Aux Furnace Heat vs Aux Electric Heat

[gabby]

Thanks, that clears up things.
I installed a Power Mizer in a man's house who had an air to air heat pump. I thought he was just being energy conscious, but it turns out he is a ....cheap comes to mind, or frugal if you prefer. He wanted to run his house on a 5KW generator when they lost power, and he could do this with a prioritized brain without handling the manual selection process himself. He bought a used gen set with a manual start. He wouldn't bare the cost of an auto transfer switch.

[mseifert]

Similar to Mark (Pine Mountain Energy) I installed a stand-by 12kw generator (propane) connected directly to my 200Amp transfer switch, to power up my entire home when utility power goes down. Even though the generator only puts out 50 amps max, I can manage this manually if I am home and if I am not home, I won't have more than 50 amps automatically running at once.

This all changes with my new install of a 5-ton ClimateMaster water to water. The original poster linked to the WaterFurnace Intellistart as a way to cut the startup draw of the compressor. No one on this thread really addressed this idea. Using this soft starter, the load would be reduced on my unit from 30 amps to 9 amps if their claims of 70% reduction are true. I don't see why this is not a good option to allow generators to run the geo. A 5kw unit should be able to handle it. I am hoping this is a solution for me as well to continue to handle my whole house with only 12kw.

[Pine Mountain Energy]

Generating Electricity with an engine is a very inefficient process, Ill use Natural gas for the example here because the math is a little easier ie: 100K btuh = aprox 100 cu ft. L.P. numbers are similar on a btu/ gallon of liquid withdrawal basis.

These numbers are from the generac-Gaurdian website
If I have a 8 KW unit running at 1/2 power it will consume 102 Cu ft per hr, or 102,000 Btuh, this will power a 5 ton Geo unit that at best will produce 54,000 btuh of heat, burning the fuel directly, to produce heat in most high efficiency appliances would result in a loss
of less than 10%, say a 93-94 % combustion efficiency , so to get the same 54,000 btuh, with combustion, I will only consume 58,000btuh, does that make sense? In reality this will only occur for a short while ( or as long as the power is out)
my point being, use the smallest generator you can get away with, and dont worry about starting a piece of equipment that probably shouldnt be run on a generator, another point Id like to bring up, Our Electrical division did a generator install on a 5 ton DX unit, with the soft start kit, and the volt drop during its start-up was enough to severely dim, lights, and cause other fed electronics to shut down,
we decided to just use the strip heaters when the generator was in operation (the homeowner was unhappy that the TV would go off during GEO startup)

Mark

[mseifert]

Yes generators are terribly inefficient, but in emergency situations, that is not an issue, even if power is out for a week (which has happened to me).

More important than efficiency (for me) is how to produce backup heat:
1) when power goes out and I am away from home short term
2) when power goes out and I am away long term (vacation) to keep the pipes from freezing.
3) when power goes out and I am home
4) when the geo primary source stops working

I chose not to set up selective circuit distribution for my generator ($$) and figured I could manually control the load. I never imagined (or had heard of) geo. Retrofitting circuit distribution would mean rewiring the whole electrical panel and that is prohibitively expensive. So those of us who are retrofitting need to find a solution.

My (hopeful) solution:
1) When I am away (short term), I would like the generator to handle keeping the geo running (the simplest solution). Other appliances, lights, TVs or computers (on UPS power) shouldn't be an issue. The issue for me is well pump, septic pump, hot tub and freezer, all of which could conceivably come on while I am out. But if the compressor (using the soft start) comes on and creates a brown-out, I wouldn't call that a good solution. Your description of voltage dropping doesn't sound great. What factors determine if this is what someone will experience? Is there any way to calculate it?

2) When I am away long term, I will turn propane on as auxiliary / backup heat. Since I will have a water to water geo unit, it will heat the same water for hydronics which the propane boiler is heating.

I don't want to keep propane on all the time as auxiliary heat because it's so expensive. I prefer to manually use wood on days where the geo can't keep up.

3) When I am home and the power goes out, I will use a wood stove.

4) When I am home or geo breaks, I have the existing system as backup: a propane boiler to keep the house via hydronics at 56*F and a wood stove to make it livable. Geo will replace all that.

So to answer bob350's original post, if it were me:
If automatic emergency heat while on vacation is a concern: choose the NG Furnace option. If not, get a wood stove (if you can).

Unless of course a soft start unit works. This would solve everything (unless the geo breaks)

[gabby]

Yes generators are terribly inefficient, but in emergency situations, that is not an issue, even if power is out for a week (which has happened to me).

More important than efficiency (for me) is how to produce backup heat:
1) when power goes out and I am away from home short term
2) when power goes out and I am away long term (vacation) to keep the pipes from freezing.
3) when power goes out and I am home
4) when the geo primary source stops working

Back up heat should be set by the thermostat and control board...no different if you were there, the propane would kick on if set point can't be reached, the same as if you had a cold spell lower than the geo could meet.

I chose not to set up selective circuit distribution for my generator ($$) and figured I could manually control the load. I never imagined (or had heard of) geo. Retrofitting circuit distribution would mean rewiring the whole electrical panel and that is prohibitively expensive. So those of us who are retrofitting need to find a solution.

There is no change in your main panel for a distributed load center addition. The breakers are in series with the breakers that control that device. A mere addition of a few wires inside the panel.

My (hopeful) solution:
1) When I am away (short term), I would like the generator to handle keeping the geo running (the simplest solution). Other appliances, lights, TVs or computers (on UPS power) shouldn't be an issue. The issue for me is well pump, septic pump, hot tub and freezer, all of which could conceivably come on while I am out. But if the compressor (using the soft start) comes on and creates a brown-out, I wouldn't call that a good solution. Your description of voltage dropping doesn't sound great. What factors determine if this is what someone will experience? Is there any way to calculate it?

Long term/short term a costly proposition. Let the propane handle the load and forget the geo. Granted you are using propane for the generator and the heating system, but compared to a whole house generator this is much cheaper for a weeks usage every now and then.

4) When I am home or geo breaks, I have the existing system as backup: a propane boiler to keep the house via hydronics at 56*F and a wood stove to make it livable. Geo will replace all that.

Asked and answered.

Unless of course a soft start unit works. This would solve everything (unless the geo breaks)

If you forget the geo during an emergency whether you are there or not you can use a Power Miser to prioritize what gets turned on. These are 220 volt loads....6 circuits. Check with your local utility for brands they recommend for their customers. They may have 120 volt circuits too, but I haven't installed them.

Important loads: Prioritize by demand, meaning what needs power more often----least is a refrigerator, freezer, water pump, septic pump
Cycling these on when the other loads are met for 30 minutes will give you 6-8 hours before they need cycling again---thus low priority....same with a hot tub---just enough to keep the water from freezing, cycle to cycle.

Figure your usage and needs on that basis and your generator requirements drop radically from a whole house demand. The LRA rating on motors tells you roughly the maximum starting current needed for start for a few seconds until the start winding drops out and the run winding takes over. A motor will normally require 2.5 times the run current for about 5 seconds.
Freezer--run current is less than 15 amps
Refrigerator---run current is less than 15 amps

Stagger the start times

Pumps can be wired 110 or 220 volts....if 220 you can control the run time on the Power Mizer---if 110 then whenever demand dictates. If you are not home, there is no demand unless you have a humidifier, boiler demand, or ice maker.

The minimum size generator that has an auto start feature is usually 10KW....I haven't seen any lower than that.

Hot tub uses resistance heat that may be in 10KW multiples. The bigger the unit the more electric to keep at setpoint. Don't try to heat the tub with a 20KW heater with a 10Kw generator. If you can set the temperature to 50 degrees, measure the current to the heaters to maintain that temperature on a cold night. That will give you an approximation of demand from your generator. 10KW/220 volts = amps needed

[mseifert]

Northern Idaho must be pretty behind the times. My Utility Company was clueless and their system engineer could not recommend any device to prioritize what gets turned on and was clueless about the Power Mizer.

I did research on the web but Power Miser didn't seem to provide the capability you mention - only that it is:

an electronic device that optimizes the power factor of the appliances in your home by reclaiming, storing, recycling and supplying unused power back to the devices in your home when you need them. This results in you using more of the electricity you pay for and putting more money back into your pocket.

I would appreciate any links for a "device to prioritize what gets turned on". I am drawing a blank.

Thank you.

[gabby]

Power Mizer was the brand name some 15 years ago. Ohio Edison was the utility so it was before First Energy changed the name and took over the service. I'll see what I can find.

[gabby]

I couldn't find Power Mizer/Powermizer, but I did find this which basically describes what the device does and one area of usage. I'm sure if you google some key phrases you can come up with more manufacturers of this type of device.

http://www.blackhillspower.com/demand2.htm

Another one:

http://www.dencorinc.com/200d.htm

Good luck

[gabby]

The small RV or RV accessory types are 120 volt only as you stated. These are probably seen by most people.
When you start going higher in the product lines the generators become more versatile….Grey Hound RV size units with 2-3 air conditioners. They can also be found in large Refrigeration trucks. The largest I have seen in use is a 10KW Onan/Kohler/Guardian (?)…... Most of these are diesel or gasoline fueled.


Onan--4.5BGDFB1L
It is a 4500 watt model and voltage is 120/240 @ 18/8 AMPS.

5751 Generac Guardian Quietpact 55G 5.5kW RV Generator
120/240 volts----amps 45.8/22.9

5750 Generac Guardian Quietpact 75G-7500 Watt RV Generator
120/240 volts---- amps 62.5/31.2

GENERAC GUARDIAN RV GENERATOR QUIETPACT 85D-8500 Watt
120/240 volts ----amps 70.8/35.4


I actually saw a large one on a refrigerated railroad car that was powered by a VW Diesel 4 cylinder.....not exactly an RV unit, but the point is there are varieties out there that are away from mainstream's eyes, such as industry or military applications. The Marine use of gen sets opens other possibilities--yachts....which is a derivation of RV units, but generally water cooled, not air cooled.