close existing vents) without compensating for that elsewhere. You likely need a variable speed blower, controlled/compensated return air flow, and system logic to control it all.
Will the house blow up if you install them yourself? Probably not. But it could result in a system operating much less efficiently, increase the number of system cycles (reducing system lifetime), cause duct ruptures/leaks due to increased back pressure, and most likely, cause condensation in places other than the condenser, possibly causing mold to grow and/or rot.
Which leaves 2 options: installing a commercial system with the integrated vent control you're looking for, or adding sensors for input for when the system should run, without modification. Biggest simple change you can make for immediate impact? Change your filters every month, even if it means using 12 $3 fiberglass filters instead of 1 $36 hepa filter.
For instance, I run a list of room temps through a simple max function to ensure my AC and/or blower runs until the hottest room falls below the set temperature.
If this results in wildly unbalanced temps throughout the house, you have a bigger issue, and likely need your system resized/adjusted by a professional.
Related, and because most people don't realize it, your AC is an engine. You want it properly sized and to run constant, when needed. Think of your car: is it more efficient to make a trip by many intermittent 100mph sprints, or driving 55mph without stopping.
Multi stage compressors now act like car transmissions to dynamically "size" the system as needed, but run constantly with minimal stopping.