hvac transformers vampire load
 

Ive been thinking about this lately but havent put a meter on any to confirm. The average gaa furnac . Xfrmer is rated at 40va, air handlers are usually 60va if theres a zone control teir might be another Xfrmer too. Since i have 2 hvacs my units cpuld be using 80 watts just sitting there 24/7 waiting on thermostat . Im pretty sure 1 40va Xfrmer should be enough to run both which could yield some easy daily power savings. My other thought would be a line voltage master thermostat to turn off the systems when the house is in the butter zone of comfort. I have a slightly more ambitious plan instead. Solar powering the Xfrmers. Not sure if the control boards will allow this power to be different from house power and equipment power and phasing. I recently picked up a 20 watt panel and charge controller. I might try to pair it with a sla battery and tiny inverter i have. Hopefully i won't smoke the control board.

Let us know what you find out.

I think I tested my furnace quite a while back and the phantom load it was drawing wasn't all that bad. That being said, I still turn it off in summer when heat isn't needed.

Standby loss would be about 2% of rated VA

Standby loss is about 5W when furnace board is included.

I've been putting my amp meter on a few, I haven't found much. It did occur to me that heat pumps and electric air handlers which are usually paired with heat pumps usually have a 60va transformer. More importantly the reversing valve solenoid is always energized depending on the season. Blue wire 'b' terminals energize for heating, orange 'o' terminal units energize for cooling. Most/all thermostats keep the valve energized as long as your system mode is switched to the appropriate heat or cool. I haven't amped one but I know the solenoid coils can get crazy hot. This loss could be prevented with a relay activated by the y terminal.

BTW there are new DOE standards rolling out. I believe hvac transformers will go down to 32va. Central split hvac minimum efficiency hvac south of the mason dixon line will be 14 seer. California, Nevada and AZ will be 14 seer with eer 11.7. Northern states will require 90% afue furnaces. What I've heard is manufactures can sell out their stock of non complying units until June of 2016.

DOE would require switching power supplies if they really cared about efficiency. 24VAC contactors will work fine with 12VDC.

Oh good, the rest of the southern world will soon catch up to the efficiency of the 3.5 ton Carrier I purchased in 1998!

I government really wanted to reduce energy use they would stop subsidizing energy companies. Energy subsidies keeps utility bills artificially low and discourage conservation.

What I see as the main benefit is apartment housing and commercial properties being forced to improve. For most of us in our own homes its a no brainer. For rentals it seems energy cost is something to pass the buck to tenants while the owners get by with the cheapest solutions. The usual cost difference between 13 and 14 seer is $200-300. Over the lifetime of 12-20 years that can be a huge difference in operating cost differed.