15kw furnace on generator?

Status
Not open for further replies.

sw_ross

Senior Member
Location
NoDak
I watched MH's recent video about sizing generators. It was well worth hearing his perspective on the subject.
His perspective seems focused on the fact that in his area, and most of the southern states, the largest load is going to be the air conditioner and keeping the AC running during a power outage.

Where I'm at, a northern state, if the heat source is electric that is definitely the largest load. It's not uncommon to have a house that has a 15-20 kW electric furnace. Or if they have baseboard heat it could be the same or similar load.

I wish people would think ahead regarding whether they might want a generator when they're designing the home and have a hybrid setup so they could switch over to propane heat during a power outage. That would allow for a smaller generator required.

I had an emergency call out last night for a customer that lost power and they were having difficulty getting their portable generator hooked up to power the freezer, fridge, and lights. It turned out to be nothing serious and I got them up and running.

Then we had a conversation about "what if's" and wintertime power outages. I commented that they had electric heat and their portable generator wasn't going to help out in the winter with heating the house.

I told them I'd come back on another day, during normal working hours, and evaluate their needs. I have a feeling it might turn into a whole house standby generator.

They live 30 minutes drive out in the country on a cattle ranch. Their nearest neighbor is a good 7-8 miles away.

I'll probably look at the cost difference between sizing for electric heat and propane heat. Then they can talk to HVAC company about possibility and cost of changing to hybrid system.
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
I just recently had a bombshell of a job, where the owner had a set of plans drawn for a complete remodel.
No mechanicals on plans, so initially i’m thinking no big deal probably gas furnace, normal run of the mill stuff.
Show up to start roughing in, find a Geo therm unit with 15KW of back up heat, 2 water heaters 4.5 KW each, Steam shower generator at 10KW, steam humidifier for hvac at 3.8KW, 2 sump pumps in a deep pit along with an original sump pump pit, wine cellar with chiller unit, the rest fairly normal.
With a gleam in his eye, says he wants everything to run like nothing happening.
Shame to waist 15KW of generator capacity for the rare inevitability that the back-up heat bank may need to operate.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Never have seen a hybrid heating system. Dual fuel usually meant a heat pump with a gas furnace.
We are seeing some, even in NC.
its basically a heat pump with propane backup rather than electric heat strips for when the unit can’t keep up with the cold temps
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
We are seeing some, even in NC.
its basically a heat pump with propane backup rather than electric heat strips for when the unit can’t keep up with the cold temps

Isn't that what I said.....??? I think the op is talking about one unit that does electric heat and switches to propane or natural gas. Heat pumps don't work great up north
 

sw_ross

Senior Member
Location
NoDak
Isn't that what I said.....??? I think the op is talking about one unit that does electric heat and switches to propane or natural gas. Heat pumps don't work great up north
Guess I might've been wrong about what I was thinking...
They don't make a furnace that has electric heat strips and propane plenum heat of some sort?
 

kwired

Electron manager
Location
NE Nebraska
Guess I might've been wrong about what I was thinking...
They don't make a furnace that has electric heat strips and propane plenum heat of some sort?
You could have a gas furnace and put a duct heater (type that needs external blower) in line with it I guess. But unless you have awesome electric rates you would only use the electric heat when the gas failed for some reason.

Electric makes good backup for heat pump presuming you don't have to depend on it very often.

I have geothermal with 15kW backup. I have run my heat pump on my 8000 W portable generator before. It doesn't leave a lot of room to run much else at same time, and pretty much must have no other loads to get the heat pump started. I still recommend a gas or even wood burning fireplace as an emergency heat source when you only have electric as the primary heating source.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Isn't that what I said.....??? I think the op is talking about one unit that does electric heat and switches to propane or natural gas. Heat pumps don't work great up north
It is.., once I read it again.
I was thinking hybrid, you said duel fuel. They are both the same thing. (Realized that after awhile)
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Too bad you can't easily use the waste heat of the generator to heat the house.
Years ago, I read about a system where a water-cooled engine-driven generator was used to supply hot water as well as electricity.

If I remember correctly., the local power company subsidized it, and considered it to be distributed power generation.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
You could have a gas furnace and put a duct heater (type that needs external blower) in line with it I guess. But unless you have awesome electric rates you would only use the electric heat when the gas failed for some reason.

Electric makes good backup for heat pump presuming you don't have to depend on it very often.

I have geothermal with 15kW backup. I have run my heat pump on my 8000 W portable generator before. It doesn't leave a lot of room to run much else at same time, and pretty much must have no other loads to get the heat pump started. I still recommend a gas or even wood burning fireplace as an emergency heat source when you only have electric as the primary heating source.
Out here in CA, the cost of propane makes it closely comparable to resistive electric heat. If you want to save money you need to go to piped natural gas or a heat pump. The big advantage of propane as backup for a heat pump is just the lower demand load for a generator (or off grid inverter.)
 

drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
Too bad you can't easily use the waste heat of the generator to heat the house.
Starting with a water-cooled engine, I can't see why a good pipefitter couldn't make it happen. For every kW of electricity supplied, there's typically a kW dissipated via the water jacket and another kW leaving out the exhaust pipe.

Combined Heat and Power is common in large systems.
 

kwired

Electron manager
Location
NE Nebraska
Starting with a water-cooled engine, I can't see why a good pipefitter couldn't make it happen. For every kW of electricity supplied, there's typically a kW dissipated via the water jacket and another kW leaving out the exhaust pipe.

Combined Heat and Power is common in large systems.
Although for OP, if he has big enough generator that it has a water cooled engine it will likely big enough to handle his electric heat load.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Starting with a water-cooled engine, I can't see why a good pipefitter couldn't make it happen. For every kW of electricity supplied, there's typically a kW dissipated via the water jacket and another kW leaving out the exhaust pipe.

Combined Heat and Power is common in large systems.

I've known about CHP for a while, I just don't see it as easy to implement for a backup generator. On the other hand, maybe the OP could sell there customer on a micro-CHP system for normal use.
 
Status
Not open for further replies.
Top